Novel xanthine oxidase-based cell model using HK-2 cell for screening antihyperuricemic functional compounds

Goat Milk Protein-Derived ACE Inhibitory Peptide SLPQ Exerts Hypertension Alleviation Effects Partially by Regulating the Inflammatory Stress of Endothelial Cells

Hypertension has always posed a severe threat to people's health. Food-derived angiotensin-converting enzyme (ACE)-inhibitory peptides have the potential to both prevent and treat hypertension. In the current investigation, two ACE-inhibitory peptides (SLPQ and PYVRYL) from goat milk were studied for their endothelial effects using EA.hy926 cells. PYVRYL outperformed SLPQ, yet neither impacted cell survival below 200 μg/mL. Investigation of SLPQ's impact on EA.hy926 cell expression revealed 114 differentially expressed genes, with 65 downregulated and 49 upregulated. The genes were enriched in cytokine interactions, coagulation cascades, Hippo signaling, and ECM-receptor interaction. Decreased c-x-c motif chemokine ligand 2 (CXCL2), integrin subunit beta 2 (ITGB2), and fbj murine osteosarcoma viral oncogene homologue (FOS) expression and increased secreted phosphoprotein 1 (SPP1) expression may protect endothelial cells from inflammation. Our findings suggest that beyond ACE inhibition, SLPQ aids blood pressure control by influencing endothelial function, paving the way for its use as an antihypertensive food ingredient.

Nisin A elevates adenosine to achieve anti-inflammatory activity

Inflammation is a ubiquitous physiological status that exists during the occurrence, development and prognosis of numerous diseases. Clinical anti-inflammatory drugs mainly include antibiotics, antivirals, non-steroids and corticosteroids, and the treatments are often accompanied by side effects, including nausea, abdominal pain, allergy, nerve injury and organ dysfunction. Current studies have focused on continuously exploring efficient anti-inflammatory natural components with high biosafety, while nisin, a natural bioactive anti-microbial peptide produced by Lactococcus, has been reported to have anti-inflammatory activity via its superior anti-bacterial abilities. Several recent studies have focused on the potent direct anti-inflammation of nisin, whereas its effects and the corresponding mechanism still remain unclear. The cellular and Caenorhabditis elegans (C. elegans) models were constructed in this study to evaluate the anti-inflammatory effects of nisin A both in vitro and in vivo, while the inflammatory mechanism was further uncovered based on omics analysis. This study reveals the direct anti-inflammatory activity of nisin A and elucidates the regulatory actions of nisin A on adenosine, followed by alteration of the sphingolipid signaling pathway and purine metabolism, enhancing the deep understanding of nisin A with its anti-inflammatory capacity, providing new ideas for future nisin A-based anti-inflammatory strategies.

A strategy to boost xanthine oxidase and angiotensin converting enzyme inhibitory activities of peptides via molecular docking and module substitution

Molecular docking and activity evaluation screened the dipeptide module GP with low xanthine oxidase (XOD) inhibitory activity and modules KE and KN with high activity, and identified them as low- and high-contribution modules, respectively. We hypothesized the substitution of low-contribution modules in peptides with high contributions would boost their XOD inhibitory activity. In the XOD inhibitory peptide GPAGPR, substitution of GP with both KE and KN led to enhanced affinity between the peptides and XOD. They also increased XOD inhibitory activity (26.4% and 10.3%) and decreased cellular uric acid concentrations (28.0% and 10.4%). RNA sequencing indicated that these improvements were attributable to the inhibition of uric acid biosynthesis. In addition, module substitution increased the angiotensin-converting enzyme inhibitory activity of GILRP and GAAGGAF by 84.8% and 76.5%. This study revealed that module substitution is a feasible strategy to boost peptide activity, and provided information for the optimization of hydrolysate preparation conditions.

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.

Hyperuricemia research progress in model construction and traditional Chinese medicine interventions

Hyperuricemia (HUA), a severe metabolic disease derived from purine metabolism disorder, will lead to abnormally increased serum uric acid (SUA) levels in the body. Studies have shown that HUA is highly related to gout, hypertension, diabetes, coronary heart disease, chronic kidney diseases, and so on. Traditional Chinese medicine (TCM) shows excellent results in treating HUA because of its unique advantages of multi-metabolites and multi-targets. This article reports on the use of TCM components for uric acid (UA)-lowering activity with excellent efficacy and low side effects based on established HUA models. This work summarizes the advantages and limitations of various HUA disease models for efficacy evaluation. Applications of TCM in HUA treatment have also been discussed in detail. This paper reveals recent research progress on HUA in constructing evaluation models and systematic TCM interventions. It will provide a scientific reference for establishing the HUA model and suggest future TCM-related HUA studies.

