Antibacterial activity and stability of mouthwash formulated with ethanolic extract of sappan wood (Caesalpinia sappan L.) against Streptococcus mutans ATCC 25173 and Pseudomonas aeruginosa ATCC 10145

This study aimed to develop and evaluate a herbal mouthwash formulation containing an ethanolic extract of sappan wood (Caesalpinia sappan L.) as a potential natural alternative to chlorhexidine-based products. The extract and derived mouthwash were assessed for antibacterial activity against Streptococcus mutans Clarke and Pseudomonas aeruginosa (Schroeter) Migula using the agar well diffusion and minimum inhibitory concentration (MIC) methods at concentrations of 1 %, 3 % and 5 %. Positive controls included 0.2 % chlorhexidine and a commercial mouthwash, while negative controls consisted of mouthwash without extract and 96 % ethanol. The stability of the mouthwash was evaluated through a six-cycle cycling test by monitoring organoleptic properties, homogeneity, pH, sedimentation and redispersion. The mouthwash exhibited a maximum inhibition zone of 21.5 mm and 15.2 mm against S. mutans and P. aeruginosa, respectively, with MIC values of 1 % and 3 %. It remained physically stable during six storage cycles with consistent pH (4.6–6.5) and homogeneous dispersion. These results demonstrate that sappan wood extract possesses strong antibacterial activity and good formulation stability, supporting its potential as a safe and effective herbal mouthwash. The study highlights the novelty of exploring a plant-based mouthwash as a promising natural alternative to chlorhexidine, showing comparable in vitro antibacterial activity with potentially fewer adverse effects.