Abstract

Background The Sidama nation of southern Ethiopia traditionally uses various medicinal plants, locally referred to as Ameessa , for the management of childhood ailments. This study investigated the antibacterial activities of six most frequently reported Ameessa plants and identified the most active fractions responsible for these effects. Methods Powdered plant materials were extracted with methanol, filtered, and concentrated to dryness. Antibacterial activity was initially evaluated using the disc diffusion assay. The minimum inhibitory concentration (MIC) was determined by the broth microdilution method, and the minimum bactericidal concentration (MBC) was established through sub-culturing from non-growth wells. Extracts showing strong antibacterial activity were subjected to column chromatography for fractionation, and the resulting fractions were tested for antibacterial properties. Results Among the six medicinal plants screened, Ekebergia capensis and Plectranthus garckeanus exhibited better antibacterial activity, with zones of inhibition ranging from 7 to 16 mm. Staphylococcus aureus was the most sensitive strain, whereas Escherichia coli showed the least susceptibility. Fractions derived from E. capensis showed MIC values between 0.0867 and 0.1734 mg/mL against S. aureus and Enterococcus faecalis , while fractions from P. garckeanus displayed MICs ranging from 0.0867 to 2.775 mg/mL. The most active E. capensis fraction demonstrated a potent bactericidal effect with the MBC of 0.1734 mg/mL. Conclusion Methanolic extracts and chromatographic fractions of E. capensis and P. garckeanus exhibited significant antibacterial activity—particularly against S. aureus and E. faecalis —highlighting as potential sources of novel antibacterial agents. Further phytochemical and pharmacological studies are warranted to purify and characterize the bioactive compounds and evaluate their in vivo efficacy and safety for potential therapeutic development.