Raising serum uric acid with a uricase inhibitor worsens PKD in rat and mouse models.

Humans are predisposed to gout because they lack uricase that converts uric acid to allantoin. Rodents have uricase, resulting in low basal serum uric acid. A uricase inhibitor raises serum uric acid in rodents. There were two aims of the study in polycystic kidney disease (PKD): 1) to determine whether increasing serum uric acid with the uricase inhibitor, oxonic acid, resulted in faster cyst growth and 2) to determine whether treatment with the xanthine oxidase inhibitor, oxypurinol, reduced the cyst growth caused by oxonic acid. Orthologous models of human PKD were used: PCK rats, a polycystic kidney and hepatic disease 1 (Pkhd1) gene model of autosomal recessive PKD (ARPKD) and Pkd1RC/RC mice, a hypomorphic Pkd1 gene model. In PCK rats and Pkd1RC/RC mice, oxonic acid resulted in a significant increase in serum uric acid, kidney weight, and cyst index. Mechanisms of increased cyst growth that were investigated were proinflammatory cytokines, the inflammasome, and crystal deposition in the kidney. Oxonic acid resulted in an increase in proinflammatory cytokines in the serum and kidney in Pkd1RC/RC mice. Oxonic acid did not cause activation of the inflammasome or uric acid crystal deposition in the kidney. In Pkd1RC/RC male and female mice analyzed together, oxypurinol decreased the oxonic acid-induced increase in cyst index. In summary, increasing serum uric acid by inhibiting uricase with oxonic acid results in an increase in kidney weight and cyst index in PCK rats and Pkd1RC/RC mice. The effect is independent of inflammasome activation or crystal deposition in the kidney.NEW & NOTEWORTHY This is the first reported study of uric acid measurements and xanthine oxidase inhibition in polycystic kidney disease (PKD) rodents. Raising serum uric acid with a uricase inhibitor resulted in increased kidney weight and cyst index in Pkd1RC/RC mice and PCK rats, elevated levels of proinflammatory cytokines in the serum and kidney in Pkd1RC/RC mice, and no uric acid crystal deposition or activation of the caspase-1 inflammasome in the kidney.

Giardia duodenalis: Flavohemoglobin is involved in drug biotransformation and resistance to albendazole.

Giardia duodenalis causes giardiasis, a major diarrheal disease in humans worldwide whose treatment relies mainly on metronidazole (MTZ) and albendazole (ABZ). The emergence of ABZ resistance in this parasite has prompted studies to elucidate the molecular mechanisms underlying this phenomenon. G. duodenalis trophozoites convert ABZ into its sulfoxide (ABZSO) and sulfone (ABZSOO) forms, despite lacking canonical enzymes involved in these processes, such as cytochrome P450s (CYP450s) and flavin-containing monooxygenases (FMOs). This study aims to identify the enzyme responsible for ABZ metabolism and its role in ABZ resistance in G. duodenalis. We first determined that the iron-containing cofactor heme induces higher mRNA expression levels of flavohemoglobin (gFlHb) in Giardia trophozoites. Molecular docking analyses predict favorable interactions of gFlHb with ABZ, ABZSO and ABZSOO. Spectral analyses of recombinant gFlHb in the presence of ABZ, ABZSO and ABZSOO showed high affinities for each of these compounds with Kd values of 22.7, 19.1 and 23.8 nM respectively. ABZ and ABZSO enhanced gFlHb NADH oxidase activity (turnover number 14.5 min-1), whereas LC-MS/MS analyses of the reaction products showed that gFlHb slowly oxygenates ABZ into ABZSO at a much lower rate (turnover number 0.01 min-1). Further spectroscopic analyses showed that ABZ is indirectly oxidized to ABZSO by superoxide generated from the NADH oxidase activity of gFlHb. In a similar manner, the superoxide-generating enzyme xanthine oxidase was able to produce ABZSO in the presence of xanthine and ABZ. Interestingly, we find that gFlHb mRNA expression is lower in albendazole-resistant clones compared to those that are sensitive to this drug. Furthermore, all albendazole-resistant clones transfected to overexpress gFlHb displayed higher susceptibility to the drug than the parent clones. Collectively these findings indicate a role for gFlHb in ABZ conversion to its sulfoxide and that gFlHb down-regulation acts as a passive pharmacokinetic mechanism of resistance in this parasite.

