Antifungal activities of selected Venda medicinal plants against Candida albicans, Candida krusei and Cryptococcus neoformans isolated from South African AIDS patients.

Abstract

Infection with HIV leads to immunosuppression and up to 90% of HIV infected individuals contract fungal infections of which 10 - 20% die as a direct consequence of these infections. In the present study, 76 extracts from 30 plants used by Venda traditional healers for the treatment of fungal related ailments, were tested for their antifungal activities against clinical isolates of Candida albicans, Candida krusei and Cryptococcus neoformans using the agar diffusion and the microdilution methods. The minimum fungicidal concentrations as well as the time kill curves of the thee most active plants were also determined. Extracts from 25 plants (83.3%) were active against C. albicans, C. krusei or C. neoformans. Thirty two extracts were active against C. neoformans, while 15 were active against C. albicans and 12 were active against C. krusei. Warburgia salutaris, Cassine transvaalensis, Piper capense, Maerua edulis, Pseudolachnostylis maprouneifolia, Berchemia discolor and Lippia javanica were not only inhibitory to fungal growth but also had fungicidal effects against one or all the 3 fungi tested (MIC/MFC between 0.11 and 7.5 mg/ml). Hexane extracts were also active indicating that many of the antifungal components of these plants are non-polar compounds. Time-to- kill experiments indicated an intense time-dependent fungicidal effect against C. albicans, achieving over a 5 h-period a 6 log10-unit decrease in CFU/ml at a concentration of 0.4 mg/ml for W. salutaris. The present study justifies the traditional use of these plants for the treatment of opportunistic infections in the region.