Lignan derivatives and a norditerpene from the seeds of Vitex negundo.

A new phenyldihydronaphthalene-type lignan, vitedoin A (1), a new phenylnaphthalene-type lignan alkaloid, vitedoamine A (2), and a new trinorlabdane-type diterpene, vitedoin B (3), were isolated from the seeds of Vitex negundo along with five known lignan derivatives (4-8). Their chemical structures were determined mainly on the basis of NMR and MS data. Compounds 1, 2, and 4-7 showed stronger antioxidative activity than alpha-tocopherol using the ferric thiocyanate method. Compounds 1, 2, and 4-7 showed higher radical-scavenging effect on the stable free radical, 1,1-diphenyl-2-picrylhydrazyl, than L-cysteine.