Modulatory effects of tea-derived bioactives on oral microbiota and their virulence-reducing properties

Tea polyphenols exhibited potent biological activity and were increasingly recognized as potential prebiotics. While their inhibitory effects on certain oral pathogens were well-documented, their impact on oral commensal bacteria remained unclear. This study investigated the effects of tea-derived bioactives on the composition of oral bacterial communities, with quantitative polymerase chain reaction (qPCR) utilized to assess changes in pathogenic and commensal bacteria. Epigallocatechin gallate (EGCG), green tea extract, and theaflavins were found to exert inhibitory effects on key oral pathogens, including Porphyromonas gingivalis (P. gingivalis), Fusobacterium nucleatum (F. nucleatum), and Prevotella intermedia (P. intermedia). Concurrently, these polyphenols promoted the growth of beneficial oral commensal bacteria, such as Lactobacillus gasseri (L. gasseri) and Lactobacillus rhamnosus (L. rhamnosus). At sub-inhibitory concentrations, tea polyphenols significantly suppressed the expression of virulence factors in P. gingivalis, suggesting that low concentrations were sufficient to mitigate pathogenicity without disrupting microbial homeostasis. Furthermore, tea polyphenols reduced oral VSCs by downregulating hydrogen sulfide/methyl mercaptan synthase genes. Hence, their dual capacity to inhibit pathogens and support commensal bacteria could make them promising candidates for oral health products.