The application of organoid models in research into metabolic diseases

Metabolic diseases have become a major threat to human health worldwide as a result of changing lifestyles. The exploration of the underlying molecular mechanisms of metabolic diseases and the development of improved therapeutic methods have been hindered by the lack of appropriate human experimental models. Organoids are three-dimensional in vitro models of self-renewing cells that spontaneously self-organize into structures similar to the corresponding in vivo tissues, recapitulating the original tissue function. Off-body organoid technology has been successfully applied to disease modelling, developmental biology, regenerative medicine, and tumour precision medicine. This new generation of biological models has received widespread attention. This article focuses on the construction process and research progress with regard to organoids related to metabolic diseases in recent years, and looks forward to their prospective applications.

Efficient discovery of active isolates from Dioscorea spongiosa by the combination of bioassay-guided macroporous resin column chromatography and high-speed counter-current chromatography

In the present study, twelve compounds from Dioscorea spongiosa were successfully purified by an efficient technique combined bioassay-guided fractionation macroporous resin column chromatography (MRCC) pretreatment and high-speed counter-current chromatography (HSCCC) separation for the first time. Then, D101 MRCC was used to fractionate the crude extract into five parts, which further applied the bioassay-guided fractionation strategy to screen the active fractions of 2 and 4. As for the separation, 200 mg Fr.2 was purified by HSCCC using EtOAc/n-BuOH/H2 O (2:2:3, v/v), leading to annulatomarin (1), dioscoresides C (2), diosniponol C (3), methyl protodioscin (4), pseudoprotodioscin (5), protogracillin (6), as well as 200 mg Fr.4 yielding montroumarin (7), dioscorone A (8), diosniponol D (9), protodioscin (10), gracillin (11), and dioscin (12) using CH2 Cl2 /MeOH/H2 O (3:3:2, v/v) with the purities over 95.0%. Finally, the isolates were assayed for their anti-inflammatory, urico-lowering, and anti-diabetic activities in vitro, which indicated that the steroidal saponins of 5, 6, and 11 showed all these three activities.

Decoction regulating phytochemicals' micromorphology changes and anti-inflammation activity enhancements originated from herb medicine supermolecules

BACKGROUND

Mahuang Fuzi decoction (MGF) is composed of three herb medicines that has been clinically used to treat inflammatory diseases for a long history. At present, more and more active phytochemicals' aggregations have been found during the thermodynamic process of herb medicine decoction, and revealing the clinical efficacy of herb medicine through supramolecular strategies is the focus of current research. However, it is not clear whether decoction induced supermolecules' morphological changes to modify activity.

METHODS

Dynamic light scattering (DLS) and field emission scanning electron microscopy (FESEM) were used to analyze the micromorphology of MGF, MGF SA (MGF supermolecules), and MIX (physical mixture of MGF single decoction). The interaction and thermodynamic parameters of single herbs in a decoction were investigated by Isothermal titration calorimetry (ITC). The phytochemicals were systematically analyzed by ultra high performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry (UHPLC-Q-Orbitrap HRMS). Under the safe dose on RAW264.7 cells, NO, IL-6 and TNF-α were determined by Enzyme-Linked ImmunoSorbent Assay (ELISA) method. NF-κB p65 translocation from the cytoplasm into the nucleus was examined using the immunofluorescence assay and the western blot, respectively. Furthermore, Metabolomics was used to discover potential biomarkers and the associated metabolic pathways of MGF SA treatment.

RESULTS

There were nanoscale aggregations in MGF, and the micromorphology of the extracted MGF SA consisted of uniform particles; while the MIX micromorphology had no uniformity. ITC showed that the interaction MH-GC and FZ-GC were a spontaneous exothermic reaction, indicating that their phytochemicals had the property of self-assembly. Though the micromorphology between MGF, MGF SA, and MIX was obviously different, UHPLC-Q-Orbitrap HRMS results displayed that the main phytochemicals of MGF and MIX had nearly the same components. Interestingly, MGF and MGF SA could significantly inhibit the production of NO, and had better inhibition effect on the expression of nuclear protein NF-κB p65 than MIX, among which MGF SA had the best effect. Further investigation indicated that the perturbance of metabolic profiling in RAW264.7 inflammatory cells was obviously reversed by MGF SA.

