Serum Xanthine Oxidase Activity Research Articles

A potential therapeutic agent for the treatment of hyperuricemia and gout: 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide

Uric acid, the metabolic product of purines, relies on xanthine oxidase (XOD) for production. XOD is a target for the development of drugs for hyperuricemia (HUA) and gout. Currently, treatment options remain limited for gout patients. 3, 4-Dihydroxy-5-nitrobenzaldehyde (DHNB) is a derivative of the natural product protocatechualdehyde with good biological activity. In this work, we identify a DHNB thiosemicarbazide class of compounds that targets XOD. 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazone can effectively inhibit XOD activity (IC50 value: 0.0437 μM) and exhibits a mixed inhibitory effect. In a mouse model of acute hyperuricemia, a moderate dose (10 mg/kg.w) of 3,4-dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide effectively controlled the serum uric acid content and significantly inhibited serum XOD activity. In addition, 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide showed favorable safety profiles, and mice treated with the target compound did not show any symptoms of general toxicity following a single dose of 500 mg/kg. In the allopurinol group, 50 % of the mice died. These results provide a structural framework and mechanism of XOD inhibition that may facilitate the design of hyperuricemia and gout treatments.

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

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

In vitro xanthine oxidase inhibitory and in vivo anti-hyperuricemic properties of sodium kaempferol-3'-sulfonate.

Xanthine oxidase (XO), a key enzyme in purine catabolism, catalyzes the oxidation of xanthine to uric acid in the body, but overproduction of uric acid may lead to hyperuricemia. This study aims to investigate in vitro XO inhibitory and in vivo anti-hyperuricemic properties of sodium kaempferol-3'-sulfonate (KS). The kinetic analysis indicates that KS is a reversible competitive inhibitor and has significant inhibitory effects on XO activity with an IC50 value of 0.338μM. Fluorescence spectra suggested that KS could cause fluorescence quenching and conformational changes of XO due to the formation of a KS-XO complex. Molecular docking studies demonstrated that KS interacted with several amino acid residues of XO by the π-π stacking, hydrogen bonds, and hydrophobic interactions. The inhibitory mechanism of KS on XO activity might be the insertion of KS into the active site of XO to prevent the entrance of the substrate xanthine and induce conformational changes of XO. The results carried out in hyperuricemic mice showed that KS reduced serum XO activity, serum uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) levels, as well as alleviating renal histopathological injury. These findings suggest that KS may be a new potent XO inhibitor against hyperuricemia-related diseases.

Disordered Glucose Levels Are Associated with Xanthine Oxidase Activity in Overweight Type 2 Diabetic Women.

Oxidative stress plays an important role in vascular complications observed in patients with obesity and Type 2 Diabetes (T2D). Xanthine oxidase (XO) breaks down purine nucleotides into uric acid and contributes to the production of reactive oxygen species (ROS). However, the relationship between XO activity and glucose homeostasis in T2D subjects with obesity is unclear. We hypothesized that disordered glucose levels are associated with serum XO activity in overweight women and men with T2D and without hyperuricemia. We studied serum XO activity in women and men with and without T2D. Our results show that serum XO activity was greater in T2D patients with body mass index (BMI) ≥ 25 kg/m2 than in those with BMI < 25 kg/m2 (p < 0.0001). Sex-based comparative analyses of overweight T2D patients showed that serum XO activity correlated with homeostasis model assessment of β-cell function (HOMA-β), fasting plasma glucose (FPG), and hemoglobin A1C in overweight T2D women but not in overweight T2D men. In addition, as compared to overweight T2D men, women had higher high-sensitivity C-reactive protein (hs-CRP) levels. However, overweight T2D men had higher XO activity and uric acid levels than women. Our results suggest that XO activity is higher in overweight T2D patients, especially in men, but is more sensitive to disordered glucose levels in overweight women with T2D.

