Fangyukangsuan granules ameliorate hyperuricemia and modulate gut microbiota in rats.

Hyperuricaemia (HUA) is a metabolic disorder characterised by high blood uric acid (UA) levels; moreover, HUA severity is closely related to the gut microbiota. HUA is also a risk factor for renal damage, diabetes, hypertension, and dyslipidaemia; however, current treatments are associated with detrimental side effects. Alternatively, Fangyukangsuan granules are a natural product with UA-reducing properties. To examine their efficacy in HUA, the binding of small molecules in Fangyukangsuan granules to xanthine oxidase (XOD), a key factor in UA metabolism, was investigated via molecular simulation, and the effects of oral Fangyukangsuan granule administration on serum biochemical indices and intestinal microorganisms in HUA-model rats were examined. Overall, 24 small molecules in Fangyukangsuan granules could bind to XOD. Serum UA, creatinine, blood urea nitrogen, and XOD levels were decreased in rats treated with Fangyukangsuan granules compared to those in untreated HUA-model rats. Moreover, Fangyukangsuan granules restored the intestinal microbial structure in HUA-model rats. Functional analysis of the gut microbiota revealed decreased amino acid biosynthesis and increased fermentation of pyruvate into short-chain fatty acids in Fangyukangsuan granule-treated rats. Together, these findings demonstrate that Fangyukangsuan granules have anti-hyperuricaemic and regulatory effects on the gut microbiota and may be a therapeutic candidate for HUA.

Design, synthesis, and biological evaluation of 5-(1H-indol-5-yl)isoxazole-3-carboxylic acids as novel xanthine oxidase inhibitors.

Xanthine oxidase (XO) is a key enzyme for the production of uric acid in the human body. XO inhibitors (XOIs) are clinically used for the treatment of hyperuricemia and gout, as they can effectively inhibit the production of uric acid. Previous studies indicated that both indole and isoxazole derivatives have good inhibitory effects against XO. Here, we designed and synthesized a novel series of N-5-(1H-indol-5-yl)isoxazole-3-carboxylic acids according to bioisosteric replacement and hybridization strategies. Among the obtained target compounds, compound 6c showed the best inhibitory activity against XO with an IC50 value of 0.13 µM, which was 22-fold higher than that of the classical antigout drug allopurinol (IC50 = 2.93 µM). Structure-activity relationship analysis indicated that the hydrophobic group on the nitrogen atom of the indole ring is essential for the inhibitory potencies of target compounds against XO. Enzyme kinetic studies proved that compound 6c acted as a mixed-type XOI. Molecular docking studies showed that the target compound 6c could not only retain the key interactions similar to febuxostat at the XO binding site but also generate some new interactions, such as two hydrogen bonds between the oxygen atom of the isoxazole ring and the amino acid residues Ser876 and Thr1010. These results indicated that 5-(1H-indol-5-yl)isoxazole-3-carboxylic acid might be an efficacious scaffold for designing novel XOIs and compound 6c has the potential to be used as a lead for further the development of novel anti-gout candidates.

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.

Green manufacturing of a hypoxanthine enzyme sensor for fish freshness based on modified nitrocellulose surface with chito-oligosaccharide.

Hypoxanthine (Hx), produced by adenosine triphosphate (ATP) metabolism, is a valuable indicator that determines the quality and degradation status of meat products and is also an important biochemical marker to certain diseases such as gout. The rapid emergence of paper-based enzyme biosensors has already revolutionized its on-site determination. But it is still limited by the complex patterning and fabrication, unstable enzyme and uneven coloration. This work aims to develop an eco-friendly method to construct engineered paper microfluidic, which seeks to produce reaction and non-reaction zones without any patterning procedure. Chito-oligosaccharide (COS), derived from shrimp shells, was used to modify nitrocellulose membranes and immobilize xanthine oxidase (XOD) and chromogenic agent of nitro blue tetrazolium chloride (NBT). After modification, micro fluids could converge into the modification area and Hx could be detected by XOD-catalyzed conversion. Due to the positively charged cationic basic properties of COS, the enzyme storage stability and the color homogeneity could be greatly strengthened through the electrostatic attraction between COS and XOD and formazan product. The detection limit (LOD) is 2.30 µM; the linear range is 0.05-0.35 mM; the complete test time can be as short as 5 min. The COS-based biosensor shows high specificity and can be used directly for Hx in complex samples such as fish and shrimp samples, and different broths. This biosensor is eco-friendly, nontechnical, economical and therefore a compelling platform for on-site or home-based detection of food freshness.

