A series of 4-methylidene sterols including three new compounds 1-3, were isolated from the marine sponge Theonella swinhoei. The structures of new compounds were determined on the basis of spectroscopic analyses. Compounds 3, 5, and 6 showed cytotoxicities against U937, MCF-7, and PC-9 cancer cells with IC50 in the range of 1.6-8.8 μM. The new compound 3 exhibited remarkable proapoptotic activity in breast cancer cells. Mechanically, 3 significantly triggered reactive oxygen species (ROS) accumulation resulting in apoptosis and DNA damage in breast cancer cells.
Keywords: 4-Methylidene sterol; Antitumor; ROS; Theonella swinhoei.
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