Effect of Eurycoma longifolia Stem Extract on Uric Acid Excretion in Hyperuricemia Mice

Punicalagin attenuates hyperuricemia via restoring hyperuricemia-induced renal and intestinal dysfunctions

INTRODUCTION

It is estimated that 90% of hyperuricemia cases are attributed to the inability to excrete uric acid (UA). The two main organs in charge of excreting UA are the kidney (70%) and intestine (30%). Previous studies have reported that punicalagin (PU) could protect against kidney and intestinal damages, which makes it a potential candidate for alleviating hyperuricemia. However, the effects and deeper action mechanisms of PU for managing hyperuricemia are still unknown.

OBJECTIVE

To investigate the effect and action mechanisms of PU for ameliorating hyperuricemia.

METHODS

The effects and action mechanisms of PU on hyperuricemia were assessed using a hyperuricemia mice model. Phenotypic parameters, metabolomics analysis, and 16S rRNA sequencing were applied to explore the effect and fundamental action mechanisms inside the kidney and intestine of PU for improving hyperuricemia.

RESULTS

PU administration significantly decreased elevated serum uric acid (SUA) levels in hyperuricemia mice, and effectively alleviated the kidney and intestinal damage caused by hyperuricemia. In the kidney, PU down-regulated the expression of UA resorption protein URAT1 and GLUT9, while up-regulating the expression of UA excretion protein ABCG2 and OAT1 as mediated via the activation of MAKP/NF-κB in hyperuricemia mice. Additionally, PU attenuated renal glycometabolism disorder, which contributed to improving kidney dysfunction and inflammation. Similarly, PU increased UA excretion protein expression via inhibiting MAKP/NF-κB activation in the intestine of hyperuricemia mice. Furthermore, PU restored gut microbiota dysbiosis in hyperuricemia mice.

CONCLUSION

This research revealed the ameliorating impacts of PU on hyperuricemia by restoring kidney and intestine damage in hyperuricemia mice, and to be considered for the development of nutraceuticals used as UA-lowering agent.

Pseudohypoadrenalism, a subclinical cortisol metabolism disorder in hyperuricemia

Background

Hyperuricemia is a known risk factor of lipid metabolism disorder. However, the mechanisms have not been fully understood.

Methods

The serum samples from hyperuricemia subjects were used to analyze the correlation between serum uric acid and clinical characteristics. Hyperuricemia mice induced by potassium oxonate (PO) and adenine were used to explore glucocorticoid metabolism.

Results

In hyperuricemia patients, the levels of serum uric acid were positively correlated with the levels of γ-glutamyltransferase, associated with a cortisol metabolism disorder. In hyperuricemia state, the adrenal glands failed to respond to adrenocorticotropic hormone properly, leading to low cortisol, but not corticosterone production, and decreased mRNA levels of aldosterone synthase, 11β-hydroxylase, and 3β-hydroxysteroid dehydrogenase 1, three key enzymes for cortisol synthesis. The expression of both hepatic 5α-reductase and renal 11β-hydroxysteroid dehydrogenase 2 was significantly reduced, which led to low cortisol clearance. We denominated this cortisol metabolism disorder in hyperuricemia as pseudohypoadrenalism (PHAL).

Conclusion

PHAL increased exposure to the bioavailable cortisol in the liver, leading to local amplification of the biological action of corticosteroids. Unregulated biosynthesis pathway of bile acid expanded bile acid pool, and further aggravated cholestatic liver injury.

Eurycoma longifolia alkaloid components ameliorate hyperuricemic nephropathy via regulating serum uric acid level and relieving inflammatory reaction

Hyperuricemia is an independent risk factor for chronic kidney disease. We have previously showed the uric-acid-lowering effect of Eurycoma longifolia Jack, yet the renal protective effect and mechanism of E. longifolia remain obscure. The mouse model of hyperuricemic nephropathy was induced by adenine combined with potassium oxonate in male C57BL/6 J mice. E. Longifolia alkaloid components could reduce the level of serum uric acid by regulating the expression of hepatic phosphoribosyl pyrophosphate synthase (PRPS), hypoxanthine-guanine phosphoribosyl transferase (HPRT), and renal urate transporter organic anion transporter 1 (OAT1) and ATP-binding box subfamily G member 2 (ABCG2) in HN mice. Additionally, E. Longifolia alkaloid components alleviated renal injury and function caused by hyperuricemia, which was characterized by improving renal histopathology, reducing urea nitrogen and creatinine levels. E. Longifolia alkaloid components treatment could reduce the secretion of pro-inflammatory factors by inhibiting the activation of NF-κB and NLRP3 inflammatory signaling pathways, including tumor necrosis factor α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), interleukin-1 β (IL-1β), and regulated activated normal T cell expression and secretion proteins (RANTES). Meanwhile, E. longifolia alkaloid components improved renal fibrosis, inhibited the transformation of calcium-dependent cell adhesion molecule E (E-cadherin) to α-smooth muscle actin (α-SMA) transformation, and decreased collagen 1 expression in HN mice.

