Abiestetranes A and B, two unique tetraterpenes from Abies fabri

Abiestetranes A (1) and B (2), two unique tetraterpenes formed by Diels-Alder cycloaddition between a lanostane triterpenoid and a monoterpenoid, were isolated from Abies fabri. Their structures were elucidated by extensive analysis of NMR data. The electronic circular dichroism was utilized to assign the absolute configuration of 1. Compounds 1 and 2 showed significant cytotoxic activities against ZR-75-30 tumor cell with IC50 values of 6.26 and 1.63 μg/mL, respectively.

Two novel Diels-Alder adducts, abiestetranes A and B, were isolated from the aerial part of Abies fabri. The absolute configuration of abiestetrane A was determined by the electronic circular dichroism. Abiestetranes A and B showed significant cytotoxicity against ZR-75-30 tumor cell with IC50 values of 6.26 and 1.63 μg/mL, respectively.