Antibacterial Activity and Mode of Action of Black Mulberry (Morus nigra) Fruits Extract Against Streptococcus mutans

Background: Black mulberry was a member of the plant groups from genus Morus, which contains the highest total phenolic compounds compared to other species. It could be a potential source of antimicrobial agents. Therefore, this study aimed to evaluate the antibacterial activity of the fruits extract against Streptococcus mutans. Methods: Agar diffusion and microdilution methods were used for evaluation of the antibacterial activity and the minimum inhibitory concentration (MIC) of the extract. Protein and ion leakage from the bacterial cells induced by the extract was analyzed spectrophotometrically. The morphological change was determined using Scanning electron microscopy (SEM). Results: Black mulberry (BM) fruits extract showed antibacterial activity against S. mutans with MIC value of 8 mg/mL, as well as contributed to the aforementioned leakage. Meanwhile, cellular membrane damage was observed, indicating that the extract might inhibit growth of the bacteria. Conclusion: BM extract could be a potential raw material for herbal medicine, especially anticaries which has antibacterial activity.