Cucurbitacin-B

Cucurbitacin B is a plant-derived triterpene that has the classic four-ring structure of mammalian steroids. It has diverse effects on mammalian cells, most notably inducing cell cycle arrest or apoptosis in a range of cancer cell lines. Cucurbitacin B inhibits the growth of several breast cancer cell lines (IC50s = 18-50 nM). It suppresses the growth of tumors developed from MDA-MB-231 and 4T-1 breast cancer cells in mice. Cucurbitacin B blocks the inflammatory response of macrophages treated with lipopolysaccharide. In Drosophila, it serves as an ecdysteroid receptor antagonist (Kd = 5 µM).