The Effect of Xanthine Oxidase Inhibitors on Blood Pressure and Renal Function

Purine xanthine oxidase inhibitors are not conducive to the prognosis of chronic heart failure: a meta-analysis

BACKGROUND

According to previous studies, the efficacy of xanthine oxidase inhibitors (XOIs) in patients with chronic heart failure (CHF) is still controversial. Therefore, the purpose of this study was to investigate the efficacy of XOIs in patients with CHF.

METHODS

Up to July 2024, we searched PubMed, EMBASE, Medline, Web of Science, and Cochrane Library for studies on the efficacy of XOI in patients with CHF. The main results included all-cause mortality, cardiovascular (CV) mortality, and heart failure (HF) hospitalization rates. The results were evaluated by hazard ratio (HR) and 95% confidence interval (95% CI).

RESULTS

A total of eight studies were included in this meta-analysis, of which five were cohort studies and three were randomized controlled trials (RCTs). The total sample size was 301,345. The experimental group was exposed to allopurinol or hydroxypurinol. The all-cause mortality (HR = 1.26, 95% CI 1.05-1.51, p = 0.013) and CV mortality (HR = 1.58, 95% CI 1.17-2.14, p = 0.03) in the experimental group were higher than those in the control group. In terms of HF hospitalization, there was no difference between both groups (HR = 1.21, p = 0.292). Subgroup analysis showed that the CV hospitalization rate of the experimental group was higher than that of the control group, regardless of frequency and dose levels. The all-cause mortality in the low-dose group was higher than that in the control group (HR = 1.39, p = 0.033). The CV mortality of the low-dose group (HR = 1.55, p = 0.006) and the prevalent group (HR = 1.50, p = 0.042) was higher than that of the control group.

CONCLUSION

Purine XOI exposure may be unfavorable for the prognosis of CHF patients and is affected by the frequency and dose of use.

Repurposing the familiar: Future treatment options against chronic kidney disease

OBJECTIVES

Chronic kidney disease (CKD) is a serious health issue with rising morbidity and mortality rates. Despite advances in understanding its pathophysiology, effective therapeutic options are limited, necessitating innovative treatment approaches. Also, current frontline treatments that are available against CKD are not uniformly effective and often come with significant side effects. Therefore, identifying new therapeutic targets or improving existing treatments for CKD is crucial. Drug repurposing is a promising strategy in the drug discovery process that involves screening existing approved drugs for new therapeutic applications.

KEY FINDINGS

This review discusses the pharmacological mechanisms and clinical evidence that support the efficacy of these repurposed drugs. Various drugs classes such as inodilators, endothelin-1 type A (ET-1A) receptor antagonists, bisphosphonates, mineralocorticoid receptor (MR) antagonists, DNA demethylating agents, nuclear factor erythroid 2-related factor 2 (NRF2) activators, P2X7 inhibitors, autophagy modulators, hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHI) are discussed that could remarkably contribute against CKD.

SUMMARY

The review critically examines the potential for repurposing well-established drugs to slow the progression of CKD and enhance patient outcomes. This review emphasizes the importance of a multidisciplinary approach in advancing the field of drug repurposing, ultimately paving the way for innovative and effective therapies for patients suffering from CKD.

Serum Albumin and Uric Acid Levels in Hypertensive Patients: A Cross-Sectional Analysis From Central Tamil Nadu, South India

Introduction Hypertension represents a significant global health challenge, with an increasing incidence among adults. Despite the prominence of infectious diseases, non-communicable conditions like hypertension remain a silent yet critical health concern. Liver and kidney functions play crucial roles in blood pressure maintenance, with serum albumin and uric acid serving as key metabolic indicators. Objective The primary objective of this study is to analyze the association between serum albumin and uric acid levels in hypertensive patients aged 30-50 years. The secondary objective is to determine whether deranged serum albumin and uric acid levels are associated with other variables like body mass index and blood pressure values. Methods An analytical cross-sectional study was conducted between September and October 2021 at a hospital in Perambalur, Tamil Nadu, India. The study employed non-probability convenient sampling to recruit hypertensive patients aged 30-50 years. Participants with coronary artery disease, stroke, liver disease, renal failure, hyperuricemia, gout, diabetes mellitus, or taking medications that affect albumin or uric acid levels were excluded. Blood pressure measurements were taken after ensuring adequate rest, and 4 ml of venous blood was collected from each participant for biochemical analysis. Serum albumin and uric acid levels were determined using the analyzer. The data analysis was performed using Microsoft Excel and statistical software. The statistical significance of the findings was evaluated using appropriate statistical tests, providing a robust framework for understanding the metabolic associations in hypertension. Results The study population of 150 hypertensive patients demonstrated a majority of 88 (58.67%) aged over 40 years and 62 (41.33%) under 40 years. The gender distribution revealed 87 (58%) males and 63 (42% females). The mean systolic blood pressure was 158.2 mmHg, with a mean diastolic blood pressure of 94.73 mmHg, indicating moderate to severe hypertension. Biochemical analysis showed an average serum uric acid level of 6.41 mg/dL and a mean serum albumin level of 3.54 mg/dL. Statistical analysis revealed a significant association between elevated uric acid levels and decreased serum albumin levels (p < 0.05), suggesting a potential interrelationship between these metabolic markers in hypertensive patients. Conclusion The study establishes hyperuricemia and hypoalbuminemia as significant risk factors for hypertension development or pathogenesis. Early detection of these metabolic derangements may provide opportunities for preventive interventions and potential disease management strategies. The findings emphasize the importance of comprehensive biochemical assessment in understanding and mitigating hypertension risk.

