Abstract
Nine components were isolated from the methanol extract of the whole herb of Polygonum perfoliatum and evaluated for their antioxidant activity. Among them, α-tocopherol and methyl trans-ferulate showed significant DPPH free radical scavenging effects with EC50 values of 11.9 and 7.8 μg/mL, respectively. In addition, five phenolic acids, caffeic acid, p-coumaric acid, p-hydroxybenzoic acid, protocatechuic acid, and vanillic acid were isolated from the aqueous extracts of the plant and identified by means of paper and high performance liquid chromatography. These five compounds were confirmed to be allelopathic substances by bioassay against the radicle growth of lettuce (Lactuca sativa), Chinese cabbage (Brassica oleracea), and radish (Raphanus acanthiformis).