Four new lignans from Schisandra sphenanthera

Three new 7,8-secolignans, schisandlignans A–C (1, 2, and 4), one new dibenzocyclooctadiene lignan, schisandlignan D (5), together with nine known lignans 3′,4′-dimethoxybenzoic acid (3″,4″-dimethoxyphenyl)-2-methyl-3-oxobutyl ester (3), gomisin J (6), rubrisandrin A(1b) (7), interiotherin B (8), schisantherin D (9), ( − )-machilusin (10), ganschisandrine (11), henricine A (12), and (+)-1-hydroxy pinoresinol (13), were isolated from the rattan of Schisandra sphenanthera. Their structures were determined by analysis of 1D and 2D NMR spectroscopic data.