Preparation of high Fischer’s ratio corn oligopeptides using directed enzymatic hydrolysis combined with adsorption of aromatic amino acids for efficient liver injury repair

Typical structural characteristics and hepatoprotective effects of novel high Fischer ratio oligopeptides from Antarctic krill on acute alcoholic liver injury

High Fischer ratio oligopeptides derived from Antarctic krill (HFOPs-AK) were screened, and their hepatoprotective effects and potential mechanisms were investigated. Herein, HFOPs-AK, with a Fischer ratio of 29 g/g (40.22 mol/mol) (MW < 1000 Da), were prepared via two-step enzymatic hydrolysis using chymotrypsin and flavourzyme and aromatic amino acid removal. Seventy-eight characteristic peptides were identified from HFOPs-AK through UHPLC-Q/TOF, with peptides containing Leu, Val, or Ile accounting for 79%. High hepatoprotective peptides were purified using GFC and RP-HPLC and identified as SDELGW and LLGWDDM. Furthermore, a murine model of acute liver injury induced by alcohol was successfully established. It was demonstrated that the oral administration of HFOPs-AK (800 mg per kg bw per d) remarkably increased the contents of ADH and ALDH compared with the model group, reaching 3.40 and 5.10 U mg-1 prot, respectively. Further, it was revealed that HFOPs-AK could effectively mitigate hepatic oxidative stress by increasing the levels of GSH-Px (p < 0.01) and decreasing the level of MDA (p < 0.05). Additionally, HFOPs-AK (800 mg per kg bw per d) attenuated liver inflammation by down-regulating the mRNA levels of TNF-α, IL-1β, and IL-6 by 40.45%, 38.48%, and 35.83%, respectively. Therefore, HFOPs-AK may have the potential as a new nutritional supplement for the treatment of alcoholic liver injury.

High Fischer Ratio Oligopeptides of Gluten Alleviate Alcohol-Induced Liver Damage by Regulating Lipid Metabolism and Oxidative Stress in Rats

High Fischer ratio oligopeptides (HFOs) exhibit diverse biological activities, including anti-inflammatory and antioxidant properties. HFOs from gluten origin were prepared through fermentation and enzymatic hydrolysis and then characterized using free amino acid analysis and scanning electron microscopy (SEM). Following intervention, the levels of serum total cholesterol (TC), triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and hepatic malondialdehyde (MDA) in the rats significantly decreased (p < 0.05). Simultaneously, there was an increasing trend in superoxide dismutase (SOD) levels, and glutathione (GSH) levels were significantly elevated (p < 0.05). The mRNA expression levels of alcohol metabolism-related genes (ADH4, ALDH2, and CYP2E1) exhibited a significant increase (p < 0.05). Histological examination revealed a reduction in liver damage. The findings indicate that high Fischer ratio oligopeptides, prepared through enzymatic and fermentation methods, significantly improve lipid levels, ameliorate lipid metabolism disorders, and mitigate oxidative stress, and exhibit a discernible alleviating effect on alcoholic liver injury in rats.

High Fischer ratio peptide of hemp seed: Preparation and anti-fatigue evaluation in vivo and in vitro

The high Fischer (F) ratio hemp peptide (HFHP) was prepared by enrichment using activated carbon adsorption, ultrafiltration, and Sephadex G-25 gel filtration chromatography. The OD₂₂₀/OD₂₈₀ ratio reached 47.1 with a molecular weight distribution from 180 to 980 Da, a peptide yield up to 21.7 %, and the F value was 31.5. HFHP had high scavenging ability of DPPH, hydroxyl free radicals, and superoxide. Mice experiments showed that the HFHP increased the activity of superoxide dismutase and glutathione peroxidase. The HFHP had no effect on the body weight of mice, but prolonged their weight-bearing swimming time. The lactic acid, serum urea nitrogen, and malondialdehyde of the mice after swimming was reduced, and the liver glycogen increased. The correlation analysis indicated that the HFHP had significant anti-oxidation and anti-fatigue properties.

Preparation and Antioxidant Activities of High Fischer's Ratio Oligopeptides from Goat Whey

This study aimed to obtain high Fischer's ratio oligopeptides from goat whey (HFO) and investigate antioxidant property of it. Hydrolysis of goat whey was done with the approach of sequential digestion of pepsin and flavourzyme. With the adsorption of aromatic amino acids by activated carbon, HFO with a Fischer's ratio of 27.070 and a molecular weight of 200-1,000 Da were obtained, and the branched-chain amino acids accounted for 22.87%. Then the antioxidant activity of HFO was evaluated. At the concentrations of 2.0 mg/mL and 0.50 mg/mL, HFO scavenged 77.27% and 99.63% of 1,1-diphenyl-2-picrylhydrazyl and 3-ethylbenzthiazoline-6-sulphonate free radicals respectively. The scavenging rate of HFO against hydroxyl radicals reached 92.31% at the concentration of 0.25 mg/mL. Animal experiments demonstrated that HFO could moderate the changes of malondialdehyde, superoxide dismutase and glutathione peroxidase caused by CCl4-induced oxidative stress in vivo. This study indicated that HFO from goat whey was capable of oxidation resistance both in vivo and in vitro, which provided a scientific basis for the high-value processing and application of goat milk whey.

