Changes in peptidomes and Fischer ratios of corn-derived oligopeptides depending on enzyme hydrolysis approaches

Anti-Fatigue Activity of Corn Protein Hydrolysate Fermented by Lactic Acid Bacteria

OBJECTIVES

This study aimed to clarify the effect of lactic acid bacteria-fermented corn protein hydrolysate (FCH) on fatigue in mice and explore the connection between fatigue-related indicators and intestinal microbial flora.

METHODS

The fatigue model of mice was constructed by exercise endurance experiment. The anti-fatigue level of FCH was evaluated by measuring physiological and biochemical indexes in mouse serum, liver and skeletal muscle. The relationship between FCH, intestinal flora and fatigue was explored through the analysis of intestinal microbial diversity in mice, and the anti-fatigue mechanism of FCH was further analyzed.

RESULTS

The results showed that the weight-bearing swimming time of mice was prolonged by 1.96 times, and the running time of mice was prolonged by 2.63 times in the high-dose FCH (FCH-H) group. Moreover, the lactic acid contents in the blood were reduced by 16.00%, and lactate dehydrogenase activity and urea nitrogen contents basically returned to the normal level. Meanwhile, the malondialdehyde contents were reduced by 31.24%, and superoxide dismutase activity and glutathione contents were increased by 1.84 times and 1.72 times, respectively. In addition, the glycogen contents of the body were restored, and the muscle glycogen and liver glycogen were increased by 1.81 and 5.81 times, respectively. Analysis of intestinal microbial flora diversity in mice showed that the highest relative abundance was Lactobacillus, and the FCH group could recover and even increase its relative abundance. Lactobacillus was significantly positively correlated with muscle glycogen and SOD.

CONCLUSIONS

FCH can alleviate fatigue by regulating fatigue-related indicators and improving the intestinal microbial flora of the organism.

Systematical Investigation on Anti-Fatigue Function and Underlying Mechanism of High Fischer Ratio Oligopeptides from Antarctic Krill on Exercise-Induced Fatigue in Mice

High Fischer ratio oligopeptides (HFOs) have a variety of biological activities, but their mechanisms of action for anti-fatigue are less systematically studied at present. This study aimed to systematically evaluate the anti-fatigue efficacy of HFOs from Antarctic krill (HFOs-AK) and explore its mechanism of action through establishing the fatigue model of endurance swimming in mice. Therefore, according to the comparison with the endurance swimming model group, HFOs-AK were able to dose-dependently prolong the endurance swimming time, reduce the levels of the metabolites (lactic acid, blood urea nitrogen, and blood ammonia), increase the content of blood glucose, muscle glycogen, and liver glycogen, reduce lactate dehydrogenase and creatine kinase extravasation, and protect muscle tissue from damage in the endurance swimming mice. HFOs-AK were shown to enhance Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities and increase ATP content in muscle tissue. Meanwhile, HFOs-AK also showed significantly antioxidant ability by increasing the activities of superoxide dismutase and glutathione peroxidase in the liver and decreasing the level of malondialdehyde. Further studies showed that HFOs-AK could regulate the body's energy metabolism and thus exert its anti-fatigue effects by activating the AMPK signaling pathway and up-regulating the expression of p-AMPK and PGC-α proteins. Therefore, HFOs-AK can be used as an auxiliary functional dietary molecules to exert its good anti-fatigue activity and be applied to anti-fatigue functional foods.

Purification, identification and molecular docking of dual-functional peptides derived from corn protein hydrolysates with antioxidant and antiadhesive activity against Helicobacter pylori

BACKGROUND

More than 50% of the world's population is infected with Helicobacter pylori, which is classified as a group I carcinogen by the World Health Organization (WHO).

RESULTS

Corn protein dual-functional peptides were identified and functionally analyzed in vitro and in silico. Two novel dual-functional peptides were identified as Cys-Gln-Asp-Val-Pro-Leu-Leu (CQDVPLL, CQ7) and Thr-Ile-Phe-Pro-Gln-Cys (TIFPQC, TI6) using nanoscale liquid chromatography coupled to tandem mass spectrometry (nano-LC-MS/MS). The antiadhesive effects against H. pylori of CQ7 and TI6 were 45.17 ± 2.41% and 48.62 ± 1.84% at 4 mg mL-1 , respectively. In silico prediction showed that CQ7 and TI6 had good physicochemical properties. Molecular docking demonstrated that CQ7 and TI6 could bind to the adhesins BabA and SabA by hydrophobic interactions and hydrogen bonds, preventing H. pylori infection. Moreover, CQ7 showed strong antioxidant activity due to its unique amino acid composition.