Elevated Serum Xanthine Oxidase and Its Correlation with Antioxidant Status in Patients with Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative movement disorder associated with a loss of dopamine neurons in the substantia nigra. The diagnosis of PD is sensitive since it shows clinical features that are common with other neurodegenerative diseases. In addition, most symptoms arise at the late stage of the disease, where most dopaminergic neurons are already damaged. Several studies reported that oxidative stress is a key modulator in the development of PD. This condition occurs due to excess reactive oxygen species (ROS) production in the cellular system and the incapability of antioxidants to neutralize it. In this study, we focused on the pathology of PD by measuring serum xanthine oxidase (XO) activity, which is an enzyme that generates ROS. Interestingly, the serum XO activity of patients with PD was markedly upregulated compared to patients with other neurological diseases (ONDs) as a control. Moreover, serum XO activity in patients with PD showed a significant correlation with the disease severity based on the Hoehn and Yahr (HY) stages. The investigation of antioxidant status also revealed that serum uric acid levels were significantly lower in the severe group (HY ≥ 3) than in the ONDs group. Together, these results suggest that XO activity may contribute to the development of PD and might potentially be a biomarker for determining disease severity in patients with PD.

AIE fluorescent nanozyme-based dual-mode biosensor for analysis of the bioactive component hypoxanthine in meat products.

The development of facile, low-cost reliable, and precise onsite assays for the bioactive component hypoxanthine (Hx) in meat products is significant for safeguarding food safety and public health. Herein, we proposed a smartphone-assissted aggregation-induced emission (AIE) fluorogen tetraphenylethene (TPE)-incorporated amorphous Fe-doped phosphotungstates (Fe-Phos@TPE) nanozyme-based ratiometric fluorescence-colorimetric dual-mode biosensor for achieving the onsite visual detection of Hx. When the Hx existed, xanthine oxidase (XOD) catalyzed Hx into H2O2 to be further catalyzed into •OH by the prominent peroxidase activity of Fe-Phos@TPE at pH = 6.5, resulting in the oxidization of nonfluorescent o-phenylenediamine (OPD, naked-eye colorless) to be yellow fluorescent emissive 2,3-diaminophenazine (DAP, naked-eye dark yellow) at 550 nm as well as the intrinsic blue fluorescence of Fe-Phos@TPE at 440 nm to be decreased via inner-filter effect (IFE) action, thereby realizing a multi-enzyme cascade catalytic reaction at near-neutral pH to overcome the traditional acidity dependence-induced time-consuming and low sensitivity troublesome.

A three-mode biosensor for hypoxanthine assay in aquatic products under various storage conditions.

Establishing a rapid and accurate method for monitoring the freshness of aquatic products is of great importance. Hypoxanthine has been considered an essential indicator of aquatic products' freshness. Here, a novel smartphone colorimetric / inductively coupled plasma mass spectrometry (ICP-MS) / photothermal three-mode sensing strategy was established for monitoring hypoxanthine. Hypoxanthine can be catalyzed by xanthine oxidase to H2O2 and uric acid, which can simultaneously degrade MnO2 nanosheets (NSs) to Mn2+. After filter-assisted separation, the smartphone and ICP-MS were performed by monitoring the color of the membrane and the Mn2+ in the filtrate. Additionally, MnO2 NSs can facilitate the oxidation of dopamine to form polydopamine nanoparticles, which exhibit strong photothermal efficiency. The approach successfully monitored the deterioration of aquatic products under various storage conditions through portable thermometers and smartphones with low limits of detection (LODs), providing a potential application for in-situ evaluation of the freshness of aquatic products.

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.

Protective effect of allicin on ischemia-reperfusion injury caused by testicular torsion-detorsion in rats.

