Identification of antihyperuricemic peptides in the proteolytic digest of shark cartilage water extract using in vivo activity-guided fractionation

Food-derived bioactive peptides with anti-hyperuricemic activity: A comprehensive review

Hyperuricemia (HU) is a metabolic disorder caused by the overproduction or underexcretion of uric acid (UA) in the human body. Several approved drugs for the treatment of HU are available in the market; however, all these allopathic drugs exhibit multiple side effects. Therefore, the development of safe and effective anti-HU drugs is an urgent need. Natural compounds derived from foods and plants have the potential to decrease UA levels. Recently, food-derived bioactive peptides (FBPs) have gained attention as a functional ingredient owing to their biological activities. In the current review, we aim to explore the urate-lowering potential and the underlying mechanisms of FBPs. We found that FBPs mitigate HU by reducing blood UA levels through inhibiting key enzymes such as xanthine oxidase, increasing renal UA excretion, inhibiting renal UA reabsorption, increasing anti-oxidant activities, regulating inflammatory mediators, and addressing gut microbiota dysbiosis. In conclusion, FBPs exhibit strong potential to ameliorate HU.

Antihyperuricemic activity and inhibition mechanism of xanthine oxidase inhibitory peptides derived from whey protein by virtual screening

Xanthine oxidase (XO), a rate-limiting enzyme in uric acid production, is the pivotal therapeutic target for gout and hyperuricemia. In this study, 57 peptides from α-lactalbumin and β-lactoglobulin were obtained via virtual enzymatic hydrolysis, and 10 XO inhibitory peptides were virtually screened using molecular docking. Then toxicity, allergenicity, solubility, and isoelectric point of the obtained 10 novel peptides were evaluated by in silico tools. The XO activity of these synthetic peptides was tested using an in vitro assay by high-performance liquid chromatography. Their inhibitory mechanism was further explored by molecular docking. The results showed that 4 peptides GL, PM, AL, and AM exhibited higher inhibitory activity, and their half maximal inhibitory concentration in vitro was 10.20 ± 0.89, 23.82 ± 0.94, 34.49 ± 0.89, and 40.45 ± 0.92 mM, respectively. The peptides fitted well with XO through hydrogen bond, hydrophobic interaction, and van der Waals forces, and amino acid residues Glu802, Leu873, Arg880, and Pro1076 played an important role in this process. Overall, this study indicated 4 novel peptides GL, PM, AL, and AM from whey protein exhibited XO inhibitory activity, and they might be useful and safe XO inhibitors for hyperuricemia prevention and treatment.

Food-derived peptides as novel therapeutic strategies for NLRP3 inflammasome-related diseases: a systematic review

NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3), a member of the nucleotide-binding domain (NOD) and leucine-rich repeat sequence (LRR) protein (NLR) family, plays an essential role in the inflammation initiation and inflammatory mediator secretion, and thus is also associated with many disease progressions. Food-derived bioactive peptides (FDBP) exhibit excellent anti-inflammatory activity in both in vivo and in vitro models. They are encrypted in plant, meat, and milk proteins and can be released under enzymatic hydrolysis or fermentation conditions, thereby hindering the progression of hyperuricemia, inflammatory bowel disease, chronic liver disease, neurological disorders, lung injury and periodontitis by inactivating the NLRP3. However, there is a lack of systematic review around FDBP, NLRP3, and NLRP3-related diseases. Therefore, this review summarized FDBP that exert inhibiting effects on NLRP3 inflammasome from different protein sources and detailed their preparation and purification methods. Additionally, this paper also compiled the possible inhibitory mechanisms of FDBP on NLRP3 inflammasomes and its regulatory role in NLRP3 inflammasome-related diseases. Finally, the progress of cutting-edge technologies, including nanoparticle, computer-aided screening strategy and recombinant DNA technology, in the acquisition or encapsulation of NLRP3 inhibitory FDBP was discussed. This review provides a scientific basis for understanding the anti-inflammatory mechanism of FDBP through the regulation of the NLRP3 inflammasome and also provides guidance for the development of therapeutic adjuvants or functional foods enriched with these FDBP.

Virtual screening and structure optimization of xanthine oxidase inhibitory peptides from whole protein sequences of Pacific white shrimp via molecular docking

Xanthine oxidase (XO) inhibitory peptides are safer than conventional pharmacological therapy in relieving hyperuricemia. However, traditional enzymatic hydrolysis, separation, and purification techniques for bio-active peptide preparation are time-consuming, inefficient, and labor-intensive. In this study, molecular docking and BLAST were used to virtually screen XO inhibitory peptides from whole protein sequences of Pacific white shrimp according to the bio-active peptides database, and the structure of peptides was optimized based on the structure-effective relationship. Seven new XO inhibitory peptides were virtual screened rapidly from Pacific white shrimp, and YNITGW (IC50 = 9.78 ± 0.13 mM) showed the strongest activity. The results of YNITGW optimization showed that the insertion of Trp residue in the middle position of peptides could effectively enhance the activity. This study revealed that screening and optimizing peptides by molecular docking were a novel and feasible method to obtain bio-active peptides.

