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Quercetin

PubChem CID
5280343
Structure
Quercetin_small.png
Quercetin_3D_Structure.png
Molecular Formula
Synonyms
  • quercetin
  • 117-39-5
  • Sophoretin
  • Meletin
  • Quercetine
Molecular Weight
302.23 g/mol
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Dates
  • Create:
    2004-09-16
  • Modify:
    2025-01-18
Description
Quercetin appears as yellow needles or yellow powder. Converts to anhydrous form at 203-207 °F. Alcoholic solutions taste very bitter. (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
Quercetin is a pentahydroxyflavone having the five hydroxy groups placed at the 3-, 3'-, 4'-, 5- and 7-positions. It is one of the most abundant flavonoids in edible vegetables, fruit and wine. It has a role as an antibacterial agent, an antioxidant, a protein kinase inhibitor, an antineoplastic agent, an EC 1.10.99.2 [ribosyldihydronicotinamide dehydrogenase (quinone)] inhibitor, a plant metabolite, a phytoestrogen, a radical scavenger, a chelator, an Aurora kinase inhibitor and a geroprotector. It is a pentahydroxyflavone and a 7-hydroxyflavonol. It is a conjugate acid of a quercetin-7-olate.
Quercetin is a flavonol widely distributed in plants. It is an antioxidant, like many other phenolic heterocyclic compounds. Glycosylated forms include RUTIN and quercetrin.
See also: Rutin (has subclass); Myricetin (has subclass); Ginkgo (part of) ... View More ...

1 Structures

1.1 2D Structure

Chemical Structure Depiction
Quercetin.png

1.2 3D Conformer

1.3 Crystal Structures

2 Names and Identifiers

2.1 Computed Descriptors

2.1.1 IUPAC Name

2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one
Computed by Lexichem TK 2.7.0 (PubChem release 2021.10.14)

2.1.2 InChI

InChI=1S/C15H10O7/c16-7-4-10(19)12-11(5-7)22-15(14(21)13(12)20)6-1-2-8(17)9(18)3-6/h1-5,16-19,21H
Computed by InChI 1.0.6 (PubChem release 2021.10.14)

2.1.3 InChIKey

REFJWTPEDVJJIY-UHFFFAOYSA-N
Computed by InChI 1.0.6 (PubChem release 2021.10.14)

2.1.4 SMILES

C1=CC(=C(C=C1C2=C(C(=O)C3=C(C=C(C=C3O2)O)O)O)O)O
Computed by OEChem 2.3.0 (PubChem release 2024.12.12)

2.2 Molecular Formula

C15H10O7
Computed by PubChem 2.2 (PubChem release 2021.10.14)

2.3 Other Identifiers

2.3.1 CAS

117-39-5
6151-25-3

2.3.2 Deprecated CAS

73123-10-1, 74893-81-5

2.3.3 European Community (EC) Number

2.3.4 UNII

2.3.5 UN Number

2.3.6 ChEBI ID

2.3.7 ChEMBL ID

2.3.8 DrugBank ID

2.3.9 DSSTox Substance ID

2.3.10 HMDB ID

2.3.11 KEGG ID

2.3.12 Lipid Maps ID (LM_ID)

2.3.13 Metabolomics Workbench ID

2.3.14 NCI Thesaurus Code

2.3.15 Nikkaji Number

2.3.16 NSC Number

2.3.17 PharmGKB ID

2.3.18 Pharos Ligand ID

2.3.19 RXCUI

2.3.20 Wikidata

2.3.21 Wikipedia

2.4 Synonyms

2.4.1 MeSH Entry Terms

  • 3,3',4',5,7-pentahydroxyflavone
  • dikvertin
  • Quercetin

2.4.2 Depositor-Supplied Synonyms

3 Chemical and Physical Properties

3.1 Computed Properties

Property Name
Molecular Weight
Property Value
302.23 g/mol
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
XLogP3
Property Value
1.5
Reference
Computed by XLogP3 3.0 (PubChem release 2021.10.14)
Property Name
Hydrogen Bond Donor Count
Property Value
5
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Hydrogen Bond Acceptor Count
Property Value
7
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Rotatable Bond Count
Property Value
1
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Exact Mass
Property Value
302.04265265 Da
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
Monoisotopic Mass
Property Value
302.04265265 Da
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
Topological Polar Surface Area
Property Value
127 Ų
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Heavy Atom Count
Property Value
22
Reference
Computed by PubChem
Property Name
Formal Charge
Property Value
0
Reference
Computed by PubChem
Property Name
Complexity
Property Value
488
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Isotope Atom Count
Property Value
0
Reference
Computed by PubChem
Property Name
Defined Atom Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Undefined Atom Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Defined Bond Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Undefined Bond Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Covalently-Bonded Unit Count
Property Value
1
Reference
Computed by PubChem
Property Name
Compound Is Canonicalized
Property Value
Yes
Reference
Computed by PubChem (release 2021.10.14)

3.2 Experimental Properties

3.2.1 Physical Description

Quercetin appears as yellow needles or yellow powder. Converts to anhydrous form at 203-207 °F. Alcoholic solutions taste very bitter. (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
Solid

3.2.2 Color / Form

Yellow needles (dilute alcohol, +2 water)
Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V2: 1570

3.2.3 Boiling Point

Sublimes (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
Sublimes
Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V2: 1570

3.2.4 Melting Point

601 to 603 °F (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
316.5 °C
PhysProp
316.5 °C
Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V2: 1570
316 - 318 °C

3.2.5 Solubility

less than 1 mg/mL at 70 °F (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
60 mg/L (at 16 °C)
SEIDELL,A (1941)
Very soluble in ether, methanol; soluble in ethanol, acetone, pyridine, acetic acid
Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V2: 1570
Soluble in alcohol and glacial acetic acid; insoluble in water
Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 14th Edition. John Wiley & Sons, Inc. New York, NY 2001., p. 945
In water, 60 mg/L at 16 °C
Seidell A; Solubilities of Organic Compounds. NY,NY: d. Van Norstrand Co., Inc. (1941)
0.06 mg/mL at 16 °C

3.2.6 Optical Rotation

Yellow needles from ethanol, dec 277-230 °C. Specific optical rotation: -83 deg at 20 °C/D (c = 0.2 in pyridine); UV max: 259, 364 nm (log epsilon 4.31, 4.39) /3-beta-Galactoside hemipentahydrate/
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 1381

3.2.7 Decomposition

When heated to decomposition it emits acrid smoke and irritating fumes.
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 3127

3.2.8 Collision Cross Section

158.98 Ų [M-H]- [CCS Type: DT; Method: single field calibrated with Agilent tune mix (Agilent)]

166.7 Ų [M+H]+ [CCS Type: DT; Method: single field calibrated with Agilent tune mix (Agilent)]

161.96 Ų [M+H]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

154.31 Ų [M+H-H2O]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

169.75 Ų [M+Na]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

173.34 Ų [M+Na]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

Ross et al. JASMS 2022; 33; 1061-1072. DOI:10.1021/jasms.2c00111
163.4 Ų [M+H]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

3.2.9 Other Experimental Properties

Yellow needles from dil alcohol. Becomes anhydrous at 95-97 °C. When anhydrous, decomposes at 314 °C; uv max (alcohol) 258, 375 nm (log epsilon 2.75, 2.75). One gram dissolves in 290 mL absolute alcohol, in 25 mL boiling alcohol. Soluble in glacial acetic acid; in aqueous alkaline solutions with yellow color. Practically insoluble in water. Alcoholic solutions taste very bitter. /Dihydrate/
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 1381
Crystals; mp 123-125 °C; UV max (chloroform): 249, 343 nm (log epsilon 4.43, 4.14) /Pentabenzyl ether/
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 1381

3.3 Chemical Classes

3.3.1 Drugs

Pharmaceuticals -> Listed in ZINC15
S55 | ZINC15PHARMA | Pharmaceuticals from ZINC15 | DOI:10.5281/zenodo.3247749

3.3.2 Endocrine Disruptors

Potential endocrine disrupting compound
S109 | PARCEDC | List of 7074 potential endocrine disrupting compounds (EDCs) by PARC T4.2 | DOI:10.5281/zenodo.10944198

3.3.3 Lipids

Polyketides [PK] -> Flavonoids [PK12] -> Flavones and Flavonols [PK1211]

4 Spectral Information

4.1 1D NMR Spectra

4.1.1 1H NMR Spectra

1 of 4
View All
Spectra ID
Frequency
600 MHz
Solvent
DMSO
Shifts [ppm]
6.20, 7.55, 6.89, 6.42, 7.68
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Spectra ID
Frequency
600 MHz
Solvent
DMSO
Shifts [ppm]
6.20, 7.55, 6.42, 6.89, 7.68
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4.1.2 13C NMR Spectra

1 of 2
Source of Sample
Tokyo Kasei Koygo Company, Ltd., Tokyo, Japan
Copyright
Copyright © 1980, 1981-2024 John Wiley & Sons, Inc. All Rights Reserved.
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2 of 2
Copyright
Copyright © 2002-2024 Wiley-VCH Verlag GmbH & Co. KGaA. All Rights Reserved.
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4.2 2D NMR Spectra

4.2.1 1H-13C NMR Spectra

2D NMR Spectra Type
1H-13C HSQC
Spectra ID
Instrument Type
Bruker
Frequency
600 MHz
Solvent
100%_DMSO
pH
7.00
Shifts [ppm] (F2:F1):Intensity
7.68:114.87:0.94, 7.54:119.84:0.53, 6.42:93.14:0.91, 6.20:97.94:1.00, 6.90:115.36:0.45
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4.3 Mass Spectrometry

4.3.1 GC-MS

1 of 6
View All
Spectra ID
Instrument Type
GC-MS
Top 5 Peaks

559.0 1

560.0 0.57

133.0 0.41

193.0 0.38

77.0 0.33

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2 of 6
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MS Category
Experimental
MS Type
GC-MS
Instrument Type
GC-MS
Top 5 Peaks

559.0 1

560.0 0.57

133.0 0.41

193.0 0.38

77.0 0.33

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4.3.2 MS-MS

1 of 10
View All
Spectra ID
Instrument Type
LC-ESI-QFT
Ionization Mode
positive
Top 5 Peaks

257.044 42.72

285.039 20.95

247.0596 12.78

165.0183 12.33

275.0552 7.02

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Notes
adduct_type [M+H]+ original_collision_energy 35% nominal Data from FlavonoidSearch July 2020 LTQ-FT-ICR, Thermo Scientific
2 of 10
View All
Spectra ID
Instrument Type
LC-ESI-IT
Ionization Mode
positive
Top 5 Peaks

