Xanthine Oxidase Activity Research Articles

Identification of Anastatica hierochuntica L. Methanolic-Leaf-Extract-Derived Metabolites Exhibiting Xanthine Oxidase Inhibitory Activities: In Vitro and In Silico Approaches.

There is a growing interest in the discovery of novel xanthine oxidase inhibitors for gout prevention and treatment with fewer side effects. This study aimed to identify the xanthine oxidase (XO) inhibitory potential and drug-likeness of the metabolites present in the methanolic leaf extract of Anastatica (A.) hierochuntica L. using in vitro and in silico models. The extract-derived metabolites were identified by liquid-chromatography-quadrupole-time-of-flight-mass-spectrometry (LC-QTOF-MS). Molecular docking predicted the XO inhibitory activity of the identified metabolites and validated the best scored in vitro XO inhibitory activities for experimental verification, as well as predictions of their anticancer, pharmacokinetic, and toxic properties; oral bioavailability; and endocrine disruption using SwissADMET, PASS, ProTox-II, and Endocrine Disruptome web servers. A total of 12 metabolites, with a majority of flavonoids, were identified. Rutin, quercetin, and luteolin flavonoids demonstrated the highest ranked docking scores of -12.39, -11.15, and -10.43, respectively, while the half-maximal inhibitory concentration (IC50) values of these metabolites against XO activity were 11.35 µM, 11.1 µM, and 21.58 µM, respectively. In addition, SwissADMET generated data related to the physicochemical properties and drug-likeness of the metabolites. Similarly, the PASS, ProTox-II, and Endocrine Disruptome prediction models stated the safe and potential use of these natural compounds. However, in vivo studies are necessary to support the development of the prominent and promising therapeutic use of A. hierochuntica methanolic-leaf-extract-derived metabolites as XO inhibitors for the prevention and treatment of hyperuricemic and gout patients. Furthermore, the predicted findings of the present study open a new paradigm for these extract-derived metabolites by revealing novel oncogenic targets for the potential treatment of human malignancies.

Exploring the mechanism and inhibitory effect of robinin on xanthine oxidase using multi-spectroscopy and molecular dynamics simulation methods

Xanthine oxidase (XOD) is a key enzyme in purine metabolism that is tightly associated with hyperuricemia (HUA). Natural flavonoids can inhibit XOD activity. In this study, the inhibitory activity and mechanism of the novel flavonoid robinin on XOD were analyzed using enzyme inhibition kinetics, multispectral techniques, molecular docking, and molecular dynamics (MD) simulations. Robinin reversibly inhibited the activity of XOD in a mixed competitive manner, with an IC50 value of 31.79 ± 0.15 μg/mL. Moreover, robinin spontaneously binds to a specific site on XOD and effectively quenches its intrinsic fluorescence via a single static quenching mechanism. The combination of XOD and robinin induced secondary structure rearrangement and conformational changes in XOD and prevented the entry of substrates, thus producing a strong inhibitory effect. Molecular docking and MD simulation revealed that robinin mainly binds to XOD through hydrogen bonding and hydrophobic interactions to form more stable complexes with a binding energy of −7.4 kcal/mol. Overall, this study established a theoretical reference for robinin as a promising natural XOD inhibitor for relieving HUA.

Ameliorative action of "daitongxiao" against hyperuricemia includes the "uric acid transporter group".

