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. 2011 Dec;39(4):119-26.
doi: 10.2149/tmh.2011-29. Epub 2011 Dec 21.

Effect of Inducers, Incubation Time and Heme Concentration on IC(50) Value Variation in Anti-heme Crystallization Assay

Nguyen Thanh Thuy Nhien  1 , Nguyen Tien Huy, Dinh Thanh Uyen, Eric Deharo, Pham Thi Le Hoa, Kenji Hirayama, Shigeharu Harada, Kaeko Kamei
Affiliations

Effect of Inducers, Incubation Time and Heme Concentration on IC(50) Value Variation in Anti-heme Crystallization Assay

Nguyen Thanh Thuy Nhien et al. Trop Med Health. 2011 Dec.

Abstract

Heme detoxification through crystallization into hemozoin has been suggested as a good target for the development of screening assays for new antimalarials. However, comparisons among the data obtained from different experiments are difficult, and the IC(50) values (the concentrations of drug that are required to inhibit 50% of hemozoin formation) for the same drug vary widely. We studied the effects of changes in heme concentration (precursor of β-hematin), incubation time and three inducers (SDS, Tween 20 and linoleic acid) on the IC(50) of some antimalarials (chloroquine, quinine, amodiaquine, and clotrimazole). The results showed that increasing both inducer concentration and incubation time raised the IC(50) of selected antimalarials. Any change in those factors caused the IC(50) value to vary. Standardization of assay conditions is, therefore, necessary to increase reproducibility and reduce discrepancies in assay performance. Considering all of the variables, the best choice of inducers is in the order of SDS > Tween 20 > linoleic acid.

Keywords: IC50; antimalarial; heme crystallization; hemozoin; inducer; β-hematin.

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Figures

Fig. 1.
Fig. 1.
Follow-up of BH formation with increased concentrations of Tween 20 (A), SDS (B) and linoleic acid (C) after 12 h (open diamond) and 5 h (open square) of incubation
Fig. 2.
Fig. 2.
Follow-up of BH formation with increasing concentrations of heme promoted with 0.0025% Tween 20 (open square), 1% SDS (open circle), and 0.25 mg/ml linoleic acid (open triangle) after 5h of incubation
See this image and copyright information in PMC

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