257.0832 25.09

229.1807 15.58

165.1593 13.82

285.0654 11.93

247.0487 8.83

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Notes
adduct_type [M+H]+ original_collision_energy 35% nominal Data from FlavonoidSearch July 2020 LTQ Ion trap, Thermo Scientific

4.3.3 LC-MS

1 of 126
View All
Authors
Kevin S. Jewell; Björn Ehlig; Arne Wick
Instrument
TripleTOF 5600 SCIEX
Instrument Type
LC-ESI-QTOF
MS Level
MS2
Ionization Mode
NEGATIVE
Ionization
ESI
Collision Energy
140
Fragmentation Mode
CID
Column Name
Zorbax Eclipse Plus C18 2.1 mm x 150 mm, 3.5 um, Agilent
Retention Time
8.074 min
Precursor m/z
301.0354
Precursor Adduct
[M-H]-
Top 5 Peaks

41.006 999

65.0033 726

41.0169 272

65.0448 181

41.0366 90

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License
dl-de/by-2-0
2 of 126
View All
Authors
Kevin S. Jewell; Björn Ehlig; Arne Wick
Instrument
TripleTOF 5600 SCIEX
Instrument Type
LC-ESI-QTOF
MS Level
MS2
Ionization Mode
NEGATIVE
Ionization
ESI
Collision Energy
10
Fragmentation Mode
CID
Column Name
Zorbax Eclipse Plus C18 2.1 mm x 150 mm, 3.5 um, Agilent
Retention Time
8.074 min
Precursor m/z
301.0354
Precursor Adduct
[M-H]-
Top 5 Peaks
301.0347 999
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License
dl-de/by-2-0

4.3.4 Other MS

1 of 6
View All
Other MS
MASS: 14457 (NIST/EPA/MSDC Mass Spectral database, 1990 version)
2 of 6
View All
Authors
Institute of Bioorganic Chemistry, Polish Academy of Sciences,Poland/Anna Staszków
Instrument
micrOTOF-Q
Instrument Type
ESI-TOF
MS Level
MS2
Ionization Mode
NEGATIVE
Ionization
ESI
Collision Energy
25 eV
Column Name
Poroshell 120,EC-C18 2.1x100mm,2.7um
Retention Time
383.336 sec
Precursor m/z
301.032
Precursor Adduct
[M-H]-
Top 5 Peaks

121.029 999

151.002 951

107.011 666

93.033 319

139.039 187

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License
CC BY-SA

4.4 UV Spectra

MAX ABSORPTION (ALCOHOL): 256 NM (LOG E= 4.32); 301 NM (LOG E= 3.89); 373 NM (LOG E= 4.32); SADTLER REF NUMBER: 594 (IR, PRISM)
Weast, R.C. (ed.). Handbook of Chemistry and Physics. 60th ed. Boca Raton, Florida: CRC Press Inc., 1979., p. C-306
UV: 7-578 (Organic Electronic Spectral Data, Phillips et al, John Wiley & Sons, New York)
Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V2: 1570

4.4.1 UV-VIS Spectra

1 of 2
Copyright
Copyright © 2008-2024 John Wiley & Sons, Inc. All Rights Reserved.
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2 of 2
Copyright
Copyright © 2008-2024 John Wiley & Sons, Inc. All Rights Reserved.
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4.5 IR Spectra

IR Spectra
IR: 18403 (Sadtler Research Laboratories IR Grating Collection)

4.5.1 FTIR Spectra

1 of 2
Technique
KBr WAFER
Source of Sample
E. MERCK AG, DARMSTADT, GERMANY
Copyright
Copyright © 1980, 1981-2024 John Wiley & Sons, Inc. All Rights Reserved.
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2 of 2
Technique
KBr WAFER
Source of Sample
R.I.T.A. Corporation
Copyright
Copyright © 1980, 1981-2024 John Wiley & Sons, Inc. All Rights Reserved.
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6 Chemical Vendors

7 Drug and Medication Information

7.1 Drug Indication

7.2 LiverTox Summary

Quercetin is a flavonoid found in many foods and herbs and is a regular component of a normal diet. Extracts of quercetin have been used to treat or prevent diverse conditions including cardiovascular disease, hypercholesterolemia, rheumatic diseases, infections and cancer but have not been shown to be effective in clinical trials for any medical condition. Quercetin as a nutritional supplement is well tolerated and has not been linked to serum enzyme elevations or to episodes of clinically apparent liver injury.

7.3 Drug Classes

Herbal and Dietary Supplements

7.4 FDA National Drug Code Directory

7.5 Drug Labels

Active ingredient and drug
Homeopathic product and label

7.6 Clinical Trials

7.6.1 ClinicalTrials.gov

7.6.2 NIPH Clinical Trials Search of Japan

7.7 Therapeutic Uses

Quercetin has been used in medicine to decrease capillary fragility.
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P498 (1999)
/EXPL THER/ ... In a randomized, double-blind, placebo-controlled trial ... /among patients with category III chronic prostatitis syndromes (nonbacterial chronic prostatitis and prostatodynia)/ ... Significant improvement was achieved in the treated group, as measured by the NIH chronic prostatitis score. Some 67% of the treated subjects had at least 25% improvement in symptoms, compared with 20% of the placebo group achieving this same level of improvement. In a follow up, unblind, open-label study ... quercetin was combined with bromelain and papain, which may enhance its absorption. In this study, 82% achieved a minimum 25% improvement score.
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.393 (2001)
/EXPL THER/ Lymphocyte protein kinase phosphorylation was inhibited by quercetin in 9 of 11 cancer patients in a phase I clinical trial. Fifty-one patients with microscopically confirmed cancer not amenable to standard therapies and with a life expectancy of at least 12 wk participated in this trial ... The patients were treated at 3-wk intervals at the beginning of the study. Quercetin was admin iv as quercetin dihydrate ... The max allowed dose was reached when 2 of 3 patients on each dose schedule reached grade 3 or 4 general toxicity, or grad 2 renal toxicity, cardiac toxicity, or neurotoxicity. Phosphorylation was inhibited at 1 hr and persisted for 16 hr. In one patient with ovarian cancer refractory to cisplatin, cancer antigen-125 (CA 125) fell from 295 to 55 units/mL after treatment with 2 courses of quercetin ... A hepatoma patient had serum alpha-fetoprotein fall.
Thomson Healthcare. PDR for Herbal Medicines 4th Ed. Thomson Health Care Inc. Montvale, NJ. 2008, p. 1002
/EXPL THER/ ... Quercetin was reported to inhibit tumor necrosis factor-alpha (TNF-alpha) overproduction and attenuate pathophysiological conditions during acute and chronic inflammation ... In asthma, the activation of mast cells and basophils by allergen releases chemical mediators and synthesizeds cytokines leading to inflammatory conditions ... Quercetin was reported to inhibit cytokine expression and synthesis by human basophils ... A metabolite of quercetin, 3-O-methylquercetin (3-MQ), was reported to provide beneficial effects on asthma by inhibiting cAMP- and cGMP-phosphodiesterase (PDE). ...
Coates, P.M., Blackman, M.R., Cragg, G.M., Levine, M., Moss, J., White, J.D. (Ed), Encyclopedia of Dietary Supplements. Marcel Dekker, New York, NY, p. 580 (2005)

7.8 Drug Warnings

Although quercetin seems to have potential as an anticancer agent, future studies are needed, because most studies are based on in vitro experiments using high concn of quercetin unachievable by dietary ingestion, and because its beneficial effects on cancer are still inconclusive in animal and/or human studies.
Coates, P.M., Blackman, M.R., Cragg, G.M., Levine, M., Moss, J., White, J.D. (Ed), Encyclopedia of Dietary Supplements. Marcel Dekker, New York, NY, p. 580 (2005)
... Quercetin has been shown to protect low density lipoprotein (LDL) from oxidation and prevent platelet aggregation. It was also reported to inhibit the proliferation and migration of smooth muscle cells ... Quercetin was reported to significantly lower the plasma lipid, lipoprotein and hepatic cholesterol levels, inhibit the production of oxLDL produced by oxidative stress, and protect an enzyme, which can hydrolyzed specific lipid peroxides in oxidized lipoproteins and in atherosclerotic lesions ... /It/ induced endothelium-dependent vasorelaxation in rat aorta via incr nitric oxide production ... Quercetin and its glycosides were also reported to inhibit the angiotensin-converting enzyme activity, and ANG II-induced JNK activation inducing vascular smooth muscle cell (VSMC) hypertrophy ... However, some effects may not be feasible or negligible in physiological conditions, because concn of quercetin in most studies are too high to be achieved by dietary ingestion ... and beneficial effects of quercetin on cardiovascular diseases are still inconclusive in human studies ...
Coates, P.M., Blackman, M.R., Cragg, G.M., Levine, M., Moss, J., White, J.D. (Ed), Encyclopedia of Dietary Supplements. Marcel Dekker, New York, NY, p. 580 (2005)

7.9 Biomarker Information

8 Food Additives and Ingredients

8.1 Food Additive Classes

JECFA Functional Classes
Food Additives -> COLOUR;

8.2 Associated Foods

8.3 Evaluations of the Joint FAO / WHO Expert Committee on Food Additives - JECFA

Chemical Name
CI NATURAL YELLOW 10
Evaluation Year
1977
ADI
NO ADI ALLOCATED

9 Pharmacology and Biochemistry

9.1 MeSH Pharmacological Classification

Antioxidants
Naturally occurring or synthetic substances that inhibit or retard oxidation reactions. They counteract the damaging effects of oxidation in animal tissues. (See all compounds classified as Antioxidants.)