This study aimed to investigate the potential mechanisms involved in the therapeutic effects of daitongxiao (DTX) on hyperuricemia (HUA). DTX was administered to two animal models of HUA via gavage feeding: HUA quail model (a uricotelic animal with urate oxidase deficiency), treated continuously for 35 days post-HUA induction, and HUA rats (an animal with active urate oxidase), treated continuously for 28days post-HUA induction. HUA was induced in quail by administering a solution of sterile dry yeast powder via gavage feeding, while in rats, it was induced by intragastric gavage feeding of a solution of adenine and ethambutol hydrochloride. DTX improved overall health; increased bodyweight; reduced renal index, serum urate levels, serum xanthine oxidase activity, blood urea nitrogen, and creatinine; and enhanced urinary and fecal uric acid (UA) excretion in these two animal models. The results of hematoxylin and eosin and hexamine silver staining of kidney sections revealed that DTX significantly mitigated HUA-induced renal structural damage and inflammatory response. The results of quantitative real-time polymerase chain reaction, Western blotting, and immunofluorescence analyses revealed that DTX downregulated the renal expression levels of glucose transporter 9 (GLUT9) and upregulated the renal expression levels of organic anion transporters (OAT1 and OAT3) in both HUA models. Thus, the findings of this study suggest that DTX suppresses the progression of HUA by modulating the expression of the UA transporter group members.

FLAVONOIDS FOR ANTI-HYPERURICEMIA: A LITERATURE REVIEW

Background: Hyperuricemia is a condition on the level of uric acid in the blood increases, it is more than 6.0 mg/dL in women and more than 7.0 mg/dL in men and is currently a public health problem because of its increasing prevalence. Hyperuricemia is believed to have contributed to an increased risk of mortality and morbidity associated with various diseases such as metabolic syndrome, kidney disease, cardiovascular disease, etc. Flavonoids in plants can be used to help treat hyperuricemia due to it is believed to have low side effects. Objective: The aim of this article was to review the effect of flavonoids on plants as anti-hyperuricemia. Design: The design used in preparing this manuscript is an integrative review by reviewing articles on the impact of flavonoids as anti-hyperuricemia. Data Sources: Sources of information were obtained from research articles from 2004-2023 which were accessed through PubMed, Scopus, Sciendirect, SpringerLink, and Google Scholar. Review Methods: In the process of selecting articles to ensure the quality of the articles used in preparing this article, the authors used the PRISMA method. Results: In this article, 15 in vivo studies related to the effect of plants containing flavonoids (kaemferol, luteolin, apigenin, rutin quercetin, morin, butein, vitexin, etc.) on reducing uric acid levels by various mechanisms from previous studies. Conclusion: Based on several studies reported that flavonoids have an effect on lowering uric acid levels by inhibiting xanthine oxidase (XO) activity, affecting the expression of uric acid transporters in the kidneys which contribute to the increase of excretion of uric acid in urine.

Elucidating the substance basis and pharmacological mechanism of Fufang Qiling granules in modulating xanthine oxidase for intervention in hyperuricemia

Ethnopharmacological relevanceFufang Qiling granules (FQG), derived from the traditional Qiling Decoction with a longstanding clinical history, is utilized for the treatment of hyperuricemia (HUA). FQG is formulated with a combination of seven Chinese herbs based on the principles of traditional Chinese medicine (TCM) theories. Clinical evidence indicates that FQG exhibits favorable therapeutic effects in reducing uric acid (UA) levels and attenuating renal damage. Aim of this studyTo elucidate the potential active components and pharmacological mechanism of FQG in the treatment of HUA, and to provide an experimental basis for the development of efficient and low-toxicity TCM for HUA treatment. Materials and methodsA HUA rat model induced by potassium oxonate and adenine was established to initially evaluate the hypouricemic effects of FQG. Chemical analyses were conducted using an ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Network pharmacology was used to investigate the active components and mechanism of FQG in the treatment of HUA. Potential Xanthine oxidase (XOD) inhibitors were screened from FQG based on ultrafiltration liquid chromatography and mass spectrometry (UF-LC-MS). Molecular docking, surface plasmon resonance (SPR) and circular dichroism (CD) spectroscopy were applied to validate the interactions between the active components and XOD. ResultsIn comparison to the model group, treatment with FQG significantly decreased serum UA, serum creatinine (CREA), serum blood urea nitrogen (BUN), and liver XOD activity. Additionally, the FQG administration notably ameliorated HUA-induced renal injury in rats. Through the pharmacodynamics of the HUA rat models and network pharmacology, it was found that XOD was a key pathway enzyme in UA metabolism. 18 XOD inhibitors were screened from FQG by UF-LC-MS, and 11 compounds with strong affinity were verified by SPR, molecular docking and CD spectroscopy. ConclusionIn summary, flavonoids, organic acids and saponins may be the active components in FQG that alleviate HUA. The primary mechanism of FQG involves inhibiting XOD enzyme activity in the plasma to reduce UA production, alleviating renal tubular epithelial cell necrosis, tubulointerstitial injury, fibrosis, and urate deposition, ultimately exerting a therapeutic effect on HUA.