CONCLUSIONS

The decoction enriched the key active phytochemicals and regulated the formation of homogeneous nanoparticles in MGF SA. The supermolecules in MGF SA significantly enhanced its anti-inflammatory activity, primarily affecting the NF-κB signaling pathway and the biosynthesis and metabolism of arginine in RAW264.7 inflammatory cells. Current study displayed that co-decocting herbal medicine were beneficial to the treatment of diseases than the mixture of the single herbs' extraction.

Integrating multi-level interactive network and in vivo/vitro studies to explore the protective mechanism of Ampelopsis grossedentata in hyperuricemia

The strategies or drugs for preventing and treating Hyperuricemia (HUA) are still lacking. As a traditional Chinese medicine (TCM) with a profound history, Ampelopsis grossedentata has been shown to play diverse biological roles. The purpose of the present study was to evaluate hypouricemic effect of A. grossedentata, and investigate its involved material basis and mechanism. A HUA mice model was established to evaluate the therapeutic effects of A. grossedentata. And then some extracts from A. grossedentata were prepared, isolated and analyzed. Furthermore, network pharmacology, based on the above results, was used to discover potential active ingredients and therapeutic targets, and they were further verified and explored by molecular docking and in vitro experiments. In vivo experiments showed that A. grossedentata exerted hypouricemic effect on mice of HUA. The core active ingredients (quercetin, myricetin and dihydromyricetin etc.) and core targets (PTGS2, XOD and ABCG2 etc.) for A. grossedentata to treat HUA were predicted by network pharmacology. And molecular docking showed that the spontaneous binding activities of above components and targets were marvelous. In vitro experiments further demonstrated that A. grossedentata exerted hypouricemic effect by decreasing the levels of UA, XOD, antioxidant factors, inflammatory factors, GLUT9 and URAT1 in HK-2 cells of HUA. Taken together, this study integrates multi-level interaction network with in vivo/vitro experiments to systematically reveal the material basis and mechanism of A. grossedentata in treating HUA, which provides a scientific basis for further study of A. grossedentata and HUA.

Selection of goat β-casein derived ACE-inhibitory peptide SQPK and insights into its effect and regulatory mechanism on the function of endothelial cells

The angiotensin I-converting enzyme (ACE)-inhibitory peptide SQPK was selected by in silico digestion and virtual screening from goat β-casein, and its effect and regulatory mechanism on function of endothelial cells was further evaluated. The results showed that SQPK exhibited relatively good ACE inhibition capacity (IC50 = 452.7 μg/mL). Treatment with 25 μg/mL SQPK for 12 h significantly elevated nitric oxide (NO) production, stimulated eNOS expression (p < 0.05) and affected the transcriptomic profiling of EA. Hy926 cells. In particular, SQPK stimulated the expression of genes encoding inflammatory cytokines (CXCL1/2 and IL6) but depressed encoding mesenchymal markers (FN1 and CNN3). Furthermore, SQPK modified the expression of genes involved in endothelial-to-mesenchymal transition (EndMT). Therefore, the selected peptide SQPK may exert potential protective effects on the function of endothelial cells by inhibiting the EndMT.

GRP/GRPR signaling pathway aggravates hyperuricemia-induced renal inflammation and fibrosis via ABCG2-dependent mechanisms

