Potassium Oxonate-induced Hyperuricemic Rats Research Articles

Fatty Acid-Rich Extract from Holothuria atra for Hyperuricemia via Expressions Modulation of GLUT9a and GLUT9b in Rat Model.

An edible sea cucumber Holothuria atra has been hypothesized to have medicinal benefits against hyperuricemia owing to its bioactive compounds, including mono- and poly-unsaturated fatty acids. Herein, we aimed to investigate the fatty acids-rich extract produced from H. atra to treat hyperuricemic rats (Rattus novergicus). The extraction was carried out using n-hexane solvent and then administered to potassium oxonate-induced hyperuricemic rats, with allopurinol acting as a positive control. The extract (50, 100, 150 mg/kg body weight) and allopurinol (10 mg/kg) were administered QD through an oral route using a nasogastric tube. Serum uric acid, creatinine, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and blood urea nitrogen of the abdominal aortic blood were investigated. Our results suggested that the extract was rich in polyunsaturated (arachidonic acid) and monounsaturated fatty acids (oleic acid), in which its administration of 150 mg/kg could significantly reduce serum uric acid (p < 0.001), AST (p = 0.001), and ALT (p = 0.0302). The anti-hyperuricemic activity could be associated with the modulation of GLUT9 by the H. atra extract. In conclusion, the n-hexane extract from H. atra is a potential serum uric acid-lowering agent targeting GLUT9, where further investigations are crucially warranted.

Ethanolic Extract from Limonia acidissima L. Fruit Attenuates Serum Uric Acid Level via URAT1 in Potassium Oxonate-Induced Hyperuricemic Rats.

A high prevalence of hyperuricemia among adult and older adult populations has intrigued the development of its therapy based on natural products. Our objective was to investigate the antihyperuricemic activity of the natural product from Limonia acidissima L. in vivo. The extract was obtained through the maceration of L. acidissima fruits using an ethanolic solvent and was tested for its antihyperuricemic activity against potassium oxonate-induced hyperuricemic rats. Serum uric acid, creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and blood urea nitrogen (BUN) were observed before and after the treatment. Expression of urate transporter 1 (URAT1) was also measured using a quantitative polymerase chain reaction. Antioxidant activity based on a 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay, along with total phenolic content (TPC) and total flavonoid content (TFC), were measured. Herein, we present the evidence of the serum uric acid lowering effect of the L. acidissima fruit extract along with improved AST and ALT (p < 0.01). The reduction of serum uric acid was in accordance with the decreasing trend of URAT1 (1.02 ± 0.05-fold change in the 200 mg group), except in a group treated with 400 mg/kg body weight extract. At the same time, BUN increased significantly in the 400 mg group (from 17.60 ± 3.286 to 22.80 ± 3.564 mg/dL, p = 0.007), suggesting the renal toxicity of the concentration. The IC50 for DPPH inhibition was 0.14 ± 0.02 mg/L with TPC and TFC of 143.9 ± 5.24 mg GAE/g extract and 390.2 ± 3.66 mg QE/g extract, respectively. Further studies should be carried out to prove this correlation along with the safe concentration range of the extract.

Reduction of the Plasma Uric Acid Level in Potassium Oxoate-Induced Hyperuricemic Rats by Heat-Concentrated Prunus mume Fruit Extract Containing Three Chlorogenic Acid Isomers

Gout is a common rheumatic disease, resulting from hyperuricemia. Prunus mume fruit extract, after being heat-concentrated named mei extract, was empirically found to reduce the risk of gout. While neochlorogenic acid was found as the predominant phenolic compound in the fresh juice of Prunus mume, neochlorogenic acid, chlorogenic acid, and cryptogenic acid were detected as the major phenolic compounds in the mei extract. In vitro testing showed that all the three chlorogenic acid isomers exhibited comparable inhibitory activities on xanthine oxidase. The hypouricemic effects of the mei extract were evaluated in potassium oxonate-induced hyperuricemic rats. Oral administrations of the mei extract significantly reduced the plasma uric acid level in hyperuricemic rats, but did not elevate the urinary uric acid level. The results provide in vivo evidence for the anti-hyperuricemic effects of mei extract for the first time, rationalize its therapeutic usage for the treatment of hyperuricemia and gout, and propose chlorogenic acid isomers as the active ingredients. Mei extract seems to be a potential natural functional food product.