Neuroprotective Effects of Dexpanthenol on Rabbit Spinal Cord Ischemia/Reperfusion Injury Model

Dexpanthenol (DXP) reportedly protects tissues against oxidative damage in various inflammation models. This study aimed to evaluate its effects on oxidative stress, inflammation, apoptosis, and neurological recovery in an experimental rabbit spinal cord ischemia/reperfusion injury (SCIRI) model. Rabbits were randomized into 5 groups of 8 animals each: group 1 (control), group 2 (ischemia), group 3 (vehicle), group 4 (methylprednisolone, 30mg/kg), and group 5 (DXP, 500mg/kg). The control group underwent laparotomy only, whereas other groups were subjected to spinal cord ischemia by aortic occlusion (just caudal to the 2 renal arteries) for 20min. After 24h, a modified Tarlov scale was employed to record neurological examination results. Malondialdehyde and caspase-3 levels and catalase and myeloperoxidase activities were analyzed in tissue and serum samples. Xanthine oxidase activity was measured in the serum. Histopathological and ultrastructural evaluations were also performed in the spinal cord. After SCIRI, serum and tissue malondialdehyde and caspase-3 levels and myeloperoxidase and serum xanthine oxidase activities were increased (P<0.05-0.001). However, serum and tissue catalase activity decreased significantly (P<0.001). DXP treatment was associated with lower malondialdehyde and caspase-3 levels and reduced myeloperoxidase and xanthine oxidase activities but increased catalase activity (P<0.05-0.001). Furthermore, DXP was associated with better histopathological, ultrastructural, and neurological outcome scores. This study was the first to evaluate antioxidant, anti-inflammatory, antiapoptotic, and neuroprotective effects of DXP on SCIRI. Further experimental and clinical investigations are warranted to confirm that DXP can be administered to treat SCIRI.

Allopurinol Lowers Serum Urate but Does Not Reduce Oxidative Stress in CKD.

Xanthine oxidase (XO) contributes to oxidative stress and vascular disease. Hyperuricemia and gout are common in patients with chronic kidney disease (CKD), a population at increased risk of vascular disease. We evaluated effects of allopurinol on serum XO activity and metabolome of CKD patients who had participated in a randomized double-blind clinical trial of allopurinol vs. placebo. XO activity was measured in participants’ serum. XO expression in venous endothelial cells was evaluated via immunofluorescence. Gas chromatography mass spectrometry (GC/MS) was utilized for metabolomics analysis. We found that in patients with stage 3 CKD and hyperuricemia, allopurinol lowered serum urate while increasing serum xanthine levels. Allopurinol, however, did not significantly suppress measured serum XO activity. Of note, baseline serum XO activity was low. Additionally, neither baseline serum XO activity nor XO protein expression were associated with measures of vascular dysfunction or with systemic or endothelial biomarkers of oxidative stress. Allopurinol affected several pathways, including pentose phosphate, pyrimidine, and tyrosine metabolism. Our findings suggest that circulating XO does not contribute to vascular disease in CKD patients. In addition to inhibition of XO activity, allopurinol was observed to impact other pathways; the implications of which require further study.

A flavonoid-rich fraction of Monolluma quadrangula inhibits xanthine oxidase and ameliorates potassium oxonate-induced hyperuricemia in rats.

Hyperuricemia represents a risk factor for the progression of chronic kidney disease. Oxidative stress and inflammation are implicated in the mechanisms underlying hyperuricemia-mediated kidney injury. Monolluma quadrangula possesses several beneficial effects; however, its effect on hyperuricemia has not been investigated. This study evaluated the renoprotective and xanthine oxidase (XO) inhibitory activity of M. quadrangula in hyperuricemic rats. Phytochemical investigation revealed the presence of six known flavonoid isolated for the first time from this species. The rats received M. quadrangula extract (MQE) and potassium oxonate (PO) for 7days. In vitro assays showed the radical scavenging and XO inhibitory activities of MQE, and in silico molecular docking revealed the inhibitory activity of the isolated flavonoids towards XO. Hyperuricemic rats showed elevated serum uric acid, creatinine, urea, and XO activity, and renal pro-inflammatory cytokines, MDA and NO, and decreased GSH, SOD, and catalase. MQE ameliorated serum uric acid, urea, creatinine, and XO activity, and renal pro-inflammatory cytokines. In addition, MQE attenuated renal oxidative stress, enhanced antioxidants, downregulated URAT-1, and GLUT-9 and upregulated OAT-1 in PO-induced rats. In conclusion, M. quadrangula attenuated hyperuricemia and kidney impairment by suppressing XO activity, oxidative stress and inflammation, and modulating urate transporters.

The Association and Mediating Biomarkers of Serum Retinol in Influencing the Development of Type 2 Diabetes: A Prospective Cohort Study in Middle-Aged and Elderly Population.

