Yongguang Yin

Comparison of anti-diabetic effects of polysaccharides from corn silk on normal and hyperglycemia rats

Corn silk is well known and frequently used in traditional Chinese herbal medicines. Polysaccharides of corn silk (POCS), which were extracted by distilled water and precipitated by 80% ethanol solution, were evaluated for its anti-diabetic effect on streptozotocin (STZ)-induced diabetic rats. The results demonstrated that daily treatment with 100-500 mg/kg body weight of POCS on the diabetic rats could not only lead a significant decrease on the animals blood glucose (BG) level, but also reduce the serum lipid level including total cholesterol (TC) and total triglyceride (TG) after determination. The oral glucose tolerance test (OGTT) was also performed to evaluate hypoglycemic effects. Through the measurements of measuring autonomic activity times and rolling stick times, the results also exhibited that the animals had been depressed by dimethyl-biguanide, but protected by the POCS. The POCS showed good antidepressant activity and lengthened remarkably the activity time during the autonomic activities test and exhibited a dose dependent activity.

Primary and secondary structure of novel ACE-inhibitory peptides from egg white protein

The primary structure of novel angiotensin converting enzyme (ACE) inhibitory peptide from egg white protein was investigated, and secondary structure of the peptide was explored for the first time. The potential effects of bioactive peptides were submitted to bioactivity screening with ACE inhibitory activity, antioxidant property, and anticoagulation activity. Bioactive peptides from egg white protein were characterized by LC tandem mass spectrometric, and secondary structures of those peptides were investigated by FT-IR. Our results showed that total 11 bioactive peptides with three new and eight known structures were identified with LC/MS/MS, which then were synthesized by Fmoc solid phase method. Peptide Thr-Asn-Gly-Ile-Ile-Arg (TNGIIR) exhibited higher activity against ACE to other two new peptides. The concentration of the peptide TNGIIR, necessary to inhibit 50% the activity of ACE was 70 μM. Results also suggested that the secondary structural differences between peptides could also influence the ACE inhibition capacity. Thus, it appears that primary and secondary structure of peptide plays the potential role inhibiting the ACE activity.

Anti-diabetic activity peptides from albumin against α-glucosidase and α-amylase

The objectives of this study were to identify novel peptides from albumin, and to evaluate and validate the anti-diabetic activity of peptides against α-glucosidase and α-amylase. In the research, albumin hydrolysate was purified and identified, tandem MS was adapted to characterise the amino acid sequences of peptides from the hydrolysate. In addition, anti-diabetic effects of the peptides with α-glucosidase and α-amylase inhibitory activity have been performed. The present work found eight novel peptides from albumin. Results also suggested that peptide KLPGF had α-glucosidase inhibitory activity with an IC(50) of 59.5±5.7μmoll(-1) and α-amylase inhibitory activity with an IC(50) of 120.0±4.0μmoll(-1). In conclusion, the results revealed that the peptide KLPGF was a potential anti-diabetic inhibitor.

Optimized extraction of polysaccharides from corn silk by pulsed electric field and response surface quadratic design

BACKGROUND Corn silk is a traditional Chinese herbal medicine, which has been widely used for treatment of some diseases. In this study the effects of pulsed electric field on the extraction of polysaccharides from corn silk were investigated. RESULTS Polysaccharides in corn silk were extracted by pulsed electric field and optimized by response surface methodology (RSM), based on a Box-Behnken design (BBD). Three independent variables, including electric field intensity (kV cm(-1) ), ratio of liquid to raw material and pulse duration (µs), were investigated. The experimental data were fitted to a second-order polynomial equation and also profiled into the corresponding 3-D contour plots. Optimal extraction conditions were as follows: electric field intensity 30 kV cm(-1) , ratio of liquid to raw material 50, and pulse duration 6 µs. Under these condition, the experimental yield of extracted polysaccharides was 7.31% ± 0.15%, matching well with the predicted value. CONCLUSION The results showed that a pulsed electric field could be applied to extract value-added products from foods and/or agricultural matrix.

Research on the preparation of antioxidant peptides derived from egg white with assisting of high-intensity pulsed electric field

Egg white protein powder, one of the main egg products, was hydrolysed by Alcalase, Trypsin, and Pepsin respectively to prepare antioxidant peptides. All hydrolysates were assayed by determination of reducing power (RP) ability. Three kinds of hydrolysates were prepared under optimal enzymatic parameters that were obtained from the preliminary one-factor-at-a-time (OFAT) and response surface methodology (RSM) experiments. The results showed that the Alcalase hydrolysates exerted the best RP ability. Thereafter, the Alcalase hydrolysates were sequentially fractionated by ultra filtration membranes in cut-off molecular weight (MW) of 30, 10, and 1 kDa, and tested their antioxidant activities in terms of RP ability, DPPH radical scavenging ability, ABTS radical scavenging ability, and FRAP assay. Effects of high intensity pulsed electric field treatment were further investigated on antioxidant peptides to improve their activities. The results showed that Alcalase hydrolysates possessed the strongest antioxidant ability compared with the other two hydrolysates, particularly for the Fraction-3 with MW <1 kDa. After PEF treatment, this fraction showed a significant improvement of RP ability within 5 h (P<0.05).

