Antiapoptotic Activity of the Bowman-Birk Inhibitor Can Be Attributed to Copurified Phospholipids

Abstract

Previous studies have shown that extracts from soy possess potent antiapoptotic activity in in vitro and in vivo models. We recently reported that this antiapoptotic activity can be attributed to the presence of specific phospholipids. In this study, a conventional preparation of the soy-derived Bowman-Birk inhibitor (BBI) was tested for antiapoptotic activity in a C3H/10T1/2 cell serum deprivation assay. The BBI preparation was separated into lipid- or protein-containing fractions by organic extraction. The lipid fraction contained only antiapoptotic activity; the protein fraction contained only enzyme inhibition activity. We therefore conclude that the antiapoptotic activity of the BBI preparation is due to specific phospholipids that copurify with BBI. These phospholipids retain their antiapoptotic activity after autoclave treatment, whereas autoclave treatment of the protein fraction results in a loss of its enzyme inhibition activity.