Identification of bioactive compounds and evaluation of antibacterial activity of selected medicinal plants against vibrio cholerae

Background: Cholera has remained a significant public health concern in sub-Saharan Africa since its emergence and is still endemic today. Despite the manageable nature of the disease, cholera in Zimbabwe continues to pose a major public health challenge due to various overwhelming factors. Medicinal plants are effective options for such infections due to their diverse bioactive compounds with notable therapeutic potential. Thus the study focused on identifying medicinal plants utilised in traditional cholera treatment and validating their medicinal use through analysis of bioactive compounds, cytotoxicity assessment, and evaluation of antibacterial activity against Vibrio cholerae. Methodology: A literature study approach was employed, to identify and select medicinal plants. The agar well diffusion method was applied to evaluate the antibacterial efficacy of these selected plants against V. cholerae, while the brine shrimp lethality assay was conducted to assess their cytotoxic activity. Finally, gas chromatography-mass spectrometry (GC-MS) analysis was performed to determine the bioactive compounds present in the selected medicinal plants. Results: Ziziphus mucronata Willd., Kirkia acuminata Oliv., Sclerocarya birrea Hochst., and Crossopteryx febrifuga Benth. were the most utilised by several ethnic groups. Significant anti-Vibrio cholerae activity was demonstrated by K. acuminata, S. birrea, and Z. mucronata, with minimum inhibitory concentrations (MIC) of stembark extracts at ≤ 1 mg/mL. Extracts of Z. mucronata and K. acuminata showed no toxic effects, with lethality concentrations (LC50) of 1023.58 μg/mL and 1583.34 μg/mL, respectively. The GC-MS analysis identified 23 distinct phytochemical constituents in the extracts of K. acuminata and 22 in Z. mucronata stembarks, including bioactive compounds with established antimicrobial, antifungal, and antioxidant properties such as behenic alcohol, 1-dodecanol, and octacosanol, as well as pharmacologically underexplored hydrocarbons like tetrapentacontane and tetracontane, albeit in varying concentrations. Conclusion: K. acuminata and Z. mucronata were successfully recognised as medicinal plants suitable for incorporation into cholera management. Their significant antibacterial and non-cytotoxic activities, along with a wide range of bioactive compounds revealed through GC-MS analysis, validate their use in traditional medicine and offer important insights into novel drug development. However, it is essential to highlight that these findings should not be viewed as a complete substitute for the established mainstream approaches to cholera treatment or prevention.

Ph.D. (Life Sciences)

College of Agriculture and Environmental Sciences