Uric Acid Biosynthesis Research Articles

Recent Progress and Future Perspectives on Anti-Hyperuricemic Agents.

Increased biosynthesis or underexcretion of uric acid (UA or urate) in the body ultimately leads to the development of hyperuricemia. Epidemiological studies indicate that hyperuricemia is closely associated with the occurrence of various diseases such as gout and cardiovascular diseases. Currently, the first-line therapeutic medications used to reduce UA levels primarily include xanthine oxidase (XO) inhibitors, which limit UA production, and urate transporter 1 (URAT1) inhibitors, which decrease urate reabsorption and enhance urate excretion. Despite significant progress in urate-lowering therapies, long-term use of these drugs can cause hepatorenal toxicity as well as cardiovascular complications. Therefore, there is an urgent need for novel anti-hyperuricemic agents with better efficacy and lower toxicity. This perspective mainly focuses on the current research progress and design strategy of anti-hyperuricemic agents, particularly those targeting XO and URAT1. It is our hope that this perspective will provide insights into the challenges and opportunities for anti-hyperuricemic drug discovery.

Comparative Transcriptomics of Fat Bodies between Symbiotic and Quasi-Aposymbiotic Adult Females of Blattella germanica with Emphasis on the Metabolic Integration with Its Endosymbiont Blattabacterium and Its Immune System.

We explored the metabolic integration of Blattella germanica and its obligate endosymbiont Blattabacterium cuenoti by the transcriptomic analysis of the fat body of quasi-aposymbiotic cockroaches, where the endosymbionts were almost entirely removed with rifampicin. Fat bodies from quasi-aposymbiotic insects displayed large differences in gene expression compared to controls. In quasi-aposymbionts, the metabolism of phenylalanine and tyrosine involved in cuticle sclerotization and pigmentation increased drastically to compensate for the deficiency in the biosynthesis of these amino acids by the endosymbionts. On the other hand, the uricolytic pathway and the biosynthesis of uric acid were severely decreased, probably because the reduced population of endosymbionts was unable to metabolize urea to ammonia. Metabolite transporters that could be involved in the endosymbiosis process were identified. Immune system and antimicrobial peptide (AMP) gene expression was also reduced in quasi-aposymbionts, genes encoding peptidoglycan-recognition proteins, which may provide clues for the maintenance of the symbiotic relationship, as well as three AMP genes whose involvement in the symbiotic relationship will require additional analysis. Finally, a search for AMP-like factors that could be involved in controlling the endosymbiont identified two orphan genes encoding proteins smaller than 200 amino acids underexpressed in quasi-aposymbionts, suggesting a role in the host-endosymbiont relationship.

Limosilactobacillus reuteri HCS02-001 Attenuates Hyperuricemia through Gut Microbiota-Dependent Regulation of Uric Acid Biosynthesis and Excretion.

Hyperuricemia is a prevalent metabolic disorder that arises from abnormal purine metabolism and reduced excretion of uric acid (UA). The gut microbiota plays a significant role in the biosynthesis and excretion of UA. Probiotics capable of purine degradation possess the potential to prevent hyperuricemia. Our study aimed to screen probiotics in areas with abundant dairy products and longevity populations in China, which could attenuate the level of UA and explore the underlying mechanism. In this study, twenty-three lactic acid bacteria isolated from healthy Chinese infant feces and traditional fermented foods such as hurood and lump milk were evaluated for the ability to tolerance acid, bile, artificial gastric juice, and artificial intestinal juice to determine the potential of the candidate strains as probiotics. Eight strains were identified as possessing superior tolerance to simulated intestinal conditions and were further analyzed by high-performance liquid chromatography (HPLC), revealing that Limosilactobacillus reuteri HCS02-001 (Lact-1) and Lacticaseibacillus paracasei HCS17-040 (Lact-2) possess the most potent ability to degrade purine nucleosides. The effect of Lact-1 and Lact-2 on hyperuricemia was evaluated by intervening with them in the potassium oxonate and adenine-induced hyperuricemia Balb/c mice model in vivo. Our results showed that the level of serum UA in hyperuricemic mice can be efficiently reduced via the oral administration of Lact-1 (p < 0.05). It significantly inhibited the levels of liver inflammatory cytokines and hepatic xanthine oxidase through a TLR4/MyD88/NF-κB pathway across the gut-liver axis. Furthermore, UA transporters ABCG2 and SLC2A9 were substantially upregulated by the intervention of this probiotic. Fecal ATP levels were significantly induced, while fecal xanthine dehydrogenase and allantoinase levels were increased following probiotics. RNA sequencing of HT-29 cells line treated with Lact-1 and its metabolites demonstrated significant regulation of pathways related to hyperuricemia. In summary, these findings demonstrate that Limosilactobacillus reuteri HCS02-001 possesses a capacity to ameliorate hyperuricemia by inhibiting UA biosynthesis via enhancing gastrointestinal barrier functions and promoting UA removal through the upregulation of urate transporters, thereby providing a basis for the probiotic formulation by targeting the gut microbiota.

