Comparative metabolite profiling, antioxidant, and antibacterial activities of three medicinal plants from Botswana

Abstract

Natural resources provide vital support to communities, and in this regard indigenous plants remain particularly important, as they are widely used for food, medicine, and cultural practices. In the quest to integrate these resources into modern applications, exploring their phytochemical composition is essential for both conservation and utilization. This study compared the phytochemical profiles, antioxidant capacity, and antimicrobial activity of Tylosema esculentum (Burch.) A.Schreib., Myrothamnus flabellifolius Welw., and Ozoroa paniculosa (Sond.) R.Fern. & A.Fern. using water, 80% methanol, and 50% acetone extracts. Ultra-Performance Liquid Chromatography–High Resolution Mass Spectrometry (UPLC-HRMS) profiling revealed M. flabellifolius bears diverse phytochemicals, with major flavonoids including quercetin 3-O-glucuronide and quercitrin. Acetone extracts of M. flabellifolius exhibited the highest DPPH radical scavenging activity (57.13%) and strongest antibacterial effects against Escherichia coli (ATCC 25922), Salmonella enterica subsp. enterica serovar typhimurium (ATCC 13311) and Staphylococcus aureus (ATCC 25923). The 50% acetone extracts particularly demonstrated dose-dependent antimicrobial activity, with inhibition zones reaching up to 20.1 mm for E. coli and 16.9 mm for S. typhimurium. Solvent type significantly influenced the phytochemical content and bioactivity of the extracts, with 50% acetone generally outperforming water and 80% methanol. Overall, the indigenous plants of Botswana demonstrated considerable potential as sources of bioactive compounds for use as natural antimicrobial agents in food packaging and preservation. In particular, Myrothamnus flabellifolius exhibited the most diverse phytochemicals profile and the strongest antimicrobial properties. These findings highlight the plant’s potential for development into natural antimicrobial products, warranting further investigation and application-focused research.