The aims of this research are to elucidate whether serum retinol is associated with type 2 diabetes and to explore the underlying mechanisms of the association in a prospective cohort study. A total of 3,526 diabetes-free participants aged 40 years or older were enrolled at baseline in 2010–2012. Multivariable logistic regression was adopted to evaluate the associations of serum retinol and dietary vitamin A (VA) intake with type 2 diabetes. Mediation analyses were used to reveal potential mediators in their associations. After a mean follow-up of 5.3 years, 280 incident cases of type 2 diabetes occurred. Serum retinol was positively associated with the incidence of type 2 diabetes. The multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for type 2 diabetes from the bottom to the top quintile of serum retinol were 1, 1.878 (1.202, 2.936), 2.110 (1.364, 3.263), 1.614 (1.027, 2.538), and 2.134 (1.377, 3.306) (p-trend = 0.009), respectively. Mediation analysis showed that increased homeostasis model assessment - insulin resistance HOMA-IR, triglycerides (TG), and serum xanthine oxidase (XO) activity could account for 8.5, 14.7, and 12.1% of the total effects of serum retinol on type 2 diabetes, respectively. Serum retinol concentration was not significantly associated with dietary VA intake (r = −0.010, p = 0.570). In addition, no significant relationship was observed between dietary VA intake and the risk of type 2 diabetes. Overall, elevated serum retinol might increase the risk of type 2 diabetes which is mainly mediated by increased insulin resistance, TG, or serum XO activity.

Cerebrolysin Amelioration of Spinal Cord Ischemia/ Reperfusion Injury in Rabbit Model.

Cerebrolysin is a well-known neuroprotective agent. This study investigated its effects on inflammation, oxidative stress, apoptosis, and neurologic recovery in the setting of spinal cord ischemia/reperfusion injury (SCIRI) in an experimental animal model. Rabbits were randomly divided into five groups: control, ischemia, vehicle, methylprednisolone (30 mg/kg), and cerebrolysin (5 ml/kg) group. The rabbits in the control group underwent laparotomy; the other groups underwent spinal cord ischemia and reperfusion injury for 20 min. Neurologic examination after 24 h was based on the Modified Tarlov scale. Myeloperoxidase activities, catalase and malondialdehyde levels, and caspase-3 concentrations were determined in serum and tissue samples. Serum xanthine oxidase levels were studied and histopathological and ultrastructural changes were examined. After SCIRI, serum and tissue myeloperoxidase activities, malondialdehyde levels, caspase-3 concentrations, and serum xanthine oxidase activities were increased (p 0.01-0.001). Catalase levels were significantly diminished (p 0.001). Cerebrolysin treatment correlated with reduced myeloperoxidase and xanthine oxidase activities, malondialdehyde levels and caspase-3 concentrations; and with increased catalase levels (p 0.001, for all). The cerebrolysin group showed improved histopathological, ultrastructural, and neurological outcomes. For the first time in the literature the current study reports anti-inflammatory, antioxidant, antiapoptotic, and neuroprotective effects of cerebrolysin in a SCIRI rabbit model.

Ellagic Acid Exerts Beneficial Effects on Hyperuricemia by Inhibiting Xanthine Oxidase and NLRP3 Inflammasome Activation.

Hyperuricemia is a metabolic disease caused by impaired uric acid (UA) metabolism. Ellagic acid (EA) is a natural small-molecule polyphenolic compound with known antioxidative and anti-inflammatory properties. Here, we evaluated the regulatory effects of EA on hyperuricemia and explored the underlying mechanisms. We found that EA is an effective xanthine oxidase (XOD) inhibitor (IC50 = 165.6 μmol/L) and superoxide anion scavenger (IC50 = 27.66 μmol/L). EA (5 and 10 μmol/L) treatment significantly and dose-dependently reduced UA levels in L-O2 cells; meanwhile, intraperitoneal EA administration (50 and 100 mg/kg) also significantly reduced serum XOD activity and UA levels in hyperuricemic mice and markedly improved their liver and kidney histopathology. EA treatment significantly reduced the degree of foot edema and inhibited the expression of NLPR3 pathway-related proteins in foot tissue of monosodium urate (MSU)-treated mice. The anti-inflammatory effect was also observed in lipopolysaccharide-stimulated RAW-264.7 cells. Furthermore, EA significantly inhibited the expressions of XOD and NLRP3 pathway-related proteins (TLR4, p-p65, caspase-1, TNF-α, and IL-18) in vitro and in vivo. Our results indicated that EA exerts ameliorative effects in experimental hyperuricemia and foot edema via regulating the NLRP3 signaling pathway and represents a promising therapeutic option for the management of hyperuricemia.