From Patents to Progress: Unraveling Gout's Journey Through Clinical Trials and Advancements

Gout, an inflammatory arthritis form, is renowned for its historical association with affluence. This review delves into its pathophysiology, exploring hyperuricemia, urate crystal formation, and the ensuing inflammatory response. The epidemiology of gout is examined, focusing on its rising prevalence and impact on public health. In this study, progress in gout management is discussed, involving pharmacological interventions, dietary changes, and emerging therapies. Genetic predisposition and triggers like alcohol, temperature, and diet are highlighted in this study. Prevention strategies, including serum urate-lowering therapy and lifestyle modifications, aim to reduce recurrent flares and complications. The inflammatory response in acute gout attacks is elucidated, involving immune cells, cytokines, and the NLRP3 inflammasome. Chronic gout manifestations, such as gouty tophus formation, are explored for their destructive impact on surrounding tissues. Recent advancements in gout treatment, including nanotherapies and novel compounds, are discussed, along with promising urate-lowering drugs. Cutting-edge research on zinc ferrite nanoparticles, dimethyl fumarate, and myricetin/nobiletin hybrids addresses oxidative stress and inflammation in gout. Additionally, the potential therapeutic role of methanolic leaf extract of Euphorbia milii and tip-loaded CLC-Soluplus® MAPs is explored as natural and transdermal alternatives for gout management. The review also covers the development status of new urate-lowering drugs, providing insights into promising candidates and their mechanisms. Patents on gout and recent diagnostic advancements using techniques like laser confocal micro Raman spectrometer, FTIR, and THz-TDS offer a more accurate approach for gout stone analysis, enabling early detection and targeted treatment.

Management of hypertension addressing hyperuricaemia: introduction of nano-based approaches

Uric acid (UA) levels in blood serum have been associated with hypertension, indicating a potential causal relationship between high serum UA levels and the progression of hypertension. Therefore, the reduction of serum UA level is considered a potential strategy for lowering and mitigating blood pressure. If an individual is at risk of developing or already manifesting elevated blood pressure, this intervention could be an integral part of a comprehensive treatment plan. By addressing hyperuricaemia, practitioners may subsidize the optimization of blood pressure regulation, which illustrates the importance of addressing UA levels as a valuable strategy within the broader context of hypertension management. In this analysis, we outlined the operational principles of effective xanthine oxidase inhibitors for the treatment of hyperuricaemia and hypertension, along with an exploration of the contribution of nanotechnology to this field.

Effect of blueberry intervention on endothelial function: a systematic review and meta-analysis

Introduction: Endothelial dysfunction indicates blood vessel injury and is a risk factor for cardiovascular diseases. Blueberry has been approved for its benefits on human health, especially on cardiovascular function. However, its effect on endothelial function remains unclear. We conducted a systematic review and meta-analysis to explore the impact of blueberries on endothelial function in adults. Methods: We searched PubMed, Web of Science, Embase, and the Cochrane Library, 16 studies were included in the systematic review, and 11 were used for the meta-analysis. Data associated with endothelial function were extracted and pooled as mean differences (MD) with 95% confidence intervals (CI). Results: Blueberry consumption significantly improved flow-mediated dilation (FMD) by 1.50% (95% CI: 0.81, 2.20; I2 = 87%) and reactive hyperemia index (RHI) by 0.26 (95% CI: 0.09, 0.42; I2 = 72%). A significant decrease in diastolic blood pressure (DBP) was also observed (MD: -2.20 mm Hg; 95% CI: -4.13, -0.27; I2 = 11%). Subgroup analysis indicated a significant decrease in blood pressure (Systolic blood pressure [SBP]: -3.92 mmHg; 95% CI: -6.88, -0.97; I2 = 20% and DBP: -2.20 mmHg; 95% CI: -4.13, -0.27; I2 = 11%) in the smoking population. However, SBP levels (MD: -1.43 mm Hg; 95% CI: -3.11, 0.26; I2 = 20%) and lipid status (high-density lipoprotein cholesterol [HDL-C]: 0.06; 95% CI: -0.04, 0.16; I2 = 77%; low-density lipoprotein cholesterol [LDL-C]: 0.05; 95% CI: -0.14, 0.24; I2 = 0%) did not significantly improve. Conclusion: Blueberry intervention improved endothelial function and DBP. Subgroup analysis revealed a notable improvement in blood pressure among the smoking population. However, no significant effects were observed on SBP, HDL-C, and LDL-C levels. Future research should delve into the mechanisms of endothelial improvement and verify blood pressure reduction in specific subpopulations through large-scale trials. Clinical Trial Registration: https://www.crd.york.ac.uk/PROSPERO/, Identifier CRD42023491277.

Celebrating Versatility: Febuxostat's Multifaceted Therapeutic Application

Febuxostat, initially developed as a xanthine oxidase inhibitor to address hyperuricemia in gout patients, has evolved into a versatile therapeutic agent with multifaceted applications. This review provides a comprehensive overview of febuxostat's mechanism of action, its effectiveness in gout management, its cardiovascular safety profile, renal and hepatic effects, musculoskeletal applications, safety considerations, and emerging research prospects. Febuxostat's primary mechanism involves selective inhibition of xanthine oxidase, resulting in reduced uric acid production. Its pharmacokinetics require personalized dosing strategies based on individual characteristics. In gout management, febuxostat offers a compelling alternative, effectively lowering uric acid levels, relieving symptoms, and supporting long-term control, especially for patients intolerant to allopurinol. Recent studies have demonstrated its cardiovascular safety, and it exhibits minimal hepatotoxicity, making it suitable for those with liver comorbidities. Febuxostat's potential nephroprotective effects and kidney stone prevention properties are noteworthy, particularly for gout patients with renal concerns. Beyond gout, its anti-inflammatory properties hint at applications in musculoskeletal conditions and a broader spectrum of clinical contexts, including metabolic syndrome. Emerging research explores febuxostat's roles in cardiovascular health, neurological disorders, rheumatoid arthritis, and cancer therapy, driven by its anti-inflammatory and antioxidative properties. Future directions include personalized medicine, combination therapies, mechanistic insights, and ongoing long-term safety monitoring, collectively illuminating the promising landscape of febuxostat's multifaceted therapeutic potential.

Ten Years Milestones in Xanthine Oxidase Inhibitors Discovery: Febuxostat-Based Inhibitors Trends, Bifunctional Derivatives, and Automatized Screening Assays

Xanthine oxidase (XO) is an enzyme involved in the oxidative process of hypoxanthine and xanthine to uric acid (UA). This process also produces reactive oxygen species (ROS) as byproducts. Both UA and ROS are dangerous for human health, and some health conditions trigger upregulation of XO activity, which results in many diseases (cancer, atherosclerosis, hepatitis, gout, and others) given the worsened scenario of ROS and UA overproduction. So, XO became an attractive target to produce and discover novel selective drugs based on febuxostat, the most recent XO inhibitor out of only two approved by FDA. Under this context, high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) have been successfully applied to rapidly and easily screen for bioactive compounds, isolated or in complex natural matrixes, that act as enzyme inhibitors through the use of an immobilized enzyme reactor (IMER). This article’s goal is to present advances comprising febuxostat-based XO inhibitors as a new trend, bifunctional moieties capable of inhibiting XO and modulating ROS activity, and in-flow techniques employing an IMER in HPLC and CE to screen for synthetic and natural compounds that act as XO inhibitors.