In vivo anti-hyperuricemia and anti-gouty arthritis effects of the ethanol extract from Amomumvillosum Lour

The incidence of hyperuricemia and gout has been increasing year by year, and it is showing a younger trend. However, the first-line drugs currently used for hyperuricemia and gouty arthritis have serious side effects that limit their clinical application. Amomum villosum Lour. has been widely used in China for thousands of years as a traditional medical and edible plant, and previous screening showed that the ethanol extract of Amomum villosum Lour. could effectively inhibit the activity of xanthine oxidase. Based on this discovery, this paper had achieved in-depth mechanism research. The results showed that the ethanol extract of Amomum villosum Lour. could treat hyperuricemia by reducing the production of uric acid via inhibition of xanthine oxidase and increasing the excretion of uric acid via regulation of urate transporters. Meanwhile, the extract also showed a certain protective effect on hepatic and renal damage caused by hyperuricemia. With the formation of extensive uric acid, gouty arthritis will be induced by the deposition of monosodium urate in the joint. The extract could also relieve the inflammation by reducing the expression of inflammatory cytokines. In conclusion, the extract deserves focused research and development as a potential medicine, health care product or supplemented food for the prevention and treatment of hyperuricemia and gouty arthritis.

Bioactive triterpenes of jujube in the prevention of colorectal cancer and their molecular mechanism research

BACKGROUND

Jujube, a popular fruit from the Rhamnaceae family, relieves colorectal inflammation caused by spleen deficiency and has been used in many formulas in clinical for decades to treat colorectal cancer (CRC). As of yet, the therapeutic substances and mechanism of their action are unknown.

PURPOSE

The purpose of this study is to define the therapeutic substances of jujube and its mechanism of action in treating CRC.

METHODS

The pharmacological effects of jujube extract and its fractions were evaluated in vivo using a CRC mouse model induced by AOM/DSS. The DAI value, colon length, mortality, tumor burden, and histological tumor size of the treated animals were compared. To explore the potential therapeutic substances, LC-MS analysis was conducted to characterize the serum migration components. A network pharmacology experiment was carried out for potential molecular targets. To verify the therapeutic substances as well as the molecular mechanism of jujube intervening CRC, cellular MTT assay of the serum migration components, Western blot and IHC tests were conducted.

RESULTS

The in vivo pharmacological studies showed that compared to AOM/DSS treated mice, the mortality and DAI value, tumor burden, and histological tumor size of jujube extract and its fat-soluble fraction (mainly contained triterpenes) treated mice were significantly reduced, and their colon lengths were obviously longer than AOM/DSS treated mice. The targeted-LC/MS analysis supposed triterpenes 3, 7, 9, 11, 12, 14, 17 - 21, and 25 - 28 to be the serum migration components, which might be the potential therapeutic substances. In the network pharmacology experiment, the GO annotation and enrichment analysis of the KEGG pathway indicated that PI3K-Akt pathway and inflammatory reaction were important factors for jujube inhibiting CRC. Cellular MTT assay of serum migration components indicated that the potential effective substances from fat-soluble fraction to be triterpenes 3, 7, 17, 19, 20, and 25. The Western blot and IHC assays implied that the jujube extract, its fat-soluble fraction, and triterpenes 7, 17, and 20 showed inhibition on the expression of PI3K/Akt/NF-κB signaling pathway-related proteins. Additionally, it was noted in the pharmacodynamic experiment that ZJL's effectiveness was more apparent than ZJH and SQL in tumor burden rate, colon length, and spleen weight, which indicated that the efficacy of ZJ is contributed from CD and SQ, and they may have a synergistic effect on anti-CRC.

CONCLUSION

These results for the first time provide evidence that jujube triterpenes possess an anti-CRC effect, their mechanism was involving the control of the PI3K/Akt/NF-κB signaling pathway. What's more, the potential synergistic effect of the fat-soluble and water-soluble components found in this study provided a solid foundation for our deep understanding of how jujube can ameliorate CRC.

