Antibacterial activities and mechanisms of vine tea extract and 2R, 3R-Dihydromyricetin on Escherichia coli

In this study, the antibacterial mechanisms of vine tea aqueous extract (VTE) and 2R, 3R-Dihydromyricetin (DMY) against Escherichia coli (E. coli) were investigated. The results showed they had good antibacterial activities on E. coli, and affected cell membrane and nucleoid. The minimum bactericidal concentrations of VTE and DMY were 3.2 and 1.25 mg/mL, respectively. The constituent leakage tests showed VTE and DMY caused significant increases of extracellular alkaline phosphatase (24.4 +/- 0.4% and 5.3 +/- 0.1%) and beta-Galactosidase (27.6 +/- 1.0% and 13.6 +/- 0.5%), indicating the membrane integrity might be damaged. The lipids studies showed the ratio of unsaturated fatty acids to saturated fatty acids in treated groups were significant decrease (P < 0.05), indicating the membrane liquidity might be affected. Moreover, fluorescence experiments showed they could cause reduction of more than 82% of the DAPI-DNA and EB-DNA initial fluorescence intensity, indicating VTE and DMY could interacted with DNA through intercalate and grooving bindings. Furthermore, they showed good antibacterial activities in cabbage food model system. All over, the results suggested VTE and DMY might be applied as candidates of food preservatives for their good antibacterial activities and multiple targets.