An extract of soybeans enriched in Bowman-Birk inhibitor (BBI), a soybean-derived, 71-amino acid, polypeptide and serine protease inhibitor with potential chemopreventive activity. Bowman-Birk inhibitor contains distinct inhibitory sites for trypsin and chymotrypsin. Although the exact mechanism by which BBI suppresses carcinogenesis is unknown, its antiproliferative activity appears to be linked to the chymotrypsin inhibitory region.