CONCLUSION

The present study demonstrated that the identified peptides, CQ7 and TI6, possess antioxidant and antiadhesive effects, preventing H. pylori infection and alleviating oxidative injury to the gastric mucosa. © 2023 Society of Chemical Industry.

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.

Production and identification of immunomodulatory peptides in intestine cells obtained from hemp industrial by-products

Hemp seeds have attracted the interest of the food industry recently, to be employed as functional food, considering their nutritional composition, highlighting the high content and quality of the proteins. In this study, ten hemp protein hydrolysates (HPHs) were obtained by enzymatic hydrolysis with two food-grade proteases from a hemp protein isolate and the inflammatory properties were evaluated in Caco-2 cell line. To this end, the gene expression and the release of proinflammatory and anti-inflammatory cytokines by Caco-2 cells stimulated with bacterial lipopolysaccharide and treated with HPHs at concentrations of 50 and 100 μg/mL were analyzed. The peptides contained in each HPH were identified and those with higher quality of the match in the spectrum were subjected to in silico analyses to determine which peptides were bioactive and contributing to the immunomodulatory activity of the hydrolysates. The results suggest that the immunomodulatory properties of these HPHs could have a beneficial effect at the level of the intestinal epithelium. The HPH20A and HPH60A + 15F exerted high immunomodulatory properties based on the cytokine levels release. The oligopeptides MAEKEGFEWVSF and GLHLPSYTNTPQLVYIVK were proposed as the most active ones. The potential of these peptides as nutraceuticals to prevent or pretreat intestinal inflammation is promising, though requires validation by in vivo assays.

Preparation and identification of a novel peptide with high antioxidant activity from corn gluten meal

The antioxidant activity of corn peptides is related to their molecular weight and structure. Corn gluten meal (CGM) was hydrolyzed using a combination of Alcalase, Flavorzyme and Protamex, and the hydrolysates were subjected to antioxidant activity analysis after further fractionation. Corn peptides with molecular weights less than 1 kDa (CPP1) exhibited excellent antioxidant activity. A novel peptide, Arg-Tyr-Leu-Leu (RYLL), was identified from CPP1. RYLL displayed preferable scavenging capacities for ABTS radicals and DPPH radicals, with IC₅₀ values of 0.122 mg/ml and 0.180 mg/ml, respectively. Based on quantum calculations, RYLL had multiple antioxidant active sites, and tyrosine was the main active site due to the highest energy of the highest occupied molecular orbit (HOMO). Moreover, the simple peptide structure and hydrogen bond network of RYLL contributed to the exposure of the active site. This study elucidated the antioxidant mechanism of corn peptides, which could provide an understanding for CGM hydrolysates as natural antioxidants.

Development and Utilization of Corn Processing by-Products: A Review

As an important food crop, corn has an important impact on people's lives. The processing of corn produces many by-products, such as corn gluten meal, corn husk, and corn steep liquor, which are rich in protein, oil, carbohydrates, and other nutrients, all of which are inexpensive. Their accumulation in large quantities during the production process not only results in a burden on the environment but also the loss of potentially valuable food materials that can be processed. In fact, the by-products of corn processing have been partially used in functional foods, nutrients, feed, and other industries. There is no doubt that the secondary utilization of these by-products can not only solve the problem of waste pollution caused by them, but also produce high value-added products and improve the economic benefits of corn. This paper describes in detail the processing and higher-value utilization of the five main by-products: corn gluten meal, corn husks, corn steep liquor, corn germ, and fuel ethanol by-product. The utilization status of corn processing by-products was discussed roundly, and the development trend of corn processing by-products in China and other countries was analyzed, which provided the reference for the development of the corn deep processing industry.

