LAUSR

Abstract Herbal medicine use is common in rural communities of Zimbabwe since generic drugs are expensive and not readily available. In this work, we carried out phytochemical screening of secondary metabolites and used GC MS and tandem mass spectroscopy (LC MS/MS) to characterize Xeroderris stuhlmannii (Taub.) Mendonca & E.P. Sousa bark extracts. The activity of bark extracts on six bacterial strains were tested in vitro using the disc diffusion method. Qualitative screening of secondary metabolites confirmed the presence of alkaloids, flavonoids, terpenoids, steroids and polyphenols in the crude bark extracts. Methanol extracted more secondary metabolites compared to other solvents. The minimum inhibitory concentrations (MICs) values for the crude extracts on six bacterial strains ranged from 0.23–0.80 mg/mL. Antibacterial tests showed higher potency for crude bark extracts on E. Coli (MIC, 0.232 mg/mL) and lower potency on coliform (MIC, 0.798 mg/mL). LC-MS/MS analysis of various fractions confirmed the presence of twenty-eight phytochemicals whereas, twelve phytochemicals were identified using GC-MS. Both techniques confirmed the presence of ursolic acid, roburic acid, reticuline, rotenone and p-coumaric acid glucoside in hexane and methanol extracts. Our findings demonstrate that Xeroderris stuhlmannii (Taub.) Mendonca & E.P. Sousa contain many phytochemical compounds that have antibacterial activity. Some of these compounds in the bark extract possess antioxidant, antiviral, antitumor and anti-inflammatory properties. Thus, Xeroderris stuhlmannii (Taub.) Mendonca & E.P. Sousa barks can act as a useful herbal supplement for treatment of a number of diseases in rural communities. Future work will involve isolation of bioactive phytochemicals and their full characterization using LC MS/MS as well as testing their antioxidant, antidiabetic, anticancer properties and toxicity.