Antimicrobial and Antibiofilm Activities of Allomyrinasin against Streptococcus mutans

Background: Dental caries represents one of the most prevalent oral diseases worldwide, with Streptococcus mutans as its primary causative pathogen.Currently used oral antimicrobial agents are associated with adverse effects, including microbial resistance and disruption of normal oral microbiota, necessitating safer natural alternatives.In this study, we evaluated the antimicrobial and antibiofilm activities of allomyrinasin, a synthetic antimicrobial peptide designed based on a peptide identified in the larvae of the dynastid beetle Allomyrina dichotoma against S. mutans.Methods: Antimicrobial activity was evaluated using a disk diffusion assay, and the resulting growth inhibition areas were quantified as fold changes (%).Biofilm formation was quantitatively evaluated using crystal violet staining and measuring optical absorbance at 595 nm.Allomyrinasin was tested at 200 and 500 μg/ml, with distilled water and Listerine Ⓡ as negative and positive controls, respectively.Statistical analysis was performed using one-way analysis of variance followed by Tukey's multiple comparison test at a significance level of α=0.05.Results: Allomyrinasin at 500 μg/ml demonstrated statistically significant growth inhibition compared to the control (p＜0.001).A dose-dependent increasing trend in inhibition area was observed (7.23±8.85 and 31.04±12.81at 200 and 500 μg/ml, respectively).In biofilm assays, 500 μg/ml allomyrinasin significantly reduced biofilm formation (p＜0.01) and exhibited no statistically significant difference compared to Listerine Ⓡ .Conclusion: Allomyrinasin at 500 μg/ml exhibited dose-dependent antimicrobial activity against S. mutans and biofilm inhibitory effects comparable to a commercial mouthrinse, suggesting its potential as a naturally derived oral antimicrobial agent for dental caries prevention.