TGFB1 and pulmonary fibrosis: Five new triterpenoids, oenotheralanosterols C-G (1–5), with seven known triterpenoidcompounds, namely 2α,3α,19α-trihydroxy-24-norurs4,12-dien-28-oic acid (6), 3β,23-dihydroxy-1-oxo-olean-12-en-28-oic acid (7), remangilone C (8), knoxivalic acid A (9), termichebulolide (10), rosasecotriterpene A (11), androsanortriterpene C (12), were extracted and separated from the dichloromethane part of Oenothera biennis L. The anti-pulmonary fibrosis activities of all the compounds against TGF-β1-induced damage tonormal human lung epithelial (BEAS-2B) cells were investigated in vitro.