The ameliorative and neuroprotective effects of dietary fibre on hyperuricaemia mice: a perspective from microbiome and metabolome.

The effect of single dietary fibre (DF) on lowering uric acid (UA) level has been reported in the literature. However, the potential protective mechanism of DF against potassium oxybate-induced hyperuricaemia (HUA), as modelled by prophylactic administration, remains unclear. The data demonstrate that DF significantly decreased serum and cerebral tissue UA concentrations, inhibited xanthine oxidase expression and activity in the liver and reduced levels of creatinine and urea nitrogen in the serum. Additionally, it mitigated the deposition of amyloid-β in cerebral tissue. Correlation analysis showed that DF modulated the Toll-like receptor 4/NF-κB signalling pathway, attenuating oxidative stress and inflammatory responses in HUA mice. Additionally, DF helps to maintain the composition of the gut microbiota, reducing harmful Desulfovibrio and enriching beneficial Akkermansia and Ruminococcus populations. The results of the faecal metabolomics analysis indicate that DF facilitates the regulation of metabolic pathways involved in oxidative stress and inflammation. These pathways include pyrimidine metabolism, tryptophan metabolism, nucleotide metabolism and vitamin B6 metabolism. Additionally, the study found that DF has a preventive effect on anxiety-like behaviour induced by HUA. In summary, DF shows promise in mitigating HUA and cognitive deficits, primarily by modulating gut microbiota and metabolites.

The impact of chrysanthemi indici flos-enriched flavonoid part on the model of hyperuricemia based on inhibiting synthesis and promoting excretion of uric acid

Ethnopharmacological relevanceIn recent years, in addition to hypertension, hyperglycemia, and hyperlipidemia, the prevalence of hyperuricemia (HUA) has increased considerably. Being the fourth major health risk factor, HUA can affect the kidneys and cardiovascular system. Chrysanthemi Indici Flos is a flavonoid-containing traditional Chinese patent medicine that exhibits a uric acid (UA)-lowering effect. However, the mechanisms underlying Chrysanthemi Indici Flos-enriched flavonoid part (CYM.E) mediated alleviation of HUA remain unelucidated. Aim of the studyThis study aimed to elucidate the efficacy of CYM.E in preventing and treating HUA and its specific effects on UA-related transport proteins, to explore possible mechanism. MethodsThe buddleoside content in CYM.E was determined through high-performance liquid chromatography. HUA was induced in mice models using adenine and potassium oxonate. Subsequently, mice were administered 10 mg/kg allopurinol, and 30, 60, and 90 mg/kg CYM.E to evaluate the effects of CYM.E on the of HUA mice model. Herein, plasma uric acid (UA), creatinine (CR), blood urea nitrogen (BUN), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-c), and low-density lipoprotein cholesterol (LDL-c) contents, along with serum alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activities were measured. Additionally, xanthine oxidase (XOD) and adenosine deaminase (ADA) activities in the liver were determined. The histomorphologies of the liver and kidney tissues were examined through hematoxylin and eosin staining. The messenger RNA (mRNA) expression of facilitated glucose transporter 9 (GLUT9), organic anion transporter (OAT)1, OAT3, and adenosine triphosphate binding cassette subfamily G2 (ABCG2) in the kidney was assessed by real-time quantitative polymerase chain reaction. Furthermore, the expression of urate transporter 1 (URAT1), GLUT9, OAT1, and OAT3 in the kidney, OAT4, and ABCG2 proteins was determined by immunohistochemistry and western blotting. ResultsThe buddleoside content in CYM.E was approximately 32.77%. CYM.E improved body weight and autonomous activity in HUA mice. Additionally, it reduced plasma UA, BUN, and CR levels and serum ALT and AST activities, thus improving hepatic and renal functions, which further reduced the plasma UA content. CYM.E reduced histopathological damage to the kidneys. Furthermore, it lowered plasma TC, TG, and LDL-c levels, thereby improving lipid metabolism disorder. CYM.E administration inhibited hepatic XOD and ADA activities and reduced the mRNA expression of renal GLUT9. CYM.E inhibited the protein expression of renal URAT1, GLUT9, and OAT4, and increased the mRNA and protein expression of renal OAT1, OAT3, and ABCG2. Altogether, these results show that CYM.E could inhibit the production and promote reabsorption of UA and its excretion.

