Layer P, Carlson G L, DiMagno E P
Gastroenterology. 1985 Jun;88(6):1895-902. doi: 10.1016/0016-5085(85)90016-2.
Whether commercial, bean-derived alpha-amylase inhibitor preparations failed to decrease starch digestion in humans because of insufficient antiamylase activity, destruction by gastrointestinal secretions, or decreased activity in the presence of starch is unknown. We used a simple partial purification procedure to markedly concentrate the inhibitor (sixfold to eightfold by total protein content, and 30-40-fold by dry weight). Compared with a commercial preparation and crude bean extract, this partially purified inhibitor inactivated intraduodenal, intraileal, and salivary amylase in vitro faster and more completely (p less than 0.001); its specific activity was not affected by exposure to gastric juice and was only minimally reduced by duodenal juice. Whereas the rate of amylase inhibition by inhibitor was markedly slowed in the presence of nondietary liquid starch, dietary solid starch had only a minimal effect. Consequently, the partially purified inhibitor had no effect on liquid starch digestion, but decreased in vitro digestion of dietary starch in a dose-dependent manner (p less than 0.001). Perfusion of the partially purified inhibitor (2.0, 3.5, or 5.0 mg/ml at 5 ml/min) into the duodenum of humans rapidly inhibited greater than 94%, greater than 99%, or greater than 99.9% of intraluminal amylase activity. We conclude that commercial amylase inhibitors failed to decrease starch digestion in vivo mainly because they have insufficient antiamylase activity. However, a partially purified inhibitor with increased specific activity is stable in human gastrointestinal secretions, slows dietary starch digestion in vitro, rapidly inactivates amylase in the human intestinal lumen, and, at acceptable oral doses, may decrease intraluminal digestion of starch in humans. Such an inhibitor therefore deserves study.
无论是商业用的、源自豆类的α-淀粉酶抑制剂制剂，未能在人体中减少淀粉消化是因为抗淀粉酶活性不足、被胃肠分泌物破坏，还是在有淀粉存在时活性降低，目前尚不清楚。我们使用了一种简单的部分纯化程序，使抑制剂显著浓缩（按总蛋白含量浓缩六至八倍，按干重浓缩30至40倍）。与一种商业制剂和粗制豆类提取物相比，这种部分纯化的抑制剂在体外能更快、更完全地使十二指肠内、回肠内和唾液淀粉酶失活（p<0.001）；其比活性不受胃液暴露的影响，仅被十二指肠液轻微降低。虽然在非膳食液态淀粉存在时，抑制剂对淀粉酶的抑制速率明显减慢，但膳食固态淀粉的影响极小。因此，部分纯化的抑制剂对液态淀粉消化没有影响，但以剂量依赖方式降低了膳食淀粉的体外消化（p<0.001）。将部分纯化的抑制剂（2.0、3.5或5.0mg/ml，流速5ml/min）灌注到人体十二指肠中，能迅速抑制管腔内大于94%、大于99%或大于99.9%的淀粉酶活性。我们得出结论，商业用淀粉酶抑制剂未能在体内减少淀粉消化，主要是因为它们的抗淀粉酶活性不足。然而，一种比活性增加的部分纯化抑制剂在人体胃肠分泌物中稳定，在体外能减缓膳食淀粉消化，能迅速使人体肠腔内的淀粉酶失活，并且在可接受的口服剂量下，可能会减少人体管腔内淀粉的消化。因此，这样一种抑制剂值得研究。