In vivo and in vitro insights into the anti-hyperuricemic effects of sacha inchi (plukenetia volubilis l.) leaves extract rich in polyphenols

Sacha inchi (SI, Plukenetia volubilis L.) is a South American oleaginous crop with multiple health benefits and has been traditionally used to treat various ailments due to its bioactive ingredients such as polyphenols and flavonoids. In this study, a variety of compounds including three flavonoids (epigallocatechin, luteolin-3′,7-di-O-glucoside and cosmosiin), two polyphenols (gallic acid and 4-hydroxycoumarin) and three organic acids (malic acid, citric acid and 2-isopropylmalic acid) were firstly identified by UHPLC-QQQ-MS. Subsequently, in vitro results show that SI leaf aqueous extract (SILE) exhibit potential to lower uric acid (UA) by affecting mRNA levels of UA synthases (XO and HGPRT) with neglectable impacts on cell viability of liver cells (L02). In vivo experiments further suggest that SILE can effectively reduce the levels of serum UA and renal inflammatory cytokines (Il-1β, Il-6 and Tnf-α), and improve renal function indicators (serum Cr and BUN), thereby repairing kidney injury in both acute and chronic hyperuricemic (HUA) animal models. In addition, SILE also improve UA metabolism by inhibiting UA biosynthesis and reabsorption and promoting UA excretion. 1H NMR-based metabolomics reveals that SILE effectively regulate the levels of glucose, amino acid, purine and pyrimidine that are involved in UA metabolic pathway in kidney of HUA mice. These findings demonstrate that SILE rich in polyphenols and flavonoids has a great potential for HUA treatment by inhibiting xanthine oxidase activity and improving UA metabolism.

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

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

Anti-Hyperuricemia Activity and Potential Mechanisms of Medicinal Mushroom Activity: A Review of Preclinical Studies.

Hyperuricemia (HUA) is characterized by abnormally elevated levels of serum uric acid, the product of purine metabolism. The primary symptom of HUA is gout; however, asymptomatic HUA is associated with complications such as hypertension, kidney disease, cardiovascular disease, and metabolic syndrome. The activation of xanthine oxidase (XO), a pivotal enzyme in uric acid biosynthesis, is coupled with extensive reactive oxygen species generation, leading to inflammatory responses, and triggers the development of HUA and its complications. In clinical practice, XO inhibitors are primarily used to treat HUA; however, their prolonged use is accompanied by serious adverse effects. Mushrooms and their bioactive constituents have shown promising anti-HUA activities in both in vitro and in vivo studies, including inhibition of urate production, modulation of renal urate transporters, enhancement of intestinal uric acid excretion, and antioxidant, anti-inflammatory, and antimetabolic syndrome properties. Clinical trials are necessary to validate the beneficial effects and safety of mushrooms in preventing or alleviating HUA and attenuating the associated complications. This review presents contemporary insights into the pathogenesis of HUA, the bioactive components of mushrooms, their therapeutic potential, and the underlying mechanisms involved in ameliorating HUA.

