SOYBEAN PROTEIN PRODUCTS AS REGULATORS OF LIVER LOW-DENSITY-LIPOPROTEIN RECEPTORS - II - ALPHA-ALPHA' RICH COMMERCIAL SOY CONCENTRATE AND ALPHA' DEFICIENT MUTANT DIFFERENTLY AFFECT LOW-DENSITY-LIPOPROTEIN RECEPTOR ACTIVATION

Activation of low-density lipoprotein (LDL) receptors has been decribe d in a human hepatoma cell line (Hep G2) exposed to the 7S globulin fr om soy (Lovati et al. J. Agric. Food Chem. 1998, 46, 2474-2480). This in vitro model supports a direct activity of say protein component(s) in lowering LDL cholesterolemia. To ascertain whether alpha or alpha' subunits from 7S globulin, or both, are responsible for the biochemica l effect, a mutant soy cultivar, devoid of the alpha' subunit (Keburi) , was evaluated in the same model. A commercial isoflavone-poor, heat- hydrolyzed soy preparation found effective in human hypercholesterolem ia (Croksoy) was also tested. While Croksoy proved to have a similar a ctivity as the whole 7S globulin, the alpha'-free Keburi variant showe d no effect on LDL receptor activation. These findings support the rel iability of the human liver cell model in predicting a human hypochole sterolemic activity and suggest that specific peptide!s! may be respon sible. Furthermore, they indicate that some say cultivars may be best suited for the preparation of products for human nutritional purposes.