Antibacterial Potential of Ethanol Extract of Plectranthus amboinicus (Lour.) Spreng against Streptococcus mutans serotype C and Streptococcus sanguinis

Abstract Caries is the most prevalent disease in the world, and in Indonesia its prevalence is 88.8%. While the causative microbial agent of caries is Streptococcus mutans, Streptococcus sanguinis is a primary colonizer related to the formation of oral biofilms. Due to concerns on cost, access and side effects of the commercial solutions, many people still depend on plant-based medicinal alternatives. Plectranthus amboinicus (Lour.) Spreng is such a medicinal plant containing carvacrol and thymol that are known to have antibacterial effects. Aim: To determine the effectiveness of P. amboinicus extract in inhibiting growth of and killing S. mutans and S. sanguinis. Methods: Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined to characterize the antibacterial properties of the ethanol extract of P. amboinicus from extract concentrations of 50%, 25%, 12.5%, 6.25 %, and 3.125% (vol) against the two bacterial species. Results: MIC and MBC levels of the ethanol extract of P. amboinicus against S. mutans were 3.125% and 50%, respectively. The corresponding MIC and MBC levels of the extract against S. sanguinis were respectively 6.25% and 25%l test showed a significant difference between each treatment (p <0.05). Conclusion: Ethanol extract of P. amboinicus can effectively inhibit growth of and kill S. mutans and S. sanguinis.