Antioxidant Potential of Mung Bean (Vigna radiata) Albumin Peptides Produced by Enzymatic Hydrolysis Analyzed by Biochemical and In Silico Methods

Recent advances in mung bean protein: From structure, function to application

With the surge in protein demand, the application of plant proteins has ushered in a new wave of research. Mung bean is a potential source of protein due to its high protein content (20-30 %). The nutrition, structure, function, and application of mung bean protein have always been a focus of attention. In this paper, these highlighted points have been reviewed to explore the potential application value of mung bean protein. Mung bean protein contains a higher content of essential amino acids than soybean protein, which can meet the amino acid values recommended by FAO/WHO for adults. Mung bean protein also can promote human health due to its bioactivity, such as the antioxidant, and anti-cancer activity. Meanwhile, mung bean protein also has well solubility, foaming, emulsification and gelation properties. Therefore, mung bean protein can be used as an antioxidant edible film additive, emulsion-based food, active substance carrier, and meat analogue in the food industry. It is understood there are still relatively few commercial applications of mung bean protein. This paper highlights the potential application of mung bean proteins, and aims to provide a reference for future commercial applications of mung bean proteins.

Effect of Plant-Based Mung Bean Products on Digestibility and Gut Microbiome Profiling Using In Vitro Fecal Fermentation

The concept of plant-based protein consumption has been increasing recently because of the growing health consciousness among people. Mung bean is one of the most consumed legumes with a dense nutrient profile. Hence, current research is aimed to study the effect of mung bean protein-based products including mung bean snack (MBS) and textured vegetable protein (TVP) for treatment groups against the control groups, commercial ingredients group consisting of mung bean powder (MBP) and pea powder (PP) and commercial products group include commercial pea texture (cPT) and commercial textured vegetable protein (cTVP) for their proximate composition, digestibility, gut microbial profile and fatty acid metabolite profiling. The MBS and TVP samples had significantly higher digestibility of 74.43% and 73.24% than the commercial products. The protein content of TVP was 0.8 times higher than its commercial control. Gut microbiome profiling showed that all the samples shared around 162 similar genera. Post-fermentation analysis provided promising results by reflecting the growth of beneficial bacteria (Parabacteroides, Bifidobacterium and Lactobacillus) and the suppression of pathogens (Escherichia-Shigella, Dorea and Klebsiella). The dual relationship between gut microbiota and nutrient interaction proved the production of abundant short- and branched-chain fatty acids. The MBS sample was able to produce SCFAs (41.27 mM) significantly and BCFAs (2.02 mM) than the TVP sample (27.58 mM and 2.14 mM, respectively). Hence, our research outcomes proved that the mung bean protein-based products might infer numerous health benefits to the host due to enriched probiotics in the gut and the production of their corresponding metabolites.

Advances in Research on the Activity Evaluation, Mechanism and Structure-Activity Relationships of Natural Antioxidant Peptides

Antioxidant peptides are a class of biologically active peptides with low molecular weights and stable antioxidant properties that are isolated from proteins. In this review, the progress in research on the activity evaluation, action mechanism, and structure-activity relationships of natural antioxidant peptides are summarized. The methods used to evaluate antioxidant activity are mainly classified into three categories: in vitro chemical, in vitro cellular, and in vivo animal methods. Also, the biological effects produced by these three methods are listed: the scavenging of free radicals, chelation of metal ions, inhibition of lipid peroxidation, inhibition of oxidative enzyme activities, and activation of antioxidant enzymes and non-enzymatic systems. The antioxidant effects of natural peptides primarily consist of the regulation of redox signaling pathways, which includes activation of the Nrf2 pathway and the inhibition of the NF-κB pathway. The structure-activity relationships of the antioxidant peptides are investigated, including the effects of peptide molecular weight, amino acid composition and sequence, and secondary structure on antioxidant activity. In addition, four computer-assisted methods (molecular docking, molecular dynamics simulation, quantum chemical calculations, and the determination of quantitative structure-activity relationships) for analyzing the structure-activity effects of natural peptides are summarized. Thus, this review lays a theoretical foundation for the development of new antioxidants, nutraceuticals, and cosmetics.

