Antioxidative and antimicrobial activities of Polygonum multiflorum Thunb. in vitro

Antioxidant and antimicrobial activities of water and ethanol extracts of Polygonum multiflorum Thunb. were investigated in vitro. The antioxidant properties of both extracts of P.multiflorum were evaluated using different antioxidant tests, including scavenging on DPPH radicals, scavenging on hydroxyl radical, reducing power, preventing effect on lipid peroxidation and assay of the total antioxidant activity. Antimicrobial activity tests were carried out using disc diffusion methods with 6 strain microbial species. In general, the enthanol extract of P.multiflorum exhibited stronger antioxidant capacity than that of water, which showed notable scavenging effect to DPPH free radical and hydroxyl radical, inhibiting lipid peroxidation, had some functions of reducing power, and the total antioxidant activity was relatively strong. The contents of total phenolic compounds and total flavonoids of the water extract and the ethanol extract were 126.52, 77.25 μg/mg and 153.04, 126.11 μg/mg, respectively. The enthanol extract showed significant inhibitory activities against Staphylococcus aureu, Micrococcus tetragenus and Escherichia coli, and the water extract showed moderate inhibitory activities against Staphylococcus aureu and Pseudomonas fluorescens.