Exploring Asphodelus microcarpus as a source of xanthine oxidase inhibitors: Insights from in silico and in vitro studies

Xanthine oxidase (XO) plays a critical role in purine catabolism, catalyzing the conversion of hypoxanthine to xanthine and xanthine to uric acid, contributing to superoxide anion production. This process is implicated in various human diseases, particularly gout. Traditional XO inhibitors, such as allopurinol and febuxostat, while effective, may present side effects.Our study focuses on Asphodelus microcarpus, a plant renowned for traditional anti-inflammatory uses. Recent investigations into its phenolic-rich flowers, notably abundant in luteolin derivatives, reveal its potential as a natural source of XO inhibitors. In the present research, XO inhibition by an ethanolic flowers extract from A. microcarpus is reported. In silico docking studies have highlighted luteolin derivatives as potential XO inhibitors, and molecular dynamics support that luteolin 7-O-glucoside has the highest binding stability compared to other compounds and controls. In vitro studies confirm that luteolin 7-O-glucoside inhibits XO more effectively than the standard inhibitor allopurinol, with an IC50 value of 4.8 μg/mL compared to 11.5 μg/mL, respectively. These findings underscore the potential therapeutic significance of A. microcarpus in managing conditions related to XO activity. The research contributes valuable insights into the health-promoting properties of A. microcarpus and its potential application in natural medicine, presenting a promising avenue for further exploration in disease management.

Screening and identification of selenium-enriched purine-lowering Lactobacillus plantarum and Lactococcus lactis with high stress tolerance and antioxidant capacity

Hyperuricemia and selenium (Se) deficiency have become world wide health issues, necessitating the development of new technologies for the prevention of hyperuricemia and daily Se supplementation. This study explored a feasible way by providing new lactic acid bacteria (LAB) with both Se-enrichment and purine-lowering functions. The expected LAB were firstly screened out and identified from fermented tea grown in seleniferous areas by a five-step screening method. Among thirty-six candidate strains exhibiting superior Se-enriched ability, seven of them showed excellent uric acid absorption, in vitro xanthine oxidase and uric acid oxidase activities. In particular, Lactobacillus plantarum L123 and Lactococcus lactis L126 degraded inosine and guanosine to hypoxanthine and guanine with degradation rates of 100%, 96.88% ± 0.33% and 93.61% ± 1.06%, 81.15% ± 1.83%, respectively, and metabolized the substrates of hypoxanthine, xanthine and uric acid into the final product allantoin. Their clearing rates of three free radicals (DPPH, •OH and ABTS+• free radical) were higher than 94% after reaction for 30 min. More than 85% of L123 and 50% of L126 could survive at pH 1.5 for 3 h, while their Se-enriched counterparts showed more enhanced acid tolerance. Both L123 and L126 with or without Se-enrichment tolerated 0.5% bile salt with survival rates above 80%. These Novel LAB provide a promising avenue for the development of new health food and pharmaceutical products that combine Se supplementation with hyperuricemia treatment.