Hypouricemic and nephroprotective effects of palmatine from Cortex Phellodendri Amurensis: A uric acid modulator targeting Keap1-Nrf2/NLRP3 axis

ETHNOPHARMACOLOGICAL RELEVANCE

Palmatine (Pal) is a major bioactive alkaloid originated from ancient Chinese herbal medicine Cortex Phellodendri Amurensis (CPA), which has long been applied to treat hyperuricemia (HUA)-related diseases. Pal possesses potent anti-inflammatory and anti-oxidant effects against metabolic diseases. However, its potential beneficial effect against PO (potassium oxonate)/HX (hypoxanthine)-induced HUA remains elusive.

AIM OF THE STUDY

This study aimed to investigate the potential pharmacological effect and mechanism of Pal on PO/HX-induced HUA in mice.

MATERIAL AND METHODS

A mouse model of HUA was established by co-administration of PO/HX once daily for 7 consecutive days. The HUA mice were orally given three doses (25, 50 and 100 mg/kg) of Pal daily for a week. Febuxostat (Feb, 5 mg/kg) was given as a positive control. At the scheduled termination of the experiment, the whole blood, liver and kidney were collected for subsequent analyses. The concentrations of uric acid (UA), creatinine (CRE) and blood urea nitrogen (BUN), and activities of adenosine deaminase (ADA) and xanthine oxidase (XOD) were evaluated. Histopathological alterations of the kidney were detected by H&E staining. The inflammatory and oxidative stress status was detected by assay kits. Additionally, key proteins involved in the urate transporter, Keap1-Nrf2 and TXNIP/NLRP3 signaling pathways were evaluated by immunohistochemistry and Western blotting. Finally, molecular docking was employed to probe the binding characteristics of Pal and target proteins Keap1, NLRP3, URAT1 and HO-1.

RESULTS

Administration of Pal substantially decreased the elevated kidney weight, lowered UA, CRE and BUN levels, and attenuated abnormal histopathological alterations. Meanwhile, treatment with Pal also dramatically lowered hepatic XOD and ADA activities. Besides, Pal treatment effectively mitigated the renal inflammatory and oxidative stress markers. Further mechanistic investigation indicated Pal distinctly downregulated the protein levels of GLUT9 and URAT1, while up-regulated the expression levels of OAT1 and ABCG2. Pal also restored Nrf2 activation, promoted subsequent expression of anti-oxidative enzymes, and downregulated the expressions of TXNIP, NLRP3, apoptosis-associated speck-like (ASC), caspase-1, IL-1β and IL-18. Molecular docking analysis also indicated Pal firmly bound with Keap1, NLRP3, URAT1 and HO-1.

CONCLUSIONS

These findings indicated that Pal exhibited favorable anti-HUA effect via modulating the expressions of transporter-related proteins and suppressing XOD activity. Furthermore, Pal also alleviated HUA-induced kidney injury, which was at least partially related to restoring Keap1-Nrf2 pathway and inhibiting TXNIP/NLRP3 inflammasome. Our investigation was envisaged to provide experimental support for the traditional application of CPA and CPA-containing classical herbal formulas in the management of HUA-related diseases and might provide novel dimension to the clinical application of Pal.

Anti-hyperuricemia effect of hesperetin is mediated by inhibiting the activity of xanthine oxidase and promoting excretion of uric acid

Hesperetin is a natural flavonoid with many biological activities. In view of hyperuricemia treatment, the effects of hesperetin in vivo and in vitro, and the underlying mechanisms, were explored. Hyperuricemia models induced by yeast extract (YE) or potassium oxonate (PO) in mice were created, as were models based on hypoxanthine and xanthine oxidase (XOD) in L-O2 cells and sodium urate in HEK293T cells. Serum level of uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) were reduced significantly after hesperetin treatment in vivo. Hesperetin provided hepatoprotective effects and inhibited xanthine oxidase activity markedly, altered the level of malondialdehyde (MDA), glutathione peroxidase (GSH-PX) and catalase (CAT), downregulated the XOD protein expression, toll-like receptor (TLR)4, nucleotide binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, interleukin-18 (IL-18), upregulated forkhead box O3a (FOXO3a), manganese superoxide dismutase (MnSOD) in a uric acid-synthesis model in mice. Protein expression of organic anion transporter 1 (OAT1), OAT3, organic cationic transporter 1 (OCT1), and OCT2 was upregulated by hesperetin intervention in a uric acid excretion model in mice. Our results proposal that hesperetin exerts a uric acid-lowering effect through inhibiting xanthine oxidase activity and protein expression, intervening in the TLR4-NLRP3 inflammasome signaling pathway, and up-regulating expression of FOXO3a, MnSOD, OAT1, OAT3, OCT1, and OCT2 proteins. Thus, hesperetin could be a promising therapeutic agent against hyperuricemia.

