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.{23448,23449,30197} Cucurbitacin B inhibits the growth of several breast cancer cell lines (IC50s = 18-50 nM).{30195} It suppresses the growth of tumors developed from MDA-MB-231 and 4T-1 breast cancer cells in mice.{30195} Cucurbitacin B blocks the inflammatory response of macrophages treated with lipopolysaccharide.{30196} In Drosophila, it serves as an ecdysteroid receptor antagonist (Kd = 5 µM).{30194}