Stilbene and dihydrophenanthrene derivatives from Pholidota chinensis and their nitric oxide inhibitory and radical-scavenging activities

Two new stilbene derivatives, (E)-2',3,3'-trihydroxy-5-methoxystilbene (1, Pholidotol C) and (Z)-3,3'-hydroxy-5-methoxystilbene (2, Pholidotol D), were isolated from the air-dried whole plant of Pholidota chinensis Lindl., together with eight known dihydrophenanthrene derivatives, lusianthridin (3), cannabidihydrophenanthrene (4), coelonin (5), hircinol (6), erianthridin (7), 4,5-dihydroxy-2-methoxy-9,10-dihydrophenanthrene (8), eulophiol (9), and 2,4,7-trihydroxy-9,10-dihydrophenanthrene (10), and a benzoxepin derivative bulbophylol B (11). Their inhibitory effects on nitric oxide (NO) production activity and 1,1-diphenyl-2-picrylhydrazil radical-scavenging activity were examined. Among these compounds, 11 exhibited the most potent activity toward NO production inhibition activity and radical-scavenging activity; moreover, 11 reduced inducible nitric oxide synthase mRNA expression.