Roles of selected non-P450 human oxidoreductase enzymes in protective and toxic effects of chemicals: review and compilation of reactions

This is an overview of the metabolic reactions of drugs, natural products, physiological compounds, and other (general) chemicals catalyzed by flavin monooxygenase (FMO), monoamine oxidase (MAO), NAD(P)H quinone oxidoreductase (NQO), and molybdenum hydroxylase enzymes (aldehyde oxidase (AOX) and xanthine oxidoreductase (XOR)), including roles as substrates, inducers, and inhibitors of the enzymes. The metabolism and bioactivation of selected examples of each group (i.e., drugs, "general chemicals," natural products, and physiological compounds) are discussed. We identified a higher fraction of bioactivation reactions for FMO enzymes compared to other enzymes, predominately involving drugs and general chemicals. With MAO enzymes, physiological compounds predominate as substrates, and some products lead to unwanted side effects or illness. AOX and XOR enzymes are molybdenum hydroxylases that catalyze the oxidation of various heteroaromatic rings and aldehydes and the reduction of a number of different functional groups. While neither of these two enzymes contributes substantially to the metabolism of currently marketed drugs, AOX has become a frequently encountered route of metabolism among drug discovery programs in the past 10-15 years. XOR has even less of a role in the metabolism of clinical drugs and preclinical drug candidates than AOX, likely due to narrower substrate specificity.

Uric Acid and Oxidative Stress-Relationship with Cardiovascular, Metabolic, and Renal Impairment

Background: The connection between uric acid (UA) and renal impairment is well known due to the urate capacity to precipitate within the tubules or extra-renal system. Emerging studies allege a new hypothesis concerning UA and renal impairment involving a pro-inflammatory status, endothelial dysfunction, and excessive activation of renin–angiotensin–aldosterone system (RAAS). Additionally, hyperuricemia associated with oxidative stress is incriminated in DNA damage, oxidations, inflammatory cytokine production, and even cell apoptosis. There is also increasing evidence regarding the association of hyperuricemia with chronic kidney disease (CKD), cardiovascular disease, and metabolic syndrome or diabetes mellitus. Conclusions: Important aspects need to be clarified regarding hyperuricemia predisposition to oxidative stress and its effects in order to initiate the proper treatment to determine the optimal maintenance of UA level, improving patients’ long-term prognosis and their quality of life.

Potential Use of Moringa oleifera Twigs Extracts as an Anti-Hyperuricemic and Anti-Microbial Source

Moringa oleifera (MO) grows throughout most of the tropics and has several industrial and medicinal uses. Besides the various uses of the plant parts such as its leaves, seed kernels, roots, or stem barks, the twigs (MT) of this plant are usually regarded as excessive parts. Although there have been few studies conducted to determine the value of this plant part, in fact, its potential uses—especially the pharmaceutical effects—of this biomaterial remains an up-to-date topic for scientists to discover due to the lack of interest so far. This study aims to identify the optimized fractions of different solvents for the extraction of antioxidants, for xanthine oxidase inhibition agents, and for anti-microbial activities. The two most active fractions obtained by column chromatography were the Hexane-Ethyl Acetate elution at a 9:1 (E1) and 8:2 (E2) ratio, respectively. With regard to antioxidant activity, E1 and E2 displayed relatively high DPPH radical scavenging capacity (IC50 = 87.7 and 99.0 µg/mL), which was only four times weaker than the control BHT (IC50 = 21.4 µg/mL). The highest inhibition activity against xanthine oxidase was also observed clearly in E1 and E2, which showed relatively low IC50 (54.7 and 42.0 µg/mL, respectively). These levels were inconsiderably higher than that of the positive control (IC50 = 20.8 µg/mL), proving that E1 and E2 exerted relatively strong antioxidant activity in terms of XOD inhibition. Regarding the antimicrobial test, E2 showed the highest inhibition activities against E. coli, K. pneumoiae, L. monocytogenes, B. subtilis, and P. mirabilis. The result indicates that (1) E1 and E2 were the strongest fractions for constraining free radical agents and several bacteria, and thus, (2) Moringa oleifera twigs are also a potential source for the prevention of gout-related symptoms.

Biomarkers of iron status in allopurinol-treated renal stone patients

Limited evidence exists on the effect of xanthine oxidase inhibitors in nephrolithiasis patients on iron status markers, beyond their effects on urate. The aim of this study was to investigate whether allopurinol therapy was associated with a significant impact on parameters related to iron status, in patients with renal stones. Allopurinol treatment was associated with a nonsignificant decline in serum uric acid. There were no significant differences in serum levels of transferrin and ferritin after treatment with allopurinol compared to pre-treatment levels. A non-significant fall in serum levels of haptoglobin was registered. The drug was associated with a significant rise in serum iron levels. Serum uric acid and iron did not show a significant correlation with any parameter in the study. Allopurinol exerted an overall non-significant effect on iron metabolism in nephrolithiasis patients, save for serum iron, this entails lack of untoward effects in populations with-iron related conditions.

Nephroprotective and anti-inflammatory potential of aqueous extract from Persea americana seeds against cadmium-induced nephrotoxicity in Wistar rats

Cadmium is a toxic metal and poses a high environmental risk to animals and humans, alike. It is thus pertinent to search for medicinal plants in protecting against cadmium toxicity. This study aims at investigating the ability of aqueous extract of Persea americana seeds (AEPA) in ameliorating the toxic effects of cadmium in the kidneys of cadmium-exposed Wistar rats. Male Wistar rats were grouped into five, of six animals each. Different groups of animals received normal saline (control group), 200 mg/kg body weight AEPA, 400 mg/kg AEPA, and standard drug, Livolin Forte, respectively. A last group of animals was left untreated. To induce toxicity, all animals, except the control group, were exposed to cadmium (200 mg/L, as CdCl₂) in their main drinking water for 21 days. Biochemical analysis of serum kidney markers, oxidative stress and antioxidant status, as well as anti-inflammatory activities, was done using standard methods and kits. In silico analysis was performed on phytochemicals reported to be abundant in AEPA. Treatment with 400 mg/kg AEPA significantly reversed (P ≤ 0.05) the adverse effect of cadmium on serum creatinine, urea, uric acid and blood urea nitrogen, and restored (P ≤ 0.05) antioxidant status, evidenced by its significant effect on superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, reduced glutathione, and lipid peroxidation activities. AEPA, at 400 mg/kg also exhibited significant anti-inflammatory effects, which was shown by reduced interleukin-2 and tumour necrosis factor α activities. Molecular docking of phytochemicals with the selected protein target also confirmed the therapeutic potential of AEPA. The study concluded that aqueous extract of AEPA protects against cadmium-induced kidney toxicity and inflammation.

