Saengmaeksan, a traditional herbal formulation consisting of Panax ginseng, ameliorates hyperuricemia by inhibiting xanthine oxidase activity and enhancing urate excretion in rats.

BACKGROUND: Saengmaeksan (SMS) is a traditional Korean medicine composed of three herbs, Panax ginseng, Schisandra chinensis, and Liriope platyphylla. SMS is used to treat respiratory and cardiovascular disorders. However, whether SMS exerts antihyperuricemic effects is unknown. METHODS: Effects of the SMS extract in water (SMS-W) and 30% ethanol (SMS-E) were studied in a rat model of potassium oxonate-induced hyperuricemia. Uric acid concentrations and xanthine oxidase (XO) activities were evaluated in the serum, urine, and hepatic tissue. Using renal histopathology to assess kidney function and uric acid excretion, we investigated serum creatinine and blood urea nitrogen concentrations, as well as protein levels of renal urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), and organic anion transporter 1 (OAT1). The effects of SMS on in vitro XO activity and uric acid uptake were also evaluated. The components of SMS were identified using Ultra Performance Liquid Chromatography (UPLC). RESULTS: SMS-E reduced serum uric acid and creatinine concentrations, and elevated urine uric acid excretion. SMS-E lowered XO activities in both the serum and liver, and downregulated the expression of renal URAT1 and GLUT9 proteins. SMS-E reduced renal inflammation and IL-1ß levels in both the serum and kidneys. SMS-E inhibited both in vitro XO activity and urate uptake in URAT1-expressing oocytes. Using UPLC, 25 ginsenosides were identified, all of which were present in higher levels in SMS-E than in SMS-W. CONCLUSION: SMS-E exhibited antihyperuricemic effects by regulating XO activity and renal urate transporters, providing the first evidence of its applicability in the treatment of hyperuricemia and gout.

Eggshell Membrane Ameliorates Hyperuricemia by Increasing Urate Excretion in Potassium Oxonate-Injected Rats.

Hyperuricemia is the primary cause of gouty arthritis and other metabolic disorders. Eggshell membrane (EM) is an effective and safe supplement for curing pain and stiffness connected with osteoarthritis. However, the effect of EM on hyperuricemia is unclear. This study determines the effects of EM on potassium oxonate-injected hyperuricemia. Uric acid, creatinine, blood urea nitrogen concentrations in the serum, and xanthine oxidase activity in the liver are measured. Protein levels of renal urate transporter 1 (URAT1), organic anion transporters 1 (OAT1), glucose transporter 9 (GLUT9), and ATP-binding cassette transporter G2 (ABCG2) in the kidney are determined with renal histopathology. The results demonstrate that EM reduces serum uric acid levels and increases urine uric acid levels in hyperuricemic rats. Moreover, EM downregulates renal URAT1 protein expression, upregulates OAT1 and ABCG2, but does not change GLUT9 expression. Additionally, EM does not change xanthine oxidase activity in the liver or the serum. EM also decreases uric acid uptake into oocytes expressing hURAT1. Finally, EM markedly reduces renal inflammation and serum interleukin-1ß levels. These findings suggest that EM exhibits antihyperuricemic effects by promoting renal urate excretion and regulating renal urate transporters. Therefore, EM may be useful in the prevention and treatment of gout and hyperuricemia.

Apigenin ameliorates hyperuricemic nephropathy by inhibiting URAT1 and GLUT9 and relieving renal fibrosis via the Wnt/ß-catenin pathway.