Mechanism of flavonoids in the treatment of gouty arthritis (Review).

The present review expounds the advancements in the application and mechanisms of flavonoids in gouty arthritis, highlighting their significance in managing the disease. Gouty arthritis is among the most common and severe inflammatory diseases, caused by hyperuricemia and the deposition of sodium urate crystals in the joints and surrounding tissues, posing a serious threat to human life and health. Flavonoids, extracted from various herbs, have attracted significant attention due to their efficacy in improving gouty arthritis. The present study systematically reviews the in vivo studies and in vitro animal studies on flavonoids from herbal medicines for the treatment of gouty arthritis that have been previously published in the PubMed, ScienceDirect, Google Scholar and China National Knowledge Infrastructure databases between 2000 and 2023. The review of the literature indicated that flavonoids can improve gouty arthritis through multiple mechanisms. These include lowering xanthine oxidase activity, inhibiting uric acid (UA) synthesis, regulating UA transporters to promote UA excretion, reducing the inflammatory response and improving oxidative stress. These mechanisms predominantly involve regulating the NOD‑like receptor 3 inflammasome, the Toll‑like receptor 4/myeloid differentiation factor 88/nuclear factor‑κB signaling pathway, and the levels of UA transporter proteins, namely recombinant urate transporter 1, glucose transporter 9, organic anion transporter (OAT)1 and OAT3. Various flavonoids used in traditional Chinese medicine hold therapeutic promise for gouty arthritis and are anticipated to pave the way for novel pharmaceuticals and clinical applications.

Effects of Smilax China L. extracts on Hyperuricemia chicken model via inhibiting xanthine oxidase activity

Hyperuricemia (HUA) is a metabolic disorder caused by excessive production of uric acid (UA) or impaired uric acid metabolism. Smilax China L. has a wide range of pharmacological activities such as immunomodulatory, anti-inflammatory, and antioxidant. Its roots and rhizomes have been widely used for the treatment of HUA. However, its mechanisms for treating HUA and reducing renal impairment have not been fully elucidated. In the present study, we evaluated the effect of Smilax China L. extract (SC) on UA metabolism and further explored its mechanism of action by feeding a high-calcium and high-protein diet to chickens to induce a model of HUA in chickens. SC significantly reduced serum UA levels and improved renal function in hyperuricemic chickens. Meanwhile, SC was able to inhibit the activity of xanthine oxidase (XOD) in vivo and in vitro, reducing the production of uric acid. In addition, SC was able to increase the expression of Breast Cancer Resistance Protein (BCRP) in the kidney and ileum and increase uric acid excretion. Therefore, our results suggest that SC may be a candidate for anti-hyperuricemia.

Investigating the effects of rare ginsenosides on hyperuricemia and associated sperm damage via nontargeted metabolomics and gut microbiota

