<![CDATA[Poor oral hygiene can promote the transition of commensal microorganisms into opportunistic pathogens and contribute to the development of oral diseases. Antimicrobial mouthwashes may serve as preventive or adjunctive therapies in the early stages of oral infections. On the other hand, propolis and roselle (Hibiscus sabdariffa), both rich in phenolic compounds, possess well-documented antimicrobial activities and are promising candidates for natural mouthwash formulations. This study evaluated the antimicrobial activity of the combination of ethanolic extract of propolis (EEP) and aqueous extract of roselle (AER) against Staphylococcus aureus, Streptococcus mutans, and Candida albicans, and developed a combined-extract mouthwash formulation. The MIC values of EEP against S. aureus, S. mutans, and C. albicans were 1280, 640, and >20,480 μg/mL, respectively, whereas AER exhibited MIC values of 320, 1280, and 10,240 μg/mL. The MBC values of EEP were 1280 μg/mL for S. aureus and 2560 μg/mL for S. mutans, while AER showed MBC/MFC values of 1280, 10,240, and 10,240 μg/mL against S. aureus, S. mutans, and C. albicans, respectively. Checkerboard assays indicated additive interactions against S. aureus (FICI = 2) and S. mutans (FICI = 3). A mouthwash containing 2% EEP and 1% AER was successfully formulated, exhibiting a transparent light-brown appearance, menthol aroma, homogeneous characteristics, pH of 5.44 ± 0.03, and viscosity of 1.36 mPa·s. The undiluted formulation achieved complete microbial reduction within 2–10 min of contact. These findings suggest that the EEP–AER combination has potential as a natural antimicrobial mouthwash for oral health management.]]>