Features of disorders of uric acid metabolism in male patients with hypertension and atrial fibrillation

Abstract Background In recent decades, a significant number of epidemiological studies showed the association between asymptomatic hyperuricemia and development of arterial hypertension (HTN) and atrial fibrillation (AF). The key enzyme participating in disintegration purines to uric acid is xanthine oxidase (XO). The accumulated data suggest the existence of a direct pathophysiological role of increased level of serum uric acid (SUA) and XO activity with a risk of HTN and AF. Purpose To evaluate the features of disorders of UA metabolism in patients with HTN and AF. Materials and methods The study included male patients 27 to 65 years, with a body mass index (BMI) less than 30 kg/m2 and more than 18.5 kg/m2. All patients were investigated of the level of a SUA, hypoxanthine/xanthine, inosine/adenosine, XO enzyme activity. Depending on the presence of AF, all patients were divided into 2 groups: group 1 (n=16) patients with HTN, group 2 (n=16) patients with HTN and AF. Results Table 1 shows the indicators of purine metabolism in the compared groups. The analysis of the results demonstrates that in group 1 the smallest level of a SUA in comparison with group 2 (0.35 [0.31; 0.41] vs 0.41 [0.39; 0.40](μmol/l), p=0.003), hypoxanthine 3.02 [1.80; 5.63] vs 7.35 [4.56; 8.25](μmol/l), p=0.008; inosine 1.59 [1.25; 4.48] vs 7.41 [1.49; 17.24](μmol/l), p=0.002. An increase level of a SUA is noted in 31.2% of patients from group 1 (5 patients out of 16) and 68.7% of patients from group 2 (11 patients out of 16). As a result of Spearman's correlation analysis in the group of patients with HTN and AF, a direct correlation was found between the experience of AF and BMI (r=0.681), SBP (r=0.487); level of hypoxanthine and inosine (r=0.808) and the inverse correlation between the level of xanthine and inosine (r=−0.547), as well as the association between the level of XO and SUA (r=0.796), XO and BMI (r=0.812). In the group of patients with HTN was determined association between the level of hypoxanthine and inosine (r=0.604), xanthine and adenosine (r=0.539), inosine and adenosine (r=0.657), a direct association between the level of XO and adenosine (r=0.642), inosine (r=0.502), BMI (r=0.791). Conclusions As a result of the study of patients with isolated HTN in combination with AF at the age of 27 to 65 years and a BMI of less than 30 kg/m2 and more than 18.5 kg/m2, an increase level of SUA and intermediate metabolites of UA synthesis such as inosine and hypoxanthine is observed compared with group with isolated HTN. An increase in level of XO is associated with an increase level of SUA and BMI. In the group of patients with HTN, an increase in level of inosine is associated with an increase level of hypoxanthine, but an increased level of inosine is associated with a decrease in level of xanthine. The XO level in this group is associated with an increase in level of adenosine and inosine, BMI. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Grodno State Medical University, Grodno, Belarus Table 1. Comparative characteristics of indicators in groups 1 and 2

Dapagliflozin and xanthine oxidase inhibitors improve insulin resistance and modulate renal glucose and urate transport in metabolic syndrome.

Disturbance in glucose and uric acid metabolism is the major disorder of metabolic syndrome (MetS). The kidneys play an important role in the management of glucose and uric acid. The aim of our study was to investigate alterations in renal glucose and uric acid transporters in animals with MetS after treatment with dapagliflozin and xanthine oxidase inhibitors (allopurinol and febuxostat). Sprague-Dawley rats were fed normal chow or a high fructose diet for the first 3months. The fructose-fed animals were then treated with dapagliflozin, allopurinol, febuxostat, or no treatment for the next 3months. Fasting glucose, insulin resistance, and hyperuricaemia were improved in all treatment groups except that in the fructose group (all p<0.05). Both allopurinol and febuxostat reversed the increase in levels of sodium glucose cotransporter (SGLT) 1, SGLT2, and glucose transporter (GLUT) 2 (all p<0.05). Dapagliflozin alleviated hyperuricaemia and induced uricosuria without affecting serum xanthine oxidase activity. Dapagliflozin suppressed the expression of GLUT9, urate transporter, and urate anion exchanger 1 (all p<0.05), which was similar to the effects of allopurinol and febuxostat. The results suggest that treatment with dapagliflozin and xanthine oxidase inhibitors improved insulin resistance and reversed the increased expression of glucose and urate transporters in the kidney.

