Eudesmane−type sesquiterpenes from the rhizomes of Atractylodes macrocephala and their bioactivities

Fifteen undescribed eudesmane−type sesquiterpenes, named atramacronoids D−R, along with fourteen known analogues were isolated from the rhizomes of Atractylodes macrocephala. The structures of atramacronoids D−R were elucidated based on extensive spectroscopic data analysis, Snatzke's rule, electronic circular dichroism (ECD) calculations, and X-ray crystallographic analysis. Notably, of the undescribed isolates, atramacronoids D and E are the first example of eudesmanolactam−phenol and eudesmanolactam−ethyl hybrids obtained from plants, respectively. A pair of enantiomers, (+)- and (−)-atramacronoids F, were successfully resolved by chiral-phase HPLC. Atramacronoid D exhibited weak cytotoxicity against SGC-7901 cells. Atramacronoid E significantly promoted the proliferation of LPS-induced IEC-6 cells.