ALA-A2 Is a Novel Anticancer Peptide Inspired by Alpha-Lactalbumin: A Discovery from a Computational Peptide Library, In Silico Anticancer Peptide Screening and In Vitro Experimental Validation

Anticancer peptides (ACPs) are rising as a new strategy for cancer therapy. However, traditional laboratory screening to find and identify novel ACPs from hundreds to thousands of peptides is costly and time consuming. Here, a sequential procedure is applied to identify candidate ACPs from a computer-generated peptide library inspired by alpha-lactalbumin, a milk protein with known anticancer properties. A total of 2688 distinct peptides, 5-25 amino acids in length, are generated from alpha-lactalbumin. In silico ACP screening using the physicochemical and structural filters and three machine learning models lead to the top candidate peptides ALA-A1 and ALA-A2. In vitro screening against five human cancer cell lines supports ALA-A2 as the positive hit. ALA-A2 selectively kills A549 lung cancer cells in a dose-dependent manner, with no hemolytic side effects, and acts as a cell penetrating peptide without membranolytic effects. Sequential window acquisition of all theorical fragment ions-proteomics and functional validation reveal that ALA-A2 induces autophagy to mediate lung cancer cell death. This approach to identify ALA-A2 is time and cost-effective. Further investigations are warranted to elucidate the exact intracellular targets of ALA-A2. Moreover, these findings support the use of larger computational peptide libraries built upon multiple proteins to further advance ACP research and development.

Identification and Anti-Hyperuricemic Activity of Xanthine Oxidase Inhibitory Peptides from Pacific White Shrimp and Swimming Crab Based on Molecular Docking Screening

The xanthine oxidase (XO) inhibitory peptides from pacific white shrimp or swimming crab were identified by molecular docking, and the anti-hyperuricemic activity of the peptides was confirmed in hyperuricemic cells. In our study, 17 novel XO inhibitory peptides were purified from pacific white shrimp or swimming crab, and Ala-Glu-Ala-Gln-Met-Trp-Arg (AEAQMWR, 891.01 Da, IC₅₀ = 8.85 ± 0.05 mM) exhibited the greatest XO inhibitory activity in vitro. Molecular docking results indicated that attractive charge, salt bridge, and hydrogen bond showed a crucial effect on the interactions of XO inhibitory peptides with the pivotal residues of Arg880, Glu802, and Glu1261. In addition, XO inhibitory peptides alleviated hyperuricemia by inhibiting inflammation and preventing increased uric acid transporter expression levels in hyperuricemia cells. Overall, these results further confirmed that screening of XO inhibitory peptides rapidly via molecular docking was feasible.

Anti-Hyperuricemic, Nephroprotective, and Gut Microbiota Regulative Effects of Separated Hydrolysate of α-Lactalbumin on Potassium Oxonate- and Hypoxanthine-Induced Hyperuricemic Mice

SCOPE

This study aims to investigate the anti-hyperuricemic and nephroprotective effects and the potential mechanisms of the separated gastrointestinal hydrolysates of α-lactalbumin on hyperuricemic mice.

METHODS AND RESULTS

The gastrointestinal hydrolysate of α-lactalbumin, the hydrolysate fraction with molecular weight (MW) < 3 kDa (LH-3k), and the fragments with smallest MW among LH-3K harvested through dextran gel chromatography (F5) are used. Hyperuricemia mice are induced via daily oral gavage of potassium oxonate and hypoxanthine. F5 displays the highest in vitro xanthine oxidase (XO) inhibition among all the fractions separated from LH-3k. Oral administration of F5 significantly reduces the levels of serum uric acid (UA), creatinine, and urea nitrogen. F5 treatment could ameliorate kidney injury through alleviating oxidative stress and inflammation. F5 alleviates hyperuricemia in mice by inhibiting hepatic XO activity and regulating the expression of renal urate transporters. Gut microbiota analysis illustrates that F5 administration increases the abundance of some SCFAs producers, and inhibits the growth of hyperuricemia and inflammation associated genera. LH-3k exhibits similar effects but does not show significance as those of the F5 fraction.

CONCLUSION

The anti-hyperuricemia and nephroprotective functions of F5 are mediated by inhibiting hepatic XO activity, ameliorating oxidative stress and inflammation, regulating renal urate transporters, and modulating the gut microbiota in hyperuricemic mice.