Medications for gout and its comorbidities: mutual benefits?

PURPOSE OF REVIEW

To review recent literature with relevance to the management of multimorbid patients with gout, i.e., gout medication repurposed for comorbidities and vice versa.

RECENT FINDINGS

Adding to the previous success of interleukin-1 inhibition, two trials on low-dose colchicine's role in cardiovascular disease (CVD) demonstrated potential benefits in patients with or without gout. In Colchicine Cardiovascular Outcomes Trial, a composite CVD endpoint was reduced by 23% among patients who had experienced a recent myocardial infarction. In Low-Dose Colchicine 2, the composite CVD endpoint was reduced 31% among those with stable coronary artery disease. Use of urate-lowering therapy (ULT) for renal protection in patients without gout produced null results. Allopurinol did not benefit the glomerular filtration rate in two trials (Controlled trial of slowing of Kidney Disease progression From the Inhibition of Xanthine oxidase and Preventing Early Renal Function Loss) among patients with chronic kidney disease (with or without hyperuricemia, but not gout). SGLT-2 inhibitors, a medication recommended for patients with diabetes and CVD, diabetic kidney disease, or heart failure, demonstrated a protective effect against gout flares in a secondary trial analysis and a large observational study.

SUMMARY

The role of colchicine may expand beyond gout flare prevention to patients with existing CVD. The renal benefit of ULT among patients with gout remains unclear. SGLT-2 inhibitors may benefit diabetic patients who have gout as a comorbidity.

Hyperuricemia Is Not an Independent Predictor of Erectile Dysfunction

INTRODUCTION

Erectile dysfunction (ED) is strongly associated with physiological and metabolic disturbances, and hyperuricemia has been proposed to predict the onset of ED.

AIM

To investigate if hyperuricemia is an independent predictor for ED when all relevant confounding factors are taken into account.

METHODS

This is a cross-sectional study of men aged between 45 and 70 years. The population was well characterized for established cardiovascular risk factors, metabolic syndrome, as well as kidney function, depression, and socioeconomic factors. Analysis was limited to 254 men with complete data and also serum uric acid (SUA) measurements were available. This included 150 men with and 104 without ED. The presence and severity of ED was evaluated using International Index of Erectile Function-5 questionnaire. Risk of ED by SUA level was calculated using univariate and multivariable-adjusted logistic regression. Effect modification by participant characteristics were evaluated in subgroup analyses.

MAIN OUTCOME MEASURES

The main outcome measures of this study are prevalence and severity of erectile dysfunction.

RESULTS

Patients with ED (59% of the study population) were older than men without ED (59 vs 54 years) and had lower serum testosterone (14.3, 95% CI 11.3-17.3 vs 15.1 nmol/l, 95% CI 12.1-18.8, respectively). Regarding all other variables, the groups were comparable. No significant difference was found for SUA by ED. SUA was not associated with ED risk in univariate or multivariable analysis (multivariable-adjusted OR 1.14, 95% CI 0.59-2.19, P = .7) for SUA level higher than median compared with median or lesser (OR 1.00, 95% CI 0.997-1.006, P = .7 for continuous variable). No subgroup analysis modified the association. After multivariable adjustment age, education level and depression were statistically significant predictors of ED.

CONCLUSIONS

Elevated SUA was not found to be an independent risk factor for ED. Metabolic syndrome, glomerular filtration rate, or cardiovascular risk factors did not modify this result. ED cannot be predicted based on the level of SUA. A Tuokko, T Murtola, P Korhonen, et al. Hyperuricemia Is Not an Independent Predictor of Erectile Dysfunction. Sex Med 2021;9:100319.

Allopurinol and Renal Outcomes in Adults With and Without Type 2 Diabetes: A Retrospective, Population-Based Cohort Study and Propensity Score Analysis

OBJECTIVES

Elevated uric acid (UA) is common in diabetes and is implicated in the pathogenesis of chronic kidney disease (CKD). Lowering UA with allopurinol may delay CKD progression. We assessed the association between allopurinol and renal outcomes in older adults both with and without diabetes, and whether this differed by diabetes status.

METHODS

We conducted a population-based, retrospective cohort study of older adults ≥66 years of age with a gout flare using administrative data from Ontario, Canada. The primary outcome was doubling of creatinine or kidney failure. Secondary outcomes were a composite of death or kidney failure, decline in estimated glomerular filtration rate by >30%, death and kidney failure. New allopurinol users were compared with nonusers using Cox proportional hazards models and inverse probability of treatment weighting (IPTW). An interaction between allopurinol use and presence or absence of diabetes was assessed.

RESULTS

Among 5,937 older adults with a gout flare (1,911 with diabetes), 1,304 (22%) were newly treated with allopurinol. Median follow-up time was 1.11 (interquartile range, 0.33 to 3.21) years for allopurinol users and 3.38 (interquartile range, 1.42 to 4.43) years for nonusers. There was no association between allopurinol use and the primary outcome (IPTW-adjusted hazard ratio, 0.97; 95% confidence interval, 0.72 to 1.31), and this did not differ by diabetes status. Allopurinol use was not associated with any of the secondary outcomes.

CONCLUSIONS

Allopurinol use was not associated with renal outcomes in older adults with or without diabetes. This supports the interpretation of UA as a biomarker of CKD risk rather than a modifiable target for prevention or treatment of CKD.

