Phytonutrient Screening and In vitro Antibacterial and Antifungal Properties of Polar and Nonpolar Extracts of Albizia gummifera, Prunus africana, and Combretum molle from Mount Elgon Region, Kenya

Background: Globally, and particularly in less-developed countries, one of the principal factors associated with morbidity and mortality is infectious diseases. Over the years, the abuse and misuse of pharmaceutical products have caused an increase in resistant microbes, and consequently, today, the rate of infectious disease cases continues to increase to dangerously high levels as most medications have lost their efficacy. This indicates that there’s a need for new effective medications and calls for active research in drug discovery to curb this dangerous trend.

Results: Obtained data demonstrated the presence of different bioactive compounds in the tested plant extracts such as glycosides, alkaloids, tannins, terpenoids, saponins, and phenols. Using the Kirby-Bauer disc diffusion method, P. africana methanol and ethyl acetate extracts showed significantly bigger inhibition zones compared to the rest against S. aureus (excluding controls). None of the tested extracts, however, were able to inhibit C. albicans and E. coli. The P. africana methanolic extract and the A. gummifera hexane, ethyl acetate, and methanolic extracts all inhibited the growth of S. aureus at the same minimum concentration of 31.25 mg/ml. The methanolic extract of C. molle exhibited the least activity against S. aureus, with an MIC of 250 mg/ml and mean zones of inhibition of 9.33±0.33 mm.

Conclusions: This study revealed the presence of various phytoconstituents in crude extracts of the selected medicinal plants, but also highlighted the resistance of E. coli and C. albicans to these phytochemicals. The P. africana methanolic extract showed strongest inhibitory effect against S. aureus compared to the other plant extracts. The highest susceptibility was demonstrated by S. aureus, while E. coli and C. albicans were resistant to all the extracts. These findings support the usage of A. gummifera, P. africana, and C. molle in folk medicine against infections caused by S. aureus and highlight them as potential sources of phytonutrients for the development of new drugs.