Łukasz Bobak

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)

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, Fe2+ chelating effect, reducing power (FRAP)) and antidiabetic (α-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 μM Troloxeq per mg protein); FRAP (296.07 μg Fe2+ per mg protein)). This peptide also revealed the strongest DPP-IV (361.5 μmol L−1) and α-glucosidase (1065.6 μmol L−1) inhibitory activities, a novel multifunctional effect for peptides from an egg-yolk hydrolysate.

Biological and functional properties of proteolytic enzyme-modified egg protein by-products

Enzymatic hydrolysis led to improve functional properties and biological activity of protein by-products, which can be further used as protein ingredients for food and feed applications. The effects of proteolytic enzyme modification of egg-yolk protein preparation (YP) and white protein preparation (WP), obtained as the by-products left during the course of lecithin, lysozyme, and cystatin isolation on their biological and functional properties, were evaluated by treating a commercial Neutrase. The antihypertensive and antioxidative properties of YP and WP hydrolysates were evaluated based on their angiotensin-converting enzyme (ACE)-inhibitory activity and radical scavenging (DPPH) capacity, ferric reducing power, and chelating of iron activity. The functionality of obtained hydrolysates was also determined. Neutrase caused a degree of hydrolysis (DH) of YP and WP by-products: 27.6% and 20.9%, respectively. In each of them, mixture of peptides with different molecular masses were also observed. YP hydrolysate showed high levels of antioxidant activity. The scavenging capacity, ferric reducing power, and chelating capacity were observed at the level: 0.44 μmol/L Trolox mg−1, 177.35 μg Fe2+ mg−1, and 549.87 μg Fe2+ mg−1, respectively. YP hydrolysate also exhibited significant ACE-inhibitory activity, in which the level was 59.2 μg. Protein solubility was significantly improved as the DH increased. WP hydrolysate showed high water-holding capacity of 43.2. This study indicated that YP and WP hydrolysates could be used in foods as natural antioxidants and functionality enhancers.

A simple and rapid method of isolation of active polypeptide complex, yolkin, from chicken egg yolk

A large number of bioactive peptides isolated from natural sources are known to play important physiological roles in the human body. It is possible to use these as alternative therapy agents. One example is yolkin which can be useful as a food supplement, a natural therapeutic agent for preventing and treating cognitive disorders of various origins, preferably in patients with unsatisfactory responses to known therapies. A new simple method of isolation of yolkin based on precipitation with ethanol or acetone was developed. The best precipitation efficiency of both ethanol and acetone was achieved when stirred into the starting material to a final concentration of 70%. These methods preserved the ability of yolkin to stimulate human whole blood cells to release anti-inflammatory cytokines and neurotrophins. At first we indicated that yolkin displayed a potential neuroprotective effect by the ability to stimulate cells to produce pro-survival brain derived neurotrophic factor (BDNF).

Positive effects of egg-derived phospholipids in patients with metabolic syndrome

PURPOSE Patients with metabolic syndrome (MBS) have an increased risk of all-cause mortality, especially from cardiovascular disease. Egg phospholipids (PL) have been shown to exert a positive impact on cholesterol metabolism and inflammation; eggs are an important source of PL. Our study examined potential effects of egg-yolk-derived PL in non-diabetic patients with MBS. METHODS The study group consisted of 40 patients with MBS diagnosed according to IDF criteria and divided into an experimental group receiving the PL preparation (n-6: n-3 fatty acids ratio: 1.79) and the comparison group receiving an olive oil preparation, for one month (2012/2013year). The studied dosage was 45ml (15ml 3 times per day). It was a randomized, double blinded study. RESULTS The waist to hip ratio, GGTP levels, plasma platelet concentrations and flow mediated vasodilation of brachial artery (FMD) significantly improved in the experimental group. A significant decrease in daytime ABPM blood pressure was noticed in both groups. CONCLUSIONS A phospholipid-enriched diet caused a significant improvement of endothelial vasodilatory function and a significant decrease in waist to hip ratio. A significant decrease in daytime systolic blood pressure were observed in both the phospholipid-enriched and oil-olive group.