OBJECTIVE: Testicular ischemia-reperfusion induced by testicular torsion-detorsion increases the level of reactive oxygen species, leading to testicular damage. Allicin, one of the most active ingredients in garlic, is a significant exogenous antioxidant. In the research, the efficacy of allicin in treating testicular ischemia-reperfusion injury was assessed. MATERIALS AND METHODS: The study included sixty Sprague-Dawley male rats. Three groups with 20 rats per group were created as follows: control group, testicular ischemia/reperfusion-induced group, and testicular ischemia-reperfusion plus treatment with allicin group. The control group underwent a sham operation of the left testis without other interventions. In the testicular ischemia/reperfusion-induced group, rat left testis was subjected to 720° torsion for two hours and then detorsion. In the allicin-treated group, in addition to testicular ischemia-reperfusion, 50 mg/kg of allicin was injected intraperitoneally, starting immediately following detorsion. Testicular tissue samples were obtained to measure the protein expression of xanthine oxidase, which is a major source of reactive oxygen species formation, malondialdehyde level (a reliable marker of reactive oxygen species), and testicular spermatogenic function. RESULTS: Testicular ischemia-reperfusion significantly increased the expression of xanthine oxidase and malondialdehyde levels in ipsilateral testes while reducing testicular spermatogenic function. The expression of xanthine oxidase and malondialdehyde levels were significantly lower in ipsilateral testes, whereas testicular spermatogenic function in the allicin-treated group was significantly higher compared with those in the testicular ischemia-reperfusion group. CONCLUSIONS: Our findings indicate that allicin administration improves ischemia/reperfusion-induced testicular damage by limiting reactive oxygen species generation via inhibition of xanthine oxidase expression.

Analyzing chemical composition of Sargentodoxae caulis water extract and their hypouricemia effect in hyperuricemic mice.

Hyperuricemia (HUA) is a metabolic disease characterized by the increase of serum uric acid (UA) level. Sargentodoxae Caulis (SC) is a commonly used herbal medicine for the treatment of gouty arthritis, traumatic swelling, and rheumatic arthritis in clinic. In this study, a total of fifteen compounds were identified in SC water extract using UHPLC-Q-TOF-MS/MS, including three phenolic acids, seven phenolic glycosides, four organic acids, and one lignan. Then, to study the hypouricemia effect of SC, a HUA mouse model was induced using a combination of PO, HX, and 20% yeast feed. After 14 days of treatment with the SC water extract, the levels of serum UA, creatinine (CRE), blood urea nitrogen (BUN) were reduced significantly, and the organ indexes were restored, the xanthine oxidase (XOD) activity were inhibited as well. Meanwhile, SC water extract could ameliorate the pathological status of kidneys and intestine of HUA mice. Additionally, quantitative real-time PCR (qRT-PCR) and western blotting results showed that SC water extract could increase the expression of ATP binding cassette subfamily G member 2 (ABCG2), organic cation transporter 1 (OCT1), organic anion transporter 1 (OAT1) and organic anion transporter 3 (OAT3), whereas decrease the expression of glucose transporter 9 (GLUT9). This study provided a data support for the clinical application of SC in the treatment of HUA.

Anti-gouty arthritis and anti-inflammatory effects of curcumin nanoparticles in monosodium urate crystals induced Balb/C mice.

Gout is a metabolic condition characterized by the accumulation of urate crystals in the synovial joints. These crystal depositions result in joint swelling and increased concentration of serum uric acid in blood. The commercially available drugs lower serum uric acid levels and reduce inflammation, but these standard therapies have many side effects. This study aimed to investigate anti-gout and anti-inflammatory properties of curcumin nanoparticles (CNPs). For this purpose, CNPs were prepared by dissolving curcumin into dichloromethane. Then, gout was induced by injecting monosodium urate crystals (MSU) in the ankle joint and in the intra-peritoneal cavity which caused ankle swelling and increased blood uric acid levels. CNPs in different concentrations (5, 10, and 20 ppm) and allopurinol were orally administered. The MSU crystals increased the xanthine oxidase levels both in serum and the liver. Moreover, MSU crystals increased the serum levels of interleukin 1ß, interleukin-6, tumor necrosis factor-alpha, liver function tests markers, renal function tests markers, and lipid profiles. However, the administration of CNPs decreased the levels of all these variables. CNPs increased the serum high-density lipoprotein and interleukin-10 levels. Moreover, CNPs also reduced ankle swelling significantly. Hence, the levels of xanthine oxidase, uric acid and ankle swelling were reduced significantly by oral administration of CNPs. Our findings indicate that CNPs through their anti-inflammatory properties significantly alleviate gouty arthritis. Thus, the study concluded that CNPs can be developed as an efficient anti-gout agent with minimal side effects.

