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The Leishmania group is headed by Dr. Luz Romero. A novel colorimetric assay was developed and standardized that provided a quantitative and efficient method for the evaluation of anti-leishmanial activity in plant extracts and purified compounds. The assay employs the tetrazolium salt, sodium-2, 3-bis-[2-Methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT). In the presence of the electron-coupling agent, phenazine methasulfate, XTT is reduced by mithocondrial dehydrogenase to a water-soluble product in the culture media supernatant whose concentration can be determined by measuring the optical density at 450 nM in a microplate reader. Optical density values obtained at 450 nM with the XTT method correlated well (r = 0.965) with parasite numbers in a growth curve of L. mexicana determined by microscopic counting. The minimal number of parasites detected over the control background was 977 promastigotes. The IC50 values obtained for the reference anti-leishmanial drugs, amphotericin-B, hexadecylphosphocholine (Miltefosine) and Ketoconazole were 0.037 g/mL, 10.2 g/mL and 0.023 g/mL, respectively, and were similar to those previously documented. [Home] [Collection Techniques] [Collection Sites] [Project Staff] [Gallery] [Inventory] [Links] |
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Samples are tested for activity in bioassays against cancer, HIV,leishmaniasis, Chagas' disease, malaria and agricultural
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