Influence of Docosahexaenoic Acid Obtained from New Generation of Eggs on the Repolarisation of Ventricles in Pigs with Experimental Tachycardiomyopathy

Abstract The influence of docosahexaenoic (DHA) acid obtained from a new generation of eggs on ventricular electrical function of 24 pigs with experimentally induced tachycardiomyopathy was described. Two groups were formed, 12 pigs had experimentally evoked tachycardiomyopathy and were getting standard feed (control group TIC). Twelve pigs with tachycardiomyopathy received feed with an addition of a dietary supplement containing phospholipids isolated from new generation of eggs at a dose of 1,000 mg of DHA/animal/24 h (experimental group TIC). Electrophysiological study was carried out from an external programmer immediately after implantation of the pacemaker. All the tests were carried out in general anaesthesia. After 8 weeks of fast ventricular pacing at 170 bpm in pigs receiving phospholipids obtained from eggs, a statistically significant shortening of ventricular refraction time was observed during sinus rhythm and also during the ventricular pacing of 130 bpm, and 150 bpm in the group of pigs fed standard feed. The ventricular refraction time in the sinus rhythm was significantly longer after 12 weeks of fast pacing and in the pacing at 130 bpm and 150 bpm it was significantly longer after 8 weeks of fast pacing. Phospholipids containing high percentage of n-3 polyunsaturated fatty acids (PUFA) obtained from new generation of eggs may contribute to the shortening ventricular refraction period after its oral administration. The n-3 PUFA obtained from a new generation of hen eggs may be an alternative to fish oil source of DHA and other polyunsaturated fatty acids.

Production and Identification of Biologically Active Peptides Derived from By-product of Hen Egg-Yolk Phospholipid Extraction

Biologically active peptides derived from food proteins have been increasingly popular due to their therapeutic properties. This paper attempts to utilize a by-product of phospholipid extraction from egg yolk as a source of peptides with antioxidant [radical scavenging capacity, Fe2+ chelating effect, reducing power (FRAP)] and ACE-inhibitory activity. In addition, in this research we analysed the ability to release bio-peptides of a non-commercial proteases obtained from Yarrowia lipolytica yeast. Yeast serine protease exert greater ability to evaluate antioxidant and ACE inhibitory activity than yeast aspartyl protease during degradation of protein by-product. Purification procedures including membrane filtration, gel filtration chromatography and reversed-phase high-performance liquid chromatography led to obtain a decapeptide QSLVSVPGMS with strong DPPH free radical scavenging and ACE inhibitory activities. A new application of the serine protease from Y. lipolytica yeast in the production of bioactive peptides from egg yolk protein by-product was demonstrated.

Lecithin derived from ω-3 PUFA fortified eggs decreases blood pressure in spontaneously hypertensive rats

Hypertension is the most common risk factor for stroke, coronary heart disease and heart failure, which are the leading causes of death worldwide. Dietary patterns and supplements intakes are becoming important factors in the hypertension. The aim of this study was to estimate the effects of new generation egg yolk phospholipids rich in lecithin (SL) esterified with omega-3 and omega-6 fatty acids on blood pressure in hypertensive rats (SHR). Here we have reported that lecithin (SL) derived from egg yolk lowers blood pressure in pathology of hypertension. The SHR rats treated with SL had significantly lower blood pressure than control group (157/104 vs. 178/121 mmHg; P < 0.05) and down-regulated mesenteric artery over-response to norepinephrine and potassium chloride, giving similar arterial response as for normotensive Wistar Kyoto rats (WKY). Hypertensive rats treated by SL demonstrated significantly lower serum level of inflammatory factors. This work also indicates that SL treatment lowers heart rate and reduces the serum level of oxidative stress marker - nitrotyrosine - by 30–34% in both hypertensive and normotensive animals. Phospholipids with lecithin derived from PUFA fortified eggs may be a valuable dietary supplement in prophylaxis of hypertension and in patients with hypertension, however, this requires further studies on humans.