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.

Comparative studies of xanthine oxidase inhibitors viz. allopurinol and febuxostat against induced hyperuricaemia in a poultry model.

In this study, an attempt was made to evaluate the relative efficacy of two important anti-gout agents, viz. allopurinol and febuxostat, in the control of hyperuricaemia/gout using a poultry model. A 21-day study was conducted on 48 Vencobb-400 broiler chicks randomly divided into four groups. In one group hyperuricaemia/gout was induced by the oral administration of diclofenac (group D); in two other groups the ameliorative effect of the two drugs under study was investigated by providing both simultaneously, i.e. diclofenac and allopurinol (group DA), diclofenac and febuxostat (group DF); and the fourth group was kept un-induced and untreated as a control (group C). Both allopurinol and febuxostat inhibit xanthine oxidase enzymes, thereby reducing the production of uric acid. The birds kept on diclofenac alone exhibited the highest level of hyperuricaemia, clinical signs of gout, and overt adverse changes in the visceral organs, whereas these changes were lesser in allopurinol- and febuxostat-treated groups. Furthermore, haematological, biochemical, patho-morphological, and ultra-structural studies using transmission electron microscopy were carried out to evaluate the pathology and, thus, the ameliorative effect of allopurinol and febuxostat. The findings proved that allopurinol and febuxostat carry definite ameliorative potential as anti-hyperuricemic and anti-gout agents in poultry, which was better expressed by febuxostat compared to allopurinol.

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.

Screening, isolation, and activity evaluation of potential xanthine oxidase inhibitors in Poria Cum Radix Pini and mechanism of action in the treatment of gout disease.

Poria Cum Radix Pini is a rare medicinal fungus that contains several potential therapeutic ingredients. On this basis, a particle swarm mathematical model was used to optimize the extraction process of total triterpenes from P. Cum Radix Pini, and xanthine oxidase inhibitors were screened using affinity ultrafiltration mass spectrometry. Meanwhile, the accuracy of the ultrafiltration assay was verified by molecular docking experiments and molecular dynamics analysis, and the mechanism of action of the active compounds for the treatment of gout was analyzed by enzymatic reaction kinetics and network pharmacology. A high-speed countercurrent chromatography method combined with the consecutive injection and the economical two-phase solvent system preparation using functional activity coefficient of universal quasichemical model (UNIFAC) mathematical model was developed for increasing the yield of target compound. In addition, dehydropachymic acid and pachymic acid were used as competitive inhibitors, and 3-O-acetyl-16alpha-hydroxydehydrotrametenolic acid and dehydrotrametenolic acid were used as mixed inhibitors. Then, activity-oriented separation and purification were performed by high-speed countercurrent chromatography combined with semi-preparative high-performance liquid chromatography and the purity of the four compounds isolated was higher than 90%. It will help to provide more opportunities to discover and develop new potential therapeutic remedies from health care food resources.

Si Miao San relieves hyperuricemia by regulating intestinal flora.

This study seeks to investigate the therapeutic effects of Si Miao San (SMS) on hyperuricemia and its underlying mechanisms, particularly focusing on the role of intestinal flora. The key components of SMS were identified using high-performance liquid chromatography (HPLC). To establish a rat model of hyperuricemia, an intraperitoneal injection of potassium oxonate was performed, followed by oral administration of various concentrations of SMS. The study evaluated the status of hyperuricemia, renal pathology, xanthine oxidase (XO) activity, and intestinal flora. Utilizing HPLC, we identified five active components of SMS. Following SMS intervention, there was a significant reduction in serum levels of uric acid (UA), blood urea nitrogen, and creatinine, accompanied by an increase in urine UA levels in rats with hyperuricemia. Distinct pathological injuries were evident in the renal tissues of hyperuricemic rats, and these were partially alleviated following SMS intervention. Moreover, SMS exhibited a dose-dependent reduction in XO activity both in the serum and hepatic tissues. Notably, SMS contributed to an enhancement in the diversity of intestinal flora in hyperuricemic rats. The intervention of SMS resulted in a reduction in the abundance of certain bacterial species, including Parabacteroides johnsonii, Corynebacterium urealyticum, and Burkholderiales bacterium. This suggests that SMS may exert anti-hyperuricemia effects, potentially by modulating the composition of intestinal flora.