The Protective Effects of Corn Oligopeptides on Acute Alcoholic Liver Disease by Inhibiting the Activation of Kupffer Cells NF-κB/AMPK Signal Pathway

Alcohol can cause injury and lead to an inflammatory response in the liver. The NF-κB/AMPK signaling pathway plays a vital role in regulating intracellular inflammatory cytokine levels. In this study, corn oligopeptides (CPs), as the research objects, were obtained from corn gluten meal, and their regulation of the activation of the Kupffer cell NF-κB/AMPK signal pathway induced by LPS was investigated. Results showed that ALT, AST, and inflammatory cytokines in mice serum after the administration of CPs at 0.2, 0.4, and 0.8 g/kg of body weight displayed a distinct (p < 0.05) reduction. On the other hand, the CPs also inhibited the expression of recognized receptor CD14 and TLR4, down-regulated P-JNK, P-ERK, and P-p-38, and thus inhibited inflammatory cytokine levels in Kupffer cells (KCs). Furthermore, four kinds of dipeptides with a leucine residue at the C-terminus that might exhibit down-regulated inflammatory cytokines in the NF-κB/AMPK signaling pathway functions were detected using HPLC-MS/MS. These results indicated that CPs have a potential application value in acute alcoholic liver disease.

Corn distillers solubles as a novel bioresource of bioactive peptides with ACE and DPP IV inhibition activity: characterization, in silico evaluation, and molecular docking

This study aimed to investigate the biological potential of underutilized and low-value corn distillers solubles, containing a unique unexplored blend of heat-treated corn and yeast proteins, from the bioethanol industries, by bioinformatic and biochemical approaches. Protein hydrolysates were produced by applying four commercially accessible proteases, among which alcalase provided the best results in terms of yield, degree of hydrolysis, molecular weight, number of proteins, bioactive peptides, and deactivation against anti-angiotensin I-converting enzyme (ACE) and anti-dipeptidyl peptidase IV (DPP IV). The optimal conditions to produce anti-ACE and anti-DPP IV peptides were using alcalase for 10.82 h and an enzyme : substrate ratio of 7.90 (%w/w), with inhibition values for ACE and DPP IV of 98.76 ± 1.28% and 34.99 ± 1.44%, respectively. Corn (α-zein) and yeast (glyceraldehyde-3-phosphate dehydrogenase) proteins were mainly suitable, upon enzymolysis, for the release of bioactive peptides. The peptides DPANLPWG, FDFFDNIN, WNGPPGVF, and TPPFHLPPP inhibited ACE more effectively as verified with binding energies of -11.3, -11.6, -10.5, and -11.6 kcal mol^-1, respectively, as compared to captopril (-6.38 kcal mol^-1). Compared with the binding energy of sitagliptin (-8.6 kcal mol^-1), WNGPPGVF (-9.6 kcal mol^-1), WPLPPFG (-9.8 kcal mol^-1), LPPYLPS (-9.7 kcal mol^-1), TPPFHLPPP (-10.1 kcal mol^-1), and DPANLPWG peptides (-10.1 kcal mol^-1) had greater inhibition potential against DPP IV. The peptides impeded ACE and DPP IV majorly via hydrophobic and hydrogen linkage interactions. The key amino acids TYR⁵²³, GLU³⁸⁴, and HIS³⁵³ were bound to the catalytic sites of ACE and GLN⁵⁵³, GLU²⁰⁶, PHE³⁶⁴, VAL³⁰³, and THR³⁰⁴ were bound to the DPP IV enzyme. The PHs can be used as ingredients in the feed or food industries with possible health advantages.

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.

A biotechnological approach for the production of branched chain amino acid containing bioactive peptides to improve human health: A review

Improper nutrition provokes many types of chronic diseases and health problems, which consequently are associated with particularly high costs of treatments. Nowadays, consumer's interest in healthy eating is shifting towards specific foods or food ingredients. As a consequence, bioactive peptides as a promising source of health promoting food additives are currently an intensely debated topic in research. Process design is still on its early stages and is significantly influenced by important preliminary decisions. Thus, parameters like peptide bioactivity within the product, selection of the protein source, enzyme selection for hydrolysis, peptide enrichment method, as well as stability of the peptides within the food matrix and bioavailability are sensitive decision points, which have to be purposefully coordinated, as they are directly linked to amino acid content and structure properties of the peptides. Branched chain amino acids (BCAA) are essential components for humans, possessing various important physiologic functions within the body. Incorporated within peptide sequences, they may induce dual functions, when used as nutraceuticals in functional food, thus preserving the foodstuff and prevent several widespread diseases. Furthermore, there is evidence that consuming this peptide-class can be a nutritional support for elderly people or improve human health to prevent diseases caused by incorrect nutrition. Based on the knowledge about the role of BCAA within various peptide functions, discussed in the review, special attention is given to different approaches for systematic selection of the protein source and enzymes used in hydrolysis, as well as suitable peptide enrichment methods, thereby showing current trends in research.