DRUG CYTOTOXICITY ASSAY FOR AFRICAN TRYPANOSOMES AND LEISHMANIA SPECIES

The trypanosomes and Leishmania species are parasitic protozoa that af flict millions of people throughout the world. If not treated, African trypanosomiasis and visceral leishmaniasis are fatal. The available d rugs are severely limited by toxicity, marginal efficacy, the requirem ent for parenteral administration, and spreading drug resistance. In t his study, a spectrophotometric assay was developed and validated for measuring the cytotoxicity of test compounds against axenically cultur ed bloodstream-form Trypanosoma brucei (African trypanosomes) and prom astigotes of Leishmania donovani. Enzymatic hydrolysis of p-nitropheny l phosphate, monitored by a microtiter plate reader, is a reliable sur rogate for parasite cell counts. The assay is simple, inexpensive, and highly reproducible. The coefficient of variation for ECS, values is <10% for determinations obtained over several months. This method perm its the rapid screening of candidates for much-needed new drugs agains t these parasites.