Cytotoxic taraxerane triterpenoids from Saussurea graminea

Four new taraxerane triterpenoids, 1β,3β-dihydroxy-11α,12α-oxidotaraxerane (1), 28-hydroxy-11α,12α-oxidotaraxerane-3-one (2), 3β-hydroxy-11α,12α-oxidotaraxerane-28-al (3), and 3-O-acetyl-11α,12α-oxidotaraxerane-28-al (4), together with three known compounds 3β-hydroxy-11α,12α-oxidotaraxerane (5), 3β,28-dihydroxy-11α,12α-oxidotaraxerane (6), and 11α,12α-oxidotaraxerane-3-one (7), were isolated from the 70% EtOH extract of Saussurea graminea. Their structures were elucidated on the basis of extensive 1D and 2D NMR (COSY, HMQC, HMBC and NOESY) analyses. The isolated compounds were evaluated in vitro for cytotoxic properties against eight tumor cell lines (A-549, BGC-823, HCT15, HeLa, HepG2, MCF-7, SGC-7901 and SK-MEL-2).