Cimifrigines A–G, cytotoxic triterpenes with an oxime group from the flowers of Cimicifuga frigida

Abstract

Seven new dahurinol-type triterpene derivatives, including three aglycones, cimifrigines A–C (1–3), and four glycosides, cimifrigines D–G (4–7), were purified from the flowers of Cimicifuga frigida. These triterpenoids are characterized by an oxime group at C-15. Spectroscopic analyses and X-ray crystallography were used to determine the new structures. In the in vitro cytotoxicity screening, glycosides (4–7) exhibited more noticeable activities than the aglycones (1–3) against human HL-60, SMMC-7721, A549, MCF-7, and SW-480 cell lines. Interestingly, compounds 5 and 7, bearing a 2′-O-acetyl moiety on the sugar unit, showed comparable cytotoxicities to the positive control, cisplatin (IC₅₀: 0.5 to 5.4 μM). Whereas, analogues 4 and 6, without the 2′-O-acetyl group, indicated weaker activities with IC₅₀ values ranging from 8.9 to 14.3 μM.