Antimicrobial activity and qualitative phytochemical composition of crude extracts from medicinal plants against selected enteric bacterial pathogens and candida albicans

Abstract

Opinde HR, Nyamache AK, Gatheri GW. 2017. Antimicrobial activity and qualitative phytochemical composition of crude extracts from medicinal plants against selected enteric bacterial pathogens and Candida albicans. Bioteknologi 14: 1-12. Determining the antimicrobial activity, combined effects of the selected plant leaf extracts of Tagetes minuta, Aloe secundiflora, Vernonia lasiopus and Bulbine frutescens against selected clinical isolates of Escherichia coli, Salmonella typhi, Staphylococcus aureus, Shigella flexineri, Enterococcus faecalis and Candida albicans obtained from Kenyatta University Health Centre; using the Kirby-Bauer method became the aim of this study. Moreover, the determination of qualitative analysis of the phytochemicals present in the extracts was also carried out. Kenyatta University arboretum and voucher specimen deposited in the University herbarium became the source of plant materials. SAS version 9.1 with ANOVA was used to analyze the collected data. Furthermore, the data was subjected to a post hoc test with P<0.05 being considered significant. In the single use or combination of microorganism test, tested microorganisms the average inhibition zones were found to be significant at P<0.05. In the low concentrations on the tested microorganisms; V. lasiopus was more active against S. flexineri (MIC 3.3 µg/mL, MBC 7.1 µg/mL), B. frutescens against S. flexineri (MIC 3.2 µg/mL, MBC 6.2 µg/mL), A. secundiflora against S. flexineri (MIC 3.7 µg/mL, MBC 8.0 µg/mL) and T. minuta against E. faecalis (MIC 5.1 µg/mL, MBC 6.3 µg/mL)*. The extracts combination also showed a significant increased and decreased antimicrobial activity i.e. P<0.05. The average inhibition zone formed by the combination of A. secundiflora and T. minuta plant leaf extracts (8.67±1.86mm) showed a decrease in antimicrobial activity as compared to T. minuta (15.17±2.71mm) and A. secundiflora (17.00±2.10mm) respectively in the usage against C. albicans. The presence of four phytochemicals; saponins, tannins, alkaloids, and flavonoids is shown in the qualitative phytochemical analysis. An insight into the antimicrobial activities of the plant extracts and their use in the treatment of bacterial or fungal infections is provided by this study. This information might be used in herbal medicine in making concoctions to maximize their effectiveness. To elucidate the actual compounds in the plant leaf extracts responsible for the antimicrobial activity is needed and this elucidation can be used in drug development.