Flavonoid extract of saffron by-product alleviates hyperuricemia via inhibiting xanthine oxidase and modulating gut microbiota.

Hyperuricemia was associated with the overproduction or inadequate excretion of uric acid, while its association with gut microbiota has emerged although few studies were focused on it. Previously, we have reported a flavonoid extract from saffron floral bio-residues lowered uric acid in potassium oxonate-induced hyperuricemic mice. In this study, the impacts of the flavonoid extract on potassium oxonate-induced hyperuricemic rats were evaluated through its effects on serum, renal, intestinal uric acid, and xanthine oxidase activity. At the same time, the microbial and metabolic features of the flavonoid extract against hyperuricemia were explored using 16S rRNA sequencing techniques and serum metabolomics, respectively. According to the results, the flavonoid extract lowered serum and intestinal uric acid levels in hyperuricemic rats without kidney damage. On the one hand, it inhibited serum and liver xanthine oxidase activities and down-regulated the expression of hepatic xanthine oxidase. On the other hand, it ameliorated the hyperuricemia-associated gut microbiota dysbiosis and alleviated the disturbance of serum metabolome, especially of lipid and amino acid metabolites. The results suggested that the flavonoid extract of saffron floral bio-residues exerts a potent antihyperuricemia effect by inhibiting xanthine oxidase to decrease uric acid production and modulating gut microbiota related to host metabolism.

Hypouricemic Effect of Submerged Culture of Ganoderma lucidum in Potassium Oxonate-Induced Hyperuricemic Rats.

Hyperuricemia is a disease caused by a high level of uric acid in the blood. It is an important factor for gout and may be linked to renal and hepatic failure. The objective of this study was to investigate the hypouricemic effects of submerged culture of Ganoderma lucidum. The lyophilized powder of mycelium (GM) and extracellular polysaccharides (GP) of the G. lucidum submerged culture were prepared. The contents of hypouricemic components, including phenolics and flavonoids, in GM (34.33 ± 0.41 mg/g and 0.32 ± 0.01 mg/g) were higher than that in GP (20.52 ± 1.49 mg/g and not detected). The hypouricemic effect of GM and GP was evaluated in potassium oxonate (PO)-injected rats. The average food intake (23.3 ± 1.2 g/day) and body weight (355.7 ± 28.0 g) were decreased, and the serum level of uric acid (5.56 ± 0.41 mg/dL) was increased in PO-injected rats. However, allopurinol (10 mg/kg b.w.) or GM treatment (200 or 400 mg/kg b.w) improved food intake (26.3 ± 2.7 g/day) and reduced the level of uric acid (4.45 ± 0.46 mg/dL). In parallel, the activity of hepatic xanthine oxidase (XOD) was downregulated from 841.29 ± 299.58 μU/mg protein to 540.80 ± 199.20 μU/mg protein. Moreover, GM and GP (200 or 400 mg/kg b.w) alleviated the level of blood urea nitrogen (BUN) from 30.49 ± 4.71 to 21.16 ± 4.25 mg/dL. GP treatment also diminished the level of alanine transaminase (ALT) from 52.63 ± 18.82 to 27.35 ±6.82 U/L. These results clearly demonstrated the hypouricemic effect of submerged G. lucidum culture and their potential against hyperuricemia-associated renal and hepatic damage. GM was more potent to alleviate hyperuricemia, and GP was more potent to improve renal and hepatic function.

