Apocarotenoids from the fresh roots of Rehmannia glutinosa and their anti-pulmonary fibrosis activity.

Six undescribed compounds (1-6) and twenty-three known analogues (7-29) were isolated from the fresh roots of Rehmannia glutinosa. The structures of the compounds (1-29) were established through the application of spectroscopic analysis. Compounds 3, 4, 6, 8, 13, 18, 21, 22, 25, and 28 exhibited excellent anti-pulmonary fibrosis activity. The potential mechanistic pathway of 3 was also investigated, whose results indicate that compound 3 ameliorate TGF-β1 induced BEAS-2B cell injury via PI3K/AKT/NF-κB signaling pathway.