Antifungal Activities of Selected Venda Medicinal Plants Against Candida Albicans, Candida Krusei and Cryptococcus Neoformans Isolated from South African AIDS Patients

1AIDS Virus Research Laboratory, Department of Microbiology, University of Venda, Thohoyandou , South Africa. 2Department of Chemical engineering, University of Virginia, Charlottesville, VA, USA. 3Department of Biochemistry and Microbiology, University of Fort Hare, Alice, South Africa. 4College of Agriculture and Life Sciences, University of South Africa, Private bag X6, Florida, Johannesburg, South Africa

Objectives: 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 these infections. Few studies have investigated the antifungal activities of Venda medicinal plants. This study was carried out to continue our identification of Venda medicinal plants with anti-fungal activity.

Methods: Seventy-six 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, C. 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 three most active plants were also determined.

Results: Extracts from 25 plants (83.3%) were active against C. albicans, C. krusei or Cryptococcus neoformans. Thirty two extracts were active against C. neoformans, while 15 were active against Candida 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 of the 3 fungi used (MIC/MFC between 0.11mg/ml and 7.5mg/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.

Conclusion: This study has identified new plants with antifungal activity that could be used as sources for the isolation of active compounds that may serve as lead compounds in antifungal drug development. Further studies of their cytotoxicity or toxicity will be beneficial in providing data on the possible harmful effects of these plants commonly used by several communities in Venda, South Africa.