Effect of Melinjo Seed Extract on GSH Levels of Hyperuricemic Wistar Rats

Background: Hyperuricemia is a condition where uric acid levels are above normal. The biosynthesis of uric acid by the enzyme xanthine oxidase (XO) produces free radicals that cause oxidative stress. Oxidative stress lowers cellular GSH levels. Gnetum gnemon L. or melinjo seeds contain stilbenoids and flavonoids that can act as natural XO inhibitors. Objective: To study the effect of melinjo seed extract on GSH levels.Methods: This research was a true experimental with pre and post-test controlled group design. Thirty six male wistar rats were randomly divided into 6 groups consisting of a healthy control (KS), negative control (K1), positive control (K2), treatment 1 (P1) extract 250 mg/kgBW, treatment 2 (P2) extract 500 mg/kgBW, treatment 3 (P3) extract 2000 mg/kgBW. Hyperuricemia was induced by the administration of Maggie® block broth and potassium oxonate. Measurement was carried out on the 21st and 35th day of treatment, then analyzed using Paired-Sample T Test, continued with One-Way Anova test and Post Hoc LSD test. Results: Administration of melinjo seed extract at P1, P2, and P3 significantly increased GSH levels (P&lt;0.05) from 1.23±0.10 to 1.55±0.16; 1.22±0.06 to 1.73±0.16; and 1.21±0.08 to 1.88±0.08. There was significant difference between the three doses with a dose of 250 mg/kgBW melinjo seed extract being more effective than allopurinol 90 mg/kgBW. Conclusion: Melinjo seed extract could increase GSH levels with the most effective dose of 250 mg/kgBB.

Untargeted metabolomics reveal sex-specific and non-specific redox-modulating metabolites in kidneys following binge drinking

Graphical abstract Abstract Binge drinking is a growing health concern among all age groups. The ability of individuals to handle ethanol in their systems differs not due to differences in enzyme expression but also due to other factors. Vital organs including brain, liver, heart, and kidneys are at high risk following repeated exposure to high concentrations of ethanol from binge drinking. The impact of chronic binge drinking on kidneys is not well studied. Using a mouse model of chronic binge drinking, we have identified major metabolic alterations that could set the stage for detrimental effects in the kidneys of male and female mice. We have deciphered that even though there are pathway overlaps, the different sexes exhibited unique and divergent metabolic pathway dysregulations as per the metabolite panels following binge drinking. We have reported that binge drinking could negatively influence renal redox homeostasis in both sexes through the regulation of different metabolite clusters. In male mice by downregulation of pantothenic acid and riboflavin synthesis, and in female mice by upregulation of α-aminoadipic acid and formyl kynurenine level. Interestingly, the uric acid biosynthesis pathway has been upregulated independent of the sex-specific effects, portraying the significance of uric acid as a potential marker for binge drinking-induced injury in both sexes. Thus, by altering renal metabolome, binge drinking sets the stage for renal damage by disturbing renal redox balance. Our data has high translational potential and will aid in finding ideal therapeutics in a sex-specific manner for subjects exposed to binge drinking- induced renal injury.

Computational Characterization of the Inhibition Mechanism of Xanthine Oxidoreductase by Topiroxostat.

Xanthine oxidase (XO) is a member of the molybdopterin-containing enzyme family. It interconverts xanthine to uric acid as the last step of purine catabolism in the human body. The high uric acid concentration in the blood directly leads to human diseases like gout and hyperuricemia. Therefore, drugs that inhibit the biosynthesis of uric acid by human XO have been clinically used for many years to decrease the concentration of uric acid in the blood. In this study, the inhibition mechanism of XO and a new promising drug, topiroxostat (code: FYX-051), is investigated by employing molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) calculations. This drug has been reported to act as both a noncovalent and covalent inhibitor and undergoes a stepwise inhibition by all its hydroxylated metabolites, which include 2-hydroxy-FYX-051, dihydroxy-FYX-051, and trihydroxy-FYX-051. However, the detailed mechanism of inhibition of each metabolite remains elusive and can be useful for designing more effective drugs with similar inhibition functions. Hence, herein we present the computational investigation of the structural and dynamical effects of FYX-051 and the calculated reaction mechanism for all of the oxidation steps catalyzed by the molybdopterin center in the active site. Calculated results for the proposed reaction mechanisms for each metabolite's inhibition reaction in the enzyme's active site, binding affinities, and the noncovalent interactions with the surrounding amino acid residues are consistent with previously reported experimental findings. Analysis of the noncovalent interactions via energy decomposition analysis (EDA) and noncovalent interaction (NCI) techniques suggests that residues L648, K771, E802, R839, L873, R880, R912, F914, F1009, L1014, and A1079 can be used as key interacting residues for further hybrid-type inhibitor development.

New insight into the management of renal excretion and hyperuricemia: Potential therapeutic strategies with natural bioactive compounds.