Research Progress of Natural Active Substances with Uric-Acid-Reducing Activity

Hyperuricemia is a metabolic disease caused by the accumulation of uric acid in the body. Allopurinol, benzbromarone, and febuxostat, which are available in the market, have reduced the circulating urate levels; however, they exhibit serious side effects. Therefore, it is reasonable to develop a new active antihyperuricemia drug with few side effects. With the deepening of research, numerous kinds of literature have shown that natural active substances are effective in the treatment of hyperuricemia with a variety of sources and few side effects, which have become the focus of research in recent years. This review focuses on natural active substances with uric-acid-reducing activity and discusses their pharmacological effects. More specifically, the bioactive compounds of natural active substances are divided into five categories: natural extracts, monomer compounds extracted from plants, natural protease hydrolysates, peptides, and probiotic bacteria. In addition, the mechanisms by which these bioactive compounds exhibit hypouricemic effects can be divided into four classes: inhibition of key enzyme activities, promotion of uric acid excretion and inhibition of reabsorption in the kidney, promotion of decomposing uric acid precursors, and promotion of decomposing uric acid. Overall, this current and comprehensive review examines the role of natural active substances in the treatment of hyperuricemia.

m(6)A methyltransferase METTL3 relieves cognitive impairment of hyperuricemia mice via inactivating MyD88/NF-κB pathway mediated NLRP3-ASC-Caspase1 inflammasome

BACKGROUND

Recent studies have uncovered that hyperuricemia (HUA) leads to cognitive deficits, which are accompanied by neuronal damage and neuroinflammation. Here, we aim to explore the role of methyltransferase-like 3 (METTL3) in HUA-mediated neuronal apoptosis and microglial inflammation.

METHODS

A HUA mouse model was constructed. The spatial memory ability of the mice was assessed by the Morris water maze experiment (MWM), and neuronal apoptosis was analyzed by the TdT-mediated dUTP nick end labeling (TUNEL) assay. Besides, enzyme-linked immunosorbent assay (ELISA) was utilized to measure the contents of inflammatory factors (IL-1β, IL-6, and TNF-α) and oxidative stress markers (MDA, SOD, and CAT) in the serum of mice. In vitro, the mouse hippocampal neuron (HT22) and microglia (BV2) were treated with uric acid (UA). Flow cytometry was applied to analyze HT22 and BV2 cell apoptosis, and ELISA was conducted to observe neuroinflammation and oxidative stress. In addition, the expression of MyD88, p-NF-κB, NF-κB, NLRP3, ASC and Caspase1 was determined by Western blot.

RESULTS

METTL3 and miR-124-3p were down-regulated, while the MyD88-NF-κB pathway was activated in the HUA mouse model. UA treatment induced neuronal apoptosis in HT22 and stimulated microglial activation in BV2. Overexpressing METTL3 alleviated HT22 neuronal apoptosis and resisted the release of inflammatory cytokines and oxidative stress mediators in BV2 cells. METTL3 repressed MyD88-NF-κB and NLRP3-ASC-Caspase1 inflammasome. In addition, METTL3 overexpression enhanced miR-124-3p expression, while METTL3 knockdown aggravated HT22 cell apoptosis and BV2 cell overactivation.

CONCLUSION

METTL3 improves neuronal apoptosis and microglial activation in the HUA model by choking the MyD88/NF-κB pathway and up-regulating miR-124-3p.

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.

