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BioAssay: AID 504604

Quantitative high throughput screen to test activity of anti-malarial compounds in the Dd2 strain of Plasmodium Falciparum

The goal of this screen is to measure the ability of a set of anti-malarial compounds to inhibit the Dd2 strain of P. falciparum. These compounds have been screened in a delayed death phenotype assay and have been identified as inhibitors of the delated death phenotype, by inhibiting the development of the apicoplast in the malarial parasite Plasmodium falciparum (described below) ..more
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 Tested Compounds
 Tested Compounds
All(53)
 
 
Active(52)
 
 
Inconclusive(1)
 
 
 Tested Substances
 Tested Substances
All(54)
 
 
Active(53)
 
 
Inconclusive(1)
 
 
 Related BioAssays
 Related BioAssays
AID: 504604
Data Source: NCGC (BDDDD2)
BioAssay Type: Confirmatory, Concentration-Response Relationship Observed
Depositor Category: NIH Molecular Libraries Probe Production Network
BioAssay Version:
Deposit Date: 2011-03-28
Hold-until Date: 2012-02-12
Modify Date: 2012-02-13

Data Table ( Complete ):           Active    All
BioActive Compounds: 52
Depositor Specified Assays
AIDNameTypeComment
488774Quantitative high throughput screen for delayed death inhibitors of the malarial parasite plastid: Summarysummary
Description:
NIH Molecular Libraries Probe Production Network [MLPCN]
NIH Chemical Genomics Center [NCGC]

MLPCN Grant: R21 NS059500
Assay Provider: David Fidock and Eric Ekland, Columbia University

The goal of this screen is to measure the ability of a set of anti-malarial compounds to inhibit the Dd2 strain of P. falciparum. These compounds have been screened in a delayed death phenotype assay and have been identified as inhibitors of the delated death phenotype, by inhibiting the development of the apicoplast in the malarial parasite Plasmodium falciparum (described below)

The biochemical processes that make this organelle essential for erythrocytic stage parasites are not well understood. However, antibiotics, such as azithromycin and tetracycline, which target the apicoplast translational machinery, have a potent antimalarial effect. The killing caused by these drugs is unusual in that it does not appear to affect the first generation of parasites that are exposed to the drug, but rather manifests itself in their progeny.
We have developed a cell-based assay that measures parasite growth based on the expression of an integrated copy of a firefly luciferase reporter. To detect small molecules that cause this 'delayed death' phenotype, erythrocytes infected with the luciferase-expressing parasites were incubated with compounds for either one or two generations, corresponding to 48 and 96 hours, respectively. Compounds that inhibit parasite growth in the second generation, but not the first, should be enriched in antimalarials that target the apicoplast. Growth inhibition is detected by a decrease in luciferase activity
Protocol
3 ul culture medium was dispensed into black clear-bottom plates (aurora) with multidrop Combi followed by a pin-transfer of 23 ul compounds and positive control into assay plates. (Controls: 1 mM Artemisinin 1:2 dilution in duplicate Multi-Drop dispense of P. falciparum infected RBCs (0.3% parasitemia, 2.5% hematocrit final concentration) followed by 72 hr incubation (37C, 5% CO2). Multi-drop dispense 2 ul 10 X SYBR Green lysis buffer (20 M Tris-HCl, 10 mM EDTA, 0.16% saponin (w/v), 1.6% Triton-X (v/v), 10 x SYBR Green I supplied as 10,000 x final concentration by Invitrogen) into assay plates. Incubated at Room temperature, overnight in the dark and then read using Envision (Perkin Elmer) with fluorescence intensity at 485 nM excitation and 535 nM emission wavelengths.
Comment
Compound Ranking:

1. Compounds are first classified as having full titration curves, partial modulation, partial curve (weaker actives), single point activity (at highest concentration only), or inactive. See data field "Curve Description". For this assay, apparent inhibitors are ranked higher than compounds that showed apparent activation.
2. For all inactive compounds, PUBCHEM_ACTIVITY_SCORE is 0. For all active compounds, a score range was given for each curve class type given above. Active compounds have PUBCHEM_ACTIVITY_SCORE between 40 and 100. Inconclusive compounds have PUBCHEM_ACTIVITY_SCORE between 1 and 39. Fit_LogAC50 was used for determining relative score and was scaled to each curve class' score range.
Result Definitions
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TIDNameDescriptionHistogramTypeUnit
OutcomeThe BioAssay activity outcomeOutcome
ScoreThe BioAssay activity ranking scoreInteger
1PhenotypeIndicates type of activity observed: inhibitor, activator, fluorescent, cytotoxic, inactive, or inconclusive.String
2Potency*Concentration at which compound exhibits half-maximal efficacy, AC50. Extrapolated AC50s also include the highest efficacy observed and the concentration of compound at which it was observed.FloatμM
3EfficacyMaximal efficacy of compound, reported as a percentage of control. These values are estimated based on fits of the Hill equation to the dose-response curves.Float%
4Analysis CommentAnnotation/notes on a particular compound's data or its analysis.String
5Curve_DescriptionA description of dose-response curve quality. A complete curve has two observed asymptotes; a partial curve may not have attained its second asymptote at the highest concentration tested. High efficacy curves exhibit efficacy greater than 80% of control. Partial efficacies are statistically significant, but below 80% of control.String
6Fit_LogAC50The logarithm of the AC50 from a fit of the data to the Hill equation (calculated based on Molar Units).Float
7Fit_HillSlopeThe Hill slope from a fit of the data to the Hill equation.Float
8Fit_R2R^2 fit value of the curve. Closer to 1.0 equates to better Hill equation fit.Float
9Fit_InfiniteActivityThe asymptotic efficacy from a fit of the data to the Hill equation.Float%
10Fit_ZeroActivityEfficacy at zero concentration of compound from a fit of the data to the Hill equation.Float%
11Fit_CurveClassNumerical encoding of curve description for the fitted Hill equation.Float
12Excluded_PointsWhich dose-response titration points were excluded from analysis based on outlier analysis. Each number represents whether a titration point was (1) or was not (0) excluded, for the titration series going from smallest to highest compound concentrations.String
13Max_ResponseMaximum activity observed for compound (usually at highest concentration tested).Float%
14Activity at 0.0000004844 uM (4.84446e-07μM**)% Activity at given concentration.Float%
15Activity at 0.0000013702 uM (1.37022e-06μM**)% Activity at given concentration.Float%
16Activity at 0.0000027404 uM (2.74044e-06μM**)% Activity at given concentration.Float%
17Activity at 0.0000054809 uM (5.48089e-06μM**)% Activity at given concentration.Float%
18Activity at 0.0000109618 uM (1.09618e-05μM**)% Activity at given concentration.Float%
19Activity at 0.0000219235 uM (2.19235e-05μM**)% Activity at given concentration.Float%
20Activity at 0.0000438471 uM (4.38471e-05μM**)% Activity at given concentration.Float%
21Activity at 0.0000876942 uM (8.76942e-05μM**)% Activity at given concentration.Float%
22Activity at 0.0001624431 uM (0.000162443μM**)% Activity at given concentration.Float%
23Activity at 0.0004837500 uM (0.00048375μM**)% Activity at given concentration.Float%
24Activity at 0.0007015535 uM (0.000701554μM**)% Activity at given concentration.Float%
25Activity at 0.00146 uM (0.00145886μM**)% Activity at given concentration.Float%
26Activity at 0.00434 uM (0.00434446μM**)% Activity at given concentration.Float%
27Activity at 0.00561 uM (0.00561243μM**)% Activity at given concentration.Float%
28Activity at 0.013 uM (0.0131017μM**)% Activity at given concentration.Float%
29Activity at 0.039 uM (0.0390165μM**)% Activity at given concentration.Float%
30Activity at 0.045 uM (0.0448994μM**)% Activity at given concentration.Float%
31Activity at 0.118 uM (0.117663μM**)% Activity at given concentration.Float%
32Activity at 0.351 uM (0.350552μM**)% Activity at given concentration.Float%
33Activity at 0.718 uM (0.718391μM**)% Activity at given concentration.Float%
34Activity at 1.070 uM (1.07011μM**)% Activity at given concentration.Float%
35Activity at 3.187 uM (3.18674μM**)% Activity at given concentration.Float%
36Activity at 9.579 uM (9.57854μM**)% Activity at given concentration.Float%
37Activity at 28.74 uM (28.7356μM**)% Activity at given concentration.Float%
38Compound QCNCGC designation for data stage: 'qHTS', 'qHTS Verification', 'Secondary Profiling'String

* Activity Concentration. ** Test Concentration.
Additional Information
Grant Number: R21 NS059500

Data Table (Concise)
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