Six New Diarylbutane Lignans from Justicia procumbens

Six new diarylbutane lignans, namely, justin A (1), (-)-dihydroclusin diacetate (2), secoisolariciresinol dimethyl ether diacetate (3), 5-methoxy-4,4'-di-O-methylsecolariciresinol diacetate (4), justin B (5), and justin C (6), together with three known diarylbutane lignans [2,3-demethoxysecisolintetralin acetate (7), secoisolariciresinol dimethyl ether (8), and 5-methoxy-4,4'-di-O-methylsecolariciresinol (9)], were isolated from the whole plant of Justicia procumbens. Their structures were established by spectral analysis.