9.2 Absorption, Distribution and Excretion

After oral administration of a single dose of 4 g quercetin to four male and two female volunteers, neither quercetin nor its conjugates was detected in the blood or urine during the first 24 hr; 53% of the dose was recovered in the feces within 72 hr. After a single intravenous injection of 100 mg quercetin to six volunteers, the blood plasma levels declined biphasically, with half-lives of 8.8 min and 2.4 hr; protein binding exceeded 98%. In the urine, 0.65% of the intravenous dose was excreted as unchanged quercetin and 7.4% as a conjugate within 9 hr; no further excretion occurred up to 24 hr ...
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P501 (1999)
When 14C-quercetin was administered orally to ACI rats, about 20% of the administered dose was absorbed from the digestive tract, more than 30% was decomposed to yield 14-CO2 & about 30% was excreted unchanged in feces..
UENO K ET AL; JPN J EXP MED 53(1): 41 (1983)
One male and one female volunteer were given a diet containing quercetin glucosides (64.2 mg expressed as the aglycone). The mean peak plasma concentration of quercetin was 196 ng/mL which was reached 2.9 hr after ingestion. The time-course of the plasma concentration of quercetin was biphasic, with half-lives of 3.8 hr for the distribution phase and 16.8 hr for the elimination phase. Quercetin was still present in plasma 48 hr after ingestion ... /Quercetin glucosides/
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P501 (1999)
Autoradiographic analysis of a fasted rat 3 hr after administration of a single oral dose of 2.3 mg/kg (4-(14)C)quercetin showed that although most of the radiolabel remained in the digestive tract it also occurred in blood, liver, kidney, lung and ribs. After oral administration of 630 mg/kg of the labelled compound to rats, 34% of the radiolabel excreted within 24 hr ... was expired carbon dioxide, 12% in bile and 9% in urine; within 48 hr, 45% was recovered in the feces. Approximately 60% of the radiolabel in the feces was identified as unmetabolized quercetin ...
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P501 (1999)
For more Absorption, Distribution and Excretion (Complete) data for QUERCETIN (9 total), please visit the HSDB record page.

9.3 Metabolism / Metabolites

The glycosides are hydrolyzed in the body to corresponding aglycones, which are then further metabolized by scission of the heterocyclic ring to give 3,4-dihydroxy-phenyl-substituted acids ... The site of ring scission depends on structure ... with flavonols (quercetin) scission occurs at the 1,2 & 3,4 bonds to yield homoprotocatechuic acid ... These acids are further metabolized by beta-oxidation of acyl side-chain, o-methylation & demethylation, & aromatic dehydroxylation.
Parke, D. V. The Biochemistry of Foreign Compounds. Oxford: Pergamon Press, 1968., p. 151
o-Beta-hydroxyethylated derivatives of quercetin were isolated from urine samples & separated by HPLC. The 5,7,3',4'-tetra compd was separated from 3,7,3',4'-tetra derivative. The 7,3',4'-tri & 7'-mono compounds gave 1 common peak, separated from the peak for the 7,4'-di compd.
KUHNZ W ET AL; STUD ORG CHEM (AMSTERDAM) 11(FLAVONOIDS BIOFLAVONOIDS): 293 (1982)
After oral admin to ACI rats, the absorbed (14)C-quercetin was rapidly excreted into the bile & urine within 48 hr as the glucuronide & sulfate conjugates of (14)C-quercetin, 3'-o-monomethyl quercetin & 4'-o-monomethyl quercetin. Efficient metabolism and elimination of quercetin may be one reason for the lack of carcinogenicity in rats.
UENO K ET AL; JPN J EXP MED 53(1): 41 (1983)
The metabolites of quercetin flavonols identified in urine samples collected from two male volunteers who consumed their habitual diets for three days were 3,4-dihydroxyphenylacetic acid, meta-hydroxyphenylacetic acid, and 4-hydroxy-3-methoxyphenylacetic acid ...
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P501 (1999)
For more Metabolism/Metabolites (Complete) data for QUERCETIN (10 total), please visit the HSDB record page.

Quercetin has known human metabolites that include Dihydroquercetin and Mikwelianin.

Quercetin is a known human metabolite of Quercitrin and tamarixetin.

S73 | METXBIODB | Metabolite Reaction Database from BioTransformer | DOI:10.5281/zenodo.4056560

9.4 Biological Half-Life

One male and one female volunteer were given a diet containing quercetin glucosides (64.2 mg expressed as the aglycone) ... Half-lives /were/ 3.8 hr for the distribution phase and 16.8 hr for the elimination phase ... /Quercetin glucosides/
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P501 (1999)
...The elimination half-life of quercetin is approx 25 hr.
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.391 (2001)

9.5 Mechanism of Action

Quercetin is a specific quinone reductase 2 (QR2) inhibitor, an enzyme (along with the human QR1 homolog) which catalyzes metabolism of toxic quinolines. Inhibition of QR2 in plasmodium may potentially cause lethal oxidative stress. The inhibition of antioxidant activity in plasmodium may contribute to killing the malaria causing parasites.
... The 5, 7, 3', 4'-hydroxyl groups on quercetin are capable of donating electrons to quench various radical oxygen species (ROS) and other radical species ... Oxygen radicals (superoxide, hydrogen peroxide, hydroxyl radicals, and other related radicals) ... are quenched by ... antioxidant systems, including antioxidant cmpd, which balance cellular redox status involved in cellular processes for cell homeostasis ... Generally, 3 criteria are considered to assess the antioxidant activity of flavonoids in vitro: first, B ring with 2 hydroxyl groups (adjacent), second, C ring with 2,3-double bond, 4-oxo, and 3-hydroxyl group, and third, A ring with 5,7-dihydroxyl groups. Quercetin meets all 3 criteria, indicating stronger antioxidant activity ... The flavonol was reported to prevent radicals from damaging carbohydrates, proteins, nucleotides, and lipids ... The glucuronide conjugates found in the plasma were also reported to have potent antioxidant activity, indicating that the activity may be retained depending on conjugation positions ...
Coates, P.M., Blackman, M.R., Cragg, G.M., Levine, M., Moss, J., White, J.D. (Ed), Encyclopedia of Dietary Supplements. Marcel Dekker, New York, NY, p. 579 (2005)
Cytokines such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in colon cancer cells through engagement of death receptors. Nevertheless, evading apoptosis induced by anticancer drugs characterizes many types of cancers. This results in the need for combination therapy. In this study ... whether the flavonoid quercetin could sensitize human colon adenocarcinoma cell lines to TRAIL-induced apoptosis /was investigated/ ... Quercetin enhanced TRAIL-induced apoptosis by causing the redistribution of DR4 and DR5 into lipid rafts. Nystatin, a cholesterol-sequestering agent, prevented quercetin-induced clustering of death receptors and sensitization to TRAIL-induced apoptosis in colon adenocarcinoma cells ... Qercetin, in combination with TRAIL, triggered the mitochondrial-dependent death pathway, as shown by Bid cleavage and the release of cytochrome c to the cytosol. Together /the/ findings propose that quercetin, through its ability to redistribute death receptors at the cell surface, facilitates death-inducing signaling complex formation and activation of caspases in response to death receptor stimulation. Based on these results, this study provides a challenging approach to enhance the efficiency of TRAIL-based therapies.
Psahoulia FH et al; Mol Cancer Ther 6(9):2591-9 (2007)
Previously /the authors/ reported that isoflavone (genistein) activated bone sialoprotein (BSP) gene transcription is mediated through an inverted CCAAT box in the proximal BSP gene promoter. The present study investigates the regulation of BSP transcription in a rat osteoblast-like cell line, ROS 17/2.8 cells, by quercetin and its conjugated metabolite quercetin 3-glucuronide. Quercetin and quercetin 3-glucuronide (5 uM) increased the BSP mRNA levels at 12 hr and quercetin upregulated the Cbfa1/Runx2 mRNA expression at 12 hr. From transient transfection assays using various sized BSP promoter-luciferase constructs, quercetin increased the luciferase activity of the construct (pLUC3), including the promoter sequence nucleotides -116 to -43. Transcriptional stimulations by quercetin were almost completely abrogated in the constructs that included 2 bp mutations in the inverted CCAAT and FRE elements whereas the CCAAT-protein complex did not change after stimulation by quercetin according to gel shift assays. Quercetin increased the nuclear protein binding to the FRE and 3'-FRE. These data suggest that quercetin and quercetin 3-glucuronide increased the BSP mRNA expression, and that the inverted CCAAT and FRE elements in the promoter of the BSP gene are required for quercetin induced BSP transcription.
Kim DS et al; J Cell Biochem 101(3):790-800 (2007)
Connexin proteins form gap junctions, which permit direct exchange of cytoplasmic contents between neighboring cells. Evidence indicates that gap junctional intercellular communication (GJIC) is important for maintaining homeostasis and preventing cell transformation. Furthermore, connexins may have independent functions including tumor growth suppression. Most tumors express less connexins, have reduced GJIC and have increased growth rates compared with non-tumorigenic cells. The purpose of this study was to determine whether common flavonoids, genistein and quercetin, increase connexin43 (Cx43) levels, improve GJIC and suppress growth of a metastatic human breast tumor cell line (MDA-MB-231). Quercetin (2.5, 5 ug/mL) and genistein (0.5, 2.5, 15 ug/mL) upregulated Cx43 but failed to increase GJIC. Cx43 localized to the plasma membrane following genistein treatment (2.5, 15 ug/mL). In contrast, Cx43 aggregated in the perinuclear region following quercetin treatment (0.5, 2.5, 5, 15 ug/mL). Both genistein (15 ug/mL) and quercetin (2.5, 5, 15 ug/mL) significantly reduced MDA-MB-231 cell proliferation. In summary, genistein and quercetin increase Cx43 and suppress MDA-MB-231 cell proliferation at physiologically relevant concentrations. These results demonstrate that genistein and quercetin are potential anti-breast cancer agents.
Conklin CM et al; Carcinogenesis 28(1):93-100 (2007)
For more Mechanism of Action (Complete) data for QUERCETIN (12 total), please visit the HSDB record page.

9.6 Human Metabolite Information

9.6.1 Cellular Locations

Membrane

9.7 Biochemical Reactions

9.8 Transformations

10 Use and Manufacturing

10.1 Uses

EPA CPDat Chemical and Product Categories
The Chemical and Products Database, a resource for exposure-relevant data on chemicals in consumer products, Scientific Data, volume 5, Article number: 180125 (2018), DOI:10.1038/sdata.2018.125
Dietary supplement
American Cancer Society; Making Treatment Decisions: Complementary & Alternative Therapies: Diet and Nutrition: Quercetin. Available from, as of March 18, 2008: https://www.cancer.org/docroot/ETO/ETO_5.asp?sitearea=ETO
Quercetin has been used in ... dyes and as a veterinary drug.
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P498 (1999)
Medicine, reported formation of epoxy resins on mixing with epichlorohydrin
Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 14th Edition. John Wiley & Sons, Inc. New York, NY 2001., p. 945
Free-radical inhibiting antioxidant useful in cosmetics intended to protect the product from oxidative damage from UV radiation or singlet oxygen formation ... Use levels are normally about 0.1% and rarely exceed 0.2%.
Rieger MM; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). NY, NY: John Wiley & Sons; Cosmetics. Online Posting Date: Dec 4, 2000.
For more Uses (Complete) data for QUERCETIN (8 total), please visit the HSDB record page.