Research Progress of Natural Active Substances with Uric-Acid-Reducing Activity

Hyperuricemia is a metabolic disease caused by the accumulation of uric acid in the body. Allopurinol, benzbromarone, and febuxostat, which are available in the market, have reduced the circulating urate levels; however, they exhibit serious side effects. Therefore, it is reasonable to develop a new active antihyperuricemia drug with few side effects. With the deepening of research, numerous kinds of literature have shown that natural active substances are effective in the treatment of hyperuricemia with a variety of sources and few side effects, which have become the focus of research in recent years. This review focuses on natural active substances with uric-acid-reducing activity and discusses their pharmacological effects. More specifically, the bioactive compounds of natural active substances are divided into five categories: natural extracts, monomer compounds extracted from plants, natural protease hydrolysates, peptides, and probiotic bacteria. In addition, the mechanisms by which these bioactive compounds exhibit hypouricemic effects can be divided into four classes: inhibition of key enzyme activities, promotion of uric acid excretion and inhibition of reabsorption in the kidney, promotion of decomposing uric acid precursors, and promotion of decomposing uric acid. Overall, this current and comprehensive review examines the role of natural active substances in the treatment of hyperuricemia.

A modified xanthine oxidase cell model for screening of antihyperuricemic functional compounds

Hyperuricemia is a purine metabolism disorder, with increasing prevalence worldwide. Here, a high throughput cell model for screening of antihyperuricemic compounds was set up. Human kidney cells (HK2 cells) were stimulated with adenosine and the resulting supernatant and lysate were then analyzed using high performance liquid chromatography (HPLC). The results showed that hypoxanthine content was increased in both HK2 cells supernatant and xanthine oxidase (XO)-overexpressing HK2 cells lysate, but no uric acid was detected due to lower endogenous XO content in these cells. Exogenous XO was added to the supernatant, and then used to evaluate the antihyperuricemic activity of Febuxostat and two the previously identified peptides, Pro-Gly-Ala-Cys-Ser-Asn (PGACSN) and Trp-Met-Leu (WML). By adding exogenous XO, this combined-adenosine-XO-induced hyperuricemia model was optimized and established, and the Febuxostat and peptides were confirmed to significantly reduce uric acid production in the HK2 cells supernatant (p < 0.05). Therefore, this cell model could be recommended for screening potential bioactive antihyperuricemic compounds.

Probiotics, bioactive compounds and dietary patterns for the effective management of hyperuricemia: a review

Hyperuricemia is closely linked with an increased risk of developing hypertension, diabetes, renal failure and other metabolic syndromes. Probiotics, bioactive compounds and dietary patterns are safe cost-efficient ways to control hyperuricemia, whereas comprehensive reviews of their anti-hyperuricemic mechanisms are limited. This review summarizes the roles of probiotics, bioactive compounds and dietary patterns in treating hyperuricemia and critically reviews the possible mechanisms by which these interventions exert their activities. The dietary patterns are closely related to the occurrence of hyperuricemia through the indirect action of gut microbiota or the direct effects of host purine metabolism. The Mediterranean and Dietary Approaches to Stop Hypertension diets help reduce serum uric acid concentrations and thus prevent hyperuricemia. Meanwhile, probiotics alleviate hyperuricemia by ways of absorbing purine, restoring gut microbiota dysbiosis and inhibiting xanthine oxidase (XO) activity. Bioactive compounds such as polyphenols, peptides and alkaloids exert various anti-hyperuricemic effects, by regulating urate transporters, blocking the active sites of XO and inhibiting the toll-like receptor 4/nuclear factor kappa B signaling pathway and NOD-, LRR- and pyrin domain-containing protein 3 signaling pathway. This review will assist people with hyperuricemia to adopt a healthy diet and contribute to the application of natural products with anti-hyperuricemic activity.

Short Hexapeptide Optimized from Rice-Derived Peptide 1 Shows Promising Anti-hyperuricemia Activities

Plant-derived peptides are a treasure trove for new-generation anti-hyperuricemia drugs. In the current study, we optimized a short hexapeptide rice-derived peptide 1 (RDP1)-M3 (AAAAGA) according to the anti-hyperuricemia RDP1 peptide identified from rice in our previous research. Results showed that RDP1-M3 exerted better hyperuricemia-alleviating and xanthine oxidase (XOD)-inhibiting potency in mice than RDP1. The biodistribution of RDP1-M3 was also analyzed. RDP1-M3 directly decreased XOD and uric acid levels in vivo and in vitro. In addition, RDP1-M3 reduced the expression of urate transporter 1 and glucose transporter 9, increased the level of organic anion transporter 1, reduced the expression of NOD-like receptor superfamily pyrin 3 inflammasomes, and reduced the levels of interleukin-1β and tumor necrosis factor-α of hyperuricemic mice. Thus, our results indicated that the optimized short hexapeptide RDP1-M3 may be a candidate drug for anti-hyperuricemia.