Plumbagin can potently enhance the activity of xanthine oxidase: in vitro, in vivo and in silico studies

BackgroundAbnormally elevated xanthine oxidase (XO) activity has been verified to cause various pathological processes, such as gout, oxidative stress injury and metabolic syndrome. Thus, XO activators may exhibit above potential toxicological properties. Plumbagin (PLB) is an important active compound in traditional Chinese medicine (TCM), while its obvious toxic effects have been reported, including diarrhea, skin rashes and hepatic toxicity. However, the potential toxicity associated with enhancement of XO activity has not been fully illuminated so far.MethodsThe present study investigated the effect of PLB on XO activity by culturing mouse liver S9 (MLS9), human liver S9 (HLS9), XO monoenzyme system with PLB and xanthine. Then, the molecular docking and biolayer interferometry analysis were adopted to study the binding properties between PLB and XO. Finally, the in vivo acceleration effect also investigated by injected intraperitoneally PLB to KM mice for 3 days.ResultsPLB could obviously accelerate xanthine oxidation in the above three incubation systems. Both the Vmax values and intrinsic clearance values (CLint, Vmax/Km) of XO in the three incubation systems increased along with elevated PLB concentration. In addition, the molecular docking study and label-free biolayer interferometry assay displayed that PLB was well bound to XO. In addition, the in vivo results showed that PLB (2 and 10 mg/kg) significantly increased serum uric acid levels and enhanced serum XO activity in mice.ConclusionIn summary, this study outlines a potential source of toxicity for PLB due to the powerful enhancement of XO activity, which may provide the crucial reminding for the PLB-containing preparation development and clinical application.

Effects of Bacillus Coagulans on growth performance, antioxidant capacity, immunity function, and gut health in broilers

This study evaluated the effects of Bacillus coagulans (B. coagulans) as an alternative to antibiotics on growth performance, antioxidant capacity, immunity function and gut health in broilers. A total of 480 one-day-old broilers were randomly divided into 3 treatments with 8 replicates comprising 20 broilers each. The experiment lasted 42 d. Treatments included: basal diet without antibiotics (NCO); basal diet supplemented with 75 mg/kg chlortetracycline (ANT); basal diet supplemented with 5 × 109 CFU/kg B. coagulans(BC). The B. coagulans enhanced body weight (BW) and average daily gain compared with the NCO group (P < 0.05). However, there were no significant differences in average daily feed intake and feed: gain ratio (F: G) among three groups (P > 0.05). The B. coagulans significantly increased catalase, superoxide dismutase, and glutathione peroxidase levels and reduced malondialdehyde levels (P < 0.05). The serum immunoglobulins (IgA, IgM, and IgY) were significantly higher in the BC group when compared to the NCO and ANT groups (P < 0.05). The B. coagulans also markedly reduced serum levels of proinflammatory factors (IL-1β, IL-6, and TNF-α) and enhanced anti-inflammatory factor (IL-10) concentrations compared with control group (P < 0.05). Moreover, compared with the control group, BC significantly inhibited serum xanthine oxidase activity (P < 0.05). The levels of acetic acid, propionic acid, butyrate, isobutyric acid and valerate in BC group were significantly increased on d 42 compared with the NCO and ANT groups (P < 0.05). Furthermore, BC significantly altered cecal microbiota by reducing Desulfovibrio and Parasutterella, and by increasing Alistipes and Odoribacter (P < 0.05, P < 0.05, P < 0.001, P < 0.01, respectively). In conclusion, dietary B. coagulans, when used as an alternative to antibiotics, improved body weight, average daily gain, antioxidant capacity, immunity function and gut health in broilers.