10.1.1 Use Classification

Food Additives -> COLOUR; -> JECFA Functional Classes

10.2 Methods of Manufacturing

Quercetin ... has been obtained for use as a natural coloring agent (Natural Yellow 10) by the rapid extraction of powdered quercitron bark with dilute ammonia and boiling of the extract with sulphuric acid ... The first successful synthesis of quercetin was reported in 1962 ... in which treatment of 2-methoxyacetyl phloroglucinol with O-benzylvanillic acid anhydride in triethylamine and then with potassium hydroxide produced 5,7-dihydroxy-4'-benzyloxy-3,3'- dimethexyflavone. The benzyl ether was cleaved with acetic acid-hydrochloric acid, and the methyl ethers were then cleaved with hydriodic acid to produce quercetin.
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V31 P214 (1983)
Isolation from Rhododendron cinnabarinum Hook, Ericaceae
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 1381
/Isolation from/ bark of fir trees, also synthetically
Crop Protection Handbook 2004. (Formerly Farm and Chemicals Handbook) Willoughby, OH: Meister Publishing Co., 2004., p. 945

10.3 Formulations / Preparations

Supplied as capsules & tablets
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.393 (2001)
Glycosylated forms include rutin and quercetrin
Wishart DS et al; DrugBank: a comprehensive resource for in silico drug discovery and exploration. Nucleic Acids Res. 2006 1;34. Available from, as of Feb 15, 2008: https://redpoll.pharmacy.ualberta.ca/drugbank/
Intravenous soln in ethanol or DMSO ...
Thomson Healthcare. PDR for Herbal Medicines 4th Ed. Thomson Health Care Inc. Montvale, NJ. 2008, p. 1002

10.4 General Manufacturing Information

EPA TSCA Commercial Activity Status
4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-: ACTIVE
Natural antioxidant ... Plant dye
Eggersdorfer M et al; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). NY, NY: John Wiley & Sons; Nutraceuticals. Online Posting Date: Jul 16, 2004.
Flavone dye ...(flavus , Latin for yellow) ... has lost commercial value since the advent of synthetic dyes in 1856
Cofrancesco AJ; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). NY, NY: John Wiley & Sons; Dyes, Natural. Online Posting Date: Dec 4, 2000.

11 Identification

11.1 Analytic Laboratory Methods

HIGH-PRESSURE LIQUID CHROMATOGRAPHY WAS USED TO ANALYZE FLAVONOIDS FROM PROPOLIS.
BANKOVA VS ET AL; HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC ANALYSIS OF FLAVONOIDS FROM PROPOLIS; J CHROMATOGR 242(1) 135 (1982)
QUERCETIN WAS DETERMINED BY GAS CHROMATOGRAPHY/FLAME IONIZATION DETECTION. THE SAMPLE WAS DERIVATIZED WITH TRIMETHYLSILYLIMIDAZOLE & CHOLESTEROL WAS USED AS INTERNAL STD. THE CALIBRATION CURVE WAS LINEAR FOR 4-16 MUG, & THE MINIMUM DETECTABLE AMT WAS 6.64X10-10 MOLE WITH 98.5% RECOVERY.
LEE SY, KIM SK; MICROQUANTITATIVE ANALYSIS OF QUERCETIN BY GAS CHROMATOGRAPHY; JAKHAK HOE CHI 26(2) 117 (1982)
Quercetin has been separated from a crude plant extract by high-performance liquid chromatography ... The reaction of quercetin with vanadyl sulphate has been used as basis for a sensitive spectrophotometric method for estimation of quercetin, with a limit of detection of about 0.3 mg/L ... Gel filtration followed by ultraviolet spectroscopy is reported to offer another selective method for determination of quercetin at a level of 5 mg/L ...
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V31 217 (1983)

11.2 Clinical Laboratory Methods

Analyte: quercetin; matrix: blood (whole), urine; procedure: high-performance liquid chromatography with photodiode-array ultraviolet detection at 202.8 nm
Gaillard Y, Pepin G; J Chromatogr A 763: 149-163 (1997). As cited in: Lunn G; HPLC and CE Methods for Pharmaceutical Analysis. CD-ROM. New York, NY: John Wiley & Sons (2000)

12 Safety and Hazards

12.1 Hazards Identification

12.1.1 GHS Classification

Note
Pictograms displayed are for 98.6% (204 of 207) of reports that indicate hazard statements. This chemical does not meet GHS hazard criteria for 1.4% (3 of 207) of reports.
Pictogram(s)
Acute Toxic
Signal
Danger
GHS Hazard Statements
H301 (97.1%): Toxic if swallowed [Danger Acute toxicity, oral]
Precautionary Statement Codes

P264, P270, P301+P316, P321, P330, P405, and P501

(The corresponding statement to each P-code can be found at the GHS Classification page.)

ECHA C&L Notifications Summary

Aggregated GHS information provided per 207 reports by companies from 3 notifications to the ECHA C&L Inventory.

Reported as not meeting GHS hazard criteria per 3 of 207 reports by companies. For more detailed information, please visit ECHA C&L website.

There are 2 notifications provided by 204 of 207 reports by companies with hazard statement code(s).

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown.

12.1.2 Hazard Classes and Categories

Acute Tox. 3 (97.1%)

12.1.3 Health Hazards

ACUTE/CHRONIC HAZARDS: When heated to decomposition this compound emits acrid smoke and irritating fumes. (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.

12.1.4 Fire Hazards

Flash point data for this compound are not available; however, it is probably combustible. (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.

12.2 First Aid Measures

12.2.1 First Aid

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment.

INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing.

INGESTION: DO NOT INDUCE VOMITING. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Be prepared to transport the victim to a hospital if advised by a physician. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital.

OTHER: Since this chemical is a known or suspected carcinogen you should contact a physician for advice regarding the possible long term health effects and potential recommendation for medical monitoring. Recommendations from the physician will depend upon the specific compound, its chemical, physical and toxicity properties, the exposure level, length of exposure, and the route of exposure. (NTP, 1992)

National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.

12.3 Fire Fighting

Fires involving this compound may be controlled with a dry chemical, carbon dioxide or Halon extinguisher. (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.

12.4 Accidental Release Measures

12.4.1 Isolation and Evacuation

Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

12.4.2 Disposal Methods

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

12.5 Handling and Storage

12.5.1 Nonfire Spill Response

SMALL SPILLS AND LEAKAGE: Should a spill occur while you are handling this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then you should dampen the solid spill material with 60-70% ethanol and transfer the dampened material to a suitable container. Use absorbent paper dampened with 60-70% ethanol to pick up any remaining material. Seal the absorbent paper, and any of your clothes, which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with 60-70% ethanol followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

STORAGE PRECAUTIONS: You should protect this chemical from exposure to light. Keep the container tightly closed under an inert atmosphere, and store under refrigerated temperatures. (NTP, 1992)

National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.

12.5.2 Storage Conditions

Quercetin tablets and capsules should be stored at room temp, away from heat, moisture, and direct light.
Thomson Healthcare. PDR for Herbal Medicines 4th Ed. Thomson Health Care Inc. Montvale, NJ. 2008, p. 1003

12.6 Exposure Control and Personal Protection

12.6.1 Personal Protective Equipment (PPE)

RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with a combination filter cartridge, i.e. organic vapor/acid gas/HEPA (specific for organic vapors, HCl, acid gas, SO2 and a high efficiency particulate filter). (NTP, 1992)
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.

12.7 Stability and Reactivity

12.7.1 Air and Water Reactions

Sensitive to exposure to air and light. Insoluble in water.

12.7.2 Reactive Group

Ketones

Phenols and Cresols

12.7.3 Reactivity Profile

QUERCETIN is a strong antioxidant and a metal chelator. Promotes the formation of nitrosamines (NTP, 1992).
National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.

12.8 Transport Information

12.8.1 DOT Label

Poison

12.9 Regulatory Information

The Australian Inventory of Industrial Chemicals
Chemical: 4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-
New Zealand EPA Inventory of Chemical Status
4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-: Does not have an individual approval but may be used under an appropriate group standard
New Zealand EPA Inventory of Chemical Status
Quercetin: Does not have an individual approval but may be used under an appropriate group standard

12.10 Other Safety Information

12.10.1 Special Reports

DHHS/NTP; Toxicology & Carcinogenesis Studies of Quercetin in F344/N Rats (Feed Studies) Technical Report Series No. 409 (1992) NIH Publication No 92-3140

13 Toxicity

13.1 Toxicological Information

13.1.1 Toxicity Summary

Quercetin is a specific quinone reductase 2 (QR2) inhibitor, an enzyme (along with the human QR1 homolog) which catalyzes metabolism of toxic quinolines. Inhibition of QR2 in plasmodium may potentially cause lethal oxidative stress. The inhibition of antioxidant activity in plasmodium may contribute to killing the malaria causing parasites.

13.1.2 Hepatotoxicity

Quercetin supplements have not been linked serum aminotransferase elevations during therapy, although there have been few focused studies of its hepatic safety. Furthermore, there have been no published reports of clinically apparent liver injury attributable to quercetin. Indeed, many in vitro and in vivo studies have shown that quercetin protects against hepatic injury caused by drugs and toxins including acetaminophen and cancer chemotherapeutic agents. These hepatoprotective effects have not been demonstrated in prospective clinical trials in humans.

Likelihood score: E (unlikely cause of clinically apparent liver injury).

Other Names: Often a component in Bioflavonoid Extracts

Drug Class: Herbal and Dietary Supplements

13.1.3 Evidence for Carcinogenicity

Evaluation: There is inadequate evidence in humans for the carcinogenicity of quercetin. There is limited evidence in experimental animals for the carcinogenicity of quercetin. Overall evaluation: Quercetin is not classifiable as to its carcinogenicity to humans (Group 3).
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. 73 510 (1999)

13.1.4 Carcinogen Classification

1 of 3
IARC Carcinogenic Agent
Quercetin
IARC Carcinogenic Classes
Group 3: Not classifiable as to its carcinogenicity to humans
IARC Monographs

Volume Sup 7: Overall Evaluations of Carcinogenicity: An Updating of IARC Monographs Volumes 1 to 42, 1987; 440 pages; ISBN 92-832-1411-0 (out of print)

Volume 73: (1999) Some Chemicals that Cause Tumours of the Kidney or Urinary Bladder in Rodents and Some Other Substances

2 of 3
Substance
NTP Technical Report
TR-409: Toxicology and Carcinogenesis Studies of Quercetin (CASRN 117-39-5) in F344 Rats (Feed Studies) (1992 )
Peer Review Date
Conclusion for Male Rat
Some Evidence Some Evidence
Conclusion for Female Rat
No Evidence No Evidence
Conclusion for Male Mice
Chemical Not Tested in Species/Sex Chemical Not Tested in Species/Sex
Conclusion for Female Mice
Chemical Not Tested in Species/Sex Chemical Not Tested in Species/Sex
Summary

Under the conditions of these 2-year feed studies there was some evidence of carcinogenic activity of quercetin in male F344/N rats based on an increased incidence of renal tubule cell adenomas. There was no evidence of carcinogenic activity of quercetin in female F344/N rats receiving 1,000, 10,000 or 40,000 ppm.

