Two new lignan glucosides from the fruit of Vitex cannabifolia

Two new phenyldihydronaphthalene-type lignan glucosides, vitecannasides A (1) and B (2) were isolated from the fruit of Vitex cannabifolia Sieb. et. Zucc. (Verbenaceae) along with the six known lignan derivatives (3-8), four known iridoid glucosides (9-12), three known flavonoids (13-15), and one known phenylbutanone glucoside (16). Their chemical structures were determined on the basis of spectroscopic data as well as chemical evidence. The scavenging effect of 1, 2, and 11-16 on the stable free radical 1,1-diphenyl-2-picrylhydrazyl was examined. Compounds 1, 2, 14, and 15 exhibited stronger activity than that of L-cysteine. Especially, 14 and 15 showed more potent activity than that of alpha-tocopherol.