Dihydromyricetin exhibits potent antibacterial activity and virulence factor inhibitory effects against Porphyromonas gingivalis.

OBJECTIVE: Dihydromyricetin has inhibitory effects on various pathogens, but its effect on Porphyromonas gingivalis is not yet known. This study investigates the effects of dihydromyricetin on planktonic cells, biofilms, and related virulence factors of Porphyromonas gingivalis, evaluates the in vitro antibacterial activity of dihydromyricetin against Porphyromonas gingivalis, and preliminarily explores its possible antibacterial mechanisms. METHODS: The microdilution method was used to explore the inhibitory effect of dihydromyricetin on planktonic Porphyromonas gingivalis. The impact of dihydromyricetin on biofilm formation was assessed via crystal violet staining. The effects on the expression of fimbrial genes (fimA, fimR, fimS) and the capsular polysaccharide gene PGN-1525 were examined using qRT-PCR. Protein substrate assays were conducted to evaluate the influence of dihydromyricetin on the proteolytic activity of gingipains (arginine protease and lysine protease). RESULTS: 1% DMSO has no significant effect on the growth of Porphyromonas gingivalis. MIC of dihydromyricetin against planktonic Porphyromonas gingivalis was 160 µg/mL, while the MBC was 320 µg/mL. DMY at 160-640 µg/mL downregulated fimbrial (fimA, fimR, fimS) and capsular polysaccharide (PGN_1525) gene expression; 40-160 µg/mL DMY concentration-dependently suppressed Rgp and Kgp proteolytic activity. CONCLUSION: Dihydromyricetin has shown relatively significant antibacterial activity and virulence factor inhibition against Porphyromonas gingivalis.