# Antibacterial Activity of a Mouthwash Containing Plectranthus amboinicus (Lour.) Spreng Extract and Lippia sidoides Cham. Essential Oil

## TL;DR

A new mouthwash made from plant extracts shows antibacterial effects against common oral bacteria.

## Contribution

A synergistic plant-based mouthwash formulation with antibacterial properties was developed and tested.

## Key findings

- Lippia sidoides essential oil and Plectranthus amboinicus extract showed antibacterial activity against S. mutans and S. aureus.
- The formulated mouthwash demonstrated a synergistic effect in reducing bacterial growth.
- Chemical analysis identified active compounds like thymol, carvacrol, and phenolic compounds in the extracts.

## Abstract

This study investigated the development of a mouthwash formulated with Plectranthus amboinicus leaf extract (PaEE) and Lippia sidoides leaf essential oil (LsOE), exploring their antibacterial potential. Antimicrobial activity was evaluated in vitro using the broth microdilution method to determine the minimum inhibitory concentration (MIC) against Streptococcus mutans and Staphylococcus aureus. Chemical analysis of LsOE by GC/MS identified active compounds such as thymol and carvacrol, while PaEE demonstrated the presence of flavonoids, anthocyanins, mucilages, tannins, and phenolic compounds. Both extracts exhibited antibacterial activity, with LsOE and the natural mouthwash showing intermediate efficacy (MIC 128 µg/mL), while PaEE alone was less effective (MIC 512 µg/mL). The formulated mouthwash (F1) significantly reduced bacterial growth, and the combined use of LsOE and PaEE indicated a synergistic effect. These findings support the potential of plant‐based formulations for dental biofilm control and encourage further research to expand their applicability in public oral health.

Plant‐Based Antibacterial Mouthwash.