Xanthine oxidase inhibitory activity and antihyperuricemic effect of Moringa oleifera Lam. leaf hydrolysate rich in phenolics and peptides

Ethnopharmacological relevanceMoringa oleifera Lam. leaf (MOL), a rich source of protein and phenolics, was traditionally used to treat various diseases including headaches, fevers, sore throat and dyslipidemia. Recently, MOL was reported to possess antioxidant, anti-dyslipidemia and hepato-renal protective activities, indicating that MOL could become a potential agent to improve metabolic disorders associated with hyperuricemia. The antihyperuricemic effect of MOL hydrolysate (MOLH) with high contents of phenolics and peptides remains unknown. Aim of the studyThe aim of this study is to investigate xanthine oxidase (XO) inhibitory activity of MOLH, to clarify phenolic and peptide profiles of MOLH, and to evaluate possible mechanism underlying the antihyperuricemic effect of MOLH. Materials and methodsMOLH was prepared by enzymatic hydrolysis using commercial trypsin. XO inhibitory activity was determined by XO reaction-UPLC-MS coupling method. The chemical profiles of the phenolic and peptide fractions of MOLH were determined by UPLC-QTOF-MS/MS. The antihyperuricemic effect of MOLH was evaluated in a potassium oxonate-induced hyperuricemic rat model at doses of 200 and 500 mg/kg. Serum uric acid (UA), urea nitrogen, creatinine (CRE), triglyceride (TG), total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol levels, serum XO activity, liver malondialdehyde (MDA) equivalent level, renal tumor necrosis factor-α and interleukin-1β levels, and protein expression of renal urate-anion transporter 1, glucose transporter 9 and ATP-binding cassette transporter G2 were determined. ResultsThe phenolic and peptide fractions played key roles in inhibiting XO activity and blocking uric acid production. Five flavonoids and sixteen polypeptides were identified in the phenolic and peptide fractions of MOLH, respectively. MOLH (200 and 500 mg/kg) could effectively reduce the serum UA level of hyperuricemic rats (p < 0.001) by regulation of serum XO activity (p < 0.05 at 200 mg/kg, p < 0.01 at 500 mg/kg) and renal urate transporters. Besides, MOLH could improve metabolic disorders associated with hyperuricemia by its multiple actions on liver MDA (p < 0.001), serum CRE (p < 0.05 at 500 mg/kg) and serum TG (p < 0.001). ConclusionThe results provided scientific evidence that MOLH rich in phenolics and peptides ameliorated hyperuricemia and metabolic disorders. This study validated the potential use of MOLH for regulation of hyperuricemia.

Effect of caffeinated and decaffeinated coffee on serum uric acid and uric acid clearance, a randomised within-subject experimental study.

The effect of coffee on serum uric acid (SUA) has shown conflicting results. This study was to determine the effects of caffeinated coffee (CC) and decaffeinated coffee (DC) on SUA, serum xanthine oxidase activity (sXOA) and urine uric acid clearance (UAC). This was a prospective randomised within-subject experimental study design of 51 healthy male participants. Each study period consisted of 3 periods, including a control, an intervention, and washout period for 1, 3 and 1 week, respectively. During the intervention period, the participants received 2, 4 or 6 gram/day of coffee, either CC or DC. For DC groups, SUA significantly decreased by 6.5 (±1.1) mg/dL to 6.2 (±1.1) mg/dL during the intervention period (p=0.014). sXOA significantly increased by 0.05 (±0.07) nmol/min/mL to 0.20 (±0.38) nmol/min/mL during the intervention period (p=0.010) of CC. For UAC, there was no significant change with CC or DC. In hyperuricaemic participants, SUA significantly decreased by 7.7 (±0.7) mg/dL to 7.2 (±0.7) mg/dL during the intervention period (p=0.028) of DC. For non-hyperuricaemic, CC significantly increased SUA by 5.9 (±0.7) mg/dL to 6.2 (±0.9) mg/dL during the intervention period (p=0.008) and significantly decreased SUA to 6.0 (±0.8) mg/dL (p=0.049) during the withdrawal period. A significant increase of sXOA according with SUA in CC groups from 0.05 (±0.07) nmol/min/mL to 0.25 (±0.44) nmol/min/mL during the intervention period (p=0.040) was presented in non-hyperuricaemic participants. DC had a significant decrease of SUA during the intervention period. However, in non-HUS participants, SUA significantly increased in CC.

