Anti-biofilm and bacteriostatic effects of three flavonoid compounds on .

() is the main cariogenic pathogen associated with dental caries. Orientin-2''-O-β-L-galactoside, orientin and vitexin are natural flavonoids compound. In this study, the antibacterial ability of these flavonoids and their mechanisms in inhibiting biofilm formation were investigated. Inhibition zone and 2-fold-dilution tests showed that these flavonoids exerted inhibitory effects on . Phenol sulfuric acid method and lactate dehydrogenase (LDH) test revealed that they could reduce EPS formation and stimulate to release LDH. Moreover, crystal violet and live/dead bacterial staining test showed that they inhibited biofilm formation. Finally, qRT-PCR test indicated that the down-regulated the transcription levels of , , , and genes of . In conclusion, orientin-2''-O-β-L-galactoside, orientin and vitexin had antibacterial and anti-biofilm activities.