Novel xanthine oxidase inhibitory peptides derived from whey protein: identification, in vitro inhibition mechanism and in vivo activity validation

Virtual-screening of xanthine oxidase inhibitory peptides: Inhibition mechanisms and prediction of activity using machine-learning

Xanthine oxidase (XO) inhibitory peptides can prevent XO-mediated hyperuricemia. Currently, QSAR about XO inhibitory peptides with different lengths remains to be enriched. Here, XO inhibitory peptides were obtained from porcine visceral proteins through virtual-screening. A prediction model was established by machine-learning. Virtual-screening retained four lengths of peptides, including 3-6. Molecular-docking recognized their binding sites with XO and showed residues W, F, and G were the key amino acids. Datasets of XO inhibitory peptides therewith were established. The optimal model was used to generalize the peptides reported. Results showed that the R2 of the tripeptide, tetrapeptide, pentapeptide and hexapeptide in the generalisation test were R2 = 0.81, R2 = 0.82, R2 = 0.83 and R2 = 0.83, respectively. Overall, this work can serve as a reference for explaining the activity mechanism of XO inhibitory peptides and predicting the activity of XO inhibitory peptides.

In silico identification and experimental validation of two types of angiotensin-converting enzyme (ACE) and xanthine oxidase (XO) milk inhibitory peptides

Bioactive peptides have received significant attention due to their natural origin, low toxicity, and targeting specificity in the past decade. This study identified highly active ACE/XO inhibitors using molecular simulation and online databases and validated their in vitro antioxidant activity and the mechanisms of molecular interactions. According to computer predictions, Asp-Gly-Gly (DGG) and Asp-Gly-Met (DGGM) were identified as potential hydrolysates of common gastrointestinal peptidases with well water-soluble, non-toxic, and non-allergenic. Fourier transform infrared spectroscopy showed that the two peptides altered the enzyme's secondary structure, decreasing α-helix content by about 13 %, along with increasing β-sheet, randam coli, and β-turns content. Molecular docking and molecular dynamics simulations showed that hydrogen bonding and electrostatic interactions caused DGG and DGGM to form stable and dense complexes with the two enzymes. This study provides a new way for economical and efficient screening of new ACE and XO inhibitory peptides from natural proteins.

A comprehensive review on recent xanthine oxidase inhibitors of dietary based bioactive substances for the treatment of hyperuricemia and gout: Molecular mechanisms and perspective

Hyperuricemia (HUA) has attained a considerable global health concern, related to the development of other metabolic syndromes. Xanthine oxidase (XO), the main enzyme that catalyzes xanthine and hypoxanthine into uric acid (UA), is a key target for drug development against HUA and gout. Available XO inhibitors are effective, but they come with side effects. Recent, research has identified new XO inhibitors from dietary sources such as flavonoids, phenolic acids, stilbenes, alkaloids, polysaccharides, and polypeptides, effectively reducing UA levels. Structural activity studies revealed that -OH groups and their substitutions on the benzene ring of flavonoids, polyphenols, and stilbenes, cyclic rings in alkaloids, and the helical structure of polysaccharides are crucial for XO inhibition. Polypeptide molecular weight, amino acid sequence, hydrophobicity, and binding mode, also play a significant role in XO inhibition. Molecular docking studies show these bioactive components prevent UA formation by interacting with XO substrates via hydrophobic, hydrogen bonds, and π-π interactions. This review explores the potential bioactive substances from dietary resources with XO inhibitory, and UA lowering potentials detailing the molecular mechanisms involved. It also discusses strategies for designing XO inhibitors and assisting pharmaceutical companies in developing safe and effective treatments for HUA and gout.

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.

