Antifungal activity of extracts from selected Kenyan medicinal plants

Abstract

The use of medicinal herbs in the treatment of diseases is an age-old practice. In Kenya' several plant species are used by many ethnic groups for treatment of various diseases raging from minor infections to asthma, dysentery, skin diseases and a horde of others. To establish the claimed therapeutic efficacy of some commonly used medicinal plants, in vitro antifungal activity tests of extracts from 28 Kenyan medicinal plant species was carried out. The activity of the extracts was studied on three human pathogens, Trichophyton mentagrophytes Robin, Microsporum gypseum Bodin and Candida albicans (Robin) Berkh. and one plant pathogenic fungus Cladosporium cucumerinum Ellis and Arth .. The disc assay method was used for the evaluation of fungitoxicity. Bioactivity guided fractionation was done for extracts that showed measurable activity. Extracts from 17 plant sQecles were variably active against Trichophyton mentagrophytes, Microsporum gypseum, Candida albicans and Cladosporium cucumerinum. The plant species included, Acacia nilotica (L.) Del, Acacia senegal (L.) Willd, Adenia volkensii Harms, Ajuga remota Benth., Aporrhiza -paniculata Radlk., Aspilia pluriseta Schwieinf. Ex. Engl., Azadirachta indica A. Juss., Senna didymobotrya (Fresen.) Irwin and Batneby, Commiphora africana (A. Rich.) Engl., Hymenodictyon parvifolium Oliv., Plectranthus barbatus Andr., Plectranthus cylindraceus Benth., Premna resinosa (Hochst Schauer, Schizozygia coffaeoides Baill, Solanum arundo Mattei, Solanum nigrum L. and Tagetes minuta L. Bioactivity guided fractionation led to the isolation of a potent antifungal compound from Schizozygia coffaeoides Baill. From spectroscopic and chemical analysis, the compound was determined as an indole alkaloid with a molecular formula C21H22N204 .The compound was fungistatic in action and affected the filamentous and yeast fungi by causing swelling and gloss morphological distortions. From the results of this study, it is evident that some Kenyan medicinal plants have properties which could be exploited for the management of pathogenic fungi in humans and plants.