Clinical Effects of Xanthine Oxidase Inhibitors in Hyperuricemic Patients

This review aims to critically present the available clinical evidence supporting the treatment of chronic hyperuricemia with xanthine oxidase inhibitors. For this reason, the studies published on uric acid (UA)-lowering drugs in the English language from 2000 to August 2019 have been carefully reviewed. The terms "serum uric acid," "xanthine oxidase," "allopurinol," "febuxostat," and "topiroxostat" were incorporated into an electronic search strategy, alone and in combinations, in both MEDLINE (National Library of Medicine, Bethesda, MD) and the Cochrane Register of Controlled Trials (The Cochrane Collaboration, Oxford, UK). Even if new urate-lowering drugs seem of particular efficacy for acute treatment of refractory hyperuricemia, their use is supported by relatively small clinical evidence. On the contrary, large long-term clinical trials have demonstrated that xanthine oxidase inhibitors (XOIs, namely, allopurinol and febuxostat) are effective, safe, and relatively well-tolerated in most of the patients. They have mainly been tested in the elderly, in patients affected by chronic diseases such as heart failure and cancer, and in patients taking a large number of drugs, confirming their safety profile. Recent data also show that they could exert some positive effects on vascular health, renal function, and glucose metabolism. Their cost is also low. In conclusion, XOIs remain the first choice of UA-lowering drug for chronic treatment.

Hyperuricemia as a Risk Factor for Cardiovascular Diseases

Serum uric acid level above 7 mg/dl is defined as hyperuricemia, which gives rise to the monosodium urate (MSU), causing gout and urolithiasis. Hyperuricemia is an independent risk factor as well as a marker for hypertension, heart failure, atherosclerosis, atrial fibrillation, and chronic kidney disease. MSU crystals, soluble uric acid (UA), or oxidative stress derived from xanthine oxidoreductase (XOR) might be plausible explanations for the association of cardio-renovascular diseases with hyperuricemia. In macrophages, MSU activates the Nod-like receptor family, pyrin　domain containing 3(NLRP3) inflammasome, and proteolytic processing mediated by caspase-1 with enhanced interleukin (IL)-1β and IL-18 secretion. Soluble UA accumulates intracellularly through UA transporters (UAT) in vascular and atrial myocytes, causing endothelial dysfunction ad atrial electrical remodeling. XOR generates reactive oxygen species (ROS) that lead to cardiovascular diseases. Since it remains unclear whether asymptomatic hyperuricemia could be a risk factor for cardiovascular and kidney diseases, European and American guidelines do not recommend pharmacological treatment for asymptomatic patients with cardio-renovascular diseases. The Japanese guideline, on the contrary, recommends pharmacological treatment for hyperuricemia with CKD to protect renal function, and it attaches importance of the cardio-renal interaction for the treatment of asymptomatic hyperuricemia patients with hypertension and heart failure.

Uric acid fluctuation had no effect on renal function among gout patients

BACKGROUND AND AIMS

To investigate the effects of serum uric acid (SUA) level and its fluctuation on renal dysfunction in gout patients.

METHODS AND RESULTS

Data on gout patients was collected from Huzhou city electronic medical record system data sharing platform, and information about relevant diagnoses, prescriptions, biochemical indexes and imaging characteristics was extracted. The gout patients with baseline normal renal function were enrolled in this analysis, and the estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² was defined as renal dysfunction. The generalized estimating equation and Cox regression analysis were used. A total of 1009 patients with gout were enrolled. Compared with the reference group (normal baseline SUA with endpoint SUA to be < 6 mg/dL), endpoint SUA ≥ 10 mg/dL was associated with an increased risk of renal dysfunction (baseline normal SUA group: HR [95% CI] = 3.28 [1.21, 8.91]; baseline high SUA group: HR [95% CI] = 3.01 [1.43, 6.35]). Subgroup analysis of 771 SUA stable gout patients demonstrated that SUA levels at 8-10 (excluding 10), and ≥10 mg/dL were significantly associated with an increased risk for renal dysfunction, with HR [95%CI] to be 1.99 [1.05, 3.77], and 2.98 [1.38, 6.43], respectively.

CONCLUSION

Regardless of the baseline SUA level, SUA >10 mg/dL was a significant risk factor for renal dysfunction. SUA between 6 and 10 mg/dL was a potential risk factor for renal dysfunction. No significant correlation of SUA fluctuation and renal function was found.

Febuxostat Use and Risks of Cardiovascular Disease Events, Cardiac Death, and All-cause Mortality: Metaanalysis of Randomized Controlled Trials

OBJECTIVE

To assess whether febuxostat use increases the risk of developing cardiovascular (CV) events, cardiac death, and all-cause mortalities.

METHODS

The relevant literature was searched in several databases including MEDLINE (PubMed, January 1, 1966-February 29, 2020), Web of Science, EMBASE (January 1, 1974-February 29, 2020), ClinicalTrials. gov, and Cochrane Central Register of Controlled Trials. Manual searches for references cited in the original studies and relevant review articles were also performed. All studies included in this metaanalysis were published in English.

RESULTS

In the end, 20 studies that met our inclusion criteria were included in our metaanalysis. Use of febuxostat was found not to be associated with an increased risk of all-cause mortality (RR 0.87, 95% CI 0.57-1.32, P = 0.51). Also, there was no association between febuxostat use and mortalities arising from CV diseases (CVD; RR 0.84, 95% CI 0.49-1.45, P = 0.53). The RR also revealed that febuxostat use was not associated with CVD events (RR 0.98, 95% CI 0.83-1.16, P = 0.83). Further, the likelihood of occurrence of CVD events was found not to be dependent on febuxostat dose (RR 1.04, 95% CI 0.84-1.30, P = 0.72).

CONCLUSION

Febuxostat use is not associated with increased risks of all-cause mortality, death from CVD, or CVD events. Accordingly, it is a safe drug for the treatment of gout.

A treat-to-target approach for gout confers renoprotective effect in patients with chronic kidney disease stage 3

The aim of this study was to assess changes in the estimated glomerular filtration rate (eGFR) in gouty patients with chronic kidney disease (CKD) using a "treat-to-target" (T2T) approach in gout. This multicenter observational retrospective study included patients diagnosed with gout and CKD stage 3 taking xanthine oxidase inhibitors (XOIs) (allopurinol or febuxostat) for at least 12 months. All patients were treated using a T2T strategy according to national gout guidelines to achieve the target levels of serum uric acid (sUA; < 5-6 mg/dl) within 6 months of the first visit. The primary outcome was to assess changes in eGFR. The effects of independent variables were analyzed over eGFR in a linear mixed-effects (LME) model. Fifty patients with gout and CKD stage 3 treated with XOIs with a T2T strategy for 12 months were included. Eighty-two percent of the patients achieved the sUA target during the study period. The improvement seen in eGFR was higher during the first 6 months, showing a median increase of 7.54 ml/min/m² (SE = 1.25) and trending towards stability over 12 months. For every 1 mg/dl of decrease in sUA, an improvement of 1.5 ml/min/m² in eGFR was observed (coefficient ± SE: - 1.58 ± 0.26) (p < 0.001) with no differences between type and dosage of XOIs treatment, colchicine administration, age, sex, and smoking status. A reduction in sUA levels using a T2T approach with XOIs at an optimal dose is possible and could help conserve and improve renal function in gouty patients with CKD stage 3.