The incidence of renal tubule hyperplasia and the severity of nephropathy were increased in exposed male rats.

3 of 3
Carcinogen Classification
3, not classifiable as to its carcinogenicity to humans. (L135)

13.1.5 Acute Effects

13.1.6 Interactions

In human myelogenous leukemia cells, quercetin was reported to arrest growth of the cell by an incr in the uptake of vincristine, a chemotherapeutic agent.
Coates, P.M., Blackman, M.R., Cragg, G.M., Levine, M., Moss, J., White, J.D. (Ed), Encyclopedia of Dietary Supplements. Marcel Dekker, New York, NY, p. 580 (2005)
Quercetin binds, in vitro, to the DNA gyrase site in bacteria. Therefore, theoretically, it can serve as a competitive inhibitor to the quinolone antibiotics which also bind to this site ... Because of the theoretical risk of genotoxicity in normal tissues in those using cisplatin along with quercetin, those using cisplatin should avoid quercetin supplements ... Bromelain and papain are reported to incr absorption of quercetin.
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.393 (2001)
Quercetin has a pro-oxidant effect and will incr the iron-dependent DNA damage induced by bleomycin. Quercetin may reduce iron to the ferrous state, which allows bleomycin to complex more readily with oxygen and produce more efficient DNA damage. A biphasic pro-oxidant effect with bleomycin has been demonstrated. At low concn incr DNA damage was noted, and at higher doses less DNA damage was noted.
Thomson Healthcare. PDR for Herbal Medicines 4th Ed. Thomson Health Care Inc. Montvale, NJ. 2008, p. 1002
Concomitant use may reduce cyclosporine /or floroquinolones/ effectiveness.
Thomson Healthcare. PDR for Herbal Medicines 4th Ed. Thomson Health Care Inc. Montvale, NJ. 2008, p. 1002
For more Interactions (Complete) data for QUERCETIN (18 total), please visit the HSDB record page.

13.1.7 Antidote and Emergency Treatment

/SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Poisons A and B/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 160
/SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poisons A and B/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 160
/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 160-1

13.1.8 Human Toxicity Excerpts

/HUMAN EXPOSURE STUDIES/ ... A double-blind, placebo-controlled study compared one gram daily of oral quercetin with placebo in 27 healthy subjects ... The study continued for 28 days, during which period subjects receiving quercetin achieved plasma quercetin level 23-fold higher than levels in those on placebo. The results showed no quercetin effect on serum total cholesterol, LDL-cholesterol, HDL-cholesterol or triglyceride levels. Nor was there any effect on other factors considered to be indicators of risk for cardiovascular/thrombogenic disease, including platelet aggregation, platelet thromboxane B2 production, blood pressure and resting heart rate. There was no effect on levels of (n-6) or (n-3) polyunsaturated fatty acids in serum or platelet phospholipids ...
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.391 (2001)
/HUMAN EXPOSURE STUDIES/ Intravenous admin of doses greater than 945 mg/sq m has been associated with nephrotoxicity.
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.393 (2001)
/SIGNS AND SYMPTOMS/ Adverse effects reported with oral quercetin include gastrointestinal effects such as nausea, and rare reports of headache and mild tingling of the extremities ... Intravenous admin of quercetin has been associated with nausea, vomiting, diaphoresis, flushing and dyspnea.
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.392 (2001)
/ALTERNATIVE and IN VITRO TESTS/ Quercetin was reported to have 1% of the estrogenic activity of estradiol in HeLa cells transfected with the human estrogen receptor and the pERE-TK-CAT reporter plasmid ...
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P503 (1999)
For more Human Toxicity Excerpts (Complete) data for QUERCETIN (13 total), please visit the HSDB record page.

13.1.9 Non-Human Toxicity Excerpts

/LABORATORY ANIMALS: Acute Exposure/ High-dose quercetin promoted mucus production and helped diminish the severity of gastric lesions in animals injured with abs ethanol. Thiobarbituric acid reactive substances in gastric mucosa, a measure of lipid peroxidation, was significantly decr by quercetin in ethanol-injured animals ...
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.392 (2001)
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... /This/ study ... investigated the effects of vitamin E and/or quercetin (Q) on renal function, oxygen radical concentrations in the kidney and some anti-oxidant enzyme activities in rats treated with cyclosporine A (CsA). ... Groups of rats (270 +/- 15 g), on standard rat chow and water, received all their treatments by gavage for either 4 or 8 weeks. Control groups received either olive oil (0.5 mL) or 25% ethanol (0.5 mL) + olive oil (0.5 mL) per day as vehicle. All experimental groups received 25 mg CsA/kg per day in 0.5 mL olive oil. The vitamin E group received 100 mg vitamin E/kg per day in olive oil in addition to CsA treatment. The quercetin group received 15 mg of Q/kg per day in 0.5 mL of 25% ethanol in addition to CsA treatment. The vitamin E + quercetin group received the two anti-oxidants at the concentrations given in addition to CsA treatment. ... Quercetin, at a concentration less than one-quarter of vitamin E, was more efficient in lowering blood urea nitrogen, serum creatinine and kidney malondialdehyde in CsA-treated rats. However, neither of the two anti-oxidants was able to normalize these analytes to control values after either 4 or 8 weeks treatment. ... Quercetin (50 umol/kg per day) elevated all renal anti-oxidant enzyme activities to values observed in the negative controls. However, vitamin E (232 umol/kg per day) only normalized glutathione peroxidase activity at the end of either 4 or 8 weeks treatment. Combination treatment with the two anti-oxidants abolished all the ill-effects of CsA. ... Combination treatment with the two anti-oxidants of renal transplant patients receiving CsA may be beneficial in ameliorating the chronic nephrotoxic effects of the important immunosuppressive drug CsA.
Zal F et al; Clin Exp Pharmacol Physiol 34(8):720-4 (2007)
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Twenty-three male and 24 female strain A (A/JJms) mice, six to eight weeks old, were fed a diet containing 5% quercetin (purity, 99%) for 23 weeks, at which time the experiment was terminated. A control group of 21 males and 27 females was fed a basal diet only. No significant difference in the incidence or multiplicity of lung adenomas was seen in the two groups ...
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V31 P218 (1983)
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Rats were maintained on a diet containing 1% or 5% quercetin for 540 days, or 10% for 850 days. Most tumors found in experimental groups were also found in the control groups. There was no significant difference between the incidence of tumors in the experimental or control groups (p= 0.05). Quercetin was not carcinogenic to ACI rats.
HIRONO I ET AL; CANCER LETT 13(1):15 (1981)
For more Non-Human Toxicity Excerpts (Complete) data for QUERCETIN (51 total), please visit the HSDB record page.

13.1.10 Non-Human Toxicity Values

LD50 Rat oral 161 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 3127
LD50 Mouse iv 18 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 3127
LD50 Mouse oral 160 mg/kg
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P502 (1999)
LD50 Mouse sc 100 mg/kg
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V73 P502 (1999)

13.1.11 Ongoing Test Status

The following link will take the user to the National Toxicology Program (NTP) Test Agent Search Results page, which tabulates all of the "Standard Toxicology & Carcinogenesis Studies", "Developmental Studies", and "Genetic Toxicity Studies" performed with this chemical. Clicking on the "Testing Status" link will take the user to the status (i.e., in review, in progress, in preparation, on test, completed, etc.) and results of all the studies that the NTP has done on this chemical. [http://ntp-apps.niehs.nih.gov/ntp_tox/index.cfm?fuseaction=ntpsearch.searchresults&searchterm=117-39-5]

13.1.12 National Toxicology Program Studies

... The NTP 2-year studies were conducted by admin 0, 1,000, 10,000, or 40,000 ppm quercetin (>95% pure) in feed to groups of 50 male and female rats for 104 wk. Ten additional animals per dose group were evaluated at 6 and 15 mo ... Body weights of exposed male and female rats given 1,000 and 10,000 ppm were within 5% of controls throughout the studies. Reduced body weight gain in male and female rats receiving 40,000 ppm was observed by wk 15 and the final mean body weights were 87% of controls at wk 104. Survival and feed consumption were similar among exposed and control groups throughout the studies. The average amt of quercetin consumed per day by the 1,000, 10,000 and 40,000 ppm dose groups after wk 52 were 40, 400, and 1,900 mg/kg of body weight ... In male rats, the principal toxic effects associated with the dietary admin of quercetin for 2 yr were observed in the kidney. There were dose-related incr in the severity of chronic nephropathy (control, 2.7; low-dose, 2.7; mid-dose, 3.0; high-dose, 3.2) and a slight incr incidence in focal hyperplasia of the renal tubule epithelium (1/50; 2/50; 3/50; 4/50). Parathyroid hyperplasia, indicative of renal secondary hyperparathyroidism, also incr incidence in dosed male rats (1/43, 6/45, 6/43, 17/43). The evaluation of single sections from the left and right kidneys revealed renal tubule adenomas in 3 male rats and adenocarcinomas in another male rat receiving 40,000 ppm quercetin; none were seen in the controls. Examination of additional step sections of the male rat kidney identified additional hyperplasia and adenomas in all dose groups (hyperplasia: 2/50, 2/50, 6/50, 8/50; adenoma: 1/50, 2/50, 7/50, 6/50). The overall incidence of renal tubule adenoma or adenocarcinoma combined in male rats was 1/50 in controls and 9/50 in the high-dose group. There was a statistically significant, dose-related decr in the incidence of mammary gland fibro-adenomas in exposed female rats (29/50, 27/50, 16/50, 9/50), which may in part be attributed to lower body weight gains. There was a treatment-related accumulation of yellow-brown granular pigment adsorbed to or absorbed by the epithelial cells of the glandular stomach, ileum, jejunum, and, to a lesser extent, the duodenum and colon. The severity of the pigmentation in these tissues incr with incr length of exposure. There were no other lesions considered to be related to chemical admin ... Conclusions: Under the conditions of these 2 year feed studies there was some evidence of carcinogenic activity of quercetin in male F344/N rats based on an increased incidence of renal tubule cell adenomas. There was no evidence of carcinogenic activity of quercetin in female F344/N rats receiving 1,000, 10,000 or 40,000 ppm.
Toxicology & Carcinogenesis Studies of Quercetin in F344/N Rats (Feed Studies). Technical Report Series No. 409 (1992) NIH Publication No. 92-3140 U.S. Department of Health and Human Services, National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709

