荞麦黄酮和荞麦糖醇对胰脂肪酶的抑制作用

目的：了解荞麦麸皮中活性成分抑制胰脂肪酶的活性。方法：以苦荞麸皮醇提物（主要成分为芦丁）、醇提残渣水解物（主要成分为芦丁、槲皮素和异槲皮素的混合物）和甜荞麸皮水提物（主要成分为荞麦糖醇）为实验材料，测定3 个样品对胰脂肪酶的抑制作用，以市售胰脂肪酶抑制剂--奥利司他为参照；通过研究底物、抑制剂和酶的加入顺序对抑制率的影响，初步确定醇提水解物的抑制机理。结果：实验材料对胰脂肪酶的抑制作用依次为奥利司他＞醇提水解物＞醇提物＞水提物，半数抑制浓度（IC50）分别为0.47、1.94、2.53、17.6 mg/mL；醇提水解物的抑制作用机理主要是通过苦荞黄酮与底物相互作用，从而阻碍了底物与酶的作用，属于竞争性抑制。结论：荞麦黄酮（即醇提物和醇提水解物）对胰脂肪酶有抑制活性；醇提残渣经高压水解后更有利于其对胰脂肪酶的抑制作用；荞麦糖醇（即水提物）在低质量浓度下抑制效果不明显，在较高的质量浓度下则表现出抑制活性。

Inhibitory Effect of Flavonoids and Fagopyritols from Buckwheat on Pancreatic Lipase

Objective: To understand the inhibitory activity of bioactive components in buckwheat bran on pancreatic lipase,
which can provide evidence to explain its mechanism for lowing serum lipids. Methods: Ethanol extract of buckwheat bran
(mainly containing rutin) and high-pressure hydrolysate of the residue left after ethanol extraction (a mixture of quercetin,
isoquercetin and rutin) were obtained from tartary buckwheat bran, while water extract (mainly consisting of fagopyritols)
was prepared from common buckwheat bran for evaluation of their inhibitory activity on pancreatic lipase in comparison
with the lipase inhibitor orlistat. The mechanism of the hydrolysate for inhibiting pancreatic lipase was investigated by
examining the effect of the order of addition of substrate, inhibitor and enzyme on the inhibitory activity. Results: The
sequence of inhibitory activity toward pancreatic lipase was orlistat > hydrolysate > ethanol extract > water extract, with IC50
values of 0.47, 1.94, 2.53 and 17.6 mg/mL, respectively. The inhibitory mechanism of the hydrolysate on pancreatic lipase
belonged to the competitive type, which was mainly associated with the presence of flavonoids interacting with the substrate
to block its interaction with the lipase. Conclusion: Buckwheat flavonoids present in the ethanol extract and the hydrolysate
exert inhibitory effects on pancreatic lipase, especially those of the latter. Buckwheat fagopyritols in the water extract from
common buckwheat bran show no inhibitory effect on pancreatic lipase at a low concentration, but can inhibit this enzyme at
a high concentration.