Hyperuricemia is the result of increased production and/or underexcretion of uric acid. Hyperuricemia has been epidemiologically associated with multiple comorbidities, including metabolic syndrome, gout with long-term systemic inflammation, chronic kidney disease, urolithiasis, cardiovascular disease, hypertension, rheumatoid arthritis, dyslipidemia, diabetes/insulin resistance and increased oxidative stress. Dysregulation of xanthine oxidoreductase (XOD), the enzyme that catalyzes uric acid biosynthesis primarily in the liver, and urate transporters that reabsorb urate in the renal proximal tubules (URAT1, GLUT9, OAT4 and OAT10) and secrete urate (ABCG2, OAT1, OAT3, NPT1, and NPT4) in the renal tubules and intestine, is a major cause of hyperuricemia, along with variations in the genes encoding these proteins. The first-line therapeutic drugs used to lower serum uric acid levels include XOD inhibitors that limit uric acid biosynthesis and uricosurics that decrease urate reabsorption in the renal proximal tubules and increase urate excretion into the urine and intestine via urate transporters. However, long-term use of high doses of these drugs induces acute kidney disease, chronic kidney disease and liver toxicity. Therefore, there is an urgent need for new nephroprotective drugs with improved safety profiles and tolerance. The current systematic review summarizes the characteristics of major urate transporters, the mechanisms underlying the pathogenesis of hyperuricemia, and the regulation of uric acid biosynthesis and transport. Most importantly, this review highlights the potential mechanisms of action of some naturally occurring bioactive compounds with antihyperuricemic and nephroprotective potential isolated from various medicinal plants.

Associations of Liver Function Parameters with New-Onset Hyperuricemia in a Large Taiwanese Population Study.

Hyperuricemia is the chief cause of gout and has been linked with hypertension, cardiovascular and renal disease, diabetes and metabolic syndrome. Liver with the highest protein expression of xanthine oxidase, the main enzyme responsible for uric acid formation, is the primary site of uric acid biosynthesis. However, there are few studies that examine the association between liver function and new-onset hyperuricemia. Hence, using the Taiwan Biobank dataset, we aimed to explore the capability of liver function parameters, including gamma-glutamyl transferase, total bilirubin, albumin, alanine aminotransferase and aspartate aminotransferase in association with the subsequent development of hyperuricemia. We analyzed 21,030 participants without hyperuricemia at baseline. Hyperuricemia was defined as a uric acid concentration &gt; 6.0 mg/dL in women or &gt;7.0 mg/dL in men. New-onset hyperuricemia was defined as participants without baseline hyperuricemia having developed hyperuricemia upon subsequent exam. Overall, 1804 (8.6%) of the study subjects developed new-onset hyperuricemia. After multivariable analysis, significant associations were found between the male sex (odds ratio [OR], 4.412; p &lt; 0.001), high values of systolic blood pressure (SBP) (OR, 1.006; p = 0.012), body mass index (BMI) (OR, 1.064; p &lt; 0.001), fasting glucose (OR, 1.005; p &lt; 0.001), triglycerides (OR, 1.001; p = 0.003), uric acid (OR, 5.120; p &lt; 0.001), low values of estimated glomerular filtration rates (eGFR) (OR, 0.995; p &lt; 0.001), total bilirubin (OR, 0.616; p &lt; 0.001) and new-onset hyperuricemia. The cutoff level of total bilirubin, according to the Youden index, of receiver operating characteristic curve for identifying new-onset hyperuricemia was 0.65 mg/dL. Low total bilirubin was defined as ≤0.65 mg/dL. After multivariable analysis, we found a significant association between low total bilirubin level (≤0.65 mg/dL) (OR = 0.806; p &lt; 0.001) and new-onset hyperuricemia. Our present study demonstrated that in addition to male sex, high SBP, BMI, fasting glucose, triglycerides, and uric acid and low eGFR, the serum's total bilirubin levels were negatively associated with new-onset hyperuricemia in a large Taiwanese cohort.

Folic acid and zinc improve hyperuricemia by altering the gut microbiota of rats with high-purine diet-induced hyperuricemia.