Harnessing Protein Hydrolysates and Peptides for Hyperuricemia Management: Insights into Sources, Mechanisms, Techniques, and Future Directions

Hyperuricemia (HUA) is a metabolic disorder characterized by an imbalance in uric acid production and excretion, frequently leading to gout and various chronic conditions. Novel bioactive compounds offer effective alternatives for managing HUA, reducing side effects of traditional medications. Recent studies have highlighted the therapeutic potential of protein hydrolysates and peptides in managing HUA. This review focuses on preparing and applying protein hydrolysates to treat HUA and explores peptides for xanthine oxidase inhibition. Particularly, we discuss their origins, enzymatic approaches, and mechanisms of action in detail. The review provides an updated understanding of HUA pathogenesis, current pharmacological interventions, and methodologies for the preparation, purification, identification, and assessment of these compounds. Furthermore, to explore the application of protein hydrolysates and peptides in the food industry, we also address challenges and propose solutions related to the safety, bitterness, oral delivery, and the integration of artificial intelligence in peptide discovery. Bridging traditional pharmacological approaches and innovative dietary interventions, this study paves the way for future research and development in HUA management, contributing to the utilization of proteins from different food sources. In conclusion, protein hydrolysates and peptides show significant promise as safe agents and dietary interventions for preventing and treating HUA.

Anti-hyperuricemia bioactive peptides: a review on obtaining, activity, and mechanism of action

Hyperuricemia, a disorder of uric acid metabolism, serves as a significant risk factor for conditions such as hypertension, diabetes mellitus, renal failure, and various metabolic syndromes. The main contributors to hyperuricemia include overproduction of uric acid in the liver or impaired excretion in the kidneys. Despite traditional clinical drugs being employed for its treatment, significant health concerns persist. Recently, there has been growing interest in utilizing protein peptides sourced from diverse food origins to mitigate hyperuricemia. This article provides a comprehensive review of bioactive peptides with anti-hyperuricemia properties derived from animals, plants, and their products. We specifically outline the methods for preparing these peptides from food proteins and elucidate their efficacy and mechanisms in combating hyperuricemia, supported by in vitro and in vivo evidence. Uric acid-lowering peptides offer promising prospects due to their safer profile, enhanced efficacy, and improved bioavailability. Therefore, this review underscores significant advancements and contributions in identifying peptides capable of metabolizing purine and/or uric acid, thereby alleviating hyperuricemia. Moreover, it offers a theoretical foundation for the development of functional foods incorporating uric acid-lowering peptides.

Identification of Hyperuricemia Alleviating Peptides from Yellow Tuna Thunnus albacares

The development of food-derived antihyperuricemic substances is important for alleviating hyperuricemia (HUA) and associated inflammation. Here, novel peptides fromThunnus albacares (TAP) with strong antihyperuricemic activity were prepared. TAP was prepared by alkaline protease (molecular weight <1000 Da), with an IC50 value of xanthine oxidase inhibitory activity of 2.498 mg/mL, and 5 mg/mL TAP could reduce uric acid (UA) by 33.62% in human kidney-2 (HK-2) cells (P < 0.01). Mice were fed a high-purine diet and injected with potassium oxonate to induce HUA. Oral administration of TAP (600 mg/kg/d) reduced serum UA significantly by 42.22% and increased urine UA by 79.02% (P < 0.01) via regulating urate transporters GLUT9, organic anion transporter 1, and ATP-binding cassette subfamily G2. Meantime, TAP exhibited hepatoprotective and nephroprotective effects, according to histological analysis. Besides, HUA mice treated with TAP showed anti-inflammatory activity by decreasing the levels of toll-like receptor 4, nuclear factors-κB p65, NLRP3, ASC, and Caspase-1 in the kidneys (P < 0.01). According to serum non-targeted metabolomics, 91 differential metabolites between the MC and TAP groups were identified, and purine metabolism was considered to be the main pathway for TAP alleviating HUA. In a word, TAP exhibited strong antihyperuricemic activity both in vitro and in vivo.

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

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.