Anti-Hyperuricemic Effect of Ethyl Acetate Sub-Fractions from Chrysanthemum morifolium Ramat. Dried Flowers on Potassium Oxonate-Induced Hyperuricemic Rats

Xanthine oxidase (XO) plays an important role in purine degradation in humans. The study aimed to determine the XO inhibitory potential of Chrysanthemum morifolium dried flower ethyl acetate sub-fractions and its anti-hyperuricemic effect in rat models. Bioassay-guided fractionation based on XO inhibitory assay was employed to obtain bioactive fractions and sub-fractions. In vitro cytotoxicity and cellular antioxidant capacity of the sub-fraction and its mode of XO inhibition were also investigated. The anti-hyperuricemic effect of the bioactive sub-fraction was investigated using rat models via oral consumption, and followed by an XO mRNA gene expression study. The compounds in the bioactive sub-fractions were identified putatively using HPLC-Q-TOF-MS/MS. Ethyl acetate (EtOAc) fraction exhibited the highest XO inhibition among the fractions. It was further fractionated into 15 sub-fractions. F10 exhibited high XO inhibitory activity, cellular pro-proliferative effect, and intracellular antioxidant activity among the sub-fractions tested. This sub-fraction was non-cytotoxic at 0.1–10 µg/mL, and very effective in lowering serum and urine uric acid level in rat models upon oral consumption. A total of 26 known compounds were identified and seven unknown compounds were detected via HPLC-Q-TOF–MS/MS analysis. The possible mechanisms contributing to the anti-hyperuricemic effect were suggested to be the non-competitive inhibition of XO enzyme, XO gene expression down-regulation, and the enhancement of uric acid excretion.

Effect of Apium Graveolens (Celery) Seed Extract on Serum Uric Acid Level of Hyperuricemic Rats and its Comparison with Allopurinol

Background: Plant derived medicines are widely used in traditional culture all over the world. Objectives: To determine the effect of Celery Seed Extract (CSE) on uric acid levels in hyperuricemic rats and to compare the effect of allopurinol and CSE. Methods: It was an animal experimental research study. Group A served as negative control whereas Group B served as positive control. CSE was given orally to three groups of rats (C, D, and E). One hour prior to administration of CSE; potassium oxonate was injected intraperitoneally in all groups except negative control to induce hyperuricemia. Similarly, group F was given allopurinol one hour after injection of potassium oxonate. Blood samples were collected for uric acid estimation. Results: It was found that administration of both CSE (group C, D, E) and allopurinol (group F) significantly lowered serum uric acid levels (p&lt;0.001) as compared to positive control (group B). Serum uric acid lowering effect of both drugs CSE and allopurinol was found to be statistically significant on day 3rd and day 7th and was almost comparable. Conclusions: Celery seed extract significantly reduces serum uric acid levels in potassium oxonate-induced hyperuricemic rats and its uric acid lowering effect was comparable with that of allopurinol.

Identifying mechanisms underlying the amelioration effect of Chrysanthemum morifolium Ramat. 'Boju' extract on hyperuricemia using biochemical characterization and UPLC-ESI-QTOF/MS-based metabolomics.

This study was aimed at evaluating the prospect of edible chrysanthemum extract as a potential substance for the prevention and treatment of hyperuricemia. Chrysanthemum morifolium Ramat. 'Boju' extract (CBE), which had the strongest xanthine oxidase inhibitory activity, showed a significant hypouricemic effect on potassium oxonate-induced hyperuricemic rats through inhibiting serum xanthine oxidase activity, regulating renal uric acid transport-related protein (ABCG2, URAT1 and GLUT9) expression and blood lipid levels, and protecting renal function. Serum metabolomics based on UPLC-ESI-QTOF/MS was used to illustrate mechanisms underlying the amelioration effect of CBE on hyperuricemia. A total of 35 potential biomarkers were identified. CBE prevented the pathological process of hyperuricemia by regulating 16/17 biomarkers associated with tryptophan, sphingolipid, glycerophospholipid and arachidonic acid metabolisms. CBE could alleviate hyperuricemia-related diseases including chronic kidney disease, hyperlipidemia and inflammation via reducing indoxyl sulfate, lysophosphatidylcholines and arachidonic acid levels, exhibiting its applicability and superiority in the treatment of hyperuricemia.