A high-purine diet can cause hyperuricemia and destroy the microbial composition of the gut microbiota. Both folic acid and zinc significantly reduce uric acid levels and alleviate hyperuricemia. However, whether the underlying mechanisms are associated with the regulation of the gut microbiota remain unknown. To explore alterations of the gut microbiota related to folic acid and zinc treatment in rats with hyperuricemia in our study. A hyperuricemic rat model was established with a high-purine diet. The effects of folic acid and zinc on uric acid levels were evaluated. Alterations of the gut microbiota related to hyperuricemia and the treatments were evaluated by sequencing using the Illumina MiSeq system. The results demonstrated that uric acid levels dropped observably, and the activities of adenosine deaminase (ADA) and xanthine oxidase (XOD) were downregulated after folic acid or zinc intervention. 16S rRNA gene sequencing-based gut microbiota analysis revealed that folic acid and zinc enhanced the abundance of probiotic bacteria and reduced that of pathogenic bacteria, thus improving intestinal barrier function. PICRUST analysis indicated that folic acid and zinc restored gut microbiota metabolism. These findings indicate that folic acid and zinc ameliorate hyperuricemia by inhibiting uric acid biosynthesis and stimulating uric acid excretion by modulating the gut microbiota. Thus, folic acid and zinc may be new and safe therapeutic agents to improve hyperuricemia.

Effects of Sporisorium reiliana polysaccharides and Phoenix dactylifera monosaccharides on the gut microbiota and serum metabolism in mice with fructose-induced hyperuricemia.

In recent decades, the prevalence of hyperuricemia has increased, and dietary fructose is an important risk factor for the development of this disease. This study investigated and compared the effects of Sphacelotheca reiliana polysaccharides and Phoenix dactylifera monosaccharides on a series of physiological and biochemical indicators and on the metagenomes and serum metabolites in mice with hyperuricemia caused by a high-fructose diet. S. reiliana polysaccharides inhibited uric acid biosynthesis and promoted uric acid excretion, thereby alleviating the hyperuricemia phenotype. In addition, hyperuricemia was closely related to the gut microbiota. After treatment with S. reiliana polysaccharides, the abundances of Bacteroidetes and Proteobacteria in the mouse intestines were decreased, the expression of genes involved in glycolysis/gluconeogenesis metabolic pathways and purine metabolism was downregulated, and the dysfunction of the gut microbiota was alleviated. With regard to serum metabolism, the abundance of hippuric acid, uridine, kynurenic acid, propionic acid and arachidonoyl decreased, and the abundances of serum metabolites in inflammatory pathways involved in kidney injury and gout, such as bile acid metabolism, purine metabolism and tryptophan metabolism pathways, decreased. P. dactylifera monosaccharides aggravated hyperuricemia. This research provides a valuable reference for the development of sugar applications.

Type 2 diabetic mice enter a state of spontaneous hibernation-like suspended animation following accumulation of uric acid

Hibernation is an example of extreme hypometabolic behavior. How mammals achieve such a state of suspended animation remains unclear. Here we show that several strains of type 2 diabetic mice spontaneously enter into hibernation-like suspended animation (HLSA) in cold temperatures. Nondiabetic mice injected with ATP mimic the severe hypothermia analogous to that observed in diabetic mice. We identified that uric acid, an ATP metabolite, is a key molecular in the entry of HLSA. Uric acid binds to the Na+ binding pocket of the Na+/H+ exchanger protein and inhibits its activity, acidifying the cytoplasm and triggering a drop in metabolic rate. The suppression of uric acid biosynthesis blocks the occurrence of HLSA, and hyperuricemic mice induced by treatment with an uricase inhibitor can spontaneously enter into HLSA similar to that observed in type 2 diabetic mice. In rats and dogs, injection of ATP induces a reversible state of HLSA similar to that seen in mice. However, ATP injection fails to induce HLSA in pigs due to the lack of their ability to accumulate uric acid. Our results raise the possibility that nonhibernating mammals could spontaneously undergo HLSA upon accumulation of ATP metabolite, uric acid.

ANTIHYPERURICEMIA ACTIVITY OF ETHANOL EXTRACT AND FRACTIONS OF AZADIRACHTA INDICA LEAF IN VIVO AND MECHANISM OF ACTION OF ACTIVE FRACTIONS IN VITRO