The gastrin-releasing peptide receptor (GRPR) binds to ligands such as gastrin-releasing peptide (GRP) and plays a variety of biological roles. In this study, we investigated the therapeutic effect of a novel gastrin-releasing peptide receptor antagonist RH-1402 in hyperuricemia-induced kidney fibrosis and its underlying mechanisms. We conducted enzyme linked immunosorbent assay (ELISA) and immunohistochemical analyses and found that proGRP and GRPR expression levels were significantly increased in patients with hyperuricemic nephropathy (HN) and HN mice. GRPR knockdown significantly attenuated inflammatory and fibrotic responses in adenosine-treated human proximal tubule epithelial cells. GRPR knockout or GRPR conditional knockout in renal tubular epithelial cells significantly alleviated the decline in renal function and fibrosis in HN mice in vivo. RNA-seq and String database analysis revealed that GRP/GRPR promoted HN by suppressing the ABCG2/PDZK1 and increasing TGF-β/Smad3 levels by activating the NF-κB pathway. Overexpression of GRPR increased TGF-β/Smad3 levels, where as it reduced ABCG2/PDZK1 levels in adenosine-treated HK2 cells, which was reversed by the NF-κB inhibitor. Furthermore, we evaluated the therapeutic effects of the novel GRPR inhibitor RH-1402 on hyperuricaemia-induced renal injury and evaluated the inflammatory and fibrosis responses in vivo and in vitro. Pre-treatment with RH-1402 attenuated hyperuricaemia-induced renal injury, restored renal function, and suppressed renal inflammation and fibrosis. Taken together, GRPR enhances hyperuricaemia-induced tubular injury, inflammation, and renal fibrosis via ABCG2-dependent mechanisms and may serve as a promising therapeutic target for HN treatment.

Corn Silk Flavonoids Ameliorate Hyperuricemia via PI3K/AKT/NF-κB Pathway

Hyperuricemia (HUA) is a widespread metabolic disease marked by an elevated level of uric acid, and is a risk factor for premature death. The protective effect of corn silk flavonoids (CSF) against HUA and its potential mechanisms were explored. Five important apoptosis and inflammation-related signaling pathways were identified by network pharmacological analysis. The CSF exhibited significant uric acid (UA)-lowering activity in vitro by decreasing xanthine oxidase (XOD) and increasing hypoxanthine-guanine phosphoribosyl transferase levels. In a potassium oxonate-induced HUA in vivo, CSF treatment effectively inhibited XOD activity and promoted UA excretion. Furthermore, it decreased the levels of TNF-α and IL-6 and restored pathological damage. In summary, CSF is a functional food component to improve HUA by reducing inflammation and apoptosis through the down-regulating PI3K/AKT/NF-κB pathway.

Estradiol protects female mice from hyperuricemia induced by PCB138 exposure

Polychlorinated biphenyls (PCBs) are a type of persistent organic pollutant (POP). Our previous study demonstrated that exposure to 0.5-50 μg/kg bw PCB138 during postnatal days (PND) 3-21 led to elevated serum uric acid (UA) levels and kidney injury in adult male mice. Given that the prevalence of hyperuricemia (HUA) is significantly lower in women than in men, it is worth investigating whether POP-induced HUA and its secondary kidney injury have sexual dimorphism. Herein, we exposed female mice to 0.5-50 μg/kg bw PCB138 during PND 3-21, resulting in elevated serum UA levels, but without causing significant kidney damage. Concurrently, we found a negative correlation between serum 17β-estradiol (E2) and serum UA levels. We also observed down-regulation of estrogen receptor (ER) protein levels in the kidneys of the PCB138-exposed groups. Furthermore, our study showed that E2 rescued the increased UA level and cytotoxicity caused by HUA in human renal tubular epithelial (HK-2) cells. Collectively, our findings suggest that E2 likely plays a crucial protective role in PCB138-induced HUA and kidney injury in female mice. Our research highlights the existence of sexual dimorphism in kidney injury secondary to HUA induced by POPs, which could provide guidance for individuals of different genders in preventing kidney injury caused by environmental factors.

Intracellular Antioxidant and Anti-Inflammatory Effects and Bioactive Profiles of Coffee Cascara and Black Tea Kombucha Beverages

