Trisecocycloartane triterpene dilactones from the cones of Pseudolarix amabilis

Two previously undescribed 3(4), 8(9), 9(10)-trisecocycloartane triterpene dilactones with a featured elevenmembered ring, pseudoladilactones A and B (1-2), together with three known ones (4-5), were isolated from the 80 % ethanol extract of the cones of Pseudolarix amabilis. The structures of compounds 1 and 2 were determined on the basis of analysis of 1D- and 2D-NMR spectroscopic data. The absolute configuration of pseudoladilactones A (1) was elucidated by single crystal X-ray diffraction (CuK alpha). All isolates were tested for cytototoxicity against four human tumor cell lines A549, HCT116, SK-BR-3, and HepG2.