Industrial application of fish cartilaginous tissues

Cartilage is primarily composed of proteoglycans and collagen. Bioactive compounds derived from animal cartilage, such as chondroitin sulfate and type II collagen, have multiple bioactivities and are incorporated in popular health products. The aging population and increases in degenerative and chronic diseases will stimulate the rapid growth of market demand for cartilage products. Commercial production of bioactive compounds primarily involves the cartilages of mammals and poultry. However, these traditional sources are associated zoonosis concerns; thus, cartilage products from the by-products of fish processing has gained increasing attention because of their high level of safety and other activities. In this review, we summarize the current state of research into fish-derived cartilage products and their application, and discuss future trends and tasks to encourage further expansion and exploitation. At present, shark cartilage is the primary source of marine cartilage. However, the number of shark catches is decreasing worldwide, owing to overfishing. This review considers the potential alternative fish cartilage sources for industrialization. Three keys, the sustainable production of fish, new fish-processing model, and market demand, have been discussed for the future realization of efficient fish cartilage use. The industrialization of fish-derived cartilage products is beneficial for achieving sustainable development of local economies and society.

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Bioactive compounds derived from fish cartilage are popular as health products.

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Type II collagen and chondroitin sulfate are the major cartilage bioactive compounds.

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Cartilaginous fishes, sturgeons, and salmonids are potential fish cartilage sources.

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Keys for industrialization are fish production, processing model, and market demands.

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Industrialization of fish cartilage products accords with sustainable development.

Hypouricemic, hepatoprotective and nephroprotective roles of oligopeptides derived from Auxis thazard protein in hyperuricemic mice

The oligopeptides derived from Auxis thazard protein (ATO) are a class of small peptides with molecular weight <1 kDa and good bioactivity. This paper aimed to explore the hypouricemic, hepatoprotective, and nephroprotective effects of ATO and its potential mechanisms in hyperuricemia in mice induced by potassium oxonate. The results showed that ATO significantly reduced serum UA, serum creatinine levels, inhibited XOD and ADA activities in the liver (p < 0.05), and accelerated UA excretion by downregulating the gene expression of renal mURAT1 and mGLUT9 and upregulating the gene expression of mABCG2 and mOAT1. ATO could also reduce the levels of liver MDA, increase the activities of SOD and CAT, and reduce the levels of IL-1β, MCP-1 and TNF-α. Histological analysis also showed that ATO possessed hepatoprotective and nephroprotective activities in hyperuricemic mice. Thus, ATO could reduce the serum UA level in hyperuricemic mice by decreasing UA production and promoting UA excretion from the kidney, suggesting that ATO could be developed as a dietary supplement for hyperuricemia treatment.

Purification and Identification of Novel Xanthine Oxidase Inhibitory Peptides Derived from Round Scad (Decapterus maruadsi) Protein Hydrolysates

The objective of the present study was to investigate the xanthine oxidase (XO) inhibitory effects of peptides purified and identified from round scad (Decapterus maruadsi) hydrolysates (RSHs). In this study, RSHs were obtained by using three proteases (neutrase, protamex and alcalase). Among them, the RSHs of 6-h hydrolysis by neutrase displayed the strongest XO inhibitory activity and had an abundance of small peptides (<500 Da). Four novel peptides were purified by immobilized metal affinity chromatography and identified by nano-high-performance liquid chromatography mass/mass spectrometry. Their amino acid sequences were KGFP (447.53 Da), FPSV (448.51 Da), FPFP (506.59 Da) and WPDGR (629.66 Da), respectively. Then the peptides were synthesized to evaluate their XO inhibitory activity. The results indicated that the peptides of both FPSV (5 mM) and FPFP (5 mM) exhibited higher XO inhibitory activity (22.61 ± 1.81% and 20.09 ± 2.41% respectively). Fluorescence spectra assay demonstrated that the fluorescence quenching mechanism of XO by these inhibitors (FPSV and FPFP) was a static quenching procedure. The study of inhibition kinetics suggested that the inhibition of both FPSV and FPFP was reversible, and the type of their inhibition was a mixed one. Molecular docking revealed the importance of π-π stacking between Phe residue (contained in peptides) and Phe⁹¹⁴ (contained in the XO) in the XO inhibitory activity of the peptides.

HMP-S7 Is a Novel Anti-Leukemic Peptide Discovered from Human Milk

Chemotherapy in childhood leukemia is associated with late morbidity in leukemic survivors, while certain patient subsets are relatively resistant to standard chemotherapy. It is therefore important to identify new agents with sensitivity and selectivity towards leukemic cells, while having less systemic toxicity. Peptide-based therapeutics has gained a great deal of attention during the last few years. Here, we used an integrative workflow combining mass spectrometric peptide library construction, in silico anticancer peptide screening, and in vitro leukemic cell studies to discover a novel anti-leukemic peptide having 3+ charges and an alpha helical structure, namely HMP-S7, from human breast milk. HMP-S7 showed cytotoxic activity against four distinct leukemic cell lines in a dose-dependent manner but had no effect on solid malignancies or representative normal cells. HMP-S7 induced leukemic cell death by penetrating the plasma membrane to enter the cytoplasm and cause the leakage of lactate dehydrogenase, thus acting in a membranolytic manner. Importantly, HMP-S7 exhibited anti-leukemic effects against patient-derived leukemic cells ex vivo. In conclusion, HMP-S7 is a selective anti-leukemic peptide with promise, which requires further validation in preclinical and clinical studies.

