Studies on bioactive peptide from Chinese soft-shelled turtle (Pelodiscus sinensis) with functionalities of ACE inhibition and antioxidation

This paper dealt with a novel anti-hypertensive collagen peptide from Chinese soft-shelled turtle ( Pelodiscus sinensis ), which was an efficient inhibitor of angiotensin converting enzyme (ACE, EC 3.4.15.1). ACE plays an important physiological role in the regulation of blood pressure by virtue of the rennin angiotensin system. In traditional Chinese medicine, Chinese soft-shelled turtle possesses many health-function properties. This study investigated the effects of Chinese soft-shelled turtle hydrolysate (CTH) on ACE inhibition. The CTH showed limited inhibition effect on ACE with an IC 50 value at 280 ± 8 μg/ml, while its graded fraction of molecular weight less than 5000 Da (CTH5K) obtained through membrane ultra filtration exhibited better inhibitory activity (IC 50 = 190 ± 5 μg/ml). The antioxidant activity of CTH was also determined by radical scavenging ability. The CTH5K showed higher antioxidant activity. These results indicate that CTH5K possesses potent antihypertensive and antioxidant activity, and provides a bioactive peptide material with potential applications as ingredients in functional foods. Key words: Chinese soft-shelled turtle, collagen peptide, angiotensin converting enzyme inhibitor, antihypertensive, antioxidant.