13.1.13 Populations at Special Risk

Precautions: Because of lack of long-term safety data, quercetin should be avoided by pregnant women and nursing mothers.
Thomson Healthcare. PDR for Nutritional Supplements. Thomson Health Care Inc. Montvale, NJ. p.392 (2001)

13.2 Ecological Information

13.2.1 Environmental Fate / Exposure Summary

Quercetin's production and use as an experimental antioxidant, cosmetic preservative, and natural dye may result in its limited release to the environment through various waste streams. Quercetin is a flavanoid widely distributed in plants. If released to air, an estimated vapor pressure of 2.8X10-14 mm Hg at 25 °C indicates quercetin will exist solely in the particulate phase in the atmosphere. Particulate-phase quercetin will be removed from the atmosphere by wet or dry deposition. Quercetin contains chromophores that absorb at wavelengths >290 nm and therefore is may be susceptible to direct photolysis by sunlight. If released to soil, quercetin is expected to have moderate mobility based upon an estimated Koc of 460. The estimated pKas of quercetin are 7.17, 8.26, 10.13, 12,30, and 13.11, indicating that this compound will exist partially in the anion form in the environment at neutral pH and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts. Volatilization from moist soil is not expected because it is an anion and anions do not volatilize. Quercetin's rapid degradation in soil suggests that biocegradation may be an important environmental fate process. If released into water, quercetin is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. The estimated pKa values indicate quercetin will exist in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process. An estimated BCF of 61 suggests the potential for bioconcentration in aquatic organisms is moderate. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Occupational exposure to quercetin may occur through inhalation and dermal contact with this compound at workplaces where quercetin is produced or used. Use data indicate that the general population may be exposed to quercetin via dermal contact with this compound or other consumer products containing quercetin. (SRC)

13.2.2 Natural Pollution Sources

Quercetin is the aglucon of quercitrin, of rutin, and other glycosides. It is widely distributed in the plant kingdom, especially in rinds and barks, in clover blossoms, and ragweed pollen and has been isolated from Rhododendron cinnabarinum Hook, Ericaceae(1)
(1) O'Neil MJ, ed; The Merck Index. 14th ed., Whitehouse Station, NJ: Merck and Co., Inc., p. 1381 (2006)
Quercetin is widely distributed in the plant kingdom, where it occurs as a condensation product (a glycoside) with sugars ... Plants /that/ contain these glycosides are: Allium ascalonicum; Allium cepa (onion); Allium porrum (leek); Anethum graveolens; Apium graveolens; Asperagus officinalis (asparagus); Brassica chinensis; Brassica napus; Brassica oleracae var. butrytis subvar. cymosa; Brassica oleraceae var. buttata; Brassica oleraceae var. captata; Brassica oleraceae var. gemmifera (plants of cabbage and mustard); Capsicum annuum (ornamental pepper); Cichorium endivia (endive); Citrus paradisi (grapefruit); Fragaria ananassa; Humulus lupulus; Latuca sativa (lettuce); Malus pumila (apple); Malus silvestris; Mangifera indica (mango); Petroselinum crispum; Prunus armeniaca; Prunus avium; Prunus domestica (European plum); Raphanus sativus (radish); Rheum spp; Ribes L.; Ribes nigrum (blackcurrant); Ribes grossularia; Rubus L.; Rubus ideaus; Rumex acetosa; Sambuccus nigra (elder); Solanum tuberosum (potato); Solanum lycopersicum; Spinacea oleraceae (spinach); Vaccinium macrocarpum ... Quercetin has been isolated from grapes, Vitis vinifera (1.4 mg/kg, fresh fruit), from leaves of the 'huckleberry', Vaccinium myrtillus (11 g/kg, dry weight, for quercetin and its glucosides), and from the leaves of Rhododendron cinnabarinum Hook. ... China tea, Camellia sinensis, has been reported to contain relatively large amounts of triglycosides of quercetin ... The total concentration of kaempferol and quercetin glycosides in tea (unspecified variety) is >10,000 mg/kg. ... This compound occurs in bracken fern (Pteridium aquilinum) ... .
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V31: 215 (1983)

13.2.3 Artificial Pollution Sources

Quercetin's production and use as an experimental antioxidant dietary supplement(1), cosmetic preservative(2), and natural dye(3) may result in its release to the environment through various waste streams(SRC).
(1) Wishart DS et al; DrugBank: a comprehensive resource for in silico drug discovery and exploration. Nucleic Acids Res. 2006 1;34. Available from the database query page at https://redpoll.pharmacy.ualberta.ca/drugbank/ as of Feb 15, 2008.
(2) Rieger MM; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). NY, NY: John Wiley & Sons; Cosmetics. Online Posting Date: Dec 4, 2000.
(3) Cofrancesco AJ; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). NY, NY: John Wiley & Sons; Dyes, Natural. Online Posting Date: Dec 4, 2000.

13.2.4 Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 460(SRC), determined from a water solubility of 60 mg/L(2) and a regression-derived equation(3), indicates that quercetin is expected to have moderate mobility in soil(SRC). The estimated pKas of quercetin are 7.17, 8.26, 10.13, 12,30, and 13.11(4), indicating that this compound will partially exist in the anion form in the environment at neutral pH and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5). Volatilization of quercetin from moist soil surfaces is not expected to be an important fate process because it is an anion and anions do not volatilize(SRC). Quercetin is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.8X10-14 mm Hg(SRC), determined from a fragment constant method(6). Quercetin's rapid degradation in soil(7) suggests that biodegradation may be an important environmental fate process(SRC).
(1) Swann RL et al; Res Rev 85: 17-28 (1983)
(2) Seidell A; Solubilities of Organic Compounds. NY,NY: d. Van Norstrand Co., Inc. (1941)
(3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 4-5 (1990)
(4) SPARC; pKa/property server. Ver 3. Jan, 2006. Available at https://ibmlc2.chem.uga.edu/sparc/ as of Feb 14, 2008.
(5) Doucette WJ; pp. 141-188 in Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds. Boca Raton, FL: Lewis Publ (2000)
(6) Lyman WJ; p. 31 in Environmental Exposure From Chemicals Vol I, Neely WB, Blau GE, eds, Boca Raton, FL: CRC Press (1985)
(7) Lewis JA, Papvizas GC; Can J Microbiol 15: 527-33 (1969)
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 460(SRC), determined from a water solubility of 60 mg/L(2) and a regression-derived equation(3), indicates that quercetin is not expected to adsorb to suspended solids and sediment(SRC). The estimated pKas of 7.17, 8.26, 10.13, 12,30, and 13.11(4) indicate quercetin will exist partially in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(5). According to a classification scheme(6), an estimated BCF of 61(SRC), from its water solubility(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is moderate(SRC). Quercetin's rapid degradation in soil(7) suggests that biodegradation may be an important environmental fate process in water(SRC).
(1) Swann RL et al; Res Rev 85: 17-28 (1983)
(2) Seidell A; Solubilities of Organic Compounds. NY,NY: d. Van Norstrand Co., Inc. (1941)
(3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 4-5, 5-5, 15-1 to 15-29 (1990)
(4) SPARC; pKa/property server. Ver 3. Jan, 2006. Available at https://ibmlc2.chem.uga.edu/sparc/ as of Feb 14, 2008.
(5) Doucette WJ; pp. 141-188 in Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds, Boca Raton, FL: Lewis Publ (2000)
(6) Franke C et al; Chemosphere 29: 1501-14 (1994)
(7) Lewis JA, Papvizas GC; Can J Microbiol 15: 527-33 (1969)
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), quercetin, which has an estimated vapor pressure of 2.8X10-14 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely in the particulate phase in the ambient atmosphere. Particulate-phase quercetin may be removed from the air by wet or dry deposition(SRC). Quercetin contains chromophores that absorb at wavelengths >290 nm(4) and therefore may be susceptible to direct photolysis by sunlight(SRC).
(1) Bidleman TF; Environ Sci Technol 22: 361-367 (1988)
(2) Lyman WJ; p. 31 in Environmental Exposure From Chemicals Vol I, Neely WB, Blau GE, eds, Boca Raton, FL: CRC Press (1985)
(3) Meylan WM, Howard PH; Chemosphere 26: 2293-99 (1993)
(4) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 8-12 (1990)

13.2.5 Environmental Biodegradation

AEROBIC: Quercetin, along with rutin and two of their decomposition products phloroglucinol and protocatechuic acid, were rapidly degraded in soil as indicated by less than 10% of their phenolic nuclei being detected in soil and 27-57% of their structural carbons remaining in soil after 9 weeks incubation(1).
(1) Lewis JA, Papvizas GC; Can J Microbiol 15: 527-33 (1969)
ANAEROBIC: Approximately 2% of microorganisms isolated from a sandy soil that were sensitive to cadmium and zinc were able to grow on quercetin(1). Zinc-resistant microorganisms were not able to utilize this compound(1).
(1) Allard AS et al; Appl Environ Microbiol 58: 961-8 (1992)

13.2.6 Environmental Abiotic Degradation

Quercetin is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(1). Quercetin contains chromophores that absorb at wavelengths >290 nm(1) and therefore may be susceptible to direct photolysis by sunlight(SRC).
(1) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 7-4, 7-5, 8-12 (1990)

13.2.7 Environmental Bioconcentration

An estimated BCF of 61 was calculated in fish for quercetin(SRC), using a water solubility of 60 mg/L(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is moderate(SRC), provided the compound is not metabolized by the organism(SRC).
(1) Seidell A; Solubilities of Organic Compounds. NY,NY: d. Van Norstrand Co., Inc. (1941)
(2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 5-5 (1990)
(3) Franke C et al; Chemosphere 29: 1501-14 (1994)

