Activity-guided isolation of antioxidative constituents of Cotinus coggygria

Six constituents (1-6) were isolated from EtOAc-soluble partitions of two separate collections of the whole plants of Cotinus coggygria, namely, disulfuretin {2,2'-[1,2-bis(3,4-dihydroxyphenyl)-1,2-ethanedylidene]-bis [6-hydroxy-3(2H)-benzofuranonel (1)}, sulfuretin (2), sulfurein (3), gallic acid (4), methyl gallate (5), and pentagalloyl glucose (6). The structure of the novel biaurone 1 was determined by spectral and chemical methods. Compounds 1-6 were found to be potent antioxidants in a 1,1-diphenyl-2-picrylhydrazyl free-radical scavenging assay.