Isoflavone Contents in Germinated Soybean Seeds

The effect of germination on isoflavone contents in two soybean varieties (Hutcheson and Caviness) was investigated. Soybean seeds were soaked at 25 ^∘C for 12 h, germinated at 40 ^∘C, and freeze-dried. The isoflavone contents of dry, soaked, germinated (hypocotyl length at 0.5, 2.5, and 6.5 mm), and nongerminated seeds were determined by high performance liquid chromatography. The maximum amount of total isoflavone, genistein, and daidzein with their β-glucoside conjugates was obtained when hypocotyl length of the germinated-seed from var. Hutcheson was 0.5 mm (2.491, 1.500, and 0.671 mg/g), and from var. Caviness was 2.5 mm (2.78, 1.523, and 0.905 mg/g). A dramatic increase in malonylgenistin and malonyldaidzin (1.305 mg/g and 0.476 mg/g in Hutcheson, and 1.308 mg/g and 0.677 mg/g in Caviness, respectively) was observed at these hypocotyl lengths. A decrease was observed after this stage. Genistein and daidzein contents were highest just after soaking. Glycitein and its β-glucoside conjugates remained almost the same during germination. Controlled germination can be used to enhance isoflavone content in soybean seed.     

大豆异黄酮甙元对结肠癌HT-29细胞增殖和凋亡的影响

大豆异黄酮通过促进肿瘤细胞凋亡可抑制多种肿瘤细胞的增殖.从大豆提取大豆异黄酮糖甙,再将其部分水解成其甙元,研究大豆异黄酮甙元抑制结肠癌细胞的增殖和促进其凋亡的作用.采用MTT比色法观察大豆异黄酮甙元对结肠癌HT-29细胞增殖的影响,采用TUNEL染色法检测其对HT-29细胞凋亡的影响,采用免疫细胞化学法检测凋亡相关蛋白bax、bcl-2和p53的表达.结果表明:大豆异黄酮甙元可在20～80 mg·L-1范围内时间和浓度依赖性地抑制结肠癌HT-29细胞增殖和诱导细胞凋亡.用40 mg·L-1大豆异黄酮甙元作用结肠癌HT-29细胞72 h时,细胞生长抑制率为(57.1±4.9)%,其对肿瘤细胞凋亡率为(20.9±2.1)%.免疫组化结果还显示,大豆异黄酮甙元可显著性增加HT-29细胞凋亡相关基因bax蛋白表达和降低bcl-2表达.提示,大豆异黄酮甙元可通过诱导结肠癌细胞凋亡发挥抗结肠癌作用.