Abstract:
This study aimed to develop herbal mouthwash formulation using essential oils extracted from two medicinal plants, Syzygium aromaticum and Zanthoxylum limonella to investigate the synergistic effects of clove (Syzygium aromaticum) essential oils on enhancing the antibacterial activity of Makhwan (Zanthoxylum limonella) essential oil against Streptococcus mutans (S. mutans). The results showed that the average yield of Makhwan essential oil was 13.68 ± 1.61%, whereas clove essential oil exhibited 16.80 ± 0.27%. The main chemical components found in Makhwan essential oil included D-Limonene (100%), Cis-sabinene (81.97%), 3-Carene (27.22%), 4(10)-Thujene (19.94%), and Terpinen-4-ol (19.44%). Meanwhile, the major chemical constituents of clove essential oil were Eugenol (100%), Eugenol acetate (58.25%), and Caryophyllene (65.90%). For the mixed essential oil from clove and Makhwan, Eugenol (100%) and D-Limonene (90.88%) were identified as the predominant constituents. The evaluation of antibacterial activity against S. mutans revealed that clove essential oil alone exhibited the lowest minimum inhibitory concentration (MIC) at 7.81 mg/ml, while Makhwan essential oil showed an MIC of 125 mg/ml and the MIC of the mixed essential oil was 62.5 mg/ml. The minimum bactericidal concentrations (MBC) of clove, Makhwan, and the combined oil were found to be the same as their respective MIC values. In the assessment the bactericidal activity of herbal mouthwash formulations developed from a combination of clove and Makhwan essential oils, the first formula containing 6.25% (w/w) of the mixed essential oil was able to reduce the number of S. mutans from 5.30 to 4.94 log CFU/mL within 4 minutes, corresponding to a reduction of 56.75%. Meanwhile, the second formulation, which contained 12.5% (w/w) of the oil mixture reduced the bacterial counts to 4.52 log CFU/mL, representing a 83.50% reduction. It can be implied that, the second formula demonstrated significantly greater antibacterial efficacy than the first formula. Therefore, mouthwash containing clove and Makhwan essential oils could be developed to enhance efficacy of commercial products.