BACKGROUND: Hyperuricemia (HUA) is characterized by abnormal serum uric acid (UA) levels and demonstrated to be involved in renal injury leading to hyperuricemic nephropathy (HN). Apigenin (API), a flavonoid naturally present in tea, berries, fruits, and vegetables, exhibits various biological functions, such as antioxidant and anti-inflammatory activity. PURPOSE: To investigate the effect of API treatment in HN and to reveal its underlying mechanisms. METHODS: The mice with HN were induced by potassium oxonate intraperitoneally and orally administered for two weeks. The effects of API on renal function, inflammation, fibrosis, and uric acid (UA) metabolism in mice with HN were evaluated. The effects of API on urate transporters were further examined in vitro. RESULTS: The mice with HN exhibited abnormal renal urate excretion and renal dysfunction accompanied by increased renal inflammation and fibrosis. In contrast, API reduced the levels of serum UA, serum creatinine (CRE), blood urea nitrogen (BUN) and renal inflammatory factors in mice with HN. Besides, API ameliorated the renal fibrosis via Wnt/ß-catenin pathway suppression. Furthermore, API potently promoted urinary UA excretion and inhibited renal urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in mice with HN. In vitro, API competitively inhibited URAT1 and GLUT9 in a dose-dependent manner, with IC50 values of 0.64 ± 0.14 µM and 2.63 ± 0.69 µM, respectively. CONCLUSIONS: API could effectively attenuate HN through co-inhibiting UA reabsorption and Wnt/ß-catenin pathway, and thus it might be a potential therapy to HN.

Baicalein alleviates hyperuricemia by promoting uric acid excretion and inhibiting xanthine oxidase.

BACKGROUND: Insufficient renal urate excretion and/or overproduction of uric acid (UA) are the dominant causes of hyperuricemia. Baicalein (BAL) is widely distributed in dietary plants and has extensive biological activities, including antioxidative, anti-inflammatory and antihypertensive activities. PURPOSE: To investigate the anti-hyperuricemic effects of BAL and the underlying mechanisms in vitro and in vivo. METHODS: We investigated the inhibitory effects of BAL on GLUT9 and URAT1 in vitro through electrophysiological experiments and 14C-urate uptake assays. To evaluate the impact of BAL on serum and urine UA, the expression of GLUT9 and URAT1, and the activity of xanthine oxidase (XOD), we developed a mouse hyperuricemia model by potassium oxonate (PO) injection. Molecular docking analysis based on homology modeling was performed to explain the predominant efficacy of BAL compared with the other test compounds. RESULTS: BAL dose-dependently inhibited GLUT9 and URAT1 in a noncompetitive manner with IC50 values of 30.17 ± 8.68 µM and 31.56 ± 1.37 µM, respectively. BAL (200 mg/kg) significantly decreased serum UA and enhanced renal urate excretion in PO-induced hyperuricemic mice. Moreover, the expression of GLUT9 and URAT1 in the kidney was downregulated, and XOD activity in the serum and liver was suppressed. The docking analysis revealed that BAL potently interacted with Trp336, Asp462, Tyr71 and Gln328 of GLUT9 and Ser35 and Phe241 of URAT1. CONCLUSION: These results indicated that BAL exerts potent antihyperuricemic efects through renal UA excretal promotion and serum UA production. Thus, we propose that BAL may be a promising treatment for the prevention of hyperuricemia owing to its multitargeted inhibitory activity.

Anti-hyperuricemic effect of Alpinia oxyphylla seed extract by enhancing uric acid excretion in the kidney.

BACKGROUND: Alpinia oxyphylla is a well-known traditional medicine used in China and Korea to treat intestinal disorders, urosis, diuresis, and chronic glomerulonephritis. PURPOSE: We investigated the anti-hyperuricemic effects of Alpinia oxyphylla seed extract (AE), and the underlying mechanisms of action through in vitro and in vivo studies. METHODS: We evaluated levels of uric acid in the serum and urine, the expression of renal urate transport proteins, and levels of inflammatory cytokines in potassium oxonate (PO)-induced hyperuricemic rats. Xanthine oxidase activity was analyzed in vitro, while cellular uric acid uptake was assessed in oocytes expressing the human urate transporter 1 (hURAT1). Moreover, the main components of AE were analyzed using UPLC. RESULTS: In PO-induced hyperuricemic rats, 200 and 400 mg/kg of AE significantly decreased levels of uric acid in serum, while 400 mg/kg of AE increased uric acid levels in urine. AE did not inhibit xanthine oxidase in vitro; however, 1, 10, and 100 µg/ml of AE significantly decreased uric acid uptake into oocytes expressing hURAT1. Furthermore, 400 mg/kg of AE increased levels of organic anion transporter (OAT) 1 protein, while 200 and 400 mg/kg of AE decreased the protein content of urate transporter, URAT1 and inflammatory cytokines in the kidneys. Nootkatone was identified as one the main chemical components in AE from UPLC analysis. CONCLUSIONS: These findings suggest that AE exerts anti-hyperuricemic and uricosuric effects, which are related to the promotion of uric acid excretion via enhanced secretion and inhibition of uric acid reabsorption in the kidneys. Thus, AE may be a potential treatment for hyperuricemia and gout.