Azadirachta indica , A.,Juss is a medicinal plant that is used traditionally for some disease, especially its leaves to treat a rheumatic diseases and lower blood uric acid levels. This study was carried out to examine antihyperuricemia activity of ethanol extract, water fraction, ethyl acetat fraction and n-hexane fraction of the A. Indica leaves in male mice of Swiss-Webster strain. Extract and fraction doses used were 250 and 500 mg/kg of body weight and the doses of allopurinol as a standard drug was 13 mg/kg of body weight. The tests were conducted on mice suffering from hyperuricemia induced by potassium oxonat at adose of 300 mg/kg of body weight intraperitoneally and chicken liver juice orally. Measurement of blood uric acid levels were performed using an Easy Touch® every hour for 4 hours after being given test preparations. The results showed that the ethanol extract and the fractions lowered blood uric acid levels in the same way as allopurinol did. The n-hexane fractions at the all doses showed the highest activity, followed by ethanol fraction, and water fraction at the dose of 250 mg/kg at the 4th hour. These results illustrated that the A. Indica leaves might be potential to be used as antihyperuricemia. The active compounds which possibly reduce blood uric acid levels in mice are believed to be flavonoid or polyphenolic compounds because they are reported to be able to inhibit the action of the xanthine oxidase enzyme that converts purines into uric acid. Then, the most active fraction, n-hexane fraction, was tested for its inhibitory activity on xanthine oxidase enzyme to determine its mechanism of action. The results showed that the n-hexane fraction, like allopurinol, inhibited uric acid biosynthesis through inhibiting the activity of xanthine oxidase enzyme with the IC 50 value of 132 μg/mL lower than that of allopurinol IC 50 58.35 μg/mL. Key words: A. indica leaves, antihyperuricemia, chicken liver juice, potassium oxonat, xanthine oxidase.

Effect of Phytic Acid Administration on the Zinc concentration, Uric Acid Biosynthesis, and Serum Lipid Components in Rats

Effect of Phytic Acid Administration on the Zinc concentration, Uric Acid Biosynthesis, and Serum Lipid Components in Rats

Potential natural inhibitors of xanthine oxidase and HMG-CoA reductase in cholesterol regulation: in silico analysis

BackgroundHypercholesterolemia has posed a serious threat of heart diseases and stroke worldwide. Xanthine oxidase (XO), the rate-limiting enzyme in uric acid biosynthesis, is regarded as the root of reactive oxygen species (ROS) that generate atherosclerosis and cholesterol crystals. β-Hydroxy β-methylglutaryl-coenzyme A reductase (HMGR) is a rate-limiting enzyme in cholesterol biosynthesis. Although some commercially available enzyme inhibiting drugs have effectively reduced cholesterol levels, most of them have failed to meet potential drug candidates’ requirements. Here, we have carried out an in-silico analysis of secondary metabolites that have already shown good inhibitory activity against XO and HMGR in a wet lab setup.MethodsOut of 118 secondary metabolites reviewed, sixteen molecules inhibiting XO and HMGR were selected based on the IC50 values reported in in vitro assays. Further, receptor-based virtual screening was carried out against secondary metabolites using GOLD Protein-Ligand Docking Software, combined with subsequent post-docking, to study the binding affinities of ligands to the enzymes. In-silico ADMET analysis was carried out to explore their pharmacokinetic properties, followed by toxicity prediction through ProTox-II.ResultsThe molecular docking of amentoflavone (GOLD score 70.54, ∆G calc. = − 10.4 Kcal/mol) and ganomycin I (GOLD score 59.61, ∆G calc. = − 6.8 Kcal/mol) displayed that the drug has effectively bound at the competitive site of XO and HMGR, respectively. Besides, 6-paradol and selgin could be potential drug candidates inhibiting XO. Likewise, n-octadecanyl-O-α-D-glucopyranosyl (6′ → 1″)-O-α-D-glucopyranoside could be potential drug candidates to maintain serum cholesterol. In-silico ADMET analysis has shown that these sixteen metabolites were optimal within the categorical range compared to commercially available XO and HMGR inhibitors, respectively. Toxicity analysis through ProTox-II revealed that 6-gingerol, ganoleucoin K, and ganoleucoin Z are toxic for human use.ConclusionThis computational analysis supports earlier experimental evidence towards the inhibition of XO and HMGR by natural products. Further study is necessary to explore the clinical efficacy of these secondary molecules, which might be alternatives for the treatment of hypercholesterolemia.

