Hisayasu S, Orimo H, Migita S, Ikeda Y, Satoh K, Shinjo S, Hirai Y, Yoshino Y
Department of Biochemistry, Nippon Medical School, Tokyo, Japan.
J Nutr. 1992 May;122(5):1190-6. doi: 10.1093/jn/122.5.1190.
Inhibitory effects of soybean protein isolate (SPI) and soybean lectin on the intestinal absorption of nonheme iron were investigated by in vivo studies in rats. Rats fed the SPI-based diet absorbed significantly less iron than did control rats fed the casein-based diet. Supplementing the SPI diets with 8% D-galactose significantly increased the incorporation of iron into liver ferritin, although D-galactose did not significantly increase iron absorption. Heat treatment of SPI significantly increased iron absorption. Ascorbate did not enhance iron absorption in rats fed the SPI-based diet. The presence of lectin in an aqueous extract of SPI was suggested by hemagglutination activity as well as by immunoreactivity with soybean lectin antibody. Soybean lectin introduced into ligated segments of the upper small intestine of rats inhibited ferrous iron absorption. This inhibitory effect, especially in the mucosal uptake, was significantly improved by addition of N-acetyl-D-galactosamine to soybean lectin. Soybean lectin had no effect on ferric iron absorption. Our results suggest that a portion of the reduction in iron absorption in rats fed SPI may be due to lectins.
通过对大鼠进行体内研究，考察了大豆分离蛋白（SPI）和大豆凝集素对非血红素铁肠道吸收的抑制作用。喂食基于SPI饮食的大鼠比喂食基于酪蛋白饮食的对照大鼠吸收的铁显著减少。在SPI饮食中补充8%的D-半乳糖可显著增加铁在肝脏铁蛋白中的掺入，尽管D-半乳糖并未显著增加铁的吸收。SPI的热处理显著增加了铁的吸收。抗坏血酸盐并未增强喂食基于SPI饮食大鼠的铁吸收。通过血细胞凝集活性以及与大豆凝集素抗体的免疫反应性表明SPI水提取物中存在凝集素。引入大鼠上段小肠结扎段的大豆凝集素抑制亚铁的吸收。通过向大豆凝集素中添加N-乙酰-D-半乳糖胺，这种抑制作用，尤其是在黏膜摄取方面，得到了显著改善。大豆凝集素对三价铁的吸收没有影响。我们的结果表明，喂食SPI的大鼠铁吸收减少的部分原因可能是凝集素。