Effects of Toona sinensis Leaf Extract and Its Chemical Constituents on Xanthine Oxidase Activity and Serum Uric Acid Levels in Potassium Oxonate-Induced Hyperuricemic Rats.

Toona sinensis leaf is used as a seasonal vegetable in Korea. A 70% ethanol extract of these leaves exhibited potent xanthine oxidase (XO) inhibition, with a 50% inhibitory concentration (IC50) of 78.4 µM. To investigate the compounds responsible for this effect, bioassay-guided purification led to the isolation of five constituents, identified as quercetin-3-O-rutinoside, quercetin-3-O-β-d-glucopyranoside, 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranose (compound 3), quercetin-3-O-α-l-rhamnopyranoside, and kaempferol-3-O-α-l-rhamnopyranoside. Compound 3 showed the most potent inhibition of XO, with an IC50 of 2.8 µM. This was similar to that of allopurinol (IC50 = 2.3 µM), which is used clinically to treat hyperuricemia. Kinetic analyses found that compound 3 was a reversible noncompetitive XO inhibitor. In vivo, the T. sinensis leaf extract (300 mg/kg), or compound 3 (40 mg/kg), significantly decreased serum uric acid levels in rats with potassium oxonate-induced hyperuricemia. Furthermore, ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis identified a high level of compound 3 in the leaf extract. These findings suggest that T. sinensis leaves could be developed to produce nutraceutical preparations.

XANTHINE OXIDASE INHIBITORY, ANTIHYPERURICEMIC, ANTI-INFLAMMATORY, ANTINOCICEPTIVE ACTIVITY OF α-LIPOIC ACID IN GOUTY ARTHRITIS MODEL

Objective: The current study was carried out to investigate the xanthine oxidase inhibitory, antihyperuricemic, anti-inflammatory, and antinociception activity of α-lipoic acid (LA) in gouty model of rats.Methods: Enzyme assay was done using bovine milk xanthine oxidase (XO). The XO inhibitory activity in vitro was performed using different doses of α-LA, and the degree of XO inhibition was expressed as IC50. The antihyperuricemic activity of α-LA was tested in the potassium oxonate-induced hyperuricemic rats for 7 consecutive days of oral treatment of 10, 25, and 50 mg/kg doses. The anti-inflammatory activity was achieved through monosodium urate crystal-induced inflammation hind paw model in mice. The antinociception effects of α-LA were explored using both of writhings induced by acetic acid test and hot plate test.Results: The study results revealed that the α-LA has a potent activity of XO inhibition with IC50 = 2.93 μg/mL. Furthermore, these results showed that all doses of α-LA were able to significant reduce of each the following: Serum uric acid levels in the hyperuricemic rats, hind paw thickness of mice at all periods of time assessment, and writhings number in the acetic acid-induced writhing test, while, the same doses significantly increased the reaction latency in mice at hot plate test.Conclusion: The α-LA showed a significant effect on the evaluated models, and therefore it may be a promising agent for the treatment of gout since it possesses XO inhibitory, antihyperuricemic, anti-inflammatory, and antinociception activity.