Xanthine oxidase inhibitory activity and antihyperuricemic effect of Moringa oleifera Lam. leaf hydrolysate rich in phenolics and peptides

ETHNOPHARMACOLOGICAL RELEVANCE

Moringa oleifera Lam. leaf (MOL), a rich source of protein and phenolics, was traditionally used to treat various diseases including headaches, fevers, sore throat and dyslipidemia. Recently, MOL was reported to possess antioxidant, anti-dyslipidemia and hepato-renal protective activities, indicating that MOL could become a potential agent to improve metabolic disorders associated with hyperuricemia. The antihyperuricemic effect of MOL hydrolysate (MOLH) with high contents of phenolics and peptides remains unknown.

AIM OF THE STUDY

The aim of this study is to investigate xanthine oxidase (XO) inhibitory activity of MOLH, to clarify phenolic and peptide profiles of MOLH, and to evaluate possible mechanism underlying the antihyperuricemic effect of MOLH.

MATERIALS AND METHODS

MOLH was prepared by enzymatic hydrolysis using commercial trypsin. XO inhibitory activity was determined by XO reaction-UPLC-MS coupling method. The chemical profiles of the phenolic and peptide fractions of MOLH were determined by UPLC-QTOF-MS/MS. The antihyperuricemic effect of MOLH was evaluated in a potassium oxonate-induced hyperuricemic rat model at doses of 200 and 500 mg/kg. Serum uric acid (UA), urea nitrogen, creatinine (CRE), triglyceride (TG), total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol levels, serum XO activity, liver malondialdehyde (MDA) equivalent level, renal tumor necrosis factor-α and interleukin-1β levels, and protein expression of renal urate-anion transporter 1, glucose transporter 9 and ATP-binding cassette transporter G2 were determined.

RESULTS

The phenolic and peptide fractions played key roles in inhibiting XO activity and blocking uric acid production. Five flavonoids and sixteen polypeptides were identified in the phenolic and peptide fractions of MOLH, respectively. MOLH (200 and 500 mg/kg) could effectively reduce the serum UA level of hyperuricemic rats (p < 0.001) by regulation of serum XO activity (p < 0.05 at 200 mg/kg, p < 0.01 at 500 mg/kg) and renal urate transporters. Besides, MOLH could improve metabolic disorders associated with hyperuricemia by its multiple actions on liver MDA (p < 0.001), serum CRE (p < 0.05 at 500 mg/kg) and serum TG (p < 0.001).

CONCLUSION

The results provided scientific evidence that MOLH rich in phenolics and peptides ameliorated hyperuricemia and metabolic disorders. This study validated the potential use of MOLH for regulation of hyperuricemia.

Xanthine oxidase inhibitory peptides derived from tuna protein: virtual screening, inhibitory activity, and molecular mechanisms

BACKGROUND

There has been growing interest in the use of xanthine oxidase (XO) as a therapeutic agent to prevent gout and hyperuricemia. In the present study, XO inhibitory peptides were identified from tuna protein by virtual screening, and molecular docking was used to elicit the interaction mechanism between XO and peptides.

RESULTS

A novel tetrapeptide, EEAK, exhibited high XO inhibitory activity with an IC₅₀ of 173.00 ± 0.06 μM. Molecular docking analysis revealed that EEAK bound with the pivotal residues of XO's active sites (i.e., Glu802, Arg880, Glu1261) through two conventional hydrogen bond interactions, two attractive charge interactions, and one salt bridge. EEAK could also bind with the residues Phe649, Leu648, Lys771, Ser876, Phe914, and Thr1010 of XO.

CONCLUSION

This study suggested that conventional hydrogen bond interactions and electrostatic interactions play an important role in XO inhibition. The novel XO inhibitory peptide EEAK from tuna protein could be used as potential candidate for controlling gout and hyperuricemia. © 2020 Society of Chemical Industry.