Kombucha is a functional beverage obtained through fermentation of sweetened Camellia sinensis infusion by a symbiotic culture of bacteria and yeasts that exerts many beneficial biological effects, mostly related to its antioxidant and anti-inflammatory effects. Alternative raw materials have been used to create new kombucha or kombucha-like products. Coffee is the most important food commodity worldwide and generates large amounts of by-products during harvest and post-harvest processing. The main coffee by-product is the dried fruit skin and pulp, popularly known as cascara. To date, no studies have evaluated the potential bioactivity of coffee cascara kombucha. In this study, we aimed to measure and compare the effects of infusions and kombuchas made with arabica coffee cascaras (n = 2) and black tea leaves (n = 1), fermented for 0, 3, 6, and 9 days on the intracellular production of Reactive Oxygen Species (ROS) and Nitric Oxide (NO) in model cells. Oxidative stress was induced in HK-2 cells with indoxyl sulfate (IS) and high glucose (G). Inflammation was induced with lipopolysaccharide (LPS) in RAW 264.7 macrophage. The contents of phenolic compounds, caffeine, and other physicochemical parameters were evaluated. To the best of our knowledge, this is the first study providing information on the bioactive profile and on the potential biological effects of coffee cascara kombucha. Fermentation caused the release of bound phenolic compounds from the infusions, especially total chlorogenic acids, with an average increase from 5.4 to 10.7 mg/100 mL (98%) and 2.6-3.4 mg/100 mL (30%) in coffee cascara and black tea kombucha, respectively, up to day 9. All evaluated beverages reduced (p < 0.0001) similarly the intracellular ROS (41% reduction, on average) and uric acid (10-55%) concentrations in HK-2 model cells, reversing the induced oxidative stress. All beverages also reduced (p < 0.0001, 81-90%) NO formation in LPS-induced macrophages, exhibiting an anti-inflammatory effect. These potential health benefits may be mostly attributed to polyphenols and caffeine, whose contents were comparable in all beverages. Coffee cascara showed similar potential to C. sinensis to produce healthy beverages and support sustainable coffee production.

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.

Ganoderma lucidum polysaccharide peptide alleviates hyperuricemia by regulating adenosine deaminase and urate transporters

Hyperuricemia (HUA) affects human health and is involved in the pathogenesis of common chronic diseases. Previous studies showed that Ganoderma lucidum extract lowered HUA in animals. However, the active ingredient and pharmacological mechanism of Ganoderma lucidum extract in the improvement of HUA are unknown. The purpose of this study was to determine the anti-HUA efficacy and related mechanism of Ganoderma lucidum polysaccharide peptide (GLPP) using a potassium oxonate (PO)-induced mouse model and an adenosine-induced cell model. The experimental results showed that blood uric acid (UA) was decreased up to 40.6% by GLPP in HUA mice in a dose-dependent manner. Additionally, GLPP significantly reduced UA production by inhibiting the hepatic and blood adenosine deaminase (ADA) activity and increased UA excretion by decreasing the expression of glucose transporter 9 (GLUT9) and increasing the expression of organic anion transporter 1 (OAT1) in kidney. The adenosine-induced cell model showed that the inhibitory effect of GLPP on ADA activity may be the main reason for the alleviation of HUA by GLPP. Furthermore, PO-induced renal histopathological damage was also alleviated by GLPP in a dose-dependent manner. The experimental results in this study indicated that GLPP exerted anti-HUA effects via regulating the UA production and excretion, suggesting that GLPP could be developed into a therapeutic agent for HUA.

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.

Comparison of 3 hyperuricemia mouse models and evaluation of food-derived anti-hyperuricemia compound with spontaneous hyperuricemia mouse model

Hyperuricemia animal models have long been used for evaluating food-derived anti-hyperuricemia compounds. Fructose and potassium oxonate are commonly used for developing hyperuricemia mouse model. Recent research also developed spontaneous hyperuricemia model by uricase knockout (Uox^-/-). In this work, we evaluated 3 kinds of models with the same gene background to illustrate the differences between the treatments. Unlike the uric acid levels in potassium oxonate (224.79 ± 33.62 μmol/L) and Uox^-/- groups (458.39 ± 38.29 μmol/L), fructose treatment did not lead to higher serum uric acid level (174.93 ± 30.46 μmol/L) comparing to the control group (153.53 ± 40.96 μmol/L). However, abnormal glycometabolism only developed in the fructose and the Uox^-/- group. In addition, anemia, inflammasome and severe renal injury occurred in the Uox^-/- group. The Uox^-/- mice were then treated with puerarin and allopurinol, and found that puerarin could reduce serum uric acid and alleviated the serious renal damage associated with high uric acid. Thus, the Uox^-/- mice could be a suitable model for screening and evaluating anti-hyperuricemia compounds.

Therapeutic effects and mechanisms of N-(9,10-anthraquinone-2-ylcarbonyl) xanthine oxidase inhibitors on hyperuricemia

Objective: To observe the antioxidative effects of N-(9,10-anthraquinone-2-ylcarbonyl) xanthine oxidase inhibitors (NAY) in vitro and in vivo models of hyperuricemia and explore the mechanism.

