Triterpenoids from the stems of Tripterygium regelii

Three new triterpenoids, triregelolides A, B (1, 2), and triregeloic acid (3), were isolated from the stems of Tripterygium regelii along with twenty known triterpene analogues (4–23). The structures of three new compounds were identified by analyzing their NMR spectroscopic and HRESIMS data. Compounds 4, 7, 8, 10, 13, 14, 17, 21–23 were isolated from T. regelii for the first time. Compounds 3, 5, 6, 8, 9, 10, 14 and 16 showed inhibitory effects on the proliferation of human breast cancer cells MCF-7 by 24.1%, 69.6%, 72.8%, 21.6%, 23.1%, 43.3%, 25.5% and 23.5% (p < 0.05) at a concentration of 10 μM, respectively.