Patchouli Alcohol as a Potential Anti-Cariogenic Compound Targeting Streptococcus mutans

Patchouli alcohol, a natural tricyclic sesquiterpene isolated from Pogostemon cablin, exhibits promising antimicrobial properties, yet its activity against Streptococcus mutans (S. mutans), a major cariogenic bacterium associated with dental caries, has not been characterized. This study determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of patchouli alcohol against S. mutans to be 40 and 80 μg/mL, respectively. A series of phenotypic assays showed that patchouli alcohol delayed bacterial growth and culture acidification, reduced extracellular polysaccharide production, and decreased the biomass and metabolic activity of established S. mutans biofilms. Scanning electron microscopy showed treatment-associated changes in the surface morphology of S. mutans, with more evident deformation at MIC and 2MIC. Real-time quantitative PCR showed that sub-MIC treatment (20 μg/mL) significantly downregulated virulence genes associated with adhesion (gbpB and spaP), EPS synthesis (gtfB, gtfC, gtfD, and ftf), acid production (ldh, atpF, and atpD), and the two-component regulatory and quorum sensing systems (vicK, vicR, and luxS). These results suggest that patchouli alcohol may serve as a potential natural anti-cariogenic candidate targeting S. mutans-associated virulence traits under in vitro conditions.