Effects of quercetin and metabolites on uric acid biosynthesis and consequences for gene expression in the endothelium

BackgroundUric acid, a metabolic product of purine degradation in humans, is a risk factor for developing gout and type 2 diabetes, and supplementation with quercetin lowers plasma uric acid in mildly hyperuricemic men. Here we examined the mechanism of inhibition of enzymes involved in uric acid metabolism by quercetin, conjugates and microbial catabolites, and measured the effect of lowered circulating uric acid on endothelial cell gene expression. MethodsInhibition of adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and xanthine oxidoreductase (XOR) activity by quercetin and metabolites was determined by HPLC. Human umbilical vein endothelial cells (HUVECs) were cultured under conditions mimicking blood flow, treated with uric acid (0, 300 or 500 μmol/L), and changes in gene expression measured using transcriptomics and quantitative droplet digital PCR. ResultsIn human plasma, no inhibition of PNP activity was observed, and only quercetin weakly inhibited ADA. XOR was not present at sufficient amount in human plasma to use for testing, but quercetin, quercetin-3′-sulfate and the gut microbial metabolite 3′,4′-dihydroxyphenylacetic acid inhibited bovine milk XOR. Several changes were observed in gene expression in HUVECs under flow compared to static conditions, but after uric acid treatment, only very few changes were detected. ConclusionsWe propose that the main mechanism by which quercetin, as quercetin-3′-sulfate, lowers uric acid in vivo is through inhibition of XOR, and not ADA nor PNP. The pertinent shift in uric acid concentration was not sufficient to produce significant changes in endothelial gene expression in a cell model.

Quantitative Prediction of Thiazole Derivatives as Potent Xanthine Oxidase Inhibitors

AbstractIn humans, xanthine oxidase (XO) is a critical rate‐limiting enzyme in biosynthesis of uric acid. Moreover, XO is the most promising target to control uric acid levels and the treat of hyperuricemia and gout. However, XO inhibitors can effectively treat gout through the inhibition of urate synthesis, and by impairing the conversion of hypoxanthine and xanthine to uric acid. In this paper, four different quantitative structure‐activity relationship (QSAR) models of 80 thiazole derivatives were constructed to comprehend chemical‐biological interactions and predict their bioactivities using GA‐MLR (Genetic Algorithm‐Multiple Linear Regression), HQSAR (Hologram Quantitative Structure Activity Relationship), Topomer CoMFA (Comparative Molecular Field Analysis) and CoMSIA (Comparative Molecular Similarity Indices Analysis) methods. Furthermore, R2 and Q2 of the obtained GA‐MLR, HQSAR, Topomer CoMFA and CoMSIA models are 0.956 and 0.911, 0.932 and 0.876, 0.946 and 0.917, 0.964 and 0.877, respectively. In addition, the external predictive values of the GA‐MLR, HQSAR, Topomer CoMFA and CoMSIA models are 0.963, 0.936, 0.973 and 0.934, respectively. Therefore, all QSAR models exhibited good prediction performances, which can be used to quantitatively evaluate bioactivity and screen new XO inhibitors. Moreover, topological charge index, atomic electronegativity and polarizability, atomic van der Waals volumes and hydrophobic van der Waals surface area are very relevant to bioactivity of thiazole derivatives.

Plasma profiling of amino acids distinguishes acute gout from asymptomatic hyperuricemia

Gout and hyperuricemia are highly prevalent metabolic diseases caused by high level of uric acid. Amino acids (AAs) involve in various biochemical processes including the biosynthesis of uric acid. However, the role of AAs in discriminating gout from hyperuricemia remains unknown. Here, we report that the plasma AAs profile can distinguish acute gout (AG) from asymptomatic hyperuricemia (AHU). We established an LC-MS/MS-based method to measure the plasma AAs without derivatization for the AG and AHU patients, and healthy controls. We found that the plasma profiling of AAs separated the AG patients from AHU patients and controls visually in both principal component analysis and orthogonal partial least-squares discriminant analysis (OPLS-DA) models. In addition, L-isoleucine, L-lysine, and L-alanine were suggested as the key mediators to distinguish the AG patients from AHU and control groups based on the S-plot analysis and variable importance in the projection values in the OPLS-DA models, volcano plot, and the receiver operating characteristic curves. In addition, the saturation of monosodium urate in the AA solutions at physiologically mimic status supported the changes in plasma AAs facilitating the precipitation of monosodium urate. This study suggests that L-isoleucine, L-lysine, and L-alanine could be the potential markers to distinguish the AG from AHU when the patients have similar blood levels of uric acid, providing new strategies for the prevention, treatment, and management of acute gout.