561-P: Activated Xanthine Oxidase in Serum Is a Potent Therapeutic Target for Experimental Diabetic Polyneuropathy

Xanthine oxidase (XO), a potent inducer of reactive oxygen species, catalyzes purine metabolism. XO is expected to be implication of the macrophage activation. XO is also expressed in the peripheral nerve system, while its role in diabetic polyneuropathy (DPN) has not been clarified. We explored the implication of XO in DPN of db/db mice (db/db) treating with XO-inhibitor, topiloxostat (To). C57BL6 mice (C57) and db/db (5 wks of age) were daily treated with 1mg/kg (dbT1) and 2mg/kg (dbT2) To (per os) for 8 wks. During experimental period, peripheral nerve function was monitored. At end, serum and dissected sciatic nerves and dorsal root ganglia (DRG) served for evaluation of uric acid metabolism. Primary culture of DRG neuron was performed to evaluate the effects of To on neurite outgrowth in vitro. To improved significant delay of nerve conduction velocities and elevation of threshold for tail flick test in db/db in a dose dependent manner (p&amp;lt;0.05 dbT2 vs. C57 for NCVs, p&amp;lt;0.05 db/db vs. dbT1, p&amp;lt;0.01 db/db vs. dbT2 for tail flick). XO activity was significantly up-regulated in DRG (p&amp;lt;0.01) and serum of db/db compared to those of W (p&amp;lt;0.05). To successfully suppressed the elevated XO activity in a dose dependent manner (p&amp;lt;0.05, W vs. T1, p&amp;lt;0.01, T1 vs. T2). Uric acid was significantly accumulated in serum and DRG of db/db compared to those of C57 (p&amp;lt;0.05). To could significantly reduce the accumulation (p&amp;lt;0.01). In primary culture of DRG neuron, extrinsic 100 μM XO depleted the neurite outgrowth more than 50 % than that of non-stimulated neurons (p&amp;lt;0.01). 4.3ng/ml To could significantly restored the reduction of neurite outgrowth compared to that of non-treated neurons (p&amp;lt;0.05). As a conclusion, increase in XO activity in serum and DRG may be implicated in the pathophysiology of DPN in db/db. Activation of XO in serum may directly exacerbate neuronal injury for DRG in DPN. To has a beneficial effect on DPN through its specific property to suppress serum XO activity. Disclosure H. Ichinohe: None. H. Mizukami: None. S. Osonoi: None. K. Kudo: None. S. Yagihashi: None.

P0964EFFECTS OF XANTHINE OXIDASE INHIBITORS AND DAPAGLIFLOZIN ON RENAL GLUCOSE AND URATE TRANSPORTERS IN METABOLIC SYNDROME

Abstract Background and Aims Metabolic syndrome consists of several medical conditions that collectively predict the risk for cardiovascular disease. Hyperglycemia and hyperuricemia are the major disorders of metabolic syndrome. Kidney reabsorbs almost all filtrated glucose by active transport at normal concentrations of plasma glucose via members of the sodium glucose transport (SGLT) family. Besides, the kidney plays a pivotal role in handling uric acid homeostasis. Uric acid is mainly controlled by urate transporter (UAT), urate anion exchanger 1 (URAT1) and glucose transporter 9 (GLUT9). The aims of the study were to determine the alteration of renal glucose and uric acid transporters in animals with metabolic syndrome after treatment of xanthine oxidase inhibitors and SGLT2 inhibitor. Method Sprague-Dawley rats were fed with normal chow (Control) or high fructose diet (60%) for totally 6 months. For those animals fed with high fructose diet for 3 months, they were divided into 4 groups including high fructose diet without treatment (FR), treatment with allopurinol (150 mg/L in drinking water), with febuxostat (30 mg/L in drinking water) or with dapagliflozin (1mg/kg/day intraperitoneal injection). Blood, urine and blood pressure were collected and measured at the end of study. Gene and protein expression of renal glucose and uric acid transporters were determined by reverse transcriptase polymerase chain reaction. The changes of transporters were then confirmed by immunohistochemical staining. Results High-fructose diet induced higher levels of fasting glucose, insulin resistance index, uric acid, triglyceride and blood pressure in FR group (all p &amp;lt;0.05 vs. control). Treatment of allopurinol, febuxostat and dapagliflozin reduced body weight significantly. Fasting glucose, insulin resistance index and hyperuricemia were improved in all drug treatment groups (all p &amp;lt;0.05). In the kidney, high fructose diet significantly upregulated SGLT1, SGLT2 and GLUT2 but downregulated GLUT1 expression. Urate transporters, including GLUT9, UAT and URAT1 were also increased (p &amp;lt;0.05). The improvement of insulin resistance by xanthine oxidase inhibitors was associated with suppression of renal SGLT1, SGLT2 and GLUT2 expression. Dapagliflozin alleviated hyperuricemia and induced uricosuria without affecting serum xanthine oxidase activity. Compared to FR, dapagliflozin significantly inhibited fructose-induced overexpression of GLUT9, UAT and URAT1 in the kidney. Conclusion Long term high fructose diet induced metabolic syndrome in rats. Treatment of xanthine oxidase inhibitors and dapagliflozin ameliorated components of metabolic syndrome. Both allopurinol and febuxostat improved insulin resistance in association with suppression of renal SGLT1, SGLT2 and GLUT2 expression. Although dapagliflozin and xanthine oxidase inhibitors reduced uric acid in different mechanisms, they shared a similar molecular changes in the kidney by downregulating GLUT9, UAT and URAT1 expression.

