玉米环二肽（组氨酸-脯氨酸）的分离纯化、结构鉴定及其生物活性

环二肽（组氨酸-脯氨酸）（cyclo (His-Pro)，CHP）是一种活性环二肽，在降血糖、抗氧化方面具有显著效果。实验通过DE-52阴离子交换层析、Sephadex G-25凝胶层析、半制备型高效液相色谱等方法，对高温高压环化后的玉米蛋白水解物进行分离纯化研究，得到CHP。采用超高效液相色谱、傅里叶变换红外光谱、核磁共振氢谱和碳谱对产物的结构进行鉴定，并通过体外降血糖和抗氧化实验初步测定了其生物活性。结果表明：采用本研究的分离纯化方法制备得到的CHP的纯度为97.36%，傅里叶变换红外光谱和核磁共振波谱的测定表明该肽的结构与预期结构相符，初步的生理活性鉴定结果表明，玉米CHP经分离纯化后对α-葡萄糖苷酶和α-淀粉酶活性具有很强抑制能力，半抑制浓度（IC50）分别为1.1、1.9 mg/mL；且具有很强的1,1-二苯基-2-三硝基苯肼自由基清除活性（IC50 67 μg/mL）和还原力。

Separation,Purification, Structural Identification and Bioactivities of Corn Cyclo (His-Pro)

Cyclo (His-Pro) (CHP) is an active dipeptide that has remarkable anti-diabetic and antioxidant activities. In the
present study, CHP was isolated and purified from corn protein hydrolysate treated by high pressure/temperature treatment
using DE-52 anion-exchange chromatography, gel filtration chromatography and semi-preparative high performance
liquid chromatography (HPLC). The structure of the purified product was identified by ultra-high performance liquid
chromatography (UPLC), Fourier infrared (FI-IR) spectroscopy and 1H and 13C nuclear magnetic resonance (NMR), and its
bioactivities including in vitro anti-diabetic and antioxidant capacity were determined. The results showed that the purity of
the prepared corn CHP was more than 97.36%. FI-IR and NMR spectra showed that the corn CHP was the target compound.
The results of physiological activities indicated that the CHP exhibited strong α-glucosidase and α-amylase inhibitory
activity with half maximal inhibitory concentrations (IC50) of 1.1 and 1.9 mg/mL, respectively, as well as high scavenging
activity on 2,2-diphenyl-1-picrylhydrazyl hydrate with IC50 of 67 μg/mL and potent reducing capacity.