Cytotoxic Germacranolides from the Whole Plant of Carpesium minus

Eight new germacranolides, minusolides A–H (1–8), along with two known analogues, 9 and 10, were isolated from the whole plant of Carpesium minus. Their structures were elucidated by spectroscopic analysis. Compounds 1 and 2, and 6 and 9 are two pairs of rare epimers with opposite configurations at C-2 of the 2-methylbutyryloxy group. The absolute configurations were determined by X-ray diffraction studies. Compound 7 exhibited cytotoxic activities against MDA-MB-231, A549, and HCT-116 cells with IC50 values of 6.1 ± 0.2, 8.4 ± 0.6, and 3.7 ± 0.6 μM, respectively. Compound 7 induced the apoptosis of HCT-116 cells via suppression of PARP and promoting cleavage of PARP.