Bibenzyl derivatives from the orchid Bulbophyllum protractum

Two new bibenzyl derivatives were isolated from the orchid Bulbophyllum protractum and designated bulbophyllin and bulbophyllidin. In addition batatasin-III (3,3′-dihydroxy-5-methoxy bibenzyl), 3,3′,5-trimethoxybibenzyl, aloifol-I (3′,4-dihydroxy-3,5-dimethoxybibenzyl), 3,3′-dimethoxy-4,5-methylenedioxybibenzyl, flavidin (2,7-dihydroxy-9,10-dihydro-5H-phenanthro[4,5-bcd]pyran), dihydroconiferyl alcohol, stigmasterol and sitosterol were isolated. The structures of bulbophyllin and bulbophyllidin were established as 2,3′-dihydroxy-3-methoxy-4,5-methylenedioxybibenzyl and 2,3′-dihydroxy-3,5-dimethoxybibenzyl, respectively, from spectral and chemical evidence.