Ethnopharmacological relevanceIn ancient times, ginseng was used for hyperuricemia treatment as described in the classic traditional Chinese medical text Shang Han Lun. Recent studies have shown that common ginsenosides and rare ginsenosides (RGS) are the main active compounds in ginseng. RGS have higher activity and are less studied in the treatment of hyperuricemia. Aim of the studyTo determine whether RGS prevents and ameliorates potassium oxonate(PO)-induced hyperuricemia and concomitant spermatozoa damage in mice and the possible underlying mechanisms. Materials and methodsPotassium oxonate (PO, 300 mg/kg) induced hyperuricemia in mice via the oral administration of RGS (50, 100, or 200 mg/kg) or allopurinol (ALL, 5 mg/kg) for 35 days. Uric acid (UA) and xanthine oxidase (XO) levels were measured to assess the degree of histopathological damage in the liver, kidney, and testis, and renal creatinine (CRE), urea nitrogen (BUN), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and inflammatory factor (IL-1β) levels were measured to calculate the sperm density. Mechanisms were also explored based on blood and urine metabolomics and the gut microbiota. ResultsIn this study, we demonstrated that RGS containing Rg3, Rk1, Rg6, and Rg5 could reduce serum UA levels, inhibit serum and hepatic XO activity, reduce renal CRE and BUN levels, further restore renal SOD and GSH activities, reduce the accumulation of MDA in the kidneys, and attenuate the production of renal IL-1β. RGS was able to restore sperm density. Metabolomic analysis revealed that RGS improved sphingolipid metabolism, pyrimidine metabolism, and other metabolic pathways. 16S rDNA sequencing revealed that RGS could increase gut microbial diversity, restore the Firmicutes/Bacteroidetes (F/B) ratio, and adjust the intestinal microbial balance. Spearman's correlation analysis revealed a correlation between differentially metabolites and the gut microbiota. Lactobacillus and Akkermansia are the core genera. ConclusionRGS can be a candidate for the prevention and amelioration of hyperuricemia and concomitant sperm damage. Its mechanism of action is closely related to sphingolipid metabolism, pyrimidine metabolism, and the modulation of gut microbiota, such as Lactobacillus and Akkermansia.

Inhibitory Activity of Quercetin, Rutin, and Hyperoside against Xanthine Oxidase: Kinetics, Fluorescence, and Molecular Docking.

Quercetin (Qc), rutin (Ru), and hyperoside (Hyp) are three common polyphenols widely distributed in the plant kingdom. This study explored the inhibition and mechanisms of Qc, Ru, and Hyp against xanthine oxidase (XOD) by enzyme kinetic analysis, fluorescence analysis, and molecular docking. The inhibitory activities of the three polyphenols on XOD showed the following trend: quercetin > hyperoside > rutin, with IC50 values of 8.327 ± 0.36 µmol/L, 35.215 ± 0.4 µmol/L and 60.811 ± 0.19 µmol/L, respectively. All three polyphenols inhibited xanthine oxidase activity in a mixed-competitive manner. Synchronous fluorescence results demonstrated that three polyphenols binding to XOD were spontaneous and showed static quenching. The binding of the three polyphenols to XOD is mainly driven by hydrogen bonding and van der Waals forces, resulting in the formation of an XOD-XA complex with only one affinity binding site. The binding sites of the three RSFQ phenolic compounds are close to those of tryptophan. Molecular docking showed that all three polyphenols enter the active pocket of XOD and maintain the stability of the complex through hydrogen bonding, hydrophobic interaction, and van der Waals forces. The results provide a theoretical basis for quercetin, rutin, and hyperoside to be used as function factors to prevent hyperuricemia.

A dual-mode sensing system for xanthine oxidase detection based on nitrogen-doped carbon dots and iron-cobalt oxide nanosheets

As one of the existing forms of xanthine oxidoreductase, xanthine oxidase (XOD) exists in many human tissues, and the overactivity of XOD will result in some serious illnesses such as gout and diabetes. Herein, a novel dual-signal sensing system for XOD activity determination was proposed based on fluorescent nitrogen-doped carbon dots (N-CDs) and iron-cobalt oxide nanosheets (FeCo-ONSs). XOD has the ability to oxidise xanthine to uric acid while also producing H2O2. As a sort of peroxidase-like enzyme, FeCo-ONSs can catalyze H2O2 to produce reactive oxygen species (ROS). And N, N-Diethyl-p-phenylenediamine sulfate salt (DPD) was oxidized to DPDox that serves as a chromogenic substrate in the presence of ROS, causing the colorless solution to turn pink. DPDox exhibits two characteristic absorption peaks at 551 nm and 512 nm and it can also efficiently quench the fluorescence emission of N-CDs at 500 nm. Therefore, the fluorometric and colorimetric dual-channel sensing platform was established to assay XOD with the lower LOD of 0.00522 mU/mL and 0.0177 mU/mL, respectively. Additionally, the dual-output strategy was found to be applicable to the quantitative analysis of XOD in serum samples with good reliability and selectivity.