Restoration and preservation effects of mung bean antioxidant peptides on H2O2-induced WRL-68 cells via Keap1-Nrf2 pathway

Mung bean antioxidant peptides (MBAPs) were prepared from mung bean protein hydrolysate, and four peptide sequences including Ser-Asp-Arg-Thr-Gln-Ala-Pro-His (~953 Da), Ser-His-Pro-Gly-Asp-Phe-Thr-Pro-Val (~956 Da), Ser-Asp-Arg-Trp-Phe (~710 Da), and Leu-Asp-Arg-Gln-Leu (~644 Da) were identified. The effects of MBAPs on the oxidation-induced normal human liver cell line WRL-68 were analyzed to determine the mechanism protecting the oxidation-induced injury. The results showed that the cells were subjected to certain oxidative damage by H2O2 induction, as evidenced by decreased cell number and viability, overproduction of intracellular ROS, and decreased mitochondrial membrane potential. Compared with the H2O2-induced group, the MBAP-treated oxidation-induced group exhibited significantly higher cell number and viability, and the intracellular ROS was similar to that of the control group, suggesting that MBAP scavenges excessive intracellular free radicals after acting on the oxidation-induced cells. Combined with Western blotting results, it was concluded that the MBAP-treated oxidation-induced group also significantly promoted the expression of proteins related to the kelch-like ech-related protein 1 (Keap1)/ nuclear factor e2-related factor 2 (Nrf2) signaling pathway, which resulted in an approximately 2-fold increase in antioxidant enzymes, and a decrease in malondialdehyde content of approximately 55% compared to oxidatively-induced cells, leading to the recovery of both cell morphology and viability. These results suggest that MBAPs scavenge intracellular free radicals and improve oxidative stress in hepatocytes through the expression of Keap1/Nrf2 pathway-related protein, thereby reducing oxidative attack on the liver. Therefore, MBAP is applied as a nutritional ingredient in the functional food field, and this study provides a theoretical basis for the high utilization of mung bean proteins.

Protein reservoirs of seeds are amyloid composites employed differentially for germination and seedling emergence

Seed protein localization in seed storage protein bodies (SSPB) and their significance in germination are well recognized. SSPB are spherical and contain an assembly of water-soluble and salt-soluble proteins. Although the native structures of some SSPB proteins are explored, their structural arrangement to the functional correlation in SSPB remains unknown. SSPB are morphologically analogous to electron-dense amyloid-containing structures reported in other organisms. Here, we show that wheat, mungbean, barley, and chickpea SSPB exhibit a speckled pattern of amyloids interspersed in an amyloid-like matrix along with native structures, suggesting the composite nature of SSPB. This is confirmed by multispectral imaging methods, electron microscopy, infrared, and X-ray diffraction analysis, using in situ tissue sections, ex vivo protoplasts, and in vitro SSPB. Laser capture microdissection coupled with peptide fingerprinting has shown that globulin 1 and 3 in wheat, and 8S globulin and conglycinin in mungbean are the major amyloidogenic proteins. The amyloid composites undergo a sustained degradation during germination and seedling growth, facilitated by an intricate interplay of plant hormones and proteases. These results would lay down the foundation for understanding the amyloid composite structure during SSPB biogenesis and its evolution across the plant kingdom and have implications in both basic and applied plant biology.

Stability and bioactivity of peptides in food matrices based on processing conditions

Bioactive peptides (BPs) generated from food proteins can serve therapeutic purposes against degenerative and cardiovascular diseases such as inflammation, diabetes, and cancer. There are numerous reports on the in vitro, animal, and human studies of BPs, but not as much information on the stability and bioactivity of these peptides when incorporated in food matrices. The effects of heat and non-heat processing of the food products, and storage on the bioactivity of the BPs, are also lacking. To this end, we describe the production of BPs in this review, followed by the food processing conditions that affect their storage bioactivity in the food matrices. As this area of research is open for industrial innovation, we conclude that novel analytical methods targeting the interactions of BPs with other components in food matrices would be greatly significant while elucidating their overall bioactivity before, during and after processing.

Exploration of the Nutritional and Functional Properties of Underutilized Grains as an Alternative Source for the Research of Food-Derived Bioactive Peptides

The estimated increase in world population will lead to a deterioration in global food security, aggravated in developing countries by hidden hunger resulting from protein deficiency. To reduce or avoid this crisis, a dietary shift towards the consumption of sustainable, nutrient-rich, and calorically efficient food products has been recommended by the FAO and WHO. Plant proteins derived from grains and seeds provide nutritionally balanced diets, improve health status, reduce poverty, enhance food security, and contain several functional compounds. In this review, the current evidence on the nutritional and functional properties of underutilized grains is summarized, focusing on their incorporation into functional foods and the role of their proteins as novel source of bioactive peptides with health benefits.