A Brief Review of Natural Products with Urate Transporter 1 Inhibition for the Treatment of Hyperuricemia

Hyperuricemia is a common disease caused by a high level of uric acid. Urate transporter 1 (URAT1) is an important protein and mediates approximately 90% of uric acid reabsorption. Therefore, the URAT1 inhibitor is a class of uricosuric medicines widely used in the clinic for the treatment of hyperuricemia. To find the new medicine with stronger URAT1 inhibition and lower toxicity, researchers have been exploring natural products. This study systematically summarizes the natural products with URAT1 inhibition. The results show that many natural products are potential URAT1 inhibitors, such as flavonoids, terpenoids, alkaloids, coumarins, stilbenes, and steroids, among which flavonoids are the most promising source of URAT1 inhibitors. It is worth noting that most studies have focused on finding natural products with inhibition of URAT1 and have not explored their activities and mechanisms toward URAT1. By reviewing the few existing studies of the structure-activity relationship and analyzing common features of natural products with URAT1 inhibition, we speculate that the rigid ring structure and negative charge may be the keys for natural products to produce URAT1 inhibition. In conclusion, natural products are potential URAT1 inhibitors, and exploring the mechanism of action and structure-activity relationship will be an important research direction in the future.

Hypouricemic effect of gallic acid, a bioactive compound from Sonneratia apetala leaves and branches, on hyperuricemic mice

As a tropical medicinal plant, Sonneratia apetala is mainly distributed in the southeast coastal areas of China. Recently, the hypouricemic effect of Sonneratia apetala leaves and branches (SAL) has been reported, but the active compound and its mechanism are unclear. Thus, this study aims to explore the effective fraction of SAL and the mechanism of its active compound on uric acid formation and excretion. SAL was extracted with ethyl acetate and concentrated to obtain solvent-free extracts (SAL-EA). The remains fraction (SAL-E) and the supernatant fraction (SAL-S) of SAL resulting from water extraction and alcohol precipitation were collected and dried. The effects of different fractions were explored on hyperuricemic mice. SAL-S showed excellent activities in decreasing the levels of uric acid (UA), blood urea nitrogen (BUN), and creatinine (CRE) in serum and in attenuating kidney damage. Then, the active compound gallic acid (GA) identified by HPLC was assayed for its mechanism of regulating uric acid metabolism in hyperuricemic mice. The hypouricemic effect of GA was probably associated with the downregulation of URAT1 and GLUT9, upregulation of ABCG2 and decreased activities of adenosine deaminase (ADA) and xanthine oxidase (XOD). Moreover, GA suppressed the level of MDA, IL-6, IL-1β, TNF-α, TGF-β1, COX-2 and cystatin-C (Cys-C), and enhanced the activities of SOD, GSH-Px, CAT, and Na⁺-K⁺-ATPase (NKA) in the kidneys. These results indicated that GA protects against hyperuricemia-induced kidney injury via suppressing oxidative stress and inflammation as well as decreasing the serum levels of UA by regulating urate transporters.

Dioscin Ameliorates Hyperuricemia-Induced Atherosclerosis by Modulating of Cholesterol Metabolism through FXR-Signaling Pathway

Hyperuricemia is one of the independent risk factors for atherosclerotic cardiovascular disease. Herein, we investigate the association between uric acid and cholesterol metabolism and the effect of dioscin on the prevention of hyperuricemia-induced atherosclerosis. In the potassium oxonate-treated ApoE^-/--/- mice, atherosclerosis was accelerated along with elevated serum cholesterol levels in the hyperuricemic state, which can be ameliorated by dioscin. Together with the in vitro assays, we found that the effect of dioscin was at least partially through the regulation of the farnesoid X receptor (FXR) -small heterodimer partner (SHP) -7α-hydroxylase (CYP7A1) signaling pathway in the liver. Tigogenin (a metabolite of dioscin) suppressed FXR activation and increased CYP7A1, resulting in an increased conversion rate of cholesterols into bile acids. Further clinical study revealed that treatment with a dioscin-enriched preparation decreased serum cholesterol levels in individuals with hyperuricemia. In summary, this study demonstrated a slowdown effect of dioscin on the progression of hyperuricemia-induced atherosclerosis.

OAT10/SLC22A13 Acts as a Renal Urate Re-Absorber: Clinico-Genetic and Functional Analyses With Pharmacological Impacts

