Fractionation of the EtOH extract of Justicia procumbens, guided by antiplatelet bioassay, led to the isolation of nine known arylnaphthalide lignans, neojusticin A (1), justicidin B (2), justicidin A (3), taiwanin E methyl ether (4), neojusticin B (5), chinensinaphthol methyl ether (6), taiwanin E (8), chinensinaphthol (9), and diphyllin (10), and a new arylnaphthalide lignan that was characterized by spectral means as 4'-demethylchinensinaphthol methyl ether (7). Compounds 1, 2, 4, and 8 significantly inhibited platelet aggregation.

The MeOH extract of the seeds of Psoralea corylifolia L. was found to inhibit the aggregation of rabbit platelets induced by arachidonic acid, collagen, and platelet activating factor. Bioassay-directed fractionation led to the isolation of three flavonoids, isobavachalcone (1), neobavaiso-flavone (2), and bavachin (3). Compounds 1 and 2 inhibited platelet aggregation.

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.

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