Abstract:

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.

Key words: cyclo (His-Pro), corn protein, separation and purification, structural identification