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BioAssay: AID 423559

Inhibition of human recombinant glutathione reductase at pH 6.9

Methylene blue (MB) has experienced a renaissance mainly as a component of drug combinations against Plasmodium falciparum malaria. Here, we report biochemically relevant pharmacological data on MB such as rate constants for the uncatalyzed reaction of MB at pH 7.4 with cellular reductants like NAD(P)H (k = 4 M(-1) s(-1)), thioredoxins (k = 8.5 to 26 M(-1) s(-1)), dihydrolipoamide (k = 53 M(-1) more ..
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 Tested Compounds
 Tested Compounds
All(1)
 
 
Active(1)
 
 
 Tested Substances
 Tested Substances
All(1)
 
 
Active(1)
 
 
AID: 423559
Data Source: ChEMBL (574903)
BioAssay Type: Confirmatory, Concentration-Response Relationship Observed
Depositor Category: Literature, Extracted
BioAssay Version:
Deposit Date: 2010-05-26
Modify Date: 2014-05-16

Data Table ( Complete ):           Active    All
Target
Sequence: RecName: Full=Glutathione reductase, mitochondrial; Short=GR; Short=GRase; Flags: Precursor
Description ..   
Protein Family: Pyridine nucleotide-disulphide oxidoreductase, dimerization domain
Comment ..   

Gene:GSR     Related Protein 3D Structures     More BioActivity Data..
BioActive Compound: 1
Description:
Title: Interactions of methylene blue with human disulfide reductases and their orthologues from Plasmodium falciparum.

Abstract: Methylene blue (MB) has experienced a renaissance mainly as a component of drug combinations against Plasmodium falciparum malaria. Here, we report biochemically relevant pharmacological data on MB such as rate constants for the uncatalyzed reaction of MB at pH 7.4 with cellular reductants like NAD(P)H (k = 4 M(-1) s(-1)), thioredoxins (k = 8.5 to 26 M(-1) s(-1)), dihydrolipoamide (k = 53 M(-1) s(-1)), and slowly reacting glutathione. As the disulfide reductases are prominent targets of MB, optical tests for enzymes reducing MB at the expense of NAD(P)H under aerobic conditions were developed. The product leucomethylene blue (leucoMB) is auto-oxidized back to MB at pH 7 but can be stabilized by enzymes at pH 5.0, which makes this colorless compound an interesting drug candidate. MB was found to be an inhibitor and/or a redox-cycling substrate of mammalian and P. falciparum disulfide reductases, with the kcat values ranging from 0.03 s(-1) to 10 s(-1) at 25 degrees C. Kinetic spectroscopy of mutagenized glutathione reductase indicates that MB reduction is conducted by enzyme-bound reduced flavin rather than by the active-site dithiol Cys58/Cys63. The enzyme-catalyzed reduction of MB and subsequent auto-oxidation of the product leucoMB mean that MB is a redox-cycling agent which produces H2O2 at the expense of O2 and of NAD(P)H in each cycle, turning the antioxidant disulfide reductases into pro-oxidant enzymes. This explains the terms subversive substrate or turncoat inhibitor for MB. The results are discussed in cell-pathological and clinical contexts.
(PMID: 17967916)
Comment
Compounds with activity <= 50uM or explicitly reported as active by ChEMBL are flagged as active in this PubChem assay presentation.

Categorized Comment
Assay Type: Binding

Assay Data Source: Scientific Literature

BAO: Assay Format: biochemical format

Target Type: Target is a single protein chain

Protein Target Class: enzyme reductase

Result Definitions
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TIDNameDescriptionHistogramTypeUnit
OutcomeThe BioAssay activity outcomeOutcome
1IC50*IC50 PubChem standard valueFloatμM
3BEIBinding Efficiency Index(nM)Float
2SEISurface Efficiency Index(nM)Float
4LELigand EfficiencyFloat
5LLELipophilic Ligand EfficiencyFloat
6IC50 activity commentIC50 activity commentString
7IC50 standard flagIC50 standard flagInteger
8IC50 qualifierIC50 qualifierString
9IC50 published valueIC50 published valueFloatμM
10IC50 standard valueIC50 standard valueFloatnM
11IC50 binding domainsIC50 binding domainsString

* Activity Concentration.

Data Table (Concise)
Classification
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