Abietane diterpenoids with potent cytotoxic activities from the resins of populus euphratica

Abstract

A new abietane norditerpenoid, 5-(6-isopropyl-2-methylnaphthalen-1-yl)pentan-2-one (1), with a rare 4,5-seco-19-nora-bietane skeleton possessing a rearranged angular methyl group at C-5, 2 new naturally occurring compounds, 19-norabie-ta-4,6,8,11,13-penttaen-3-one (2) and 14-hydroxy-7-oxo ester (3), along with 10 known analogs (4−13) were isolated from the resins of Populus euphratica. The new structures were elucidated by spectroscopic analysis (one-/two-dimensional nuclear magnetic resonance and high-reolution electrospray ionization mass spectrometry). Biological evaluation showed that compounds 1 and 2 display low cytotoxicity against normal cells and appreciable cytotoxicity in cancer cells, with 2 to be more sensitive in HepG2 cells with a half-maximal inhibitory concentration value of 27.0 μM.