Nagaoka S, Miwa K, Eto M, Kuzuya Y, Hori G, Yamamoto K
Department of Food Science, Faculty of Agriculture, Gifu University, Gifu 501-1193, Japan.
J Nutr. 1999 Sep;129(9):1725-30. doi: 10.1093/jn/129.9.1725.
This experiment was designed to evaluate the effects of casein, soy protein, soy protein with bound phospholipids (SP), soy protein peptic hydrolysate (SPH) or soy protein peptic hydrolysate with bound phospholipids (SPHP) on the micellar solubility of cholesterol and the taurocholate binding capacity in vitro. We also evaluated the effects of various proteins on cholesterol metabolism in rats and Caco-2 cells. SPHP had a significantly greater bile acid-binding capacity than that of SPH in vitro. Micellar cholesterol solubility in vitro was significantly lower in the presence of SPHP compared to casein tryptic hydrolysate (CTH). The cholesterol micelles containing SPHP and SPH significantly suppressed cholesterol uptake by Caco-2 cells compared to the cholesterol micelles containing CTH. Consistent with these findings in the in vivo cholesterol absorption study using radioisotopes, fecal excretion of total steroids was significantly greater in rats fed the SPHP diet compared with those fed the casein, soy protein, SP and SPH diets. Serum total cholesterol was significantly lower in rats fed SPHP than in those fed casein. The concentrations of total lipids and cholesterol in liver were significantly lower in the SPHP-fed group compared with all other groups. These results suggest that the suppression of cholesterol absorption by direct interaction between cholesterol-mixed micelles and SPHP in the jejunal epithelia is part of the mechanism underlying the hypocholesterolemic action of SPHP. SPHP may also inhibit the reabsorption of bile acids in the ileum, thus lowering the serum cholesterol level.
本实验旨在评估酪蛋白、大豆蛋白、结合磷脂的大豆蛋白（SP）、大豆蛋白酶解物（SPH）或结合磷脂的大豆蛋白酶解物（SPHP）对胆固醇胶束溶解度和牛磺胆酸盐体外结合能力的影响。我们还评估了各种蛋白质对大鼠和Caco-2细胞胆固醇代谢的影响。在体外，SPHP的胆汁酸结合能力明显高于SPH。与酪蛋白胰蛋白酶解物（CTH）相比，在存在SPHP的情况下，体外胆固醇胶束溶解度显著降低。与含有CTH的胆固醇胶束相比，含有SPHP和SPH的胆固醇胶束显著抑制Caco-2细胞对胆固醇的摄取。与使用放射性同位素进行的体内胆固醇吸收研究中的这些发现一致，与喂食酪蛋白、大豆蛋白、SP和SPH饮食的大鼠相比，喂食SPHP饮食的大鼠粪便中总类固醇的排泄量显著更高。喂食SPHP的大鼠血清总胆固醇显著低于喂食酪蛋白的大鼠。与所有其他组相比，SPHP喂养组肝脏中的总脂质和胆固醇浓度显著更低。这些结果表明，空肠上皮中胆固醇混合胶束与SPHP之间的直接相互作用对胆固醇吸收的抑制作用是SPHP降胆固醇作用机制的一部分。SPHP还可能抑制回肠中胆汁酸的重吸收，从而降低血清胆固醇水平。