Methods: A classical experimental method of acute toxicity and a chronic toxicity test were used to compare the toxic effects of different doses of NAY in mice. The hyperuricemia mouse model was established by gavage of potassium oxonate in vivo. After treatment with different doses of NAY (low dose: 10 mg/kg, medium dose: 20 mg/kg, and high dose: 40 mg/kg) and allopurinol (positive drug, 10 mg/kg), observe the levels of uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) in urine and serum, respectively, and detect the activities of xanthine oxidase in the liver. The hyperuricemia cell model was induced by adenosine and xanthine oxidase in vitro. The cells were given different doses of NAY (50, 100, and 200 μmol/L) and allopurinol (100 μmol/L). Then the culture supernatant UA level of the medium was measured. The next step was to detect the xanthine oxidase activity in the liver and AML12 cells, and the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), and NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammatory factors in the kidney and serum of mice. Western blot was used to detect xanthine oxidase protein expression in mouse liver tissue and AML12 cells, ASC, Caspase-1, NLRP3, GLUT9, OAT1, and OAT3 protein expression in mouse kidney tissue and HK-2 cells. Hematoxylin–eosin staining was used to stain the liver and kidney tissues of mice and observe the tissue lesions.

Results: NAY had little effect on blood routine and biochemical indexes of mice, but significantly reduced the serum UA level. NAY significantly reduced the level of UA in hyperuricemia mice and cells by inhibiting xanthine oxidase activity and reduced the levels of TNF-α, IL-6, and other inflammatory factors in serum and kidney of mice. NAY can inhibit inflammation by inhibiting the NLRP3 pathway. In addition, NAY can downregulate GLUT9 protein expression and upregulate OAT1 and OAT3 protein expression to reduce the UA level by promoting UA excretion and inhibiting UA reabsorption.

Conclusion: These findings suggested that NAY produced dual hypouricemic actions. On the one hand, it can inhibit the formation of UA by inhibiting xanthine oxidase inhibitors activity, and on the other hand, it can promote the excretion of UA by regulating the UA transporter. It provides new ideas for the development of hyperuricemia drugs in the future.

Tea and its components reduce the production of uric acid by inhibiting xanthine oxidase

Background

The health benefits of tea are as diverse including the reduction of uric acid levels. Xanthine oxidase is the most directly mediated enzyme in the production of uric acid.

Objective

To explore the inhibitory effects of different teas and its main bioactive components on the production of uric acid.

Design

Experimental study. The experiments were conducted in vitro using human immortalized normal liver cell line HL-7702 (L-02).

Results

The inhibition of the xanthine oxidase activities and the expression level of xanthine dehydrogenase mRNA stimulated in the hyperuric hepatocyte cell model showed that the unfermented green tea and th1e lightly fermented yellow tea, white tea, and oolong tea significantly stronger than the highly fermented black tea and dark tea. The main bioactive compound, gallic acid, showed the strongest inhibitory effect on uric acid production, followed by tea polyphenols and theaflavins.

Discussion

All teas exhibited significant inhibition of xanthine oxidase activities, and the degree of fermentation of tea may be inversely proportional to its ability to inhibit the production of uric acid. Compared with tea polyphenols rich in tea, gallic acid may be a more potential uric acid-lowering component.

Conclusion

In this article, we first compared the effects of six traditional Chinese tea made from a single variety in stabilizing the synthesis of uric acid and found that the lighter the fermentation, the greater the potential for inhibiting the production of uric acid. Furthermore, we analyzed the inhibitory effects of its main biochemical active ingredients and found that the inhibitory effects of polyphenols rich in lightly fermented tea were significantly stronger than caffeine rich in highly fermented tea. Our findings will be helpful for people to choose a proper tea for alleviating hyperuricemia and provide a scientific basis for uric acid-lowering tea processing.

Novel anti-hyperuricemic hexapeptides derived from Apostichopus japonicus hydrolysate and their modulation effects on the gut microbiota and host microRNA profile

Hyperuricemia (HUA) is the second most common metabolic disease nowadays, and is characterized by permanently increased concentrations of serum uric acid. In this study, two novel hexapeptides (GPAGPR and GPSGRP) were identified from Apostichopus japonicus hydrolysate and predicted to have xanthine oxidase (XOD) inhibitory activity by molecular docking. Their in vitro XOD inhibition rates reached 37.3% and 48.6%, respectively, at a concentration of 40 mg mL^-1. Subsequently, in vivo experiments were carried out in a HUA mouse model, and we found that both peptides reduced the serum uric acid by inhibiting uric acid biosynthesis and reabsorption, as well as alleviated renal inflammation via suppressing the activation of the NLRP3 inflammasome. 16S rDNA sequencing indicated that both peptide treatments reduced the richness and diversity of the gut microbiota, altered the composition in the phylum and genus levels, but different change trends were observed in the phylum Verrucomicrobia and genera Akkermansia, Dubosiella, Alloprevotella, Clostridium unclassified and Alistipes. In addition, changes in the renal microRNA (miRNA) profiles induced by GPSGRP treatment were analyzed; 21 differentially expressed (DE) miRNAs were identified among groups, and KEGG pathway analysis indicated that their potential target genes were involved in pluripotency of stem cell regulation, mTOR signaling pathway and proteoglycans. Moreover, ten miRNAs involved in the HUA onset and alleviation were identified, which showed a high correlation with genera related to the metabolism of short-chain fatty acids, bile acids and tryptophan. This study delineated two hexapeptides as potential microbiota modulators and miRNA regulators that can ameliorate HUA.

Effect on purine releasement of Lentinus edodes by different food processing techniques

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Freeze-drying could notably decrease the purine release from lentinus edodes.

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Roast-drying reduced guanine and adenine levels in lentinus edodes.

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Roast-drying raised the level of strong uricogenic purine hypoxanthine in lentinus edodes.

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The total purine content was higher than that of raw LE after moist heating.

Lentinus edodes (LE) is very popular in the world and also considered as high purine food. However, few focuses on purine types and its change during food processing. Here, we first compared 3 drying techniques, including roast-drying, freeze-drying, sun-drying on purine contents of LE by using acidolysis and HPLC. It showed that adenine decreased significantly after roast-drying (120 °C), which may be caused by thermal damage of DNA. Total purine decreased significantly after freeze-drying, while roast-dried and sun-dried LE remained unchanged. The effect of moist heat (boiling) on LE purine were also evaluated. Total purine increased due to xanthine increasement (331.72 ± 50.07%). And purine contents transferred into boiled liquid was higher than that in boiled solid. Compared with sun-dry and roast-dry processing, freeze-drying could notably affect the purine release from LE and decrease purine contents. Therefore, freeze-drying is recommended for process techniques for hyperuricemia and gouts populations.

Xanthine oxidase targeted model setup and its application for antihyperuricemic compounds prediction by <i>in silico</i> methods

To achieve potential alternatives for hyperuricemia therapeutics, a novel structure-docking energy relationship model was established for high-throughput screening inhibitors of xanthine oxidase (XO). Molecular docking was performed between XO and 311 natural compounds from 6 traditional Chinese herbs. Then, structure-docking energy relationship model was simulated between molecular docking energy and 63 molecular descriptors by multiple linear regressions (MLR), principal component regression (PCR), and artificial neural network (ANN), respectively. The results showed that the ANN model was the best model to predict the docking energy of XO with the coefficient of determination (R2) and mean squared error (MSE) at 0.8746 and 0.9414, respectively. The data of XO inhibitory activity were consistent with the prediction in vitro, which was also further confirmed by hyperuricemia cell model. The results suggested that the structure-docking energy relationship model provides a paradigm framework for the screening of XO inhibitors.

Establishment of a 3D hyperuricemia model based on cultured human liver organoids

Hyperuricemia (HUA) is a metabolic disorder caused by abnormal purine metabolism, the prevalence of which has increased worldwide. Here, a 3D organoid culture system for mimicking HUA in vitro was established using cultured human liver organoids. Liver organoids can be generated from single hepatocytes and passaged for several months, retaining key morphological features, functional purine metabolism and global gene expression profile. Furthermore, organoids can be differentiated into hepatocytes with high expression of maturation markers including the hepatocyte nuclear factor-4-alpha (HNF4α), E-cadherin (E-Ca), and albumin (ALB). Importantly, organoids can produce high level of uric acid after xanthine induction which is the substrate of xanthine oxidase. Furthermore, the preclinical application potential of this organoid model was verified by measuring the antihyperuricemic effect of the widely used allopurinol, as well as the reported bioactive substance puerarin. The results demonstrate that this novel organoid model could be used for high-throughput screening of both chemical and food-derived compounds with antihyperuricemic bioactivity.

Systematic investigation of the amino acid profiles that are correlated with xanthine oxidase inhibitory activity: Effects, mechanism and applications in protein source screening

This study aimed to investigate the dipeptide amino acid profiles correlated with xanthine oxidase (XOD) inhibitory activity and guide screening to determine suitable sources for XOD inhibitor protein hydrolysate preparation. The XOD inhibitory activities of 400 dipeptides were predicted via molecular docking and measured in vitro, and amino acids containing aromatic structures and charged residues were correlated with high XOD inhibitory properties. Subsequently, the effects of Cys-Glu and Lys-Glu, which showed the highest in vitro activities, were examined in hyperuricaemic mice, and were found to alleviate hyperuricaemia and modulate the gut microbiota. Furthermore, a suitable protein from Oreochromis mossambicus with high contents of charged (8.6%) and aromatic (1.67%) amino acids was screened, and the in vitro inhibitory rates of protein hydrolysate prepared from O. mossambicus against XOD were found to be 21.90% and 44.51% at 40 and 100 mg/ml, respectively. This study provides a strategy for screening protein hydrolysate sources with certain activities based on amino acid profiles.

Culture and establishment of self-renewing human liver 3D organoids with high uric acid for screening antihyperuricemic functional compounds

Hyperuricemia (HUA) is a metabolic disease caused by disorders of purine metabolism, the prevalence of which has increased worldwide. At present, most drugs aimed at lowering uric acid have toxic side effects, and in vitro screening of uric acid-lowering active substances are inefficient. Here, a long-term 3D human liver organoid culture system with high uric acid for screening and evaluating the efficacy of uric acid-lowering functional compounds. This liver organoids can be established from single hepatocytes and grown for multiple months, while retaining key morphological and functional features. Furthermore, establishment of HUA organoids model was verified by antihyperuricemic drugs allopurinol, as well as reported bioactive peptides, which significantly reduced uric acid production in the liver organoids (p < 0.05). The results demonstrated that it has the potential to be used as a rapid and valid in vitro model to screen antihyperuricemic compounds that mimics in vivo cell growth patterns.

Pharmacological Basis for Use of a Novel Compound in Hyperuricemia: Anti-Hyperuricemic and Anti-Inflammatory Effects

Background: The prevalence of hyperuricemia is considered high worldwide. Hyperuricemia occurs due to decreased excretion of uric acid, increased synthesis of uric acid, or a combination of both mechanisms. There is growing evidence that hyperuricemia is associated with a decline of renal function. Purpose: This study is aimed at investigating the effects of the novel compound on lowering the serum uric acid level and alleviating renal inflammation induced by high uric acid in hyperuricemic mice. Methods: Hyperuricemic mice model was induced by potassium oxonate and used to evaluate the effects of the novel compound named FxUD. Enzyme-linked immunosorbent assay was used to detect the related biochemical markers. Hematoxylin-eosin (HE) staining was applied to observe pathological changes. The mRNA expression levels were tested by qRT-PCR. The protein levels were determined by Western blot. In parallel, human proximal renal tubular epithelial cells (HK-2) derived from normal kidney was used to further validate the anti-inflammatory effects in vitro. Results: FxUD administration significantly decreased serum uric acid levels, restored the kidney function parameters, and improved the renal pathological injury. Meanwhile, treatment with FxUD effectively inhibited serum and liver xanthine oxidase (XOD) levels. Reversed expression alterations of renal inflammatory cytokines, urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) were observed in hyperuricemic mice. Western blot results illustrated FxUD down-regulated protein levels of inflammasome components. Further studies showed that FxUD inhibited the activation of NF-κB signaling pathway in the kidney of hyperuricemic mice. In parallel, the anti-inflammatory effect of FxUD was also confirmed in HK-2. Conclusion: Our study reveals that FxUD exhibits the anti-hyperuricemic and anti-inflammatory effects through regulating hepatic XOD and renal urate reabsorption transporters, and suppressing NF-κB/NLRP3 pathway in hyperuricemia. The results provide the evidence that FxUD may be potential for the treatment of hyperuricemia with kidney inflammation.

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.