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.

Single substrate-functionalized molybdenum oxide nanozyme for specific colorimetric monitoring of xanthine oxidase activity.

Xanthine-functionalized molybdenum oxide nanodots (X-MoO3-x NDs) with peroxidase (POD)-like activity were developed for selective, sensitive, and facile colorimetric quantification of xanthine oxidase (XO). Xanthine functionalization can not only be favorable for the successful nanozyme preparation, but also for the specific recognition of XO as well as the simultaneous generation of hydrogen peroxide, which was subsequently transformed into hydroxyl radical to oxidize the chromogenic reagent based on the POD-like catalysis. Under the optimized conditions, the colorimetric biosensing platform was established for XO assay without addition of further substrates, showing good linearity relationship between absorbance difference (ΔA) and XO concentrations in the range 0.05-0.5 U/mL (R2 = 0.998) with a limit of detection (LOD) of 0.019 U/mL. The quantification of XO occurs in 25 min, which is superior to the previously reported and commercial XO assays. The proposed method has been successfully used in the assay of human serum samples, showing its high potential in the field of clinical monitoring.

Triazole derivatives as potential xanthine oxidase inhibitors: Design, enzyme inhibition potential, and docking studies.

Considerable ingenuity has been shown in the recent years in the discovery of novel xanthine oxidase (XO) inhibitors that fall outside the purine scaffold. The triazole nucleus has been the cornerstone for the development of many enzyme inhibitors for the clinical management of several diseases, where hyperuricemia is one of them. Here, we give a critical overview of significant research on triazole-based XO inhibitors, with respect to their design, synthesis, inhibition potential, toxicity, and docking studies, done till now. Based on these literature findings, we can expect a burst of modifications on triazole-based scaffolds in the near future by targeting XO, which will treat hyperuricemics, that is, painful conditions like gout that at present are hard to deal with.

Rapid screening, isolation, and activity evaluation of potential xanthine oxidase inhibitors in Polyporus umbellatus and mechanism of action in the treatment of gout.

INTRODUCTION: Studies show that Polyporus umbellatus has some pharmacological effects in enhancing immunity and against gout. OBJECTIVES: We aimed to establish new techniques for extraction, biological activity screening, and preparation of xanthine oxidase inhibitors (XODIs) from P. umbellatus. METHODS: First, the extraction of P. umbellatus was investigated using the back propagation (BP) neural network genetic algorithm mathematical regression model, and the extraction variables were optimised to maximise P. umbellatus yield. Second, XODIs were rapidly screened using ultrafiltration, and the change of XOD activity was tested by enzymatic reaction kinetics experiment to reflect the inhibitory effect of active compounds on XOD. Meanwhile, the potential anti-gout effects of the obtained active substances were verified using molecular docking, molecular dynamics simulations, and network pharmacology analysis. Finally, with activity screening as guide, a high-speed countercurrent chromatography (HSCCC) method combined with consecutive injection and two-phase solvent system preparation using the UNIFAC mathematical model was successfully developed for separation and purification of XODIs, and the XODIs were identified using MS and NMR. RESULTS: The results verified that polyporusterone A, polyporusterone B, ergosta-4,6,8(14),22-tetraen-3-one, and ergosta-7,22-dien-3-one of P. umbellatus exhibited high biological affinity towards XOD. Their structures have been further identified by NMR, indicating that the method is effective and applicable for rapid screening and identification of XODIs. CONCLUSION: This study provides new ideas for the search for natural XODIs active ingredients, and the study provide valuable support for the further development of functional foods with potential therapeutic benefits.