Modified Chuanhu anti-gout mixture, a traditional Chinese medicine, protects against potassium oxonate-induced hyperuricemia and renal dysfunction in mice.

OBJECTIVE: Acute gout is a painful, inflammatory arthritis that features a rapidly escalating inflammatory response resulting from the formation of monosodium urate crystals in the affected joint space. Previously, we found that Chuanhu anti-gout mixture (CAGM) had similar effects as colchicine against gout in the clinic. Subsequently, to improve its effectiveness and efficacy, we modified the original formulation of CAGM. The current study evaluated the effectiveness of the modified formulation in mice. METHODS: Potassium oxonate (PO) was used to establish a mouse model of hyperuricemia. Plasma levels of uric acid and creatine were determined using the respective test kits. Hepatic xanthine oxidase (XOD) expression was examined by enzyme-linked immunosorbent assay. To explore the underlying mechanism, renal urate transporter 1 (URAT1) mRNA levels were evaluated by quantitative real-time PCR. Allopurinol and benzbromarone were used as reference drugs. RESULTS: The original CAGM and its modified high-dose formulation significantly reduced serum uric acid and creatine levels in hyperuricemic mice. In addition, the CAGM-treated groups displayed lower mRNA levels of hepatic XOD and renal URAT1. CONCLUSIONS: CAGM and its modified formulation significantly ameliorated PO-induced hyperuricemia in mice, which might be partially attributable to reductions of hepatic XOD and renal URAT1 levels.

Effects of Chinese herb ingredients with different properties on OAT4, URAT1 and serum uric acid level in acute hyperuricemia mice / 中草药

Objective To study the effects of Chinese herb ingredients with different properties on transporters (URAT1 and OAT4) involved in renal urate reabsorption and serum uric acid level in acute hyperuricemia mice. Methods The OAT4, URAT1- overexpressed monoclonal cell line (MDCK-hOAT4, HEK293-hURAT1) was constructed. The inhibition effect and the half maximal inhibitory concentration (IC50) of different ingredients to transport activity of OAT4 and URAT1 mediating 14C-uric acid were determined. The effects of protocatechuic, liquiritigenin and isoliquiritigenin on serum uric acid levels in acute hyperuricemia mice were studied by the acute hyperuricemia mice induced by potassium oxonate and xanthine. Results The results indicated that nobiletin,liquiritigenin, isoliquiritigenin, licochalcone A with bitter flavor showed strong inhibition to OAT4. The IC50 of nobiletin, liquiritigenin, isoliquiritigenin, and licochalcone A on OAT4 were 0.556 μmol/L, 18.40 μmol/L, 6.831 μmol/L, and 6.825 μmol/L, respectively. Protocatechuic acid and liquiritigenin showed strong inhibition to URAT1 with IC50 of 7.709 μmol/L and 14.54 μmol/L, respectively. Liquiritigenin can significantly reduce the level of serum uric acid of acute hyperuricemia mice, increase the excretion of uric acid, and reduce the level of serum creatinine and blood urea nitrogen. Conclusion Nobiletin, liquiritigenin, isoliquiritigenin and licochalcone A can inhibit the transport activity of OAT4, while protocatechuic acid and liquiritigenin can inhibit the transport activity of URAT1. Liquiritigenin can significantly reduce the level of serum uric acid in acute hyperuricemia mice and protect kidney, the mechanism of which may be associated with the decreasing reabsorption of uric acid by inhibiting the activity of URAT1 and OAT4.

