Phytochemical Composition, Biological Activities, and Mechanisms of Antibacterial Action of Selected Cameroonian Medicinal Plants

Background Medicinal plants have always played a very important role in the control and prevention of diseases, especially those caused by antibiotic-resistant bacteria. This study aimed to evaluate the antibacterial activity, antioxidant potential, synergistic effect, phytochemical content, and mechanisms of antibacterial action of the selected Cameroonian medicinal plants. Methodology The extracts were prepared by maceration in ethanol. The antibacterial activities of the extracts alone and the combinations of extracts with Augmentin were determined by the microdilution method in a liquid medium. The mode of action of plant extracts was studied by targeting bacterial ATPases/H⁺ proton pump function, outer membrane permeability, dehydrogenase activity, and leakage of nucleic acids. The antioxidant activities and phytochemical analysis were evaluated using colorimetric methods. Results All the crude extracts tested showed different degrees of antibacterial activities (minimum inhibitory concentration (MIC) = 64-2048 µg/ml) on Gram-positive and negative bacteria, which can be linked to their total phenolic, flavonoid, sterol, triterpene, and tannin contents. <i>Kotschya strigosa</i> leaf extract was the most active tested sample and exerted, with Augmentin, additive, synergistic, and indifferent effects on bacterial species. <i>K. strigosa</i> leaf extract induced changes in the permeability of bacterial membranes, leakage of the nucleic acids, and the inhibition of the bacterial ATPases/H⁺ proton pump. <i>K. strigosa</i> and <i>Kalanchoe</i> <i>pinnata</i> extracts displayed potent antioxidant (EC₅₀ = 2.20-2.24 μg/ml; ferric-reducing antioxidant power = 142.58-142.67 μg/ml) activity. Conclusions The results of this study demonstrated the antibacterial and antioxidant activities of the tested plants and confirmed their traditional use in the treatment of infectious diseases caused by the tested bacteria.