A derivative of trihydroxynaphthalenone and a pyrone metabolite from the endophytic fungus Talaromyces purpurpgenus.

A newly discovered trihydroxynaphthalenone derivative, epoxynaphthalenone (1) involving the condensation of ortho-hydroxyl groups into an epoxy structure, and a novel pyrone metabolite characterized as pyroneaceacid (2), were extracted from Talaromyces purpurpgenus, an endophytic fungus residing in Rhododendron molle. The structures of these compounds were elucidated through a comprehensive analysis of their NMR and HRESIMS data. The determination of absolute configurations was accomplished using electronic circular dichroism (ECD) calculations and CD spectra. Notably, these recently identified metabolites exhibited a moderate inhibitory activity against xanthine oxidase (XOD).

Analysis of Polyphenol Extract from Hazel Leaf and Ameliorative Efficacy and Mechanism against Hyperuricemia Zebrafish Model via Network Pharmacology and Molecular Docking.

Hazel leaf, a by-product of hazelnuts, is commonly used in traditional folk medicine in Portugal, Sweden, Iran and other regions for properties such as vascular protection, anti-bleeding, anti-edema, anti-infection, and pain relief. Based on our previous studies, the polyphenol extract from hazel leaf was identified and quantified via HPLC fingerprint. The contents of nine compounds including kaempferol, chlorogenic acid, myricetin, caffeic acid, p-coumaric acid, resveratrol, luteolin, gallic acid and ellagic acid in hazel leaf polyphenol extract (ZP) were preliminary calculated, among which kaempferol was the highest with 221.99 mg/g, followed by chlorogenic acid with 8.23 mg/g. The inhibition of ZP on α-glucosidase and xanthine oxidase activities was determined via the chemical method, and the inhibition on xanthine oxidase was better. Then, the effect of ZP on hyperuricemia zebrafish was investigated. It was found that ZP obviously reduced the levels of uric acid, xanthine oxidase, urea nitrogen and creatinine, and up-regulated the expression ofOAT1 and HPRT genes in hyperuricemia zebrafish. Finally, the targeted network pharmacological analysis and molecular docking of nine polyphenol compounds were performed to search for relevant mechanisms for alleviating hyperuricemia. These results will provide a valuable basis for the development and application of hazel leaf polyphenols as functional ingredients.

Effect of Hydroxytyrosol Derivatives of Donepezil on the Activity of Enzymes Involved in Neurodegenerative Diseases and Oxidative Damage.

Monoamine oxidase and xanthine oxidase inhibitors represent useful multi-target drugs for the prevention, attenuation, and treatment of oxidative damage and neurodegenerative disorders. Chimeric molecules, constituted by naturally derived compounds linked to drugs, represent lead compounds to be explored for the discovery of new synthetic drugs acting as enzyme inhibitors. We have previously reported that seven hydroxytyrosol-donepezil hybrid compounds play a protective role in an in vitro neuronal cell model of Alzheimer's disease. In this work, we analyzed the effects exerted by the hybrid compounds on the activity of monoamine oxidase A (MAO-A) and B (MAO-B), as well as on xanthine oxidase (XO), enzymes involved in both neurodegenerative disorders and oxidative stress. The results pointed to the identification, among the compounds tested, of selective inhibitors between the two classes of enzymes. While the 4-hydroxy-3-methoxyphenethyl 1-benzylpiperidine-4-carboxylate- (HT3) and the 4-hydroxyphenethyl 1-benzylpiperidine-4-carboxylate- donepezil derivatives (HT4) represented the best inhibitors of MAO-A, with a scarce effect on MAO-B, they were almost ineffective on XO. On the other hand, the 4,5-dihydroxy-2-nitrophenethyl 1-benzylpiperidine-4-carboxylate donepezil derivative (HT2), the least efficient MAO inhibitor, acted like the best XO inhibitor. Therefore, the differential enzymatic targets identified among the hybrid compounds synthesized enhance the possible applications of these polyphenol-donepezil hybrids in neurodegenerative disorders and oxidative stress.

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.

