Five new eremophilane-type sesquiterpenes from the fresh roots of Rehmannia glutinosa

Five undescribed eremophilane-type sesquiterpenes, remophilanetriols E-I (1–5), along with seven known compounds (6–12) were isolated from the fresh roots of Rehmannia glutinosa. Their structures were characterized by extensive spectroscopic data analysis and their absolute configurations were determined by comparing their calculated electronic circular dichroism (ECD) spectra and experimental ECD spectra. The anti-pulmonary fibrosis activities of all compounds were evaluated in vitro by MTT methods, and compounds 2, 8, 10, and 12 exhibited excellent anti-pulmonary fibrosis activities. In addition, compound 2 can reduce the levels of ROS and apoptosis in TGF-β1-induced BEAS-2B cells.