Whey Protein Peptide Pro-Glu-Trp Ameliorates Hyperuricemia by Enhancing Intestinal Uric Acid Excretion, Modulating the Gut Microbiota, and Protecting the Intestinal Barrier in Rats

Hyperuricemia (HUA) is a metabolic disorder characterized by an increase in the concentrations of uric acid (UA) in the bloodstream, intricately linked to the onset and progression of numerous chronic diseases. The tripeptide Pro-Glu-Trp (PEW) was identified as a xanthine oxidase (XOD) inhibitory peptide derived from whey protein, which was previously shown to mitigate HUA by suppressing UA synthesis and enhancing renal UA excretion. However, the effects of PEW on the intestinal UA excretion pathway remain unclear. This study investigated the impact of PEW on alleviating HUA in rats from the perspective of intestinal UA transport, gut microbiota, and intestinal barrier. The results indicated that PEW inhibited the XOD activity in the serum, jejunum, and ileum, ameliorated intestinal morphology changes and oxidative stress, and upregulated the expression of ABCG2 and GLUT9 in the small intestine. PEW reversed gut microbiota dysbiosis by decreasing the abundance of harmful bacteria (e.g., Bacteroides, Alloprevotella, and Desulfovibrio) and increasing the abundance of beneficial microbes (e.g., Muribaculaceae, Lactobacillus, and Ruminococcus) and elevated the concentration of short-chain fatty acids. PEW upregulated the expression of occludin and ZO-1 and decreased serum IL-1β, IL-6, and TNF-α levels. Our findings suggested that PEW supplementation ameliorated HUA by enhancing intestinal UA excretion, modulating the gut microbiota, and restoring the intestinal barrier function.

Pathology, target discovery, and the evolution of XO inhibitors from the first discovery to recent advances (2020-2023)

Hyperuricemia, a disease characterized by elevation of serum uric acid level beyond 6 mg/dL. This elevation led to appearance of symptoms from joint pain to gout and from gout to difficulty in mobility of the patient. So, in this review, we have summarized the pathology of hyperuricemia, discovery of target and discovery of first XO inhibitor. At last, this review provides in-sights about the recently discovered as natural XO inhibitors, followed by design, structure activity relationship and biological activity of synthetic compounds as XO inhibitors discovered between 2020 and 2023 years. At last, the pharmacophores generated in this study will guide new researchers to design and modify the structure of novel XO inhibitors.

Using deep learning and molecular dynamics simulations to unravel the regulation mechanism of peptides as noncompetitive inhibitor of xanthine oxidase

Xanthine oxidase (XO) is a crucial enzyme in the development of hyperuricemia and gout. This study focuses on LWM and ALPM, two food-derived inhibitors of XO. We used molecular docking to obtain three systems and then conducted 200 ns molecular dynamics simulations for the Apo, LWM, and ALPM systems. The results reveal a stronger binding affinity of the LWM peptide to XO, potentially due to increased hydrogen bond formation. Notable changes were observed in the XO tunnel upon inhibitor binding, particularly with LWM, which showed a thinner, longer, and more twisted configuration compared to ALPM. The study highlights the importance of residue F914 in the allosteric pathway. Methodologically, we utilized the perturbed response scan (PRS) based on Python, enhancing tools for MD analysis. These findings deepen our understanding of food-derived anti-XO inhibitors and could inform the development of food-based therapeutics for reducing uric acid levels with minimal side effects.

Molecular simulation for food protein-ligand interactions: A comprehensive review on principles, current applications, and emerging trends

In recent years, investigations on molecular interaction mechanisms between food proteins and ligands have attracted much interest. The interaction mechanisms can supply much useful information for many fields in the food industry, including nutrient delivery, food processing, auxiliary detection, and others. Molecular simulation has offered extraordinary insights into the interaction mechanisms. It can reflect binding conformation, interaction forces, binding affinity, key residues, and other information that physicochemical experiments cannot reveal in a fast and detailed manner. The simulation results have proven to be consistent with the results of physicochemical experiments. Molecular simulation holds great potential for future applications in the field of food protein-ligand interactions. This review elaborates on the principles of molecular docking and molecular dynamics simulation. Besides, their applications in food protein-ligand interactions are summarized. Furthermore, challenges, perspectives, and trends in molecular simulation of food protein-ligand interactions are proposed. Based on the results of molecular simulation, the mechanisms of interfacial behavior, enzyme-substrate binding, and structural changes during food processing can be reflected, and strategies for hazardous substance detection and food flavor adjustment can be generated. Moreover, molecular simulation can accelerate food development and reduce animal experiments. However, there are still several challenges to applying molecular simulation to food protein-ligand interaction research. The future trends will be a combination of international cooperation and data sharing, quantum mechanics/molecular mechanics, advanced computational techniques, and machine learning, which contribute to promoting food protein-ligand interaction simulation. Overall, the use of molecular simulation to study food protein-ligand interactions has a promising prospect.

