In vitro Antimicrobial Activities, Qualitative Phytochemical Screening, and Free Radical Scavenging Capacities of Gymnanthemum myrianthum

Various members of the genus Vernonia are commonly used in traditional medicine to treat fever, malaria, diarrhoea, dysentery, hepatitis, cough, fertility inducer and as a laxative. Vernonia myrianthum (Gymnanthemum myrianthum) is one of the medicinal plants used by traditional healers in Uasin-Gishu and Elgeiyo Marakwet counties to treat communicable and non-communicable diseases such as diabetes mellitus. The objectives of this study were to evaluate the phytochemicals, free radical scavenging capacity and antimicrobial activities of the methanolic root extract of Vernonia myrianthum. Standard phytochemical screening methods were employed to qualitatively evaluate the classes of phytochemicals present in the plant. The anti-oxidant capacity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The disc diffusion method and minimum inhibitory concentration (MIC) were used to screen for antimicrobial activity against Escherichia coli and Staphylococcus aureus. Vernonia myrianthum was found to contain secondary metabolites such as alkaloids, flavonoids, tannins, terpenoids, carotenoids, and coumarin. The antioxidant activity on the extract as based on its IC₅₀ values indicated good antioxidant activity. There was no significant difference (p≥0.01) between the zones of inhibition of Vernonia myrianthum and those of those of the positive control gentamycin (GEN, at 10 mcg) and amoxicillin (AMC, 30 mcg) at various test concentrations demonstrating that V. myrianthum could inhibit the growth of E. coli and S. aureus. The   findings of this study are critical in understanding and documenting the phytochemistry, the antimicrobial properties and the antioxidant capabilities of V. myrianthum thus, laying the groundwork for future research on isolating bioactive compounds from these plants, as well as building the body of evidence needed to justify the ethnomedicinal usage of this plant in the treatment of numerous diseases by different communities.