Traditional Chinese medicine Pudilan synergizes with smc gene to impair cell growth and exopolysaccharides synthesis of Streptococcus mutans

Abstract

Objective

This study examines the impact of Pudilan mouthwash in conjunction with the smc gene of Streptococcus mutans (S. mutans) on biofilm formation.

Design

We constructed the smc gene null mutant strains of S. mutans (Δsmc) via homologous recombination, and overexpression strains (smc^OE) and complementary strains (smc^Comp) through chemical transformation of smc recombinant plasmid. We then tested Pudilan's MIC and MBC on UA159 parent strains and smc mutants. Growth curves were used to analyze growth rates. Bacterial viability was assessed with Live/Dead Staining. Biofilm formation and structure were examined using crystal violet staining, confocal laser scanning microscopy, and scanning electron microscopy. Genes involved in exopolysaccharides (EPS) metabolism were quantified by qRT-PCR. Network pharmacology built a compound-target network, and molecular docking studied interactions between Pudilan's components and S. mutans proteins.

Results

The combination of Pudilan and knockout of smc gene exhibited a synergistic antibacterial effect on S. mutans. Results indicated that this pairing effectively inhibited the growth and viability of S. mutans, reduced biofilm biomass, and rearranged the structure of 8-hour and 24-hour biofilms. Additionally, Pudilan treatment downregulated gene expression related to water-soluble glucan in Δsmc. Compounds like (S)-cheilanthifoline in Pudilan may significantly influence dental plaque development by modulating GtfD activity.

Conclusions

This finding demonstrates that Pudilan enhances the inhibitory effect caused by smc deletion on S. mutans growth and viability, reduces biofilm EPS, and downregulates the expression of genes involved in water-soluble glucan synthesis.