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.

CRISPR/Cas9 System-Mediated Multi-copy Expression of an Alkaline Serine Protease in Aspergillus niger for the Production of XOD-Inhibitory Peptides

CRISPR/Cas9 system-mediated multi-copy expression of an alkaline serine protease (AoproS8) from Aspergillus oryzae was successfully built in Aspergillus niger. Furthermore, AoproS8 was continuously knocked in the glaA, amyA, and aamy gene loci in A. niger to construct multi-copy expression strains. The yield of the AoproS8 3.0 strain was 2.1 times higher than that of the AoproS8 1.0 strain. Then, a high protease activity of 11,023.2 U/mL with a protein concentration of 10.8 mg/mL was obtained through fed-batch fermentation in a 5 L fermenter. This is the first report on the high-level expression of alkaline serine proteases in A. niger. AoproS8 showed optimal activity at pH 9.0 and 40 °C. It was used for the production of xanthine oxidase (XOD)-inhibitory peptides from eight food processing protein by-products. Among them, the duck hemoglobin hydrolysates showed the highest XOD-inhibitory activity with an IC50 value of 2.39 mg/mL. Thus, our work provides a useful way for efficient expression of proteases in A. niger and high-value utilization of protein by-products.

Exploring the Potential of Black Soldier Fly Larval Proteins as Bioactive Peptide Sources through in Silico Gastrointestinal Proteolysis: A Cheminformatic Investigation

Despite their potential as a protein source for human consumption, the health benefits of black soldier fly larvae (BSFL) proteins following human gastrointestinal (GI) digestion are poorly understood. This computational study explored the potential of BSFL proteins to release health-promoting peptides after human GI digestion. Twenty-six proteins were virtually proteolyzed with GI proteases. The resultant peptides were screened for high GI absorption and non-toxicity. Shortlisted peptides were searched against the BIOPEP-UWM and Scopus databases to identify their bioactivities. The potential of the peptides as inhibitors of myeloperoxidase (MPO), NADPH oxidase (NOX), and xanthine oxidase (XO), as well as a disruptor of Keap1–Nrf2 protein–protein interaction, were predicted using molecular docking and dynamics simulation. Our results revealed that about 95% of the 5218 fragments generated from the proteolysis of BSFL proteins came from muscle proteins. Dipeptides comprised the largest group (about 25%) of fragments arising from each muscular protein. Screening of 1994 di- and tripeptides using SwissADME and STopTox tools revealed 65 unique sequences with high GI absorption and non-toxicity. A search of the databases identified 16 antioxidant peptides, 14 anti-angiotensin-converting enzyme peptides, and 17 anti-dipeptidyl peptidase IV peptides among these sequences. Results from molecular docking and dynamic simulation suggest that the dipeptide DF has the potential to inhibit Keap1–Nrf2 interaction and interact with MPO within a short time frame, whereas the dipeptide TF shows promise as an XO inhibitor. BSFL peptides were likely weak NOX inhibitors. Our in silico results suggest that upon GI digestion, BSFL proteins may yield high-GI-absorbed and non-toxic peptides with potential health benefits. This study is the first to investigate the bioactivity of peptides liberated from BSFL proteins following human GI digestion. Our findings provide a basis for further investigations into the potential use of BSFL proteins as a functional food ingredient with significant health benefits.