Dysfunctional missense variant of organic anion transporter 10 (OAT10/SLC22A13), rs117371763 (c.1129C>T; p.R377C), is associated with a lower susceptibility to gout. OAT10 is a urate transporter; however, its physiological role in urate handling remains unclear. We hypothesized that OAT10 could be a renal urate re-absorber that will be a new molecular target of urate-lowering therapy like urate transporter 1 (URAT1, a physiologically-important well-known renal urate re-absorber) and aimed to examine the effect of OAT10 dysfunction on renal urate handling. For this purpose, we conducted quantitative trait locus analyses of serum urate and fractional excretion of uric acid (FE_UA) using samples obtained from 4,521 Japanese males. Moreover, we performed immunohistochemical and functional analyses to assess the molecular properties of OAT10 as a renal urate transporter and evaluated its potential interaction with urate-lowering drugs. Clinico-genetic analyses revealed that carriers with the dysfunctional OAT10 variant exhibited significantly lower serum urate levels and higher FE_UA values than the non-carriers, indicating that dysfunction of OAT10 increases renal urate excretion. Given the results of functional assays and immunohistochemical analysis demonstrating the expression of human OAT10 in the apical side of renal proximal tubular cells, our data indicate that OAT10 is involved in the renal urate reabsorption in renal proximal tubules from urine. Additionally, we found that renal OAT10 inhibition might be involved in the urate-lowering effect of losartan and lesinurad which exhibit uricosuric effects; indeed, losartan, an approved drug, inhibits OAT10 more strongly than URAT1. Accordingly, OAT10 can be a novel potential molecular target for urate-lowering therapy.

Eurycomanol alleviates hyperuricemia by promoting uric acid excretion and reducing purine synthesis

BACKGROUND

An elevated level of blood uric acid (UA) leads to serious damages to human health. In clinic, xanthine oxidase inhibitor is commonly used to reduce uric acid production. However, UA excretion promotion drug is rare. Our previous study demonstrated that the 70% ethanolic extract of stem of Eurycoma longifolia could effectively increase UA excretion and decrease blood level of UA in hyperuricemia animal model. In this paper, we tried to find active substance on UA regulation from E. longifolia.

METHODS

The constituents of stem from E. longifolia were isolated and analyzed by chemical and spectral methods. Ultra Performance Liquid Chromatography was applied to measure the concentrations of UA in serum and urine. H&E staining was used to characterize renal histopathological changes. The protein and mRNA expressions of UA transporters were measured by western blot and quantitative real-time PCR analysis.

RESULTS

Ten kinds of quassinoids were isolated from stem of E. longifolia, and the structures were identified. Pharmacological research revealed the major component, eurycomanol (5-20 mg/kg, p.o.) significantly decreased serum UA level and increased 24 h clearance of uric acid in potassium oxonate and adenine induced hyperuricemic mice. Eurycomanol ameliorated UA induced kidney histological injury, inhibited hepatic purine synthesis through decreasing phosphoribosyl pyrophosphate synthetase, promoted UA excretion by modulation of renal and intestinal urate transporters, such as GLUT9, ABCG2, OAT1, and NPT1.

CONCLUSION

The results showed eurycomanol from E. longifolia can promote UA excretion through kidney and intestine, decrease hepatic purine synthesis and further keep UA homeostasis, suggesting that eurycomanol has the potential to be developed into a novel drug for the treatment of under-excretion type hyperuricemia.

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-1β 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.

Physicochemical Evaluation and Pharmacodynamics of Itraconazole-loaded Liquid Crystal Precursor for Vaginal Delivery

PURPOSE

To develop liquid crystal (LC) precursor that can be used as a novel vaginal delivery system for Itraconazole (ITZ) and evaluate its pharmacodynamics. Methods: The LC precursor was prepared by using phytantriol (PYT) as lipid matrix and N, N-dimethylformamide (DMAC) as solvent. Swelling studies were performed to assess the phase conversion ability. The formulations were characterized by crossed polarized light microscopy (CPLM), small-angle X-ray scatterin (SAXS). Moreover, the rheological and in vitro drug release behavior were investigated. Then the vaginal retention time of ITZ in the optimal prescription was evaluated. Finally, the pharmacodynamics studies of the ITZ-loaded LC precursor were performed in a mouse model of vulvovaginal candidiasis (VVC). Results: The LC precursor could transform to LC gels after administration into the vagina. Based on PLM and SAXS, the LC gels, formed after phase-conversion, were cubic LC. The LC precursor was Non-Newtonian, while the LC gels exhibited a pseudo-plastic fluid behavior. In vitro release results revealed that F2 (68.0 %) had a higher cumulative drug release than that of F1 (59.17 %) at 72 h. Most of the LC gels could be retained in the vagina of mice for 24 - 36 h. Pharmacodynamics studies showed that there was only mild inflammation or no inflammatory stimulation in the control group. The ITZ-loaded LC precursor significantly improved the symptoms of vaginitis in mice and had a better therapeutic effect than that of positive control group. Conclusions: The ITZ-loaded LC precursor would be a promising formulation for vaginal drug delivery.