13.2.8 Soil Adsorption / Mobility

The Koc of quercetin is estimated as 460(SRC), using a water solubility of 60 mg/L(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that quercetin is expected to have moderate mobility in soil. The estimated pKas of quercetin are 7.17, 8.26, 10.13, 12,30, and 13.11(4), indicating that this compound will partially exist in the anion form in the environment at neutral pH and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5).
(1) Seidell A; Solubilities of Organic Compounds. NY,NY: d. Van Norstrand Co., Inc. (1941)
(2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 4-5 (1990)
(3) Swann RL et al; Res Rev 85: 17-28 (1983)
(4) SPARC; pKa/property server. Ver 3. Jan, 2006. Available at https://ibmlc2.chem.uga.edu/sparc/ as of Feb 14, 2008.
(5) Doucette WJ; pp. 141-188 in Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds. Boca Raton, FL: Lewis Publ (2000)

13.2.9 Volatilization from Water / Soil

The estimated pKas of 7.17, 8.26, 10.13, 12,30, and 13.11(1) indicate quercetin will partially exist anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(2). Volatilization of quercetin from moist soil surfaces is not expected to be an important fate process because it is an anion and anions do not volatilize(SRC). Quercetin is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.8X10-14 mm Hg(SRC), determined from a fragment constant method(3).
(1) SPARC; pKa/property server. Ver 3. Jan, 2006. Available at https://ibmlc2.chem.uga.edu/sparc/ as of Feb 14, 2008.
(2) Doucette WJ; pp. 141-188 in Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds. Boca Raton, FL: Lewis Publ (2000)
(3) Lyman WJ; p. 31 in Environmental Exposure From Chemicals Vol I, Neely WB, Blau GE, eds, Boca Raton, FL: CRC Press (1985)

13.2.10 Plant Concentrations

The concentration in onions varies widely depending on the type of onion. Those with colored skins ... contain 25,000-65,000 mg/kg quercetin mainly as the aglycone; however, onions with white skins have only traces of flavonols, e.g., 10 mg/kg quercetin in dry skins. The quercetin concentration decreases from the outer to inner scales, with the highest levels in the outer epidermis ...
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V31 P216 (1983)

Adapted from Table 1 & 2

Table: CONCENTRATION OF QUERCETIN AS ITS GLYCOSIDE IN PLANTS

Plant
Apple
Parts of Plant
Skin & Peel
Concentration (mg/kg)
58 to 263
Plant
Pear
Parts of Plant
Skin & Peel
Concentration (mg/kg)
28
Plant
Quince
Parts of Plant
Skin & Peel
Concentration (mg/kg)
180
Plant
Bell pepper
Parts of Plant
Skin & Peel
Concentration (mg/kg)
63
Plant
Potato
Parts of Plant
Skin & Peel
Concentration (mg/kg)
47
Plant
Potato
Parts of Plant
Leaves
Concentration (mg/kg)
770 to 1000
Plant
Brussels sprout
Parts of Plant
Leaves
Concentration (mg/kg)
50
Plant
Brussels sprout
Parts of Plant
Sprout
Concentration (mg/kg)
25
Plant
Cailiflower
Parts of Plant
Leaves
Concentration (mg/kg)
30
Plant
Kohlrabi (oepn air)
Parts of Plant
Leaves
Concentration (mg/kg)
25
Plant
Kale (open air)
Parts of Plant
Leaves
Concentration (mg/kg)
50
Plant
Kale (greenhouse)
Parts of Plant
Leaves
Concentration (mg/kg)
35
Plant
Radish
Parts of Plant
Leaves
Concentration (mg/kg)
0 to 35
Plant
Rutabaga
Parts of Plant
Leaves
Concentration (mg/kg)
40
Plant
Horseradish
Parts of Plant
Leaves
Concentration (mg/kg)
50
Plant
Scorzonera (salsify)
Parts of Plant
Leaves
Concentration (mg/kg)
230
Plant
Tomato (open air)
Parts of Plant
Leaves
Concentration (mg/kg)
420
Plant
Tomato (greenhouse)
Parts of Plant
Leaves
Concentration (mg/kg)
155
Plant
Pea
Parts of Plant
Leaves
Concentration (mg/kg)
1580 to 1590
Plant
Pea
Parts of Plant
Pod without seeds
Concentration (mg/kg)
125 to 130
Plant
Broad bean
Parts of Plant
Leaves
Concentration (mg/kg)
1340
Plant
Broad bean
Parts of Plant
Pods without seeds
Concentration (mg/kg)
36
Plant
Broad bean
Parts of Plant
Pod
Concentration (mg/kg)
19

IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V31 P216 (1983)

13.2.11 Other Environmental Concentrations

Quercetin is a flavanoid component of hardwood wood dust(1). It is found in leaf tobacco(2) and tea leaves(3).
(1) Dement J; Patty's Toxicology. (2007). NY, NY: John Wiley & Sons, Inc. Wood Dust. On-line posting date: Apr 16, 2001.
(2) Tso TC; Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (2008). NY, NY: John Wiley & Sons; Tobacco. Online Posting Date: Jun 15, 2000.
(3) Balentine DA et al; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). NY, NY: John Wiley & Sons; Tea. Online Posting Date: Feb 16, 2007.

13.2.12 Probable Routes of Human Exposure

Occupational exposure to quercetin may occur through inhalation and dermal contact with this compound at workplaces where quercetin is produced or used. Use data indicate that the general population may be exposed to quercetin via dermal contact with this compound or other consumer products containing quercetin. (SRC)

14 Associated Disorders and Diseases

Disease
Diabetes mellitus type 2
References

PubMed: 15899597, 15982426, 6321058, 6810706, 7758205, 12067838, 9591306, 1456422, 10694785, 10431355, 16731998, 11887176, 2614280, 18184896, 11815509, 9357814, 17659063, 14512036, 17161231, 7096503, 11315839, 17705693, 484160, 8234346, 16966827, 18760976, 17919531, 17190852, 22031514, 23637065

World Health Organisation Department of Noncommunicable Disease Surveillance (1999). "Definition, Diagnosis and Classification of Diabetes Mellitus and its Complications"

Rosa Va ́zquez-Fresno et al. An NMR metabolomics approach reveals a combined-biomarkers model in a wine interventional trial with validation in free-living individuals of the PREDIMED study. Metabolomics (2015) 11:797- 806: https://link.springer.com/content/pdf/10.1007/s11306-014-0735-x.pdf

15 Literature

15.1 Consolidated References

15.2 NLM Curated PubMed Citations

15.3 Springer Nature References

15.4 Thieme References

15.5 Wiley References

15.6 Nature Journal References

15.7 Chemical Co-Occurrences in Literature

15.8 Chemical-Gene Co-Occurrences in Literature

15.9 Chemical-Disease Co-Occurrences in Literature

16 Patents

16.1 Depositor-Supplied Patent Identifiers

16.2 WIPO PATENTSCOPE

16.3 Chemical Co-Occurrences in Patents

16.4 Chemical-Disease Co-Occurrences in Patents

16.5 Chemical-Gene Co-Occurrences in Patents

17 Interactions and Pathways

17.1 Protein Bound 3D Structures

17.1.1 Ligands from Protein Bound 3D Structures

PDBe Ligand Code
PDBe Structure Code
PDBe Conformer

17.2 Chemical-Target Interactions

17.3 Drug-Drug Interactions

17.4 Pathways

18 Biological Test Results

18.1 BioAssay Results

19 Taxonomy

The LOTUS Initiative for Open Natural Products Research: frozen dataset union wikidata (with metadata) | DOI:10.5281/zenodo.5794106
S29 | PHYTOTOXINS | Toxic Plant Phytotoxin (TPPT) Database | DOI:10.5281/zenodo.2652993

