Antioxidant and antidiabetic activities of peptides isolated from a hydrolysate of an egg-yolk protein by-product prepared with a proteinase from Asian pumpkin (Cucurbita ficifolia)

Abstract

Bioactive peptides derived from food have been increasingly popular due to their therapeutic properties. Of particular importance are peptides with a multidirectional activity that can be used in the treatment and prevention of diet-related diseases. This paper attempts to utilize a by-product of phospholipid extraction from egg yolk as a source of peptides with a broad spectrum of biological activity. In addition, in this research we used a non-commercial enzyme obtained from Asian pumpkin, which has not been sufficiently researched in terms of its ability to release biopeptides from food proteins. In the present study the biological properties of peptides, derived from egg-yolk protein by-products (YP) remaining after phospholipid extraction, and their four synthetic analogs were investigated with regard to their antioxidant (radical scavenging capacity, Fe 2+ chelating effect, reducing power (FRAP)) and antidiabetic (a-glucosidase and DPP-IV inhibitory activities) properties. One of them, with the sequence LAPSLPGKPKPD, exhibited the highest antioxidant activity (free radical scavenging activity (6.03 mM Trolox eq per mg protein); FRAP (296.07 mg Fe 2+ per mg protein)). This peptide also revealed the strongest DPP-IV (361.5 mmol L À1 ) and a-glucosidase (1065.6 mmol L À1 ) inhibitory activities, a novel multifunctional effect for peptides from an egg-yolk hydrolysate.

Peptides: Production, bioactivity, functionality, and applications

“…They further reported that one of the peptides, KLPGF, had the highest effect against a-glucosidase and a-amylase with IC 50 values of 59.5 § 5.7 and 120 §4.0 mmol¢l ¡1 , respectively (Yu et al, 2012). Moreover, Zambrowicz et al (2015) reported high level of anti-diabetic effects of bioactive peptides in a by-product of phospholipid extraction from egg yolk through inhibition of a-glucosidase and DPP-IV. They claimed that a peptide from the by-product, with amino acid sequence of LAPSLPGKPKPD, showed the strongest a-glucosidase inhibitory (1065.5 mmol¢l…”

Structural properties of bioactive peptides with α‐glucosidase inhibitory activity

“…Findings on peptides derived from albumin [10] and egg white proteins [20] also suggested that the presence of proline and a basic amino acid (lysine and arginine) may be important for enhanced activity because RVPSLM, KLPGF, and TPSPR displayed higher α-glucosidase inhibition than other peptides investigated in both studies. [23,29,30] Although most of the peptides investigated for αglucosidase inhibition did not contain methionine, Yu et al [20] observed that RVPSLM (IC 50 = 23.07 μm) had much higher activity than RVPSL (IC 50 = >150.0 μm) clearly indicating a requirement for methionine for enhanced activity. [23,29,30] Although most of the peptides investigated for αglucosidase inhibition did not contain methionine, Yu et al [20] observed that RVPSLM (IC 50 = 23.07 μm) had much higher activity than RVPSL (IC 50 = >150.0 μm) clearly indicating a requirement for methionine for enhanced activity.…”

“…In fact, even the most potent peptide STYV (IC 50 = 0.012 μm) was digested to STY. This might be of great impact in the search of multifunctional antidiabetic peptides [4,29,31] as peptides of longer sequences can be designed which could release fragments with α-glucosidase and DPP-IV inhibitory activities after GIT digestion. Considering the activities and sequences of both peptides, minor structural and physicochemical changes may be needed to produce a highly active α-glucosidase inhibitory peptide that is resistant to GIT digestion.…”

Effect of boiling on the antidiabetic property of enzyme treated sheep milk casein

“…In this, context comes the importance of natural remedial measures like the use of food-derived bioactive peptides. The antidiabetic peptide has also been reported in case of egg yolk protein hydrolysates [7]. These food-borne bioactive peptides can be produced by various methods like processing of food using various physical and chemical agents that hydrolyze proteins, treatment with various proteolytic enzymes, and by the activity of various microbes in case of fermented foods [8].…”