Liquid chromatography-tandem mass spectrometry profile and antioxidant, antimicrobial, antiproliferative, and enzyme activities of Thymus pectinatus and Thymus convolutus: in vitro and in silico approach.

BACKGROUND: The objective of this study is to investigate the antiproliferative, antioxidant, antimicrobial, and enzyme activity capacities and phytochemical compositions of Thymus pectinatus (TP), Thymus convolutus (TC), which are endemic to Türkiye. Quantitative analysis of phenolic compounds in the extracts was conducted using liquid chromatography-tandem mass spectrometry, targeting 53 phenolic compounds. RESULTS: Rosmarinic acid, quinic acid, and cynaroside were identified as the major compounds, exhibiting quantitative variation in both extracts. The extracts had a high total phenolic content, with 113.57 ± 0.58 mg gallic acid equivalents (GAE)/g extract for TP and 130.52 ± 1.05 mg GAE/g extract for TC. Furthermore, although both extracts exhibited high total flavonoid content; the TP extract (75.12 ± 1.65 mg quercitin equivalents (QE)/g extract) displayed a higher flavonoid content than the TC extract (30.24 ± 0.74 mg QE/g extract) did. The extracts had a promising antiproliferative effect on C6, HeLa, and HT29 cancer cell lines with a less cytotoxic effect (10.5-14.2%) against normal cells. Both extracts exhibited very potent inhibitory activity against the xanthine oxidase enzyme, with half-maximal inhibitory concentration values of respectively 2.07 ± 0.03 µg mL-1 and 2.76 ± 0.06 µg mL-1 and moderate activity against tyrosinase and α-glucosidase. Docking simulations proved that rosmarinic acid and cynaroside, the major components of the extracts, were the most potent inhibitors of xanthine oxidase. According to antimicrobial activity results, the TC extract exhibited moderate activity against Staphylococcus aureus, and the TP extract had strong activity against both Enterococcus faecium and S. aureus. CONCLUSION: These findings emphasize the beneficial effects of the two endemic Thymus species on human health and suggest their potential use as plant-derived bioactive agents. © 2024 Society of Chemical Industry.

Serum Urate Lowering with Allopurinol and Kidney Function in Type 1 Diabetes.

BACKGROUND: Higher serum urate levels are associated with an increased risk of diabetic kidney disease. Lowering of the serum urate level with allopurinol may slow the decrease in the glomerular filtration rate (GFR) in persons with type 1 diabetes and early-to-moderate diabetic kidney disease. METHODS: In a double-blind trial, we randomly assigned participants with type 1 diabetes, a serum urate level of at least 4.5 mg per deciliter, an estimated GFR of 40.0 to 99.9 ml per minute per 1.73 m2 of body-surface area, and evidence of diabetic kidney disease to receive allopurinol or placebo. The primary outcome was the baseline-adjusted GFR, as measured with iohexol, after 3 years plus a 2-month washout period. Secondary outcomes included the decrease in the iohexol-based GFR per year and the urinary albumin excretion rate after washout. Safety was also assessed. RESULTS: A total of 267 patients were assigned to receive allopurinol and 263 to receive placebo. The mean age was 51.1 years, the mean duration of diabetes 34.6 years, and the mean glycated hemoglobin level 8.2%. The mean baseline iohexol-based GFR was 68.7 ml per minute per 1.73 m2 in the allopurinol group and 67.3 ml per minute per 1.73 m2 in the placebo group. During the intervention period, the mean serum urate level decreased from 6.1 to 3.9 mg per deciliter with allopurinol and remained at 6.1 mg per deciliter with placebo. After washout, the between-group difference in the mean iohexol-based GFR was 0.001 ml per minute per 1.73 m2 (95% confidence interval [CI], -1.9 to 1.9; P = 0.99). The mean decrease in the iohexol-based GFR was -3.0 ml per minute per 1.73 m2 per year with allopurinol and -2.5 ml per minute per 1.73 m2 per year with placebo (between-group difference, -0.6 ml per minute per 1.73 m2 per year; 95% CI, -1.5 to 0.4). The mean urinary albumin excretion rate after washout was 40% (95% CI, 0 to 80) higher with allopurinol than with placebo. The frequency of serious adverse events was similar in the two groups. CONCLUSIONS: We found no evidence of clinically meaningful benefits of serum urate reduction with allopurinol on kidney outcomes among patients with type 1 diabetes and early-to-moderate diabetic kidney disease. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; PERL ClinicalTrials.gov number, NCT02017171.).