20 Classification

20.1 MeSH Tree

20.2 NCI Thesaurus Tree

20.3 ChEBI Ontology

20.4 LIPID MAPS Classification

20.5 KEGG: Lipid

20.6 KEGG: Phytochemical Compounds

20.7 ChemIDplus

20.8 CAMEO Chemicals

20.9 ChEMBL Target Tree

20.10 UN GHS Classification

20.11 EPA CPDat Classification

20.12 NORMAN Suspect List Exchange Classification

20.13 CCSBase Classification

20.14 EPA DSSTox Classification

20.15 International Agency for Research on Cancer (IARC) Classification

20.16 EPA TSCA and CDR Classification

20.17 LOTUS Tree

20.18 EPA Substance Registry Services Tree

20.19 MolGenie Organic Chemistry Ontology

21 Information Sources

  1. Australian Industrial Chemicals Introduction Scheme (AICIS)
    4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-
    https://services.industrialchemicals.gov.au/search-inventory/
  2. CAMEO Chemicals
    LICENSE
    CAMEO Chemicals and all other CAMEO products are available at no charge to those organizations and individuals (recipients) responsible for the safe handling of chemicals. However, some of the chemical data itself is subject to the copyright restrictions of the companies or organizations that provided the data.
    https://cameochemicals.noaa.gov/help/reference/terms_and_conditions.htm?d_f=false
    CAMEO Chemical Reactivity Classification
    https://cameochemicals.noaa.gov/browse/react
  3. CAS Common Chemistry
    LICENSE
    The data from CAS Common Chemistry is provided under a CC-BY-NC 4.0 license, unless otherwise stated.
    https://creativecommons.org/licenses/by-nc/4.0/
  4. ChemIDplus
    ChemIDplus Chemical Information Classification
    https://pubchem.ncbi.nlm.nih.gov/source/ChemIDplus
  5. DrugBank
    LICENSE
    Creative Common's Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/legalcode)
    https://www.drugbank.ca/legal/terms_of_use
  6. DTP/NCI
    LICENSE
    Unless otherwise indicated, all text within NCI products is free of copyright and may be reused without our permission. Credit the National Cancer Institute as the source.
    https://www.cancer.gov/policies/copyright-reuse
  7. EPA Chemicals under the TSCA
    4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-
    https://www.epa.gov/chemicals-under-tsca
    EPA TSCA Classification
    https://www.epa.gov/tsca-inventory
  8. EPA DSSTox
    CompTox Chemicals Dashboard Chemical Lists
    https://comptox.epa.gov/dashboard/chemical-lists/
  9. European Chemicals Agency (ECHA)
    LICENSE
    Use of the information, documents and data from the ECHA website is subject to the terms and conditions of this Legal Notice, and subject to other binding limitations provided for under applicable law, the information, documents and data made available on the ECHA website may be reproduced, distributed and/or used, totally or in part, for non-commercial purposes provided that ECHA is acknowledged as the source: "Source: European Chemicals Agency, http://echa.europa.eu/". Such acknowledgement must be included in each copy of the material. ECHA permits and encourages organisations and individuals to create links to the ECHA website under the following cumulative conditions: Links can only be made to webpages that provide a link to the Legal Notice page.
    https://echa.europa.eu/web/guest/legal-notice
  10. FDA Global Substance Registration System (GSRS)
    LICENSE
    Unless otherwise noted, the contents of the FDA website (www.fda.gov), both text and graphics, are not copyrighted. They are in the public domain and may be republished, reprinted and otherwise used freely by anyone without the need to obtain permission from FDA. Credit to the U.S. Food and Drug Administration as the source is appreciated but not required.
    https://www.fda.gov/about-fda/about-website/website-policies#linking
  11. Hazardous Substances Data Bank (HSDB)
  12. Human Metabolome Database (HMDB)
    LICENSE
    HMDB is offered to the public as a freely available resource. Use and re-distribution of the data, in whole or in part, for commercial purposes requires explicit permission of the authors and explicit acknowledgment of the source material (HMDB) and the original publication (see the HMDB citing page). We ask that users who download significant portions of the database cite the HMDB paper in any resulting publications.
    http://www.hmdb.ca/citing
  13. New Zealand Environmental Protection Authority (EPA)
    LICENSE
    This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International licence.
    https://www.epa.govt.nz/about-this-site/general-copyright-statement/
  14. BindingDB
    LICENSE
    All data curated by BindingDB staff are provided under the Creative Commons Attribution 3.0 License (https://creativecommons.org/licenses/by/3.0/us/).
    https://www.bindingdb.org/rwd/bind/info.jsp
    2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one
    https://www.bindingdb.org/rwd/bind/chemsearch/marvin/MolStructure.jsp?monomerid=7460
  15. Comparative Toxicogenomics Database (CTD)
    LICENSE
    It is to be used only for research and educational purposes. Any reproduction or use for commercial purpose is prohibited without the prior express written permission of NC State University.
    http://ctdbase.org/about/legal.jsp
  16. Drug Gene Interaction database (DGIdb)
    LICENSE
    The data used in DGIdb is all open access and where possible made available as raw data dumps in the downloads section.
    http://www.dgidb.org/downloads
  17. Therapeutic Target Database (TTD)
  18. Toxin and Toxin Target Database (T3DB)
    LICENSE
    T3DB is offered to the public as a freely available resource. Use and re-distribution of the data, in whole or in part, for commercial purposes requires explicit permission of the authors and explicit acknowledgment of the source material (T3DB) and the original publication.
    http://www.t3db.ca/downloads
  19. ChEBI
  20. E. coli Metabolome Database (ECMDB)
    LICENSE
    ECMDB is offered to the public as a freely available resource.
    https://ecmdb.ca/citations
  21. LiverTox
  22. LOTUS - the natural products occurrence database
    LICENSE
    The code for LOTUS is released under the GNU General Public License v3.0.
    https://lotus.nprod.net/
  23. NCI Thesaurus (NCIt)
    LICENSE
    Unless otherwise indicated, all text within NCI products is free of copyright and may be reused without our permission. Credit the National Cancer Institute as the source.
    https://www.cancer.gov/policies/copyright-reuse
  24. Open Targets
    LICENSE
    Datasets generated by the Open Targets Platform are freely available for download.
    https://platform-docs.opentargets.org/licence
  25. Yeast Metabolome Database (YMDB)
    LICENSE
    YMDB is offered to the public as a freely available resource.
    http://www.ymdb.ca/downloads
  26. CCSbase
    CCSbase Classification
    https://ccsbase.net/
  27. ChEMBL
    LICENSE
    Access to the web interface of ChEMBL is made under the EBI's Terms of Use (http://www.ebi.ac.uk/Information/termsofuse.html). The ChEMBL data is made available on a Creative Commons Attribution-Share Alike 3.0 Unported License (http://creativecommons.org/licenses/by-sa/3.0/).
    http://www.ebi.ac.uk/Information/termsofuse.html
  28. ClinicalTrials.gov
    LICENSE
    The ClinicalTrials.gov data carry an international copyright outside the United States and its Territories or Possessions. Some ClinicalTrials.gov data may be subject to the copyright of third parties; you should consult these entities for any additional terms of use.
    https://clinicaltrials.gov/ct2/about-site/terms-conditions#Use
  29. Crystallography Open Database (COD)
    LICENSE
    All data in the COD and the database itself are dedicated to the public domain and licensed under the CC0 License. Users of the data should acknowledge the original authors of the structural data.
    https://creativecommons.org/publicdomain/zero/1.0/
  30. DailyMed
  31. KNApSAcK Species-Metabolite Database
  32. Natural Product Activity and Species Source (NPASS)
  33. NORMAN Suspect List Exchange
    LICENSE
    Data: CC-BY 4.0; Code (hosted by ECI, LCSB): Artistic-2.0
    https://creativecommons.org/licenses/by/4.0/
    Quercetin
    NORMAN Suspect List Exchange Classification
    https://www.norman-network.com/nds/SLE/
  34. EPA Chemical and Products Database (CPDat)
  35. FooDB
    LICENSE
    FooDB is offered to the public as a freely available resource. Use and re-distribution of the data, in whole or in part, for commercial purposes requires explicit permission of the authors and explicit acknowledgment of the source material (FooDB) and the original publication.
    https://foodb.ca/about
  36. MassBank Europe
  37. MassBank of North America (MoNA)
    LICENSE
    The content of the MoNA database is licensed under CC BY 4.0.
    https://mona.fiehnlab.ucdavis.edu/documentation/license
  38. NIST Mass Spectrometry Data Center
    LICENSE
    Data covered by the Standard Reference Data Act of 1968 as amended.
    https://www.nist.gov/srd/public-law
  39. SpectraBase
    RUTIN-ARTIFACT (PENTAHYDROXYFLAVONE)
    https://spectrabase.com/spectrum/7biDIzwjiXP
    4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-
    https://spectrabase.com/spectrum/2MmkpBAXWB
    3,3',4',5,7-pentahydroxyflavone
    https://spectrabase.com/spectrum/7evGiFKZaEE
    3,3',4',5,7-PENTAHYDROXYFLAVONE
    https://spectrabase.com/spectrum/8M1xbyTfWtK
    3,3',4',5,7-PENTAHYDROXYFLAVONE
    https://spectrabase.com/spectrum/GJk4bt8IxWz
    3,3',4',5,7-pentahydroxyflavone
    https://spectrabase.com/spectrum/GvBDafvzXPO
    3,3',4',5,7-pentahydroxyflavone
    https://spectrabase.com/spectrum/G3tgio68UXd
  40. International Agency for Research on Cancer (IARC)
    LICENSE
    Materials made available by IARC/WHO enjoy copyright protection under the Berne Convention for the Protection of Literature and Artistic Works, under other international conventions, and under national laws on copyright and neighbouring rights. IARC exercises copyright over its Materials to make sure that they are used in accordance with the Agency's principles. All rights are reserved.
    https://publications.iarc.fr/Terms-Of-Use
    IARC Classification
    https://www.iarc.fr/
  41. NTP Technical Reports
  42. Japan Chemical Substance Dictionary (Nikkaji)
  43. Joint FAO/WHO Expert Committee on Food Additives (JECFA)
    LICENSE
    Permission from WHO is not required for the use of WHO materials issued under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Intergovernmental Organization (CC BY-NC-SA 3.0 IGO) licence.
    https://www.who.int/about/policies/publishing/copyright
  44. KEGG
    LICENSE
    Academic users may freely use the KEGG website. Non-academic use of KEGG generally requires a commercial license
    https://www.kegg.jp/kegg/legal.html
  45. LIPID MAPS
    Lipid Classification
    https://www.lipidmaps.org/
  46. MarkerDB
    LICENSE
    This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
    https://markerdb.ca/
  47. Metabolomics Workbench
  48. National Drug Code (NDC) Directory
    LICENSE
    Unless otherwise noted, the contents of the FDA website (www.fda.gov), both text and graphics, are not copyrighted. They are in the public domain and may be republished, reprinted and otherwise used freely by anyone without the need to obtain permission from FDA. Credit to the U.S. Food and Drug Administration as the source is appreciated but not required.
    https://www.fda.gov/about-fda/about-website/website-policies#linking
  49. Nature Chemical Biology
  50. NIPH Clinical Trials Search of Japan
  51. NLM RxNorm Terminology
    LICENSE
    The RxNorm Terminology is created by the National Library of Medicine (NLM) and is in the public domain and may be republished, reprinted and otherwise used freely by anyone without the need to obtain permission from NLM. Credit to the U.S. National Library of Medicine as the source is appreciated but not required. The full RxNorm dataset requires a free license.
    https://www.nlm.nih.gov/research/umls/rxnorm/docs/termsofservice.html
  52. PharmGKB
    LICENSE
    PharmGKB data are subject to the Creative Commons Attribution-ShareALike 4.0 license (https://creativecommons.org/licenses/by-sa/4.0/).
    https://www.pharmgkb.org/page/policies
  53. Pharos
    LICENSE
    Data accessed from Pharos and TCRD is publicly available from the primary sources listed above. Please respect their individual licenses regarding proper use and redistribution.
    https://pharos.nih.gov/about
  54. Protein Data Bank in Europe (PDBe)
  55. RCSB Protein Data Bank (RCSB PDB)
    LICENSE
    Data files contained in the PDB archive (ftp://ftp.wwpdb.org) are free of all copyright restrictions and made fully and freely available for both non-commercial and commercial use. Users of the data should attribute the original authors of that structural data.
    https://www.rcsb.org/pages/policies
  56. Springer Nature
  57. Thieme Chemistry
    LICENSE
    The Thieme Chemistry contribution within PubChem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.
    https://creativecommons.org/licenses/by-nc-nd/4.0/
  58. Wikidata
  59. Wikipedia
  60. Wiley
  61. Medical Subject Headings (MeSH)
    LICENSE
    Works produced by the U.S. government are not subject to copyright protection in the United States. Any such works found on National Library of Medicine (NLM) Web sites may be freely used or reproduced without permission in the U.S.
    https://www.nlm.nih.gov/copyright.html
  62. PubChem
  63. GHS Classification (UNECE)
  64. EPA Substance Registry Services
  65. MolGenie
    MolGenie Organic Chemistry Ontology
    https://github.com/MolGenie/ontology/
  66. PATENTSCOPE (WIPO)
  67. NCBI
CONTENTS