In vivo anti-hyperuricemic and xanthine oxidase inhibitory properties of tuna protein hydrolysates and its isolated fractions

This study follows recent attempts to discover natural xanthine oxidase (XO) inhibitors from foods, focusing herein on under-researched fish proteins. The anti-hyperuricemic function of tuna flesh hydrolysate (TPH) produced using Alcalase 2.4L was confirmed in potassium oxonate-induced hyperuricemic rats. TPH was separated using 80 wt% aqueous ethanol. The ethanol-soluble fraction (ESF) abundant in small peptides (<1000 Da) afforded the highest XO inhibition. Separation of ESF by Sephadex G-15 and UPLC/MS/MS revealed 13 di-/tri-peptides (12 are newly identified XO inhibitors). Their XO inhibitory activities were assessed using corresponding synthetic peptides via an improved HPLC method. Results indicate that Phe-containing peptides were more potent XO inhibitors than Trp-containing peptides, with Phe-His having the highest XO inhibitory activity (IC50 = 25.7 mM). Molecular docking studies revealed the importance of two hydrogen bonds and one π-π stacking interaction with Phe-914 in XO for XO-peptide inhibitor binding. Phe-containing di-/tri-peptides could be potent XO inhibitors against hyperuricemia.

Hypouricemic and Nephroprotective Effects of an Active Fraction from Polyrhachis Vicina Roger On Potassium Oxonate-Induced Hyperuricemia in Rats

Background/Aims: The objective of this study is to evaluate the hypouricemic and nephroprotective effects of an active fraction from Polyrhachis vicina Roger (AFPR) in potassium oxonate-induced hyperuricemic rats. Methods: Hyperuricemia was induced by potassium oxonate in male rats. AFPR was orally administered to hyperuricemic rats for 12 consecutive weeks. Serum, liver and kidney samples were collected for effects and mechanism analysis. The levels of serum uric acid (SUA) were measured by the phosphotungstic acid method, xanthine oxidase (XOD) activity in the hepatic and serum samples were measured by ultraviolet spectrophotometry, serum levels of interleukin-1 (IL-1β), interleukin-1 (IL-6) and tumor necrosis factor-α (TNF-α) were measured by ELISA, the levels of serum creatinine (SCr), blood urea nitrogen (BUN), super oxide dismutase (SOD) and malondialdehyde (MDA) in serum were determined by colorimetric method. Protein expression of renal URAT1, GLUT9, and OAT1 were analyzed by Western blot. Results: AFPR significantly decreased the levels of SUA, serum and hepatic XOD, SCr, BUN, and MDA as well as increased SOD. In addition, AFPR treatment significantly reduced the levels of proinflammatory cytokines in serum, including IL-1β, IL-6 and TNF-α. Moreover, we found the significant decrease in protein expression of URAT1 and GLUT9, and the significant increase in protein expression of OAT1 in the kidney in AFPR treated groups compared to the model groups of hyperuricemia. Conclusion: These findings suggest that AFPR has anti-hyperuricemic activity attributed to the inhibition of uric acid generation in the liver and probably to the enhancement of urate excretion in the kidney, and possess nephroprotective effect in hyperuricemic rats due to its anti-inflammatory and antioxidant activities.

Hypouricemic Effect of Ethanol Extract of Aster glehni Leaves in Potassium Oxonate-Induced Hyperuricemic Rats.

The prevalence of gout is increasing worldwide, and control of serum uric acid level has been regarded as one of the therapeutic methods for gout. Inhibition of xanthine oxidase (XO) activity which can oxidize hypoxanthine to uric acid has been commonly proposed to decrease serum uric acid level. The aim of this study was to demonstrate the hypouricemic effect of ethanol extract of Aster glehni leaves (EAG) by in vitro and in vivo study in potassium oxonate (PO)-induced hyperuricemic rats. EAG possessed 132.5 ± 6.8 mg QE/g of total flavonoid and showed antioxidant activity. EAG showed in vitro and in vivo inhibitory activity against XO and significantly decreased serum uric acid level in PO-induced hyperuricemic rats without liver toxicity. These results show that EAG significantly attenuates hyperuricemia by inhibiting XO activity, which resulted in the decrease of serum uric acid level. Therefore, EAG might possess a potential therapeutic ability for improving gout.

Identification and characterization of a potent and selective inhibitor of human urate transporter 1.

