Antimicrobial effect of edible mixed herbal extracts on oral microorganisms

Background: The oral cavity is inhabited by pathogenic bacteria, the growth of which is inhibited by synthetic oral drugs composed of antibiotics or chemical compounds. However, upon long-term use, the negative side effects of these drugs outweigh their benefits. Natural antimicrobial substances that do not elicit negative side effects may serve as effective synthetic agent substitutes for long-term use. Therefore, we evaluated the effects of edible mixed herbal extracts, comprising Schizonepeta tenuifolia Briq., Mentha piperascens , Acanthopanax sessiliflous Seem., and Glycyrrhiza uralensis, on oral pathogenic bacteria. Methods: The yield of each herbal extract was as follows: 5% S. tenuifolia , 10.94% M. piperascens , 5.47% A. sessiliflous , and 10.66% G. uralensis . For each extract, antimicrobial tests, morphological analysis using scanning electron microscopy, microbial surface hydrophobicity measurements, and oral malodor reduction tests, were performed. Results: The mixed herbal extracts significantly inhibit the growth of Streptococcus mutans , Enterococcus faecalis , Candida albicans , and Porphyromonas gingivalis compared to growth in the control group. Scanning electron microscopy results further reveal altered cellular morphology in the groups treated with mixed herbal extracts. Additionally, the hydrophobicity assay results show that the mixed herbal extracts reduce the oral adhesion of bacteria. Levels of volatile sulfur compounds, as the main components of oral malodor, are also reduced by the mixed herbal extracts. Conclusions: The edible mixed herbal extracts effectively eliminate oral pathogens and may be useful for improving oral health.