Antibacterial activity of Pycnostachys abyssinica and Rhamnus prinoides root and leaf extracts against targeted bacterial strains

Abstract

The flora of Ethiopia comprises 6,500 to 7,000 species, with 12–19 % being endemic, including valuable medicinal plants. The study aimed to evaluate the antibacterial activity of Pycnostachys abyssinica and Rhamnus prinoides root and leaf extracts against bacteria associated with various infections, particularly in clinical settings. Four different bacterial species associated with human infections in clinical settings namely; Staphylococcus epidermidis (ATCC 25923), Enterobacter aerogenes (ATCC 25922), Streptococcus pyogenes (ATCC 49619), and Pseudomonas aeruginosa (ATCC 27853) were obtained from the Ethiopian Public Health Institute (EPHI). The extraction and phytochemical screening were conducted using ethanol, methanol, and aqueous solvents. The antibacterial activity of the extracts was assessed using disc diffusion on agar medium, as well as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) analysis. The qualitative phytochemical analysis of the extracts indicated varied phytochemical profiles among the plant species, their parts, and the extraction solvents used. The most susceptible bacterial species in the present study, based on MIC and MBC values, were P. aeruginosa and E. aerogenes, respectively. The least susceptible bacterial species was S. epidermidis, with significantly higher MIC and MBC values (p < 0.001). Future studies should focus on isolating active compounds, conducting toxicity testing, and performing in vivo validations to assess clinical applications.