In-vitro Antibacterial and Antifungal Activities of the Stem Bark Extract and Fractions of Warbugia. ugadensis, Prunus africana and Albizia gummifera from Mt Kenya and Elgon Regions in Kenya

Abstract

Fungal and bacterial infections pose a major global public health challenge due to rising antimicrobial resistance. Over 50% of hospital infections now involve pathogens resistant to multiple drugs, contributing to higher death rates, longer patient illness, and increased/prolonged hospital stays. Exploration of medicinal plants' phytochemical properties provides one avenue for developing new treatment options outside the traditional drug development process to address the intensifying antimicrobial resistance crisis. The plant materials were subjected to cold maceration followed by liquid-liquid partitioning using hexane, dichloromethane (DCM), and ethyl acetate in order of increasing polarity. The derived methanol extracts were screened for phytochemicals using standard procedures. The disk diffusion method evaluated the antimicrobial activity of 50mg/mL of W. ugadensis, P. africana, and A. gummifera against S. aureus, E. coli, and C. albicans. The study qualitatively and quantitatively assessed antibacterial and antifungal activities by observing inhibition zones and determining minimum inhibitory concentration (MIC) values.  Several bioactive compounds were detected in the methanolic extract of these plants such as saponins, alkaloids, terpenoids, tannins, flavonoids, phenols, and glycosides. Preliminary disk diffusion screening revealed that W. ugadensis DCM extract exhibited the strongest antimicrobial activity against C. albicans, E. coli, and S. aureus, with mean inhibition zones of 21.0, 10.3, and 15.7mm respectively. MIC analyses with 96-well microliter plate assays confirmed S. aureus as the most susceptible and E. coli as the least vulnerable to the extracts. Tukey’s Multiple Comparison Test (P < 0.05) demonstrated significant differences in antimicrobial activity among A. gummifera, W. ugandensis, and P. africana. The inhibition of the various plant extracts against the tested microorganisms indicates that further study could reveal their potential use in treating infections caused by these microorganisms.  Additional research is required to fully elucidate their therapeutic potential and explore practical applications for combating microbial infections.