Antibacterial and anti-adherent activity of great mullein (Verbascum thapsus L.) ethanolic extract on in vitro biofilm formation of three oral streptococci

The oral microbial flora comprises one of the most diverse human-associated biofilms. Its development is heavily influenced by oral streptococci. Numerous studies have shown that these bacteria are capable of adhering and forming biofilm on oral cavity and tooth. Verbascum thapsus (VT) is a medicinal plant that chemical constituents of it revealed the presence of biologically active compounds with antibacterial properties. The aim of the present study was to evaluate the antimicrobial and anti-adherent activities of ethanol extract of (VT) against of three oral streptococci in vitro. In this study, biofilm formation of S. mutans 1683ATCC35.668, S. sanguinis 1449CIP53.15 and S. salivarius 1448 CIP55.128 with ethanol extract of VT was tested using Micro-dilution assay and microtitre plate assay. Results showed that the biofilm formation of three oral streptococci with ethanol extract (leaves and root) of VT was significantly lower than the control group without ethanol extract of VT. Meanwhile, the reduction degree was correlated to the concentration of ethanol extract of VT positively. These results suggest that antimicrobial activity of ethanol extract of VT against three oral streptococci. VT extracts have inhibitory effects on biofilm formation of oral streptococci as the reduction of bacterial growth and reduction of biofilm formation ability.