Effects of Allopurinol on the Progression of Chronic Kidney Disease.

BACKGROUND: Elevated serum urate levels are associated with progression of chronic kidney disease. Whether urate-lowering treatment with allopurinol can attenuate the decline of the estimated glomerular filtration rate (eGFR) in patients with chronic kidney disease who are at risk for progression is not known. METHODS: In this randomized, controlled trial, we randomly assigned adults with stage 3 or 4 chronic kidney disease and no history of gout who had a urinary albumin:creatinine ratio of 265 or higher (with albumin measured in milligrams and creatinine in grams) or an eGFR decrease of at least 3.0 ml per minute per 1.73 m2 of body-surface area in the preceding year to receive allopurinol (100 to 300 mg daily) or placebo. The primary outcome was the change in eGFR from randomization to week 104, calculated with the Chronic Kidney Disease Epidemiology Collaboration creatinine equation. RESULTS: Enrollment was stopped because of slow recruitment after 369 of 620 intended patients were randomly assigned to receive allopurinol (185 patients) or placebo (184 patients). Three patients per group withdrew immediately after randomization. The remaining 363 patients (mean eGFR, 31.7 ml per minute per 1.73 m2; median urine albumin:creatinine ratio, 716.9; mean serum urate level, 8.2 mg per deciliter) were included in the assessment of the primary outcome. The change in eGFR did not differ significantly between the allopurinol group and the placebo group (-3.33 ml per minute per 1.73 m2 per year [95% confidence interval {CI}, -4.11 to -2.55] and -3.23 ml per minute per 1.73 m2 per year [95% CI, -3.98 to -2.47], respectively; mean difference, -0.10 ml per minute per 1.73 m2 per year [95% CI, -1.18 to 0.97]; P = 0.85). Serious adverse events were reported in 84 of 182 patients (46%) in the allopurinol group and in 79 of 181 patients (44%) in the placebo group. CONCLUSIONS: In patients with chronic kidney disease and a high risk of progression, urate-lowering treatment with allopurinol did not slow the decline in eGFR as compared with placebo. (Funded by the National Health and Medical Research Council of Australia and the Health Research Council of New Zealand; CKD-FIX Australian New Zealand Clinical Trials Registry number, ACTRN12611000791932.).

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.

Inactivation of Human Aldehyde Oxidase by Small Sulfhydryl-Containing Reducing Agents.

Human aldehyde oxidase (hAOX1) is a molybdoflavoenzyme that belongs to the xanthine oxidase (XO) family. hAOX1 is involved in phase I drug metabolism, but its physiologic role is not fully understood to date, and preclinical studies consistently underestimated hAOX1 clearance. In the present work, we report an unexpected effect of the common sulfhydryl-containing reducing agents, e.g., dithiothreitol (DTT), on the activity of hAOX1 and mouse aldehyde oxidases. We demonstrate that this effect is due to the reactivity of the sulfido ligand bound at the molybdenum cofactor with the sulfhydryl groups. The sulfido ligand coordinated to the Mo atom in the XO family of enzymes plays a crucial role in the catalytic cycle and its removal results in the total inactivation of these enzymes. Because liver cytosols, S9 fractions, and hepatocytes are commonly used to screen the drug candidates for hAOX1, our study suggests that DTT treatment of these samples should be avoided, otherwise false negative results by an inactivated hAOX1 might be obtained. SIGNIFICANCE STATEMENT: This work characterizes the inactivation of human aldehyde oxidase (hAOX1) by sulfhydryl-containing agents and identifies the site of inactivation. The role of dithiothreitol in the inhibition of hAOX1 should be considered for the preparation of hAOX1-containing fractions for pharmacological studies on drug metabolism and drug clearance.