Antifungal and antibacterial activity of some medicinal plants used traditionally in Kenya

Abstract

Abstract. Jacqueline I, Okemo P, Maingi J, Bii C. 2018. Antifungal and antibacterial activity of some medicinal plants used traditionally in Kenya. Asian J Ethnobiol 2: 75-90. Many plants have been used by various communities in Kenya in the treatment of bacterial and fungal infections but they have not been validated. The aim of this study was to determine the efficacy of some medicinal plants used by various communities in Kenya that treat the selected bacterial and the selected fungal diseases in man. An ethnobotanical survey was used to select and collect plants from Mwingi North, Kisii South and Rarieda Districts based on their use to treat infectious diseases such as skin infection, diarrhea and many others. Crude extracts from Zanthoxylum chalybeum Engl., Boscia angustifolia A. Rich, Melia volkensii Gürke, Zanthoxylum gilletii (De Wild.) Waterman, Fuerstia africana T.C.E.Fr., Urtica dioica L., Vernonia amygdalina Delile, Ricinus communis L., Commiphora africana (A. Rich) Engl., Psiadia punctulata DC.) Oliv. & Hiern ex Vatke, Senna didymobotrya (Fresen.) H.S.Irwin & Barneby, Ormocarpum trichocarpum (Taub.) Engl., Sesbania sesban L., Balanites aegyptiaca (L.) Delile, Albizia coriaria Welw. ex Oliv., Ficus sycomorus L., Rhus natalensis Bernh. ex Krauss and Tamarindus indica L. believed to contain secondary metabolites were screened against ten microorganisms, including the bacteria: Salmonella typhi ATCC 19430, Escherichia coli ATCC 25922, Bacillus subtilis, Staphylococcus aureus ATCC 25923 and Methicillin-resistant S. aureus. The fungal strains that were used are; Aspergillus niger, Candida albicans ATCC 90028, Microsporum gypseum, Cryptococcus neoformans ATCC 18310 and Trichophyton mentagrophyte. The plants were screened using Kirby Bauer disc diffusion method. Phytochemical screening was carried out to identify the presence or absence of classes of bioactive compounds. Data were analyzed using one way ANOVA, significant means were separated using Tukey’s test. Generally, F. africana, Z. chalybeum, B. aegyptiaca, O. trichocarpum, S. didymobotrya and T. indica gave strong antibacterial results of between 14.5 mm and 20 mm as A. coriaria, F. sycomorus, C. africana, R. natalensis, S. didymobotrya, P. punctulata, and T. indica produced strong antifungal results of between 15.5 mm and 20.5 mm. The results of MICs and the MBCs/MFCs of the extracts of A. coriaria, F. sycomorus, S. didymobotrya, P. punctulata, F. africana, B. aegyptiaca and T. indica showed good activity of 0.9375 mg/mL in some test cultures. S. typhi ATCC 19430 and E. coli ATCC 25922 were the least sensitive bacteria while C. albicans ATCC 90028 was the least sensitive fungus. The present study indicates that the majority of the plants tested are an important source of antibacterial agents, especially on Gram-positive bacteria (S. aureus, B. subtilis and Methicillin-resistant S. aureus) and antifungal agents against the dermatophytes, especially M. gypseum. This study recommends that the plant extracts with good antimicrobial activity be subjected to pharmacological and toxicological studies.