Purification, identification, and computational analysis of xanthine oxidase inhibitory peptides from kidney bean

Hyperuricemia is related to plenty of diseases, seriously damaging human health. Current clinical drugs used to treat hyperuricemia have many adverse effects. In this study, kidney bean hydrolysate (KBH) was found to exert high xanthine oxidase inhibitory (XOI) activity. Compared to KBH (50.31 ± 2.73%), XOI activities of three fractions (M_w <5 kDa, M_w <3 kDa, M_w  < 1 kDa) by ultrafiltration were higher and increased to 58.58 ± 3.57%, 59.34 ± 1.78%, and 55.05 ± 5.00%, respectively (P < 0.05). A total of 69 peptides were identified by HPLC-ESI-MS/MS and analyzed binding affinities with XO with the help of molecular docking. AVDSLVPIGR, DWYDIK, LDNLLR, ISPIPVLK, ISSLEMTR showed well binding affinities with XO and DWYDIK presented the highest XOI activity (68.63 ± 5.07%) among five synthetic peptides (P < 0.05). Additionally, visual analysis results indicated that DWYDIK was pushed into the hydrophobic channel and formed hydrogen bonds with pivotal amino acids of xanthine oxidase. Overall, KBH could be a promising candidate as anti- hyperuricemia functional food. PRACTICAL APPLICATION: This research initially revealed that kidney bean peptides could significantly inhibit the activity of xanthine oxidase, indicating kidney bean peptides could be a treatment for hyperuricemia. Kidney bean peptides may have commercial potentials as a safer alternative with few side effects to drugs.

Discovery of a novel rice-derived peptide with significant anti-gout potency

As a metabolic disease, gout, which seriously affects the normal life of patients, has become increasingly common in modern society. However, the existing medicines cannot completely meet the clinical needs. In the current study, a novel short peptide (named rice-derived-peptide-2 (RDP2), AAAAGAMPK-NH2, 785.97 Da) was isolated and identified from water extract of shelled Oryza sativa fruits, without toxic side effects but excellent stability. Our results indicated that RDP2 (the minimum effective concentration is 5 μg kg^-1) induced a significant reduction in serum uric acid levels in hyperuricemic mice via suppressing xanthine oxidase activity and urate transporter 1 expression, as well as alleviated renal damage through inhibiting the activation of NLRP3 inflammasome. In addition, RDP2 can also alleviate paw swelling and inflammatory reactions in mice after subcutaneous injection of monosodium urate crystals. As mentioned above, we obtained a novel peptide which could work through all stages of gout, not only reducing uric acid levels and renal damage in hyperuricemic mice, but also alleviating inflammatory responses associated with acute gout attack, and thus provided a new peptide molecular template for the development of anti-gout drugs.

Use of Alcalase in the production of bioactive peptides: A review

This review aims to cover the uses of the commercially available protease Alcalase in the production of biologically active peptides since 2010. Immobilization of Alcalase has also been reviewed, as immobilization of the enzyme may improve the final reaction design enabling the use of more drastic conditions and the reuse of the biocatalyst. That way, this review presents the production, via Alcalase hydrolysis of different proteins, of peptides with antioxidant, angiotensin I-converting enzyme inhibitory, metal binding, antidiabetic, anti-inflammatory and antimicrobial activities (among other bioactivities) and peptides that improve the functional, sensory and nutritional properties of foods. Alcalase has proved to be among the most efficient proteases for this goal, using different protein sources, being especially interesting the use of the protein residues from food industry as feedstock, as this also solves nature pollution problems. Very interestingly, the bioactivities of the protein hydrolysates further improved when Alcalase is used in a combined way with other proteases both in a sequential way or in a simultaneous hydrolysis (something that could be related to the concept of combi-enzymes), as the combination of proteases with different selectivities and specificities enable the production of a larger amount of peptides and of a smaller size.

RDP3, A Novel Antigout Peptide Derived from Water Extract of Rice

Gout and hyperuricemia can seriously affect the quality of life; at present, however, existing medicines are unable to meet all clinical needs. In the current study, a novel peptide (i.e., rice-derived-peptide-3 (RDP3), AAAAMAGPK-NH₂, 785.97 Da) in water extract obtained from shelled Oryza sativa fruits was identified. Testing revealed that RDP3 (minimum effective concentration 100 μg/kg) did not show both hemolytic and acute toxicity, and reduced uric acid levels in the serum of hyperuricemic mice by inhibiting xanthine oxidase activity and decreasing urate transporter 1 expression. RDP3 also alleviated renal injury in hyperuricemic mice by decreasing NLRP3 inflammasome expression. Furthermore, RDP3 alleviated formalin-induced paw pain and reduced monosodium urate crystal-induced paw swelling and inflammatory factors in mice. Thus, this newly identified peptide reduced uric acid levels and renal damage in hyperuricemic mice and showed anti-inflammatory and analgesic activities, indicating the potential of RDP3 as an antigout medicine candidate.