Bioactive and health-promoting properties of enzymatic hydrolysates of legume proteins: a review

This study comprehensively reviewed the effect of controlled enzymatic hydrolysis on the bioactivity of pulse protein hydrolysates (PPHs). Proteolysis results in the partial structural unfolding of pulse proteins with an increase in buried hydrophobic groups of peptide sequences. The use of PPHs in a dose-dependent manner can enhance free radical scavenging and improve antioxidant activities regarding inhibition of lipid oxidation, ferric reducing power, metal ion chelation, and β-carotene bleaching inhibition. Ultrafiltered peptide fractions with low molecular weights imparted angiotensin-I converting enzyme (ACE) inhibitory effects during in vitro simulated gastrointestinal digestion and in vivo conditions. Ultrasonication, high-pressure pretreatments, and glycosylation as post-treatments can improve the antiradical, antioxidant, and ACE inhibitory activities of PPHs. The electrostatic attachment of pulse peptides to microbial cells can inhibit the growth and activity of bacteria and fungi. Bioactive pulse peptides can reduce serum cholesterol and triglycerides, and inhibit the formation of adipocyte lipid storage, allergenic factors, inflammatory markers, and arterial thrombus without cytotoxicity. The combination of germination and enzymatic hydrolysis can significantly increase the protein digestibility and bioavailability of essential amino acids. Moreover, the utilization and enrichment of bakery and meat products with functional PPHs ensure quality, safety, and health aspects of food products.

Albumin from Erythrina edulis (Pajuro) as a Promising Source of Multifunctional Peptides

Multifunctional peptides, capable of acting on different body systems through multiple mechanisms of action, offer many advantages over monofunctional peptides, including lower adverse side effects and costs. Erythrina edulis (pajuro) is a legume with a large number of high-quality proteins, of which their potential as a source of antioxidant peptides has been recently reported. In this study, the behavior of these proteins under a sequential enzymatic hydrolysis with digestive and microbial enzymes was investigated by evaluating the multi-functionality of the hydrolyzates. The albumin hydrolyzates obtained after the action of pepsin, pancreatin, and Alcalase showed antioxidant, angiotensin-converting enzyme (ACE), α-amylase, α-glucosidase, and dipeptidyl peptidase (DPP)-IV inhibitory activities. The radical scavenging properties of the hydrolyzate could be responsible for the potent protective effects observed in FeSO4-induced neuroblastoma cells. The findings support the role of pajuro protein as an ingredient of functional foods or nutraceuticals for health promotion and the prevention of oxidative stress, hypertension, and metabolic alteration-associated chronic diseases.

The Effects of Mung Bean Peptide and Its’ Complexes on the Treatment of Lead Poisoning

Objective. To investigate the effects of mung bean peptide and its’ complexes on promoting lead excretion and neuroprotection of zebrafish. Methods. The lead poisoning models of zebrafish were established by lead acetate solution; the models were treated with high and low concentrations (58.3 and 175 μg/mL) of mung bean peptides, with high, medium, and low concentrations (27.8, 83.3, and 250 μg/mL) of mung bean peptide complexes, separately. The effects of the mung bean peptide complexes on the lead content, axonal fluorescence intensity, and peripheral motor nerve length changes were identified in the zebrafish model, and the effects of mung bean peptide and its’ complexes on zebrafish's lead excretion, axonal protection rate, and peripheral movement promotion rate of nerve regeneration were calculated. Results. The effects of high concentration of mung bean peptide (175 μg/mL) in promoting lead excretion was 29% ( $p<0.05$ ), and the effect of high concentration of mung bean peptide complexes (250 μg/mL) in promoting lead excretion was 30% ( $p<0.05$ ). The other concentrations of mung bean peptide and its’ complex groups did not show a noticeable lead excretion effect. The protective effects of mung bean peptide at concentrations of 58.3 and 175 μg/mL against zebrafish axonal injury were 98% and 101% ( $p<0.01$ ), and the peripheral nerve regeneration promotion effects were 29% ( $p>0.05$ ) and 42% ( $p<0.05$ ), respectively. The protective effects of mung bean peptide complexes at concentrations of 27.8, 83.3, and 250 μg/mL against zebrafish axonal injury were 85%, 78%, and 93% ( $p<0.01$ ); peripheral nerve regeneration promotion rates were 46%, 50%, and 50% ( $p<0.05$ ). Conclusion. The mung bean peptide and its’ complexes can effectively promote the discharge of lead in the zebrafish lead poisoning and have protective and regeneration effects on zebrafish nerves.