Recent Updates of Natural and Synthetic URAT1 Inhibitors and Novel Screening Methods

Human urate anion transporter 1 (hURAT1) is responsible for the reabsorption of uric acid in the proximal renal tubules and is a promising therapeutic target for treating hyperuricemia. To mitigate the side effects of URAT1-targeted clinical agents such as benzbromarone, there is significant interest in discovering new URAT1 inhibitors and developing technology that can evaluate URAT1 inhibition. This review summarizes the methods for assay of URAT1 inhibition and the progress on the discovery of natural and synthetic URAT1 inhibitors in the past five years.

Antihyperuricemic Effect of Dendropanax morbifera Leaf Extract in Rodent Models

Dendropanax morbifera is a well-known traditional medicine used in China and Korea to treat intestinal disorders, urosis, diuresis, and chronic glomerulonephritis. Hyperuricemia is a metabolic disorder characterized by a high uric acid level in serum due to an imbalance between uric acid production and excretion and causes gout. Recently, the prevalence of hyperuricemia worldwide has been continuously increasing. Xanthine oxidase (XOD) inhibitors (allopurinol (ALP) and febuxostat) and uricosuric agents (benzbromarone and probenecid) are used to treat hyperuricemia clinically. However, because these drugs are poorly tolerated and cause side effects, such as kidney diseases, hepatotoxicity, gastrointestinal symptoms, and hypersensitivity syndrome, only a limited number of drugs are available. We investigated the antihyperuricemic effects of Dendropanax morbifera leaf ethanol extract (DMLE) and its underlying mechanisms of action through in vitro and in vivo studies. We evaluated uric acid levels in serum and urine, and xanthine oxidase (XOD) inhibition activity in the serum and liver tissue of a hyperuricemic rat model of potassium oxonate (PO)-induced hyperuricemic rats. In vitro study, XOD-inhibitory activity was the lowest among the test substances at the IC50 of ALP. However, the IC50 of DMLE-70 was significantly low compared with that of other DMLEs (p < 0.05). In PO-induced hyperuricemic rats, uric acid (UA) levels in serum and urine were significantly reduced in all DMLE-70 and allopurinol-treated (ALT) groups than in the PC group (p < 0.05). UA levels in urine were lower than those in serum in all DME groups. In PO-induced hyperuricemic rats, DMEE-200 reduced UA concentration in serum and increased UA excretion in the urine. These findings suggest that DMLE exerts antihyperuricemic and uricosuric effects on promoting UA excretion by enhanced secretion and inhibition of UA reabsorption in the kidneys. Thus, DMLE may be a potential treatment for hyperuricemia and gout.

A brief review of urate transporter 1 (URAT1) inhibitors for the treatment of hyperuricemia and gout: Current therapeutic options and potential applications

Hyperuricemia is a common metabolic condition, cause by increased levels of serum urate (SUA). Reduced excretion of uric acid is reported as the key factor of primary hyperuricemia, accounting for approximately 90% of the cases. Urate transporter 1 (URAT1) is a major protein involved in uric acid reabsorption (about 90%). Therefore, URAT1 inhibitors are considered to be a highly effective and promising class of uricosuric agents for treating hyperuricemia. This review summarizes the development of URAT1 inhibitors for the treatment of hyperuricemia, including approved URAT1 inhibitors, URAT1 inhibitors under development in clinical trials, substances with URAT1 inhibitory effects from derivatives and natural products, and conventional drugs with new uses. This review provides new ideas regarding research on URAT1 inhibitors by introducing the structure, properties, and side effects of chemical drugs, as well as the sources and categories of natural drugs. We also discuss new mechanisms of classic drugs, which may provide guidance to many practicing clinicians. The research and discovery of new inhibitors remain in full swing, and tremendous developments are expected in the field.

Investigation of Obesity-Alleviation Effect of Eurycoma longifolia on Mice Fed with a High-Fat Diet through Metabolomics Revealed Enhanced Decomposition and Inhibition of Accumulation of Lipids

