Comparison of Tetrazolium Salt Assays for Evaluation of Drug Activity against Leishmania spp

Abstract

In French Guiana, leishmaniasis is an essentially cutaneous infection. It constitutes a major public health problem, with a real incidence of 0.2 to 0.3%. Leishmania guyanensis is the causal species most frequently encountered in French Guiana. The treatment of leishmaniasis is essentially drug based, but the therapeutic compounds available have major side effects (e.g., liver damage and diabetes) and must be administered parenterally or are costly. The efficacy of some of these agents has declined due to the emergence of resistance in certain strains of Leishmania. There is currently no vaccine against leishmaniasis, and it is therefore both necessary and urgent to identify new compounds effective against Leishmania. The search for new drugs requires effective tests for evaluations of the leishmanicidal activity of a particular molecule or extract. Microculture tetrazolium assays (MTAs) are colorimetric tests based on the use of tetrazolium salts. We compared the efficacies of three tetrazolium salts-3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT), and 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-8)-for quantification of the promastigotes of various species of Leishmania. We found that the capacity of Leishmania to metabolize a tetrazolium salt depended on the salt used and the species of Leishmania. WST-8 was the tetrazolium salt best metabolized by L. guyanensis and gave the best sensitivity.

Propofol protects human cardiac cells against chemical hypoxiainduced injury by regulating the JNK signaling pathways

“…In view of the higher detection sensitivity than other tetrazolium salts such as an MTT assay, CCK-8 is widely used for determination of cell viability in cell proliferation and cytotoxicity assays (29). In the present study, although absorbance values were different in control groups of different cells, which may have resulted from different incubation times, cell viability in all assays was accurately assessed by CCK-8.…”

Cytotoxicity of Exfoliated Layered Vanadium Dichalcogenides

“…MTT and WST‐8 assays were selected as they have been commonly used for in vitro nanotoxicity assessments; this allows easy comparison with other studies . Both assays have similar working principles, whereby they contain active tetrazolium reagents that become reduced in the presence of viable cells to coloured formazan dyes . For the MTT assay, purple insoluble crystals of formazan dye are produced that require an organic solvent, such as dimethyl sulfoxide, for dissolution prior to absorbance measurement .…”

In Vitro Sensitivity of Cutaneous Leishmania Promastigote Isolates Circulating in French Guiana to a Set of Drugs

“…Viability tests were performed in triplicate using the Cell Counting Kit-8 assay (Sigma, St. Louis, MO), according to the procedure of Ginouves and others. 31 Briefly, 10 6 parasites/well, in the exponential growth phase, were placed in contact with different drug concentrations in a 96-well plate for 48 hours at 26°C. Then, 10% of WST-8 was added and the parasites were incubated for a further 24 hours at 26°C.…”