Effect of Lacticaseibacillus rhamnosus L08 fermentation on xanthine oxidase inhibitory activity and flavour profile of honeysuckle (Lonicera japonica thunb.)

Xanthine oxidase (XOD) catalyses the oxidation of hypoxanthine and xanthine to uric acid, and inhibition of its activity has become the main strategy to reduce uric acid production. Honeysuckle (HON) which is rich in polyphenols potentially has the capacity to inhibit XOD activity. However, it carries the bitter and astringent flavor as well as many traditional Chinese medicines, along with that most of the polyphenols in HON exist in bound form, the exploitation and application of HON in food is limited. In this study, we investigated the effects of Lacticaseibacillus rhamnosus L08 fermentation on the bioactive components, XOD inhibitory activity and flavour characteristics of HON. The results showed that the XOD inhibitory activity was increased by 2.08 times after 96 h of fermentation. It was demonstrated that the increase in the total flavonoid content and total phenol content was the main reason for the enhancement of the fermentation solution's XOD inhibitory activity and antioxidant activity. Moreover, the fermentation also enriched the composition of volatile components of HON and reduced levels of undesirable flavour substances, which made the usage of fermented HON as functional food or in pharmaceutical use feasible and applicable.

Beneficial Effects of Mild Hyperuricemia in Salt-Sensitive Hypertension

Hyperuricemia (HrU) or increased plasma uric acid (UA) is associated with worsening hypertension (HTN) and kidney damage. Paradoxically, UA is also known to be an endogenous antioxidant. Some studies suggest that only HrU with crystals, but not asymptomatic HrU promotes the progression of these diseases. We hypothesized that mild asymptomatic HrU is beneficial in controlling the progression of salt-sensitive (SS) HTN. Due to sex differences in urate handling and SS HTN, we used both male and female Dahl SS rats in this study. Radiotelemetry was used to measure blood pressure and various approaches, including RNA-Seq, were employed to assess kidney injury and identify potential molecular mechanisms. Mild HrU was induced using 2% oxonic acid in the diet, a uricase inhibitor that prevents the breakdown of UA further into more soluble allantoin. Groups: 1-2) male and female 4% NaCl high salt (HS) diet; 3-4) male and female HS + 2% oxonic acid (HS/oxo) diet. After 3 weeks, in response to oxonic acid supplementation, both sexes showed a significant increase of UA in plasma compared to their respective HS-only controls (Males: 0.63 ±0.07 vs. 2.17 ±0.34; Females 0.78 ±0.15 vs. 2.04 ±0.35 mg/dl, HS vs. HS/oxo). Interestingly, only male HS/oxo rats showed a significant increase in uricosuria (Males: 0.23 ±0.03 vs. 0.45 ±0.06; Femaels: 0.26 ±0.06 vs. 0.26 ±0.001 UA/Cre, HS vs. HS/oxo). Moreover, the mild HrU was associated with a significant attenuation of the progression and magnitude of the mean arterial pressure in male but not female rats (Males: 157 ±3 vs. 136 ±3; Females: 155 ±6 vs. 154 ±5 mmHg, HS vs. HS/oxo). Xanthine oxidase (XO) is one of the enzymes that produce UA, and its activity has been shown to affect HTN as well. Therefore, we examined the level of XO activity in the plasma after the treatment. While there was no difference in the activity based on the diet within each sex, females had significantly lower levels of XO activity compared to males in each of the diets. To further investigate the beneficial phenotype seen in male rats, we evaluate changes in the progression of renal pathology. The HS/oxo group compared to the HS group had a lower kidney weight/body weight ratio and lower protein cast accumulation, indicating lower kidney damage. RNA-Seq analysis showed that the attenuated HTN phenotype was associated with an increased expression in Mas1 (MAS receptor), Klk-1 (Kallikrein-1), and Pcsk6 (PCSK6 enzyme) which can all lead to the activation of different vasodilatory pathways. Our study showed that in male but not female Dahl SS rats, asymptomatic mild HrU accompanied by hyperuricosuria ameliorates the progression of SS HTN and protects kidneys from further damage. This work is supported by the American Society of Nephrology Ben J. Lipps Research Fellowship Program (Dimitrios G. Oreopoulos Research Fellowship Award to L.V.D.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Depletion of hepatic glutathione and adenosine by glucocorticoid exposure in Wistar rats is pregnancy-independent

