Efficacy confirmation of Traditional Chinese Medicine Yuchi Powder in preventing dental caries and active ingredients screening.

ETHNOPHARMACOLOGICAL RELEVANCE: Yuchi Powder (YCP) is a classical Traditional Chinese Medicine formula traditionally used for oral and dental disorders. Despite its long history of clinical application, its anti-caries efficacy and active constituents remain insufficiently understood. This study provides scientific evidence supporting the traditional use of YCP for dental caries prevention and identifies key bioactive constituents associated with its anti-cariogenic activity. AIM OF STUDY: We aimed to confirm the anti-caries efficacy of YCP and to screen its pharmacodynamic constituents through in vivo and in vitro experiments. METHODS: A rat dental caries model was established by inoculating cariogenic bacteria (S. mutans and S. sobrinus) and feeding cariogenic Diet 2000. Rats were topically treated with YCP (12.5, 25.0, or 50.0 mg/mL) twice daily for 50 days; caries lesions were assessed by murexide staining, Keyes scoring and Micro-CT, and the oral microbiota was profiled by 16S rRNA gene sequencing. In vitro, the anti-biofilm activity was evaluated by crystal violet staining, EPS quantification and lactic acid assays, and the active fraction was identified by bioassay-guided fractionation combined with a bacterial-binding assay and HPLC-Q-TOF-MS/MS. RESULTS: In vivo, topical YCP at 50.0 mg/mL reduced enamel (E) and moderate dentinal (Dm) caries scores from 16.17 to 10.17 and from 7.17 to 1.17, respectively, compared with the Model group (both P < 0.01). YCP also increased the Shannon diversity index of the oral microbiota. In vitro, YCP inhibited the growth of S. mutans and S. sanguinis, with MICs of 25.0 and 50.0 mg/mL, respectively, and reduced biofilm biomass, EPS production, and lactic acid generation. Bioassay-guided screening identified a GH-derived active fraction containing mulberrin (5.15 ± 0.10 mg/g), quercetin (14.67 ± 0.20 mg/g), and liquiritigenin (2.14 ± 0.25 mg/g), which were identified as candidate active constituents based on their inhibitory effects on S. mutans biofilm formation. CONCLUSION: YCP alleviates dental caries mainly by suppressing cariogenic biofilm formation, EPS accumulation and acid production, with inhibition of S. mutans and S. sanguinis growth (MICs of 25.0 and 50.0 mg/mL, respectively). The GH-derived active fraction contributes substantially to this activity, and mulberrin, quercetin and liquiritigenin were identified as candidate active constituents, providing an experimental basis for the quality control and further development of YCP.