Gossypol (BL 193) is an orally-active polyphenol isolated from cotton seeds and roots. Gossypol is a potent inhibitor of 5α-reductase 1 and 3α-hydroxysteroid dehydrogenase with IC50 of 3.33 μM and 0.52 μM in cell-free assay, respectively. Gossypol also inhibits the binding of BH3 peptide to Bcl protein with IC50 of 0.4 μM and 10 μM for Bcl-XL and Bcl-2, respectively. Gossypol induces apoptosis and cell growth inhibition in various cancer cells.