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.).

Α higher ratio of serum uric acid to serum creatinine could predict the risk of total and cause specific mortality- insight from a US national survey

INTRODUCTION

The link between serum uric acid to serum creatinine ratio (SUA/SCr) and mortality has not been studied yet.

METHODS

We prospectively evaluated the association between SUA/SCr and risk of total and cause specific [cardiovascular disease (CVD) and cancer] mortality by applying on the National Health and Nutrition Examination Surveys (NHANES, 1999-2010). Vital status through December 31, 2011 was ascertained. Adjusted Cox proportional hazard regression models were performed to determine the links between SUA/SCr and mortality.

RESULTS

Overall, 20,209 individuals were included (mean age = 47.5 years, 48.9% men) and 3523 deaths occurred during the 76.4 months of follow-up. In a fully adjusted model, individuals in the fourth (Q4) and third (Q3) quartile of SUA/SCr had a 44 and 35% greater risk of total mortality [risk ratio (RR): 1.44 (95% confidence interval, 95%CI: 1.05-1.98) and 1.35 (1.10-1.66), respectively], as well as a 69 and 47% higher risk of CVD death [RR: 1.69 (1.09-2.62) and 1.47 (1.14-1.89), respectively] compared with the lowest (Q1) quartile. With regard to SUA/SCr and cancer mortality, a significant association was found only between participants in Q4 and those in Q1 [RR: 1.12 (1.06-1.19)] in the partially adjusted model, whereas this relationship became non-significant after further adjustments [RR: 1.15 (0.96-1.39)].

CONCLUSIONS

This is the first time that SUA/SCr has been associated with total and cause specific mortality in a large, representative sample of US adults. Further studies are needed to confirm these findings and establish their clinical implications.

The role of physical activity in individuals with cardiovascular risk factors: an opinion paper from Italian Society of Cardiology-Emilia Romagna-Marche and SIC-Sport

: Regular physical activity is a cornerstone in the prevention and treatment of atherosclerotic cardiovascular disease (CVD) due to its positive effects in reducing several cardiovascular risk factors. Current guidelines on CVD suggest for healthy adults to perform at least 150 min/week of moderate intensity or 75 min/week of vigorous intensity aerobic physical activity. The current review explores the effects of physical activity on some risk factors, specifically: diabetes, dyslipidemia, hypertension and hyperuricemia. Physical activity induces an improvement in insulin sensitivity and in glucose control independently of weight loss, which may further contribute to ameliorate both diabetes-associated defects. The benefits of adherence to physical activity have recently proven to extend beyond surrogate markers of metabolic syndrome and diabetes by reducing hard endpoints such as mortality. In recent years, obesity has greatly increased in all countries. Weight losses in these patients have been associated with improvements in many cardiometabolic risk factors. Strategies against obesity included caloric restriction, however greater results have been obtained with association of diet and physical activity. Similarly, the beneficial effect of training on blood pressure via its action on sympathetic activity and on other factors such as improvement of endothelial function and reduction of oxidative stress can have played a role in preventing hypertension development in active subjects. The main international guidelines on prevention of CVD suggest to encourage and to increase physical activity to improve lipid pattern, hypertension and others cardiovascular risk factor. An active action is required to the National Society of Cardiology together with the Italian Society of Sports Cardiology to improve the prescription of organized physical activity in patients with CVD and/or cardiovascular risk factors.

WITHDRAWN: Α higher ratio of serum uric acid to serum creatinine could predict the risk of total and cause specific mortality - Insight from a US national survey

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Changeover Trial of Febuxostat and Topiroxostat for Hyperuricemia with Cardiovascular Disease: Sub-Analysis for Chronic Kidney Disease (TROFEO CKD Trial)

Background: The TROFEO trial demonstrated that febuxostat causes greater and more rapid reduction of serum uric acid (s-UA) than topiroxostat. We compared these drugs in patients with chronic kidney disease (CKD) by sub-analysis of the TROFEO trial.

Methods: This sub-analysis targeted patients with an estimated glomerular filtration rate (eGFR) ≤60 mL/min/1.73 m². The primary endpoint was the s-UA level. Secondary endpoints included creatinine, eGFR, urinary albumin, cystatin-C, oxidized low-density lipoprotein (Ox-LDL), eicosapentaenoic acid/arachidonic acid ratio, lipid biomarkers, high-sensitivity C-reactive protein, and B-type natriuretic peptide (BNP).

Results: There was no significant difference of s-UA between the two groups either before or after treatment. However, s-UA did not exceed 6.0 mg/dL in febuxostat group during the study period, but it exceeded this level in seven patients from topiroxostat group, with the number being significantly higher in topiroxostat group. Serum creatinine (s-Cr) and eGFR were significantly better after 6 months of febuxostat treatment compared with topiroxostat Cystatin-C was significantly lower after 6 months of febuxostat treatment compared with topiroxostat. The Ox-LDL was significantly lower after 3 and 6 months of febuxostat treatment compared with topiroxostat.

Conclusion: Febuxostat had stronger renoprotective and antioxidant effects than topiroxostat in patients with hyperuricemia and CKD.

Hydralazine improves ischemia-induced neovasculogenesis via xanthine-oxidase inhibition in chronic renal insufficiency

Oxidative stress is related to the progression of renal diseases and modulation of oxidative stress can lead to a reduction in vascular events in patients with chronic renal insufficiency (CRI). Indoxyl sulfate (IS) and xanthine oxidase (XO) are related to impaired neovasculogenesis in CRI. Hydralazine is suggested for blood pressure control in CRI. This study aimed to investigate whether hydralazine could improve ischemia-induced neovasculogenesis in CRI animals by reducing reactive oxygen species (ROS) levels. Mice underwent subtotal nephrectomy or sham surgery. Nitrendipine, probenecid, and allopurinol were used to reduce blood pressure, uric acid (UA), and XO activity levels, respectively, for comparison. Blood pressure, XO activity and UA levels that were increased after subtotal nephrectomy were reduced by hydralazine treatment. Allopurinol decreased blood XO activity and UA levels. Only hydralazine and allopurinol increased the number of circulating endothelial progenitor cells (EPCs) and improved neovasculogenesis in CRI mice. IS activated XO mRNA and ROS and inhibited the functions of EPCs and endothelial cells, which could be reversed by hydralazine. However, no additional beneficial effects were observed when XO was inhibited with both hydralazine and siRNA. In conclusion, hydralazine, as a potential XO inhibitor, not only reduced blood pressure and UA levels but also increased the number of circulating EPCs and improved neovasculogenesis in CRI animals. Hydralazine directly inhibited IS-induced ROS and XO activation in EPCs and endothelial cells, and restored their functions in vitro. Future studies should evaluate whether hydralazine could provide additional vascular protection in patients with CRI.