Selective inhibitors of human urate transporter 1 (hURAT1) are considered to be effective treatment for hyperuricemia and gout, which can reduce the reabsorption of more than 90% of uric acid in the proximal tubule of the kidney. We aimed to design and synthesize a more potent hURAT1 based on the structure of Lesinurad (LU), which was reported to lower uric acid levels with IC50 value of hURAT1 (about 60μM). A cell model was conducted and characterized via Real-time qRCR and Western blot. We synthesized and identified a new midazole analogue of LU. Cells stably-expressing hURAT1 or human organic anion transporter 1 (hOAT1) were used in the [14C] urate or 6-carboxyfluorescein (6-CF) uptake assays to test the activities of the newly synthesized compound. The uric acid lowering effects of LU and LUM and their effects on urea nitrogen and creatinine in potassium oxonate-induced hyperuricemic rats were analyzed. The [14C] Urate uptake assay using hURAT1 stably transfected MDCK cells indicated that LUM was more potent than LU against hURAT1, with IC50 values of 3.22μM and 65.47μM, respectively. LU and LUM also effectively suppressed hOAT1-mediated 6-CF uptake, and the IC50 hURAT1/IC50 hOAT1 of LU and LUM was1.49 and 0.35 respectively, indicating a better selectivity for LUM than LU. In vivo, LUM-Na (40mg/kg) showed more potent activity in reducing serum uric acid levels in potassium oxonate-induced hyperuricemic rats, compared to similar doses of LU-Na. LUM was demonstrated to be as potent a uricosuric drug as LU.

Polydatin attenuates potassium oxonate-induced hyperuricemia and kidney inflammation by inhibiting NF-κB/NLRP3 inflammasome activation via the AMPK/SIRT1 pathway.

This study was designed to investigate the effects of polydatin (PLD) on potassium oxonate-induced hyperuricemic rats. Hyperuricemic rats were treated with potassium oxonate (250 mg kg-1) intragastrically for 7 days, and polydatin (25, 50 mg kg-1) or allopurinol (5 mg kg-1) was administered to the rats 1 h after the potassium oxonate exposure. Polydatin administration decreased the levels of uric acid and creatinine in serum and urine, leading to inhibition of pro-inflammatory cytokine production in serum and kidney. Western blot analyses illustrated that polydatin down-regulated the translocation of NF-κB p65, the degradation of IκBα, and the protein levels of inflammasome components (NLRP3, ASC, and caspase-1), which led to reduced IL-1β secretion. Notably, polydatin treatment activated AMP kinase (AMPK) protein and increased SIRT1 expression. Taken together, polydatin might be a promising agent for gouty treatment to inhibit renal NF-κB/NLRP3 inflammasome activation via the AMPK/SIRT1 pathway.

Antihyperuricemic effect of liquiritigenin in potassium oxonate-induced hyperuricemic rats.

The aim is to investigate the anti-hyperuricemic and renal protective effects of liquiritigenin in potassium oxonate-induced hyperuricemic rats. Hyperuricemia in rats was induced were induced with potassium oxonate (250mg/kg) intragastrically for 7 days, and liquiritigenin (20, 40mg/kg) and allopurinol (5mg/kg) were daily administrated to the rats orally 1h after the potassium oxonate exposure. Liquiritigenin significantly reversed the elevated productions of uric acid in serum and urine and pro-inflammation cytokines in serum and kidney, which shown that liquiritigenin has renal protective effects. Histological study shows that liquiritigenin inhibited severe necrosis and inflammatory cell infiltration in potassium oxonate-treated rats. Furthermore, liquiritigenin mediated the activities of aquaporins 4 (AQP4), and regulated the activation of NF-κB p65 and the degradation of IκBα. Finally, significant increases of nod-like receptor protein 3 (NLRP3) inflammasome, apoptosis-associated speck-like protein adaptor (ASC) adaptor and cleaved caspased-1 were restored by liquiritigenin. Therefore, liquiritigenin might improve renal inflammation by suppressing renal AQP4/NF-κB/IκBα and NLRP3 inflammasome activation in hyperuricemic rats.