Synergistic Antibacterial Activity of Ethanolic Extracts of Mondia whytei Roots and Physalis peruviana Leaves against S. aureus and E. coli

Aims: This work investigated the phytochemical constituents and synergistic antibacterial activity of ethanolic extracts of Mondia whytei roots and Physalis peruviana leaves.

Study Design: This study employed both qualitative and quantitative methods.

Place and Duration of Study: All research works were performed at the Central Science Laboratories, Faculty of science, Kyambogo University between September 2021 and March 2022.

Methodology: Standard methods were followed for phytochemical screening of ethanolic extracts of Mondia whytei roots, and Physalis peruviana leaves. The potential synergistic antibacterial activity of ethanolic extracts were evaluated through agar well diffusion assay. The bacteria strains were cultured on Mueller-Hinton agar. Sterile cork borer (6 mm diameter) was used to create the wells on petri discs and filled aseptically with 10 µl of the test extract (100 mg/ml) and Chloramphenicol (0.5 mg/ml) was used as the positive control. The interaction between the extracts and the combined extract was assessed by determining their fractional inhibitory concentration (FIC) index.

Results: Alkaloids, flavonoids, tannins, saponins, phenols were found to be present in both extracts. Cardiac glycosides, terpenoids, anthraquinnones and steroids were present only in ethanolic extract of Physalis peruviana leaves. The antibacterial activities of Mondia whytei roots extract, Physalis peruviana leaves extract and combined extract were obtained with the following zone of inhibitions; 19.20 ± 0.72 mm, 19.77 ± 0.60 mm, 25.93 ± 0.83 mm for S. aureus and 15.50 ± 0.46 mm, 15.00 ± 0.26 mm, 17.87 ± 0.61 mm for E.coli respectively, as compared with the standard reference antibiotic with zone of inhibitions; 26.00 ± 0.00 mm for S. aureus and 24.00 ± 0.00 mm E. coli. The MICs were determined at 0.1-100 mg/ml, and the FIC index were obtained from the evaluated MIC values with the corresponding values of 0.5 (synergistic) for S. aureus and 1.0 (additive) for E. coli.

Conclusion: The results obtained from the present study support the traditional claims of using the selected plants to treat bacterial infections. The extracts had low antibacterial activities on the selected human pathogens, Hence, if these extracts are used in unison, greater efficacy could be achieved; further studies should be done using combined extracts combined with commercial antibiotics.