Role of Nitric Oxide Carried by Hemoglobin in Cardiovascular Physiology: Developments on a Three-Gas Respiratory Cycle

A continuous supply of oxygen is essential for the survival of multicellular organisms. The understanding of how this supply is regulated in the microvasculature has evolved from viewing erythrocytes (red blood cells [RBCs]) as passive carriers of oxygen to recognizing the complex interplay between Hb (hemoglobin) and oxygen, carbon dioxide, and nitric oxide-the three-gas respiratory cycle-that insures adequate oxygen and nutrient delivery to meet local metabolic demand. In this context, it is blood flow and not blood oxygen content that is the main driver of tissue oxygenation by RBCs. Herein, we review the lines of experimentation that led to this understanding of RBC function; from the foundational understanding of allosteric regulation of oxygen binding in Hb in the stereochemical model of Perutz, to blood flow autoregulation (hypoxic vasodilation governing oxygen delivery) observed by Guyton, to current understanding that centers on S-nitrosylation of Hb (ie, S-nitrosohemoglobin; SNO-Hb) as a purveyor of oxygen-dependent vasodilatory activity. Notably, hypoxic vasodilation is recapitulated by native S-nitrosothiol (SNO)-replete RBCs and by SNO-Hb itself, whereby SNO is released from Hb and RBCs during deoxygenation, in proportion to the degree of Hb deoxygenation, to regulate vessels directly. In addition, we discuss how dysregulation of this system through genetic mutation in Hb or through disease is a common factor in oxygenation pathologies resulting from microcirculatory impairment, including sickle cell disease, ischemic heart disease, and heart failure. We then conclude by identifying potential therapeutic interventions to correct deficits in RBC-mediated vasodilation to improve oxygen delivery-steps toward effective microvasculature-targeted therapies. To the extent that diseases of the heart, lungs, and blood are associated with impaired tissue oxygenation, the development of new therapies based on the three-gas respiratory system have the potential to improve the well-being of millions of patients.

Effects of allopurinol and febuxostat on cardiovascular mortality in elderly heart failure patients

Hyperuricemia is an emerging risk factor for the development of heart failure (HF) and is associated with a worsen prognosis of the disease. The effect of urate lowering drugs (ULT) and, in particular, the xanthine oxidase inhibitor in patients with HF is controversial. The aim of the study is to compare the effects of treatment with two different xanthine oxidase inhibitors (allopurinol or febuxostat) on cardiovascular mortality in elderly patients with chronic HF in a setting of clinical practice. In this observational trial, 255 elderly patients affected by chronic HF and treated with ULT on top of optimal medical treatment for HF. The sample included only outpatients with mild-to-moderate HF mainly secondary to chronic arterial hypertension or coronary artery disease and not previously hospitalized for HF. Patient treated with febuxostat (N. 120) and allopurinol (N. 135) were balanced for most of the baseline variables. In particular age, NYHA class distribution, drug treatment and renal function were comparable at the baseline and during the observation in both groups (p > 0.05). After a mean follow-up period of 5.1 years, the cumulative cardiovascular survival was 0.96 (95% CI 0.93-0.99) in febuxostat-treated patients and 0.89 (95% CI 0.84-0.93) in those treated with allopurinol. The between group difference, adjusted for the main confounding risk factors, was statistically significant (p = 0.04). Our study results suggest that possibility that febuxostat, a selective XO inhibitor, may favorably affect cardiovascular mortality in comparison with allopurinol in elderly patients with mild-to-moderate HF. This preliminary observation deserves further evaluation in the next future.

Association between allopurinol and cardiovascular outcomes and all-cause mortality in diabetes: A retrospective, population-based cohort study

AIM

To assess the association between allopurinol and mortality and cardiovascular outcomes in an allopurinol-treated diabetes cohort.

MATERIALS AND METHODS

We conducted a population-based retrospective cohort study in Ontario, Canada. Eligible subjects were ≥ 66 years old with diabetes and a first prescription for allopurinol between 1 April, 2002 and 31 March, 2012 and were followed until 31 March, 2016. The primary outcome was a composite: all-cause mortality, non-fatal cardiovascular event (myocardial infarction, revascularization procedure, or stroke) or congestive heart failure (CHF). Secondary outcomes were components of the primary outcome and pneumonia as a negative tracer. Allopurinol was modelled as time-varying exposed versus unexposed, daily dose category and cumulative dose using sex-specific multivariable Cox proportional hazards models.

RESULTS

Over a median follow-up of 4.65 years (interquartile range 1.79-7.81), 16 266/23 103 males and 10 571/15 313 females experienced the primary outcome. Allopurinol was associated with a reduction in the primary outcome [adjusted hazard ratios (aHR) 0.77 (95% confidence interval 0.75-0.80) and 0.81 (0.78-0.84) for males and females, respectively], driven by marked reductions in all-cause mortality and modest reductions in cardiovascular events/CHF. There was no effect of cumulative allopurinol dose on any outcome, and allopurinol was also associated with reduced risk of pneumonia in males [aHR 0.88 (0.83, 0.93)].

CONCLUSIONS

Allopurinol was associated with reduced mortality and cardiovascular outcomes. However, lack of cumulative dose effect and a positive tracer outcome in males suggests residual bias. Future research assessing whether allopurinol prevents vascular complications in diabetes requires a clinical trial.