Protective effects of tuna meat oligopeptides (TMOP) supplementation on hyperuricemia and associated renal inflammation mediated by gut microbiota

Recently, interest in using whole food-derived mixtures to alleviate chronic metabolic syndrome through potential synergistic interactions among different components is increasing. In this study, the effects and mechanisms of tuna meat oligopeptides (TMOP) on hyperuricemia and associated renal inflammation were investigated in mice. Dietary administration of TMOP alleviated hyperuricemia and renal inflammation phenotypes, reprogramed uric acid metabolism pathways, inhibited the activation of NLRP3 inflammasome and TLR4/MyD88/NF-κB signaling pathways, and suppressed the phosphorylation of p65-NF-κB. In addition, TMOP treatments repaired the intestinal epithelial barrier, reversed the gut microbiota dysbiosis and increased the production of short-chain fatty acids. Moreover, the antihyperuricemia effects of TMOP were transmissible by transplanting the fecal microbiota from TMOP-treated mice, indicating that the protective effects were at least partially mediated by the gut microbiota. Thus, for the first time, we clarify the potential effects of TMOP as a whole food derived ingredient on alleviating hyperuricemia and renal inflammation in mice, and additional efforts are needed to confirm the beneficial effects of TMOP on humans.

Comparisons of protective effects between two sea cucumber hydrolysates against diet induced hyperuricemia and renal inflammation in mice

Differences in the anti-hyperuricemic and anti-inflammation effects between two sea cucumber hydrolysates in diet induced hyperuricemic mice.

New Rice-Derived Short Peptide Potently Alleviated Hyperuricemia Induced by Potassium Oxonate in Rats

Gout that caused by hyperuricemia affects human health seriously and more efficient drugs are urgently required clinically. In this study, a novel peptide named RDP1 (AAAAGAKAR, 785.91 Da) was identified from the extract of shelled fruits of Oryza sativa. Our results demonstrated that RDP1 (the minimum effective concentration is 10 μg/kg) could significantly reduce the serum uric acid and creatinine and alleviate hyperuricemic nephropathy in rats by intragastric administration. RDP1 inhibited xanthine oxidase, which also was verified at the animal level. Results from molecular docking indicated that RDP1 can inhibit uric acid formation by occupying the binding site of xanthine oxidase to xanthine. Besides, RDP1 showed no toxicity on rats and was stable in several temperatures, demonstrating its advantages for transportation. This research was the first discovery of antihyperuricemic peptide from the shelled fruits of O. Sativa and provided a new candidate for the development of hypouricemic drugs.

Anti-hyperuricemic peptides derived from bonito hydrolysates based on in vivo hyperuricemic model and in vitro xanthine oxidase inhibitory activity

Traditional drugs used to treat hyperuricemia have adverse effects. In this study, to identify safer anti-hyperuricemic bioactive peptides isolated from food-derived protein hydrolysates, a hyperuricemia rat model induced by potassium oxonate (PO) was used to evaluate the activity of bonito hydrolysates (BH), dephenolised walnut hydrolysates (DWH), and soybean hydrolysates (SH). The serum uric acid level of rats in the BH group (95.4 ± 27.4 μM, p < 0.01) was significantly reduced compared to that in the model group (212.00 ± 30.00 μM) to a level even lower than that in allopurinol group (114.3 ± 53.0 μM). Furthermore, BH alleviated renal impairment caused by PO in vivo and exhibited the greatest xanthine oxidase (XOD) inhibitory activity (65.5 ± 8.0%) in vitro compared to the other hydrolysates. Two peptides identified from BH bound the catalytic site of XOD, among which the hydrophobic peptide WML entered the active site of XOD more easily compared to the hydrophilic peptide PGACSN, possibly because of hydrophobic interactions. The chemically synthesized WML demonstrated high XOD inhibitory effect compared to PGACSN and a significant change in the secondary structure of XOD. Therefore, hexapeptide PGACSN and tripeptide WML are partially responsible for the anti-hyperuricemic activity of BH, and hydrophobic amino acids play important roles in the XOD inhibitory activity of peptides.

Selective Extraction and Antioxidant Properties of Thiol-Containing Peptides in Soy Glycinine Hydrolysates

A highly selective procedure to extract thiol-containing peptides (TCPs) from complicated soy glycinin hydrolysates (SGHs) was described. This procedure included the reduction of disulfide bonds by 1,4-dithiothreitol (DTT) and enrichment of TCPs through Thiopropyl-Sephrose 6B covalent chromatography. TCPs were confirmed using a strategy based on mass shift after differential alkylation of sulfhydryl groups with iodoacetamide and N-ethylmaleimide by matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF-MS). The antioxidant activities of TCPs were evaluated using chemical assays. DTT reduction increased the concentration of sulfhydryl groups from 1.8 μmol/g to 113.8 μmol/g. The efficiency of the extraction was improved by optimizing the loading of sample, extraction and desorption time and the content of desorption reagent. Both of the adsorption and desorption process were found to fit a pseudo-second order model. MALDI-TOF-MS showed that 36 of the 45 extracted peptides were TCPs. The EC50 of TCPs for DPPH, hydroxyl radical, and superoxide anion radical was 0.1, 1.49 and 0.084 mg/mL, respectively. The reducing power of TCPs (0.2 mg/mL) was of 0.375. These results suggest that the combination of DTT reduction and Thiopropyl-Sepharose 6B covalent chromatograph was a successful pathway to extract TCPs from SGHs and the TCPs could be used as potential antioxidants.

