A new dihydrophenanthrene from Cymbidium finlaysonianum and structure revision of cymbinodin-A

Abstract

1-(4-Hydroxybenzyl)-4,6-dimethoxy-9,10-dihydrophenanthrene-2,7-diol (13), a new dihydrophenanthrene, was isolated along with ferulic acid esters (1), eight phenanthrene derivatives (2, 3, 6–11) and three bibenzyls (4, 5, 12) from an epiphytic orchid, Cymbidium finlaysonianum. The molecular structure of cymbinodin-A (2) was revised based on spectroscopic data and comparison with the literature. Compounds 2, 3, and 6–13 were evaluated and shown to be cytotoxic against human small cell lung cancer (NCI-H187) cell line. Cymbinodin-A displayed the highest cytotoxicity with an IC50 value of 3.73 µM.