Wenzhu Zhao

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.

QIGLF, a novel angiotensin I-converting enzyme-inhibitory peptide from egg white protein

BACKGROUND Novel angiotensin I-converting enzyme (ACE)-inhibitory peptides from egg white protein can be rapidly screened by liquid chromatography/tandem mass spectrometry (LC/MS/MS). In this study, several peptides with higher ACE-inhibitory activity were prepared from egg white protein by enzymatic hydrolysis with Alcalase, purified with Sephadex G25, identified by LC/MS/MS and their structure determined by circular dichroism (CD) spectroscopy. RESULTS Peptide sequences DHPFLF, HAEIN and QIGLF that showed ACE-inhibitory activity were investigated further for their stability in gastrointestinal solution and for changes in their secondary structure in solution mixtures. QIGLF exhibited the highest activity (IC(50)=75 µmol L(-1)) and was resistant to digestion by proteases of the gastrointestinal tract. The CD spectrum of QIGLF showed the presence of the α-helix conformation. CONCLUSION Three peptides were identified by LC/MS/MS and synthesised by Fmoc solid phase synthesis. Of the three, only the peptide sequence QIGLF was a potential ACE inhibitor, with an IC(50) value of 75 µmol L(-1) . Moreover, QIGLF showed low gastrointestinal enzyme susceptibility and contained a relatively high amount of α-helix.

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.

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.

Characterization of ACE-Inhibitory Peptide Associated with Antioxidant and Anticoagulation Properties

A bioactive peptide Arg-Val-Pro-Ser-Leu (RVPSL) obtained from egg white protein was characterized by LC-MS and further chemically synthesized by the Fmoc solid phase method and investigated in terms of its angiotensin converting enzyme (ACE)-inhibitory activity, antioxidant property, and anticoagulation activity, as well as its stability in a simulated gastrointestinal digestion. The peptide exhibited an ACE-inhibitory activity with an IC(50) value of 20 μM. Also, the peptide could efficiently quench the (1,1)-diphenyl-2-picrylhydrazyl free radicals and exhibit high anticoagulation activity with a complete inhibition at 100 mM. Moreover, the peptide has a good stability against protease digestion. These results suggest that the peptide RVPSL may have potential to be used in nutraceuticals and functional food. Practical Application:  The present research revealed a novel multifunctional peptide hydrolyzed from egg white protein. The peptide RVPSL was not only able to block the amplification of the coagulation cascade, but also able to inhibit ACE activity.

Impacts of Sandification on Ecological Functions and Conservation Measures in Xianghai Wetlands

The present conditions, causes of sandification and its impacts on the ecological functions of Xianghai wetlands have been studied. Results indicate that human irrational exploitation is the key cause of the sandification of the wetland. The ecological functions of the wetlands, for instance, in flood control, pollution filter, water purification, aquatic productivity, and habitat provision for a wide range of animal species, have been seriously affected. To effectively exploit and utilize the river flooding wetland resources, it is necessary to create integrate assessment index system for wetland. It is suggested that positive management strategies and measures for regulation and restoration of wetlands, sustainable exploitation of wetlands and water resource should be taken, so as to control sandification.