The metabolic and bioactivity effects of Eurycoma longifolia (Eucalyptus longifolia) in obesity treatment were studied in mice fed with a high-fat diet using a metabolomics approach. Aqueous extracts of E. longifolia were obtained via grinding, dissolving, and freeze-drying. The hepatic steatosis effect of E. longifolia was characterized by hematoxylin and eosin histological staining. External performance of the obesity-alleviation effect was monitored by measuring body and food weight. In addition, the metabolomics analysis of the E. longifolia-mice interaction system was performed using the established platform combining liquid chromatography-tandem mass spectrometry with statistical analysis. The presence and spatial distribution patterns of differential molecules were further evaluated through desorption electrospray ionization-mass spectrometry imaging. The results showed that E. longifolia played a vital role in downregulating lipid accumulation (especially triacylglycerols) and fatty acids biosynthesis together with enhanced lipid decomposition and healing in Bagg albino mice. During such a process, E. longifolia mainly induced metabolomic alterations of amino acids, organic acids, phospholipids, and glycerolipids. Moreover, under the experimental concentrations, E. longifolia induced more fluctuations of aqueous-soluble metabolites in the plasma and lipids in the liver than in the kidneys. This study provides an advanced alternative to traditional E. longifolia-based studies for evaluating the metabolic effects and bioactivity of E. longifolia through metabolomics technology, revealing potential technological improvement and clinical application.

Discovery of a novel rice-derived peptide with significant anti-gout potency

As a metabolic disease, gout, which seriously affects the normal life of patients, has become increasingly common in modern society. However, the existing medicines cannot completely meet the clinical needs. In the current study, a novel short peptide (named rice-derived-peptide-2 (RDP2), AAAAGAMPK-NH2, 785.97 Da) was isolated and identified from water extract of shelled Oryza sativa fruits, without toxic side effects but excellent stability. Our results indicated that RDP2 (the minimum effective concentration is 5 μg kg^-1) induced a significant reduction in serum uric acid levels in hyperuricemic mice via suppressing xanthine oxidase activity and urate transporter 1 expression, as well as alleviated renal damage through inhibiting the activation of NLRP3 inflammasome. In addition, RDP2 can also alleviate paw swelling and inflammatory reactions in mice after subcutaneous injection of monosodium urate crystals. As mentioned above, we obtained a novel peptide which could work through all stages of gout, not only reducing uric acid levels and renal damage in hyperuricemic mice, but also alleviating inflammatory responses associated with acute gout attack, and thus provided a new peptide molecular template for the development of anti-gout drugs.

The Time-Feature of Uric Acid Excretion in Hyperuricemia Mice Induced by Potassium Oxonate and Adenine

Hyperuricemia is an important risk factor of chronic kidney disease, metabolic syndrome and cardiovascular disease. We aimed to assess the time-feature relationship of hyperuricemia mouse model on uric acid excretion and renal function. A hyperuricemia mouse model was established by potassium oxonate (PO) and adenine for 21 days. Ultra Performance Liquid Chromatography was used to determine plasma uric acid level. Hematoxylin-eosin staining was applied to observe kidney pathological changes, and Western blot was used to detect renal urate transporters’ expression. In hyperuricemia mice, plasma uric acid level increased significantly from the 3rd day, and tended to be stable from the 7th day, and the clearance rate of uric acid decreased greatly from the 3rd day. Further study found that the renal organ of hyperuricemia mice showed slight damage from the 3rd day, and significantly deteriorated renal function from the 10th day. In addition, the expression levels of GLUT9 and URAT1 were upregulated from the 3rd day, while ABCG2 and OAT1 were downregulated from the 3rd day, and NPT1 were downregulated from the 7th day in hyperuricemia mice kidney. This paper presents a method suitable for experimental hyperuricemia mouse model, and shows the time-feature of each index in a hyperuricemia mice model.

RDP3, A Novel Antigout Peptide Derived from Water Extract of Rice

Gout and hyperuricemia can seriously affect the quality of life; at present, however, existing medicines are unable to meet all clinical needs. In the current study, a novel peptide (i.e., rice-derived-peptide-3 (RDP3), AAAAMAGPK-NH₂, 785.97 Da) in water extract obtained from shelled Oryza sativa fruits was identified. Testing revealed that RDP3 (minimum effective concentration 100 μg/kg) did not show both hemolytic and acute toxicity, and reduced uric acid levels in the serum of hyperuricemic mice by inhibiting xanthine oxidase activity and decreasing urate transporter 1 expression. RDP3 also alleviated renal injury in hyperuricemic mice by decreasing NLRP3 inflammasome expression. Furthermore, RDP3 alleviated formalin-induced paw pain and reduced monosodium urate crystal-induced paw swelling and inflammatory factors in mice. Thus, this newly identified peptide reduced uric acid levels and renal damage in hyperuricemic mice and showed anti-inflammatory and analgesic activities, indicating the potential of RDP3 as an antigout medicine candidate.