Structure, Content, and Bioactivity of Food-Derived Peptides in the Body

Orally administered peptides are assumed to be degraded into amino acids in the body. However, our recent studies revealed some food-derived prolyl and pyroglutamyl peptides with 2-3 amino acid residues in the blood of humans and animals, while most of the peptides in the endoproteinase digest of food protein are degraded by exopeptidase. Some food-derived dipeptides in the body display in vitro and in vivo biological activities. These facts indicate that the biological activities of food-derived peptides in the body rather than those in food are crucial to understanding the mechanism of the beneficial effects of orally administered peptides.

Bioactive Peptides from Cartilage Protein Hydrolysate of Spotless Smoothhound and Their Antioxidant Activity In Vitro

In the experiment, crude proteins from spotless smoothhound (Mustelus griseus), cartilages were isolated by HCl-Guanidine buffer, and its hydrolysate was prepared using trypsin at pH 8.0, 40 °C with a total enzyme dose of 2.5%. Subsequently, three antioxidant peptides were purified from the hydrolysate using membrane ultrafiltration, anion-exchange chromatography, gel filtration chromatography, and reverse phase high-performance liquid chromatography. The amino acid sequences of isolated peptides were identified as Gly-Ala-Glu-Arg-Pro (MCPE-A); Gly-Glu-Arg-Glu-Ala-Asn-Val-Met (MCPE-B); and Ala-Glu-Val-Gly (MCPE-C) with molecular weights of 528.57, 905.00, and 374.40 Da, respectively, using protein amino acid sequence analyzer and mass spectrum. MCPE-A, MCPE-B and MCPE-C exhibited good scavenging activities on 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH•) (EC₅₀ 3.73, 1.87, and 2.30 mg/mL, respectively), hydroxyl radicals (HO•) (EC₅₀ 0.25, 0.34, and 0.06 mg/mL, respectively), 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radicals (ABTS⁺•) (EC₅₀ 0.10, 0.05, and 0.07 mg/mL, respectively) and superoxide anion radicals (O2−•) (EC₅₀ 0.09, 0.33, and 0.18 mg/mL, respectively). MCPE-B showed similar inhibiting ability on lipid peroxidation with butylated hydroxytoluene (BHT) in a linoleic acid model system. Furthermore, MCPE-A, MCPE-B, and MCPE-C could protect H₂O₂-induced HepG2 cells from oxidative stress by decreasing the content of malonaldehyde (MDA) and increasing the levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione reductase (GSH-Rx). Glu, Gly, Met, and Pro in their sequences and low molecular weight could be attributed to the antioxidant activities of three isolated peptides. These results suggested that GAERP (MCPE-A), GEREANVM (MCPE-B), and AEVG (MCPE-C) from cartilage protein hydrolysate of spotless smoothhound might serve as potential antioxidants and be used in the pharmaceutical and health food industries.

Moderation of hyperuricemia in rats via consuming walnut protein hydrolysate diet and identification of new antihyperuricemic peptides

Walnut-derived antihyperuricemic peptides were purified and identified based on decreasing serum uric acid level and inhibiting xanthine oxidase.

Relationship between hyperuricemia and dietary risk factors in Chinese adults: a cross-sectional study

Previous studies focusing on identification of dietary risk factors for hyperuricemia reported controversial findings. Moreover, evidence for relationship between hyperuricemia and eating and cooking habits remained scanty. The purpose of this study was to evaluate the associations between hyperuricemia and dietary risk factors. A cross-sectional study was conducted among 1583 participants in a Beijing community. Face-to-face interviews were conducted using questionnaires. Anthropometric measurements and biochemical tests were also performed. The prevalence of hyperuricemia was 14.1 % (20.2 % for males and 7.4 % for females). Among the 1372 subjects included for analysis, 720 (52.5 %) were males and the mean age was 37.7 years. For males, statistically significant associations between hyperuricemia and tea intake, breakfast and midnight snack consumption were found, with an odds ratio of 0.56 (high vs. low), 2.14 (often vs. always) and 0.52 (rarely vs. always), respectively. Smoking, fatty liver disease, triglyceride, low-density lipoprotein cholesterol and fasting blood glucose were significantly related to increased serum uric acid (SUA), with a coefficient of 20.06, 11.52, 7.29, 18.97 and 13.37 on SUA, respectively. For females, no statistically significant associations between hyperuricemia and dietary risk factors were observed. In summary, hyperuricemia is highly prevalent among the adult participants in this Chinese community, especially for men. High tea intake and consuming midnight snack rarely are significantly related to decreased risk of hyperuricemia, while often-eating breakfast is associated with increased risk of hyperuricemia compared with always-eating breakfast in males. Further prospective studies are needed to confirm the findings and to establish dietary recommendations for the prevention and treatment of hyperuricemia.