A new bibenzyl compound from Dendrobium nobile

: In this study, seven bibenzyl compounds were isolated from the stem of Dendrobium nobile by silica gel, MCI column chromatographic and preparative HPLC technology. By using spectroscopic techniques including NMR and MS, these compounds were identified as 4,α-dihydroxy-3,5,3’-trimethoxybibenzyl (1), 4,5-dihydroxy-3,3’,α-trimethoxybibenzyl (2), 4,4’-dihydroxy-3,5,3’-trimethoxybibenzyl (3), 4,5-dihydroxy-3,3’-dimethoxybibenzyl(4), 4,3’-dihydroxy-3,5-dimethoxybibenzyl (5), 5,4’-dihydroxy-3,3’-dimethoxybibenzyl (6) and 5,3’-dihydroxy-3-methoxybibenzyl (7). Compound 1 is a new compound and compound 4 was isolated from this plant for the first time.