Peptides from Cauliflower By-Products, Obtained by an Efficient, Ecosustainable, and Semi-Industrial Method, Exert Protective Effects on Endothelial Function

The large amount of cauliflower industry waste represents an unexplored source of bioactive compounds. In this work, peptide hydrolysates from cauliflower leaves were characterized by combined bioanalytical approaches. Twelve peptide fractions were studied to evaluate unexplored biological activities by effect-based cellular bioassays. A potent inhibition of intracellular xanthine oxidase activity was observed in human vascular endothelial cells treated with one fraction, with an IC50 = 8.3 ± 0.6 μg/ml. A different fraction significantly induced the antioxidant enzyme superoxide dismutase 1 and decreased the tumor necrosis factor α-induced VCAM-1 expression, thus leading to a significant improvement in the viability of human vascular endothelial cells. Shotgun peptidomics and bioinformatics were used to retrieve the most probable bioactive peptide sequences. Our study shows that peptides from cauliflower waste should be recycled for producing valuable products useful for the prevention of endothelial dysfunction linked to atherogenesis progression.

Uric acid and angiotensin II additively promote inflammation and oxidative stress in human proximal tubule cells by activation of toll-like receptor 4

Renal proximal tubular cells (PTECs) participate in several mechanisms of innate immunity, express toll-like receptors (TLRs), and proinflammatory cytokines. Hyperuricemia may be a promoter of inflammation and renal damage. Angiotensin II (Ang II) modulate immune and inflammatory responses in renal tubular cells. With the aim to evaluate the effect of uric acid (UA) and Ang II on oxidative stress and inflammation mediated by toll-like receptor 4 (TLR4) activation in human PTECs, human kidney 2 (HK2) were incubated for 24 hr with UA (12 mg/dl) and Ang II (10 ^-7  M). HK2 were pretreated with an antagonist of TLR4 (TAK 242), valsartan or losartan. The genic expression of TLR4, monocyte chemoattractant protein-1 (MCP1), and Nox4 was quantified with reverse transcription polymerase chain reaction, proteins were evaluated with Western blot. The incubation of HK2 either with UA or with Ang II determines an increased expression of TLR4, production of proinflammatory cytokines as MCP1 and pro-oxidants as Nox4 ( p < 0.05). TAK 242 attenuates the expression of MCP1 induced both by UA and Ang II. Valsartan attenuated all the effects we described after exposure to Ang II but not those observed after UA exposure. At variance, pretreatment with losartan, which inhibits UA internalization, attenuates the expression of TLR4, MCP1, and Nox4 in cells previously treated with UA, Ang II, and UA plus Ang II. Proinflammatory pathways are induced in an additive manner by UA and Ang II ( p < 0.05) and might be mediated by TLR4 in PTECs. Renin-angiotensin-aldosterone system (RAAS) activation, hyperuricemia, and innate immunity interplay in the development of chronic tubular damage and the interaction of several nephrotoxic mechanisms blunt the protective effect of RAAS inhibition.

Ameliorative effect of Rutin on sodium fluoride-induced hypertension through modulation of Kim-1/NF-κB/Nrf2 signaling pathway in rats

Sodium fluoride is one of the neglected environmental contaminants. Inorganic fluorides in the environment are found in the air, water, and land. In the study, forty-male Wistar albino rats were randomly divided into four groups with 10 rats in a group. Group A was the control group which was given normal saline, Group B was exposed to 300 ppm of NaF in drinking water, while Groups C and D received NaF along Rutin (100 mg/kg and 200 mg/kg) orally daily for a week. Administration of NaF alone led to significant increases in blood pressure, and deceased serum nitric oxide. Immunohistochemistry revealed higher expressions of kidney injury molecule I (Kim-1), nuclear factor kappa beta (NF-κB), and down regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) in rats administered NaF. Rutin co-treatment with NaF normalized blood pressure, lowered Kim-1 and NF-κB expressions, and improved nitric oxide bioavailability.

Production Inhibition and Excretion Promotion of Urate by Fucoidan from Laminaria japonica in Adenine-Induced Hyperuricemic Mice

This work aims to explore the amelioration of fucoidan on adenine-induced hyperuricemia and hepatorental damage. Adenine-induced hyperuricemic mice were administered with fucoidan, allopurinol and vehicle control respectively to compare the effects of the drugs. Serum uric acid, urea nitrogen, hepatorenal functions, activities of hepatic adenosine deaminase (ADA), xanthine oxidase (XOD), renal urate transporter 1 (URAT1) and NF-κB p65 were assessed. As the serum uric acid, urea nitrogen, creatinine, glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) data demonstrated, the adenine not only mediated hepatorenal function disorders, but also induced hyperuricemia in mice. Meanwhile, activities of hepatic ADA and XOD were markedly augmented by adenine, and the expression of URAT1 was promoted, which was conducive to the reabsorption of urate. However, exposure to fucoidan completely reversed those adenine-induced negative alternations in mice, and the activities of hepatic ADA and XOD were recovered to the normal level. It was obvious that hepatic and renal functions were protected by fucoidan treatment. The expression of URAT1 was returned to normal, resulting in an increase of renal urate excretion and consequent healing of adenine-induced hyperuricemia in mice. Expression and activation of NF-κB p65 was promoted in kidneys of adenine treated mice, but suppressed in kidneys of mice exposed to fucoidan from Laminaria japonica or allopurinol. In conclusion, the fucoidan is a potential therapeutic agent for the treatment of hyperuricemia through dual regulatory roles on inhibition of hepatic metabolism and promotion of renal excretion of urate.

MOF based fluorescent assay of xanthine oxidase for rapid inhibitor screening with real-time kinetics monitoring

The activity assay of xanthine oxidase (XO) is of great application value in clinical diagnosis because the abnormal level of this enzyme is related to a series of pathological states. In this work, a Zr based metal-organic framework (BTB-MOF) with stable photoluminescence in pure water and buffer solution was synthesized. The examination about the fluorescent responses of this material to xanthine and its oxidation product, uric acid, showed that, although both of them affected the emission of BTB-MOF in quenching form, the efficiencies presented much difference. Taking advantage of this feature, a fluorescent method was developed for the activity assay of XO, that is, BTB-MOF was added to the enzymatic oxidation system as a sensor to transduce the proceeding of the reaction real-timely to the signal of fluorescent intensity change. Our method can work under the interference of normal biologically related species, and precisely reflect XO activity in the range of 0.2-40 U L^-1 (detection limit = 0.004 U L^-1). With consecutive fluorescence intensity scan, this assay could be applied as a high speed screening method of XO inhibitors with the testing time of 1 min. This work shows the wide potential application of MOFs in enzyme analysis.