Health Benefits of Antioxidative Peptides Derived from Legume Proteins with a High Amino Acid Score

Legumes such as soybean, chickpea, lentil, cowpea, and mung bean, are valuable sources of protein with a high amino acid score and can provide bioactive peptides. This manuscript presents a review on legume-derived peptides, focusing on in vitro and in vivo studies on the potential antioxidative activities of protein hydrolysates and their characterization, amino acid sequences, or purified/novel peptides. The health implications of legume-derived antioxidative peptides in reducing the risks of cancer and cardiovascular diseases are linked with their potent action against oxidation and inflammation. The molecular weight profiles and amino acid sequences of purified and characterized legume-derived antioxidant peptides are not well established. Therefore, further exploration of legume protein hydrolysates is necessary for assessing the potential applications of antioxidant-derived peptides in the functional food industry.

Fabrication of Functional Bioelastomer for Food Packaging from Aronia (Aronia melanocarpa) Juice Processing By-Products

Carbon-neutral and eco-friendly biomass-based processes are recognized as a frontier technology for sustainable development. In particular, biopolymers are expected to replace petrochemical-based films that are widely used in food packaging. In this study, the fabrication conditions of functional (antioxidant and antibacterial) bioelastomers were investigated using by-products from the juice processing (experimental group) and freeze-dried whole fruit (control group). Bioelastomer was fabricated by a casting method in which polydimethylsiloxane (PDMS) was mixed with 25 or 50 wt% aronia powder (juice processing by-products and freeze-dried whole fruit). The mechanical properties of the bioelastomers were measured based on tensile strength and Young's modulus. When the mixture contained 50 wt% aronia powder, the strength was not appropriate for the intended purpose. Next, the surface and chemical properties of the bioelastomer were analyzed; the addition of aronia powder did not significantly change these properties when compared to PDMS film (no aronia powder). However, the addition of aronia powder had a significant effect on antioxidant and antimicrobial activities and showed higher activity with 50 wt% than with 25 wt%. In particular, bioelastomers fabricated from aronia juice processing by-products exhibited approximately 1.4-fold lower and 1.5-fold higher antioxidant and antimicrobial activities, respectively, than the control group (bioelastomers fabricated from freeze-dried aronia powder).

Structure and Function of Mung Bean Protein-Derived Iron-Binding Antioxidant Peptides

An iron-binding mung bean protein hydrolysate (MBPH) was prepared using a continuous enzymatic membrane reactor followed by peptide separation on anion-exchange (AEC) and reverse-phase HPLC (RP-HPLC) columns. Amino acid sequences of peptides present in the RP-HPLC fraction with the strongest iron-binding capacity were identified using mass spectrometry, and ten peptides of 5-8 amino acids synthesized for antioxidant characterization. Five fractions (AF1- AF5) with higher iron-binding capacity (88.86 ± 6.43 to 153.59 ± 2.18 mg/g peptide) when compared to the MBPH (36.81 ± 0.93 mg/g peptide) were obtained from AEC. PAIDL had the significantly (p < 0.05) highest iron-binding capacity, but LLLLG and LLGIL showed the strongest metal chelating activity. However, PAIDL (46.63%) and LLGIL (81.27%) had significantly (p < 0.05) better DPPH radical scavenging activity than the other peptides. PAIDL and LLGIL were also the most effective (p < 0.05) hydroxyl radical neutralizers with an effective concentration that scavenged 50% (EC₅₀) values of 0.09 and 0.37 mM, respectively. PAIDL and AIVIL showed the lowest EC₅₀ values of 0.07 mM each for superoxide radical scavenging activity. We conclude that short chain length in combination with leucine as the C-terminal amino acid residue contributed to the strong antioxidant properties of peptides in this study.