Phenolic compounds with radical scavenging and cyclooxygenase-2 (COX-2) inhibitory activities from Dioscoreaopposita

Phytochemical studies of the chloroform soluble fraction of Dioscoreaopposita resulted in the isolation of four new compounds, 3,5-dihydroxy-4-methoxybibenzyl (1), 3,3′,5-trihydroxy-2′-methoxybibenzyl (2), 10,11-dihydro-dibenz[b,f]oxepin-2,4-diol (3), and 10,11-dihydro-4-methoxy-dibenz[b,f]oxepin-2-ol (4), together with an additional fifteen known compounds. The structures of 1–4 were elucidated by spectroscopic methods including 2D NMR. All of the nineteen isolated compounds were tested in the DPPH, superoxide anion radical scavenging assays and cyclooxygenases (COXs) inhibition assay. Of those, compounds 7, 9, 11, 12, 13, 15 and 18 exhibited radical scavenging activities and compounds 2, 3, 8, 13, 15 and 16 showed selective inhibitory activities against COX-2.

Two new dihydrostilbenes (1, 2) and two new dibenzoxepins (3, 4) together with 15 known compounds were isolated from the chloroform fraction of Dioscorea opposita. Of these, 3,3′,5-trihydroxy-2′-methoxy-bibenzyl (2) showed most potent inhibitory activity against cyclooxygenase-2 (COX-2).Figure optionsDownload as PowerPoint slide