[Advances in separation and analysis of aromatic amino acids in food]

Amino acids are important building blocks of proteins in the human body, which are involved in many metabolic pathways. Patients with metabolic diseases such as phenylketonuria, tyrosinemia, and hepatic encephalopathy are genetically defective and cannot metabolize aromatic amino acids (AAA) in food; hence, a regular diet may lead to permanent physiological damage. For this reason, it is necessary to restrict the intake of AAA in their daily diet by limiting natural protein intake, while ensuring normal intake of low protein foods and supplementation with low-AAA protein equivalents. Sources of low-AAA protein equivalents currently rely on free amino acid complex mixtures and low-AAA peptides (also known as high-Fischer-ratio peptides), which have better absorption availability and palatability. AAA separation and analysis techniques are essential for the preparation and detection of low-AAA peptides. Researchers in this field have explored a variety of efficient adsorption materials to selectively remove AAA from complex protein hydrolysates and thus prepare low-AAA peptide foods, or to establish analysis strategies for AAA. Covering more than 70 publications on AAA removal and separation in the last decade from Web of Science Core Collection and China National Knowledge Infrastructure, this review analyzes the structural characteristics and physicochemical properties of AAA, and summarizes the technological progress of AAA removal based on adsorbents such as activated carbon and resin. The applications of two-dimensional nanomaterials, molecular imprinting, cyclodextrins, and metal-organic frameworks in AAA adsorption and analysis from three dimensions, i. e., sample pretreatment, chiral separation and adsorption sensing, are also reviewed. The mainstream adsorbents for AAA removal, such as activated carbon, still suffer from poor specificity and cause environmental pollution during post-use treatment. Existing AAA separating materials show impressive selective adsorption capability in food samples and chiral mixtures as well as high sensitivity in adsorption sensing. The development of an efficient detection technology for AAA may help in detecting trace AAA in food and in evaluating chiral AAA adulteration in food samples. By exploring the advantages and disadvantages of each type of technology, we provide support for the advancement of the removal and analysis techniques for AAA.

Engineering a carboxypeptidase from Aspergillus niger M00988 by mutation to increase its ability in high Fischer ratio oligopeptide preparation

High Fischer ratio oligopeptides have better conditioning effects on chronic diseases caused by long-term sub-health. At present, the enzymatic method for producing high Fischer ratio oligopeptides has a low yield, complicated purification, and a high cost. The use of exopeptidases with specific catalytic activity for aromatic amino acids in the preparation of high Fischer ratio oligopeptides is an important means to solve this problem. The carboxypeptidase from Aspergillus niger M00988 was cloned, which has good specificity for hydrophobic amino acids. Mutations at important substrate binding sites 135, 160, and 206 were performed to study important factors affecting the enzyme-specific recognition of aromatic groups. The results showed that the steric hindrance of amino acid residues at position 135 and the effects of positions 160 and 206 on the binding force of the enzyme to the substrate have important effects on the specific recognition of aromatic groups by the enzyme. Therefore, the S135 G, Y160S, and Y206S mutant enzymes have good application prospects in the preparation of high Fischer ratio oligopeptides with Chlorella powder. The obtained oligopeptides' Fischer ratio reached 31.45, 38.42, and 36.54, respectively. Compared with the original enzyme, the Fischer ratio increased by 2.58 %, 25.31 %, and 19.18 %, respectively.

Impact of Microwave Thermal Processing on Major Grain Quality Traits of Linseed (Linum usitatissium L.)

The current study investigated the effects of thermal processing of the microwave technology on nutritive value, crude protein solubility, urease activity and amino acid profile on linseed grains. Samples were treated in a SAMSUNG GE82N-B microwave oven at 450W for 0 (L1), 60 (L2), 180 (L3), 300 (L4), and 420 (L5) seconds, respectively. Microwave treatment for 300 seconds showed a significant (p ≤ 0.05) decrease in activity urease comparing to raw linseed. The raw and treated linseed protein solubility index (PDI) show statistical differences (p ≤ 0.05) between all the treatments compared. High performance liquid chromatography (HPLC) analyses of samples differences in the amino acid composition between controls and experimental treatments showed that amino acids were not significantly affected (p ≥ 0.05), except isoleucine and leucine amino acid (p ≤ 0.05). From the results of the present study, it is possible to identify that the best method for improving linseed quality for animal feed is the application of microwave for 60 second (treatment L2). Our results indicate that microwave thermal processing or micronizing dry thermal processing of grains could be successfully used in large industrial feed production with a short period of time and the improved nutritional parameters of grains, increased shelf-life and the unchanged amino acid profile of treated grains.