Liver diseases have gained increasing attention due to their substantial impact on health, independently as well as in association with cardio-metabolic disorders. Studies have suggested that glutathione and adenosine assist in providing protection against oxidative stress and inflammation while glucocorticoid (GC) therapy has been associated with chronic inflammatory disorders, even in pregnancy. The implications of Glucocorticoid exposure on maternal health and fetal growth is a concern, however, the possible role of glutathione and adenosine has not been thoroughly investigated. The study therefore hypothesize that exposure to glucocorticoids leads to depletion of hepatic glutathione and adenosine levels, contributing to oxidative stress and tissue injury. Additionally, we aim to investigate whether the effects of glucocorticoids on hepatic health are pregnancy dependent in female rats. Twelve Pregnant and twelve age-matched non-pregnant rats were used for this study; an exogenous administration of glucocorticoid (Dex: 0.2 mg/kg) or vehicle (po) was administered to six pregnant and six non-pregnant rats from gestational day 14 to 19 or for a period of 6 days respectively. Data obtained showed that GC exposure led to a decrease in hepatic glucose-6-phosphate dehydrogenase, glutathione peroxidase, GSH/GSSG ratio and adenosine content in both pregnant and non-pregnant rats. In addition, increased activities of adenosine deaminase and xanthine oxidase, along with increased production of uric acid and increased levels of lactate dehydrogenase, aspartate aminotransferase, alanine transferase, alkaline phosphatase and gamma-glutamyl transferase were observed. In summary, the study indicates that GC-induced liver damage is underlined by depleted hepatic adenosine and glutathione levels as well as elevated markers of tissue inflammation and/or injury. Furthermore, the findings suggest that the effects of GC exposure on hepatic health are pregnancy independent.

Inhibition of xanthine oxidase alleviated pancreatic necrosis via HIF-1α-regulated LDHA and NLRP3 signaling pathway in acute pancreatitis

Acute pancreatitis (AP) is a potentially fatal condition with no targeted treatment options. Although inhibiting xanthine oxidase (XO) in the treatment of AP has been studied in several experimental models and clinical trials, whether XO is a target of AP and what its the main mechanism of action is remains unclear. Here, we aimed to re-evaluate whether XO is a target aggravating AP other than merely generating reactive oxygen species that trigger AP. We first revealed that XO expression and enzyme activity were significantly elevated in the serum and pancreas of necrotizing AP models. We also found that allopurinol and febuxostat, as purine-like and non-purine XO inhibitors, respectively, exhibited protective effects against pancreatic acinar cell death in vitro and pancreatic damage in vivo at different doses and treatment time points. Moreover, we observed that conditional Xdh overexpression aggravated pancreatic necrosis and severity. Further mechanism analysis showed that XO inhibition restored the hypoxia-inducible factor 1-alpha (HIF-1α)-regulated lactate dehydrogenase A (LDHA) and NOD-like receptor family pyrin domain containing 3 (NLRP3) signaling pathways and reduced the enrichment of 13C6-glucose to 13C3-lactate. Lastly, we observed that clinical circulatory XO activity was significantly elevated in severe cases and correlated with C-reactive protein levels, while pancreatic XO and urate were also increased in severe AP patients. These results together indicated that proper inhibition of XO might be a promising therapeutic strategy for alleviating pancreatic necrosis and preventing progression of severe AP by downregulating HIF-1α-mediated LDHA and NLRP3 signaling pathways.

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.