Effects of Aster glehni Extract on Serum Uric Acid in Subjects with Mild Hyperuricemia: A Randomized, Placebo-Controlled Trial.

Aster glehni extracts (AGE) reduced serum uric acid levels in hyperuricemia rats in several previous studies. However, its efficacy in human has not been yet explored. This study aimed at investigating the efficacy and safety of AGE on the anti-hyperuricemia effect in subjects with slightly high serum uric acid. A randomized, double-blinded, placebo-controlled clinical trial was conducted for 12 weeks. Eligible subjects were randomly assigned to either AGE (480 mg/day) or placebo. The primary endpoint was the change in serum uric acid concentrations from baseline to follow-up time points. The secondary endpoints were the change of serum xanthine oxidase activity, and the levels of C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-α) in the blood from baseline to follow-up time points. Safety was assessed by clinical laboratory parameters and adverse events reported by subjects. Six weeks of AGE supplementation significantly reduced serum uric acid level from baseline (P = .0468) but at the end of the intervention the participants did not show the beneficial effect of AGE supplementation. Also, the serum uric acid level in the AGE group was not significantly different at the follow-up time points, when compared with placebo. The mean changes of secondary endpoints from baseline to each time point did not show significant differences within and between the two groups. There were no adverse events reported by subjects or changes in safety parameters after intervention. In conclusion, AGE supplementation for 12 weeks did not show significant benefits for reducing serum uric acid concentrations in subjects with mild hyperuricemia.

Lycium barbarum polysaccharides protect mice from hyperuricaemia through promoting kidney excretion of uric acid and inhibiting liver xanthine oxidase

Context Lycium barbarum L. (Solanaceae) polysaccharides (LBPs) are important active constituents that have demonstrated kidney protection. Objective This study investigated the effect of LBPs on hyperuricaemia and explored the underlying mechanism in mice. Materials and methods Thirty-six C57BL/6 mice were randomly divided into the control group, hyperuricaemia group, allopurinol group (5 mg/kg) and three LBP groups (n = 6). The LBP groups were treated orally with LBPs at 50, 100 and 200 mg/kg body weight for 7 days. We examined the levels of serum uric acid (SUA) and urinary uric acid (UUA), as well as xanthine oxidase (XOD) activities. mRNA and protein were quantified by quantitative real-time PCR and Western blotting, respectively. Results LBPs treatment (100 and 200 mg/kg) significantly reduced the SUA levels to 4.83 and 4.48 mg/dL, and markedly elevated the UUA levels to 4.68 and 5.18 mg/dL (p < 0.05), respectively, while significantly increased the mRNA and protein expression levels of renal organic anti-transporter 1 (OAT1) and organic anti-transporter 3 (OAT3), and markedly decreased the levels of glucose transporter 9 (GLUT9) (p < 0.05). Additionally, the serum XOD activities were reduced to 31.5 and 31.1 mU/mL, and the liver XOD activities were reduced to 80.6 and 75.6 mU/mL after treatment with 100 and 200 mg/kg LBPs (p < 0.01), respectively. Discussion and conclusions This study demonstrated the potential role of LBPs in reducing the uric acid level in hyperuricemic mice. A border study population should be evaluated. These results are valuable for the development of new anti-hyperuricaemia agents from LBPs.