Optimization of extraction parameters for trehalose from beer waste brewing yeast treated by high-intensity pulsed electric fields (PEF)

High-intensity pulsed electric fields (PEF) was applied to treat beer waste brewing yeasts (BWBY) to improve the permeability of yeast cell membrane in order to extract trehalose. Several independent variables such as pH (3 to 7), electric field strength (0 to 50 kV/cm), pulse numbers (0 to 10) and liquidsolid ratio (20: 1 to 60: 1) were investigated. The optimal parameters were obtained by one-factor-at-atime (OFAT) experiment and quadratic regression orthogonal design. The results showed that under the conditions of electric fields intensity of 19.97 kV/cm, pulse number of 6, and liquid-solid ratio of 30:1, the extraction rate of trehalose could reach 2.635%. In addition, the extraction efficiency of trehalose treated by PEF was compared with other two trehalose extraction methods, example microwave and ultrasound, and the efficiency of PEF was found to be 103.15 µg/s; it was 15.96 times higher than microwave and 34.08 times higher than ultrasound. This demonstrated that the PEF could be regarded as a promising technique for bio-material extraction.

Antihypertensive Effect of Angiotensin-Converting Enzyme Inhibitory Peptide RVPSL on Spontaneously Hypertensive Rats by Regulating Gene Expression of the Renin–Angiotensin System

Hen eggs are well-known for their biological functions beyond basic nutrition. In this study, the antihypertensive effect of peptide RVPSL from egg protein has been evaluated by an in vivo model. In addition, the mRNA levels of renin, AT1 receptor, angiotensin-converting enzyme (ACE), and AT2 receptor in the rat kidney were investigated through real-time polymerase chain reaction. The Ang I, Ang II, renin, and aldosterone concentrations of serum were also measured. Our results indicated that the blood pressure of the spontaneously hypertensive rats administered RVPSL for 4 weeks decreased significantly compared to that of the negative group. The mRNA levels of renin, ACE, and AT1 receptor in kidney also decreased significantly. The serum Ang II, renin, and aldosterone concentrations of the treatment group were reduced in comparison to those of the negative group. It is hoped this study will help our understanding and potential use of RVPSL in the treatment or prevention of hypertension.

Preparation of antioxidant peptide from egg white protein and improvement of its activities assisted by high-intensity pulsed electric field

BACKGROUND Egg white protein powder was hydrolyzed by three proteases-alcalase, trypsin, and pepsin-to produce antioxidant peptides. Three kinds of hydrolysates were prepared under optimal enzymatic parameters that were obtained from the preliminary one-factor-at-a-time test and response surface methodology. Thereafter, three enzymatic hydrolysates were sequentially fractionated by ultrafiltration membranes in cut-off MW of 30, 10, and 1 kDa, and tested in terms of their reducing power (RP). Effects of high-intensity pulsed electric field (PEF) were further investigated on the antioxidant peptides to improve their activities. RESULTS Alcalase hydrolysates possessed stronger RP ability than the other two hydrolysates, particularly for the fraction within < 1 kDa. After PEF treatment, this fraction showed an improvement of RP ability within 4 h; however, the effects were reversible. High-performance liquid chromatographic analysis showed some MW changes of PEF-treated sample compared with control. CONCLUSIONS Among the three kinds of proteases, alcalase could be regarded as the most appropriate enzyme for preparation of bioactive peptide from egg white protein, with the best antioxidant activity. Also, PEF showed some effects on the peptide and could be further applied to improve its antioxidant activity.

Optimisation extraction of chondroitin sulfate from fish bone by high intensity pulsed electric fields.

High intensity pulsed electric fields (PEF) was used to extract chondroitin sulphate (CS) from fish bone. Results show that PEF extraction speed is much faster, and the content of CS is much higher compared with traditional methods. Variation of PEF parameters and the content of CS were determined by single factor experiments. The processing conditions were optimised by quadratic general rotary unitised design experiments. The maximum yield of 6.92 g/L was achieved under the following conditions: material-liquid ratio of 1:15 g/mL, electric field intensity of 16.88 kV/cm, pulse number of 9, and NaOH concentration of 3.24%. The purity of CS was analysed by agarose gel electrophoresis. CS purity was high, and the extract did not contain any other glycosaminoglycans. PEF can be widely used to extract CS with non-thermal performance, high speed, and low pollution.

Application and bioactive properties of proteins and peptides derived from hen eggs: opportunities and challenges

Several proteins and peptides that are released in vitro and/or in vivo from hen eggs are biologically active and have a variety of functional properties in humans beyond normal nutrition, for which extensive studies have been performed. This review focuses on their biological activities, including antihypertensive, antioxidant, antimicrobial, antiadhesive, immunomodulatory and antithrombotic activities and enhancement of mineral absorption. These proteins and peptides have been shown to regulate the nervous system, cardiovascular system, immune system and gastrointestinal system. The potential application and future directions of research on these bioactive peptides and proteins in the food industry are also addressed.