Effects of Osthol Isolated from Cnidium monnieri Fruit on Urate Transporter 1.

(1) Background: Crude drugs used in traditional Japanese Kampo medicine or folk medicine are major sources of new chemical entities for drug discovery. We screened the inhibitory potential of these crude drugs against urate transporter 1 (URAT1) to discover new drugs for hyperuricemia. (2) Methods: We prepared the MeOH extracts of 107 different crude drugs, and screened their inhibitory effects on URAT1 by measuring the uptake of uric acid by HEK293/PDZK1 cells transiently transfected with URAT1. (3) Results: We found that the extract of the dried mature fruit of Cnidium monnieri inhibited urate uptake via URAT1. We isolated and identified osthol as the active ingredient from this extract. Osthol noncompetitively inhibited URAT1 with an IC50 of 78.8 µM. We evaluated the effects of other coumarins and found that the prenyl group, which binds at the 8-position of coumarins, plays an important role in the inhibition of URAT1. (4) Conclusions: Cnidium monnieri fruit may be useful for the treatment of hyperuricemia or gout in traditional medicine, and its active ingredient, osthol, is expected to be a leading compound for the development of new drugs for hyperuricemia.

Discovery of novel curcumin derivatives targeting xanthine oxidase and urate transporter 1 as anti-hyperuricemic agents.

A series of curcumin derivatives as potent dual inhibitors of xanthine oxidase (XOD) and urate transporter 1 (URAT1) was discovered as anti-hyperuricemic agents. These compounds proved efficient effects on anti-hyperuricemic activity and uricosuric activity in vivo. More importantly, some of them exhibited proved efficient effects on inhibiting XOD activity and suppressing uptake of uric acid via URAT1 in vitro. Especially, the treatment of 4d was demonstrated to improve uric acid over-production and under-excretion in oxonate-induced hyperuricemic mice through regulating XOD activity and URAT1 expression. Docking study was performed to elucidate the potent XOD inhibition of 4d. Compound 4d may serve as a tool compound for further design of anti-hyperuricemic drugs targeting both XOD and URAT1.

Actions of water extract from Cordyceps militaris in hyperuricemic mice induced by potassium oxonate combined with hypoxanthine.

ETHNOPHARMACOLOGICAL RELEVANCE: Cordyceps militaris was recorded in the classic traditional Chinese medicine book with the main functions of "protecting liver and enhancing kidney functions", influencing serum uric acid levels. AIM OF STUDY: The aim is to investigate the hypouricemic effects and possible mechanism of C. militaris in hyperuricemic mice. MATERIALS AND METHODS: A water extract (WECM) was prepared by decocting C. militaris directly at 80 °C in water bath, followed by lyophilization. WECM at 50, 100 and 200mg/kg was orally administered to hyperuricemic mice induced by potassium oxonate and hypoxanthine combinedly and allopurinol (5mg/kg) was served as a positive control. RESULTS: WECM exhibited excellent hypouricemic activity, which could decrease the serum uric acid levels of the hyperuricemic mice (306µmol/L) to 189, 184 and 162µmol/L at different doses respectively (P<0.01), approaching the levels of normal mice (184µmol/L). The urate transporter 1 (URAT1) protein levels of kidney at different doses of WECM were 28.15, 17.43, 9.03pg/mL respectively, much lower than that in the hyperuricemia group (93.45pg/mL, P<0.01); and suggested WECM may interact with URAT1. Docking simulations using modeled structure of URAT1 suggested that LYS145, ARG325, ARG477 and ASP168 of URAT1 are key functional residues of URAT1. Four active compounds in C. militaris were identified and their interaction energies with target were estimated between -200 and -400kcal/mol. CONCLUSIONS: These findings suggested that C. militaris produced significant hypouricemic actions and the hypouricemic effects of WECM may be attributed to the inhibitive effect of WECM on URAT1 protein levels. The results of blood urine nitrogen and serum creatinine levels and liver, kidney and spleen coefficients showed that WECM have no negative impacts on liver, renal and spleen functions. The screened four active compounds using molecular docking method deserve further investigation in other work.