Anti-hyperuricemic and anti-inflammatory actions of vaticaffinol isolated from Dipterocarpus alatus in hyperuricemic mice / 中国天然药物

The present study was designed to examine the anti-hyperuricemic and anti-inflammatory effects and possible mechanisms of vaticaffinol, a resveratrol tetramer isolated from ethanol extracts of Dipterocarpus alatus, in oxonate-induced hyperuricemic mice. At 1 h after 250 mg·kg potassium oxonate was given, vaticaffinol at 20, 40, and 60 mg·kg was intragastrically administered to hyperuricemic mice once daily for seven consecutive days. Vaticaffinol significantly decreased serum uric acid levels and improved kidney function in hyperuricemic mice. It inhibited hepatic activity of xanthine dehydrogenase (XDH) and xanthine oxidase (XOD), regulated renal mRNA and protein levels of urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporter 1 (OAT1), organic cation transporter 1 (OCT1), OCT2, organic cation/carnitine transporter 1 (OCTN1), and OCTN2 in hyperuricemic mice. Moreover, vaticaffinol markedly down-regulated renal protein levels of NOD-like receptor 3 (NLRP3), apoptosis-associated speck-like (ASC), and Caspase-1, resulting in the reduction of interleukin (IL)-1β, IL-18, IL-6 and tumor necrosis factor-α (TNF-α) levels in this animal model. Additionally, HPLC and LC-MS analyses clearly testified the presence of vaticaffinol in the crude extract. These results suggest that vaticaffinol may be useful for the prevention and treatment of hyperuricemia with kidney inflammation.

Siwu decoction attenuates oxonate-induced hyperuricemia and kidney inflammation in mice / 中国天然药物

The aim of the study was to investigate the effects of Siwu decoction on hyperuricemia, kidney inflammation, and dysfunction in hyperuricemic mice. Siwu decoction at 363.8, 727.5, and 1 455 mg·kg(-1) was orally administered to potassium oxonate-induced hyperuricemic mice for 7 days. Serum urate, creatinine, and blood urea nitrogen levels and hepatic xanthine oxidase (XOD) activity were measured. The protein levels of hepatic XOD and renal urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporters 1 (OAT1), ATP-binding cassette subfamily G member 2 (ABCG2), organic cation transporter 1 (OCT1), OCT2, organic cation/carnitine transporter 1 (OCTN1), OCNT2, Nod-like receptor family, pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein (ASC), Caspase-1, and interleukin-1β (IL-1β) were determined by Western blotting. Renal histopathology change was obtained following hematoxylin-eosin staining. Our results indicated that Siwu decoction significantly reduced serum urate, creatinine and blood urea nitrogen levels and increased fractional excretion of uric acid in hyperuricemic mice. It effectively reduced hepatic XOD activity and protein levels in this animal model. Furthermore, Siwu decoction down-regulated URAT1 and GLUT9 protein levels, and up-regulated the protein levels of OAT1, