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

## TL;DR

This study evaluates the antibacterial and antioxidant properties of Cameroonian medicinal plants, focusing on their potential to combat antibiotic-resistant bacteria.

## Contribution

The study identifies Kotschya strigosa and Kalanchoe pinnata as potent antibacterial and antioxidant agents with possible synergistic effects when combined with Augmentin.

## Key findings

- Kotschya strigosa leaf extract showed strong antibacterial activity and synergistic effects with Augmentin.
- The plant extracts altered bacterial membrane permeability and inhibited ATPases/H+ proton pump function.
- Kalanchoe pinnata and Kotschya strigosa exhibited significant antioxidant activity.

## Abstract

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. Kotschya strigosa leaf extract was the most active tested sample and exerted, with Augmentin, additive, synergistic, and indifferent effects on bacterial species. K. strigosa 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. K. strigosa and Kalanchoe pinnata 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.