Exploring the anti-gout potential of sunflower receptacles alkaloids: A computational and pharmacological analysis.

Gout, a painful condition marked by elevated uric acid levels often linked to the diet's high purine and alcohol content, finds a potential treatment target in xanthine oxidase (XO), a crucial enzyme for uric acid production. This study explores the therapeutic properties of alkaloids extracted from sunflower (Helianthus annuus L.) receptacles against gout. By leveraging computational chemistry and introducing a novel R-based clustering algorithm, "TriDimensional Hierarchical Fingerprint Clustering with Tanimoto Representative Selection (3DHFC-TRS)," we assessed 231 alkaloid molecules from sunflower receptacles. Our clustering analysis pinpointed six alkaloids with significant gout-targeting potential, particularly emphasizing the fifth cluster's XO inhibition capabilities. Through molecular docking and the BatchDTA prediction model, we identified three top compounds-2-naphthylalanine, medroxalol, and fenspiride-with the highest XO affinity. Further molecular dynamics simulations assessed their enzyme active site interactions and binding free energies, employing MM-PBSA calculations. This investigation not only highlights the discovery of promising compounds within sunflower receptacle alkaloids via LC-MS but also introduces medroxalol as a novel gout treatment candidate, showcasing the synergy of computational techniques and LC-MS in drug discovery.

Unsymmetrical thiourea derivatives: synthesis and evaluation as promising antioxidant and enzyme inhibitors.

Background: Unsymmetrical thioureas 1-20 were synthesized and then characterized by various spectroscopy techniques such as UV, IR, fast atom bombardment (FAB)-MS, high-resolution FAB-MS, 1H-NMR and 13C-NMR. Methods: Synthetic compounds 1-20 were tested for their ability for antioxidant, lipoxygenase and xanthine oxidase activities. Results: Compounds 1, 2, 9, 12 and 15 exhibited strong antioxidant potential, whereas compounds 1-3, 9, 12, 15 and 19 showed good to moderate lipoxygenase activity. Ten compounds demonstrated moderate xanthine oxidase inhibition. Conclusion: Compound 15 displayed the highest potency among the series, exhibiting good antioxidant, lipoxygenase and xanthine oxidase activities. Theoretical calculations using density functional theory and molecular docking studies supported the experimental findings, indicating the potential of the synthesized compounds as potent antioxidants, lipoxygenases and xanthine oxidase agents.

Comparative Assessment of In Vitro Xanthine Oxidase and α-Glucosidase Inhibitory Activities of Cultured Cambial Meristematic Cells, Adventitious Roots, and Field-Cultivated Ginseng.

Panax ginseng, a traditional Chinese medicine with a history spanning thousands of years, faces overexploitation and challenges related to extended growth periods. Tissue-cultured adventitious roots and stem cells are alternatives to wild and field-cultivated ginseng. In this study, we assessed the in vitro xanthine oxidase and α-glucosidase inhibitory activities of saponin extracts among cultured cambial meristematic cells (CMC), adventitious ginseng roots (AGR), and field-cultivated ginseng roots (CGR). The xanthine oxidase (XO) and α-glucosidase inhibitory activities were determined by uric acid estimation and the p-NPG method, respectively. Spectrophotometry and the Folin-Ciocalteu, aluminum nitrate, and Bradford methods were employed to ascertain the total saponins and phenolic, flavonoid, and protein contents. The calculated IC50 values for total saponin extracts against XO and α-glucosidase were 0.665, 0.844, and >1.6 mg/mL and 0.332, 0.745, and 0.042 mg/mL for AGR, CMC, CGR, respectively. Comparing the total saponin, crude protein, and total phenolic contents revealed that AGR > CMC > CGR. To the best of our knowledge, this study presents the first report on the in vitro comparison of xanthine oxidase and α-glucosidase inhibitory activities among AGR, CMC, and CGR. The findings offer valuable insights into the development of hypoglycemic and antihyperuricemic medicinal, nutraceutical, and functional products utilizing AGR and CMC.

Data mining-guided alleviation of hyperuricemia by Paeonia veitchii Lynch through inhibition of xanthine oxidase and regulation of renal urate transporters.

BACKGROUND: Hyperuricemia (HUA) is a metabolic disease characterized by a high level of uric acid (UA). The extensive historical application of traditional Chinese medicine (TCM) offers a range of herbs and prescriptions used for the treatment of HUA-related disorders. However, the core herbs in the prescriptions and their mechanisms have not been sufficiently explained. PURPOSE: Our current investigation aimed to estimate the anti-HUA effect and mechanisms of Paeonia veitchii Lynch, an herb with high use frequency identified from data mining of TCM prescriptions. METHODS: Prescriptions for HUA/gout treatment were statistically analyzed through a data mining approach to determine the common nature and use frequency of their composition herbs. The chemical constituents of Paeonia veitchii extract (PVE) were analyzed by UPLC-QTOF-MS/MS, while its UA-lowering effect was further evaluated in adenosine-induced liver cells and potassium oxonate (PO) and hypoxanthine (HX)-induced HUA mice. RESULTS: A total of 225 prescriptions involving 246 herbs were sorted out. The properties, flavors and meridians of the appearing herbs were mainly cold, bitter and liver, respectively, while their efficacy was primarily concentrated on clearing heat and dispelling wind. Further usage frequency analysis yielded the top 20 most commonly used herbs, in which PVE presented significant inhibitory activity (IC50 = 131.33 µg/ml) against xanthine oxidase (XOD), and its constituents showed strong binding with XOD in a molecular docking study and further were experimentally validated through XOD enzymatic inhibition and surface plasmon resonance (SPR). PVE (50 to 200 µg/ml) dose-dependently decreased UA levels by inhibiting XOD expression and activity in BRL 3A liver cells. In HUA mice, oral administration of PVE exhibited a significant UA-lowering effect, which was attributed to the reduction of UA production by inhibiting XOD activity and expression, as well as the enhancement of UA excretion by regulating renal urate transporters (URAT1, GLUT9, OAT1 and ABCG2). Noticeably, all doses of PVE treatment did not cause any liver injury, and displayed a renal protective effect. CONCLUSIONS: Our results first comprehensively clarified the therapeutic effect and mechanisms of PVE against HUA through suppressing UA production and promoting UA excretion with hepatic and renal protection, suggesting that PVE could be a promising UA-lowering candidate with a desirable safety profile for the treatment of HUA and prevention of gout.

Glutamine Alleviates I/R-Induced Intestinal Injury and Dysmotility Via the Downregulation of Xanthine Oxidase/Uric Acid Signaling and Lactate Generation in Wistar Rats.

INTRODUCTION: Disruption of intestinal histoarchitecture and intestinal dysmotility is critical to intestinal ischemia/reperfusion (IR) injury and xanthine oxidase (XO)/uric acid (UA) signaling and increased lactate generation have been reported to play a role. More so, glutamine treatment has been demonstrated to inhibit XO/UA signaling. However, the role of glutamine in intestinal IR injury-induced intestinal dysmotility and the associated mechanisms of action are unclear. Therefore, this study was to investigate the mechanisms underlying the role of glutamine in intestinal IR injury. METHODS: Forty male Wistar rats were acclimatized for two weeks and then randomized into four groups. The sham-operated, glutamine-treated, intestinal IR, and IR + glutamine groups. RESULTS: Glutamine therapy attenuated the IR-induced increase in intestinal weight, disruption of intestinal histoarchitecture, and intestinal dysmotility. In addition, glutamine ameliorated IR-induced intestinal oxidative stress (increased malondialdehyde, reduced glutathione and superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, and glucose-6-phosphate dehydrogenase activities), inflammation (increased TNF-α and IL-1ß), and apoptosis (increased caspase three activity). These events were accompanied by glutamine alleviation of IR-induced upregulation of intestinal nuclear factor kappa B, XO/UA, and lactate generation. CONCLUSIONS: In conclusion, XO/UA signaling and lactate levels are key factors in IR-induced intestinal injury and dysmotility, and glutamine-mediated XO/UA/lactate modulation may attenuate IR-induced intestinal injury and dysmotility.

Inhibition of Xanthine Oxidase by 4-nitrocinnamic Acid: In Vitro and In Vivo Investigations and Docking Simulations.

Background: Cinnamic acid and its derivatives have gained significant attention in recent medicinal research due to their broad spectrum of pharmacological properties. However, the effects of these compounds on xanthine oxidase (XO) have not been systematically investigated, and the inhibitory mechanism remains unclear.

Objectives: The objective of this study was to screen 18 compounds and identify the XO inhibitor with the strongest inhibitory effect. Furthermore, we aimed to study the inhibitory mechanism of the identified compound.

Methods: The effects of the inhibitors on XO were evaluated using kinetic analysis, docking simulations, and in vivo study. Among the compounds tested, 4-NA was discovered as the first XO inhibitor and exhibited the most potent inhibitory effects, with an IC50 value of 23.02 ± 0.12 µmol/L. The presence of the nitro group in 4-NA was found to be essential for enhancing XO inhibition. The kinetic study revealed that 4-NA inhibited XO in a reversible and noncompetitive manner. Moreover, fluorescence spectra analysis demonstrated that 4-NA could spontaneously form complexes with XO, referred to as 4-NA-XO complexes, with the negative values of △H and ΔS.

Results: This suggests that hydrogen bonds and van der Waals forces play crucial roles in the binding process. Molecular docking studies further supported the kinetic analysis and provided insight into the optimal binding conformation, indicating that 4-NA is located at the bottom outside the catalytic center through the formation of three hydrogen bonds. Furthermore, animal studies confirmed that the inhibitory effects of 4-NA on XO resulted in a significant reduction of serum uric acid level in hyperuricemia mice.

Conclusion: This work elucidates the mechanism of 4-NA inhibiting XO, paving the way for the development of new XO inhibitors.

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 ß-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.

Advances in xanthine biosensors and sensors: A review.

Xanthine is derived from hypoxanthine by xanthine oxidase (XOD), a flavoprotein containing molybdenum and non-haem iron, sulfur and from guanine by guanine deaminase enzyme. Xanthine is oxidized into uric acid by XOD. Xanthine is used as an indicator of fish freshness, based on the reactions in which ATP is degraded into xanthine and its quantity increases with time of fish death. Fresh fish meat is required in food industry for making high quality items. The determination of xanthine in biological fluids is also used in diagnosing and curing many diseases like renal failure, gout, xanthinuria, hyperuricemia. Various methods are available for detection of xanthine but most of them are complicated, time consuming less sensitive & specific and require expensive instrumental setup and trained person to operate. Enzyme based biosensors and non enzymic sensors overcome these disadvantages, as these are simple, rapid, specific, sensitive and easy to operate. Present review describes xanthine biosensors, which work optimally between pH 3.5-9.0, temperature 25 °C-65 °C, xanthine concentration ranging from 0.001-50 × 104 µM. These biosensors have also been used to measure xanthine concentration in beverages, urine and serum samples. Various modified electrodes have been discussed for the detection of xanthine using both enzymatic and non-enzymatic approaches in the present review.

Peptide NCTX15 derived from spider toxin gland effectively relieves hyperuricemia in mice.

Hyperuricemia is a clinical disease characterized by a continuous increase in uric acid (UA) due to purine metabolism disorder. As current drug treatments are limited, it is imperative to explore new drugs that offer better safety and efficacy. In this study, Nephila clavata toxin gland homogenates were isolated and purified by exclusion chromatography and high-performance liquid chromatography, resulting in the identification and isolation of a short peptide (NCTX15) with the sequence 'QSGHTFK'. Analysis showed that NCTX15 exhibited no cytotoxicity in mouse macrophages or toxic and hemolytic activity in mice. Notably, NCTX15 inhibited UA production by down-regulating urate transporter 1 and glucose transporter 9 and up-regulating organic anion transporter 1, thus promoting UA excretion. In addition, NCTX15 alleviated the inflammatory response and renal injury by inhibiting the expression of inflammatory factors interleukin-6, interleukin-1ß, tumor necrosis factor alpha, NLR family, pyrin domain-containing 3, and pyroptosis-related factor gasdermin D. These results indicate that NCTX15 displayed urate-lowering, anti-inflammatory, and analgesic effects. As the first urate-reducing short peptide isolated from a spider toxin gland homogenate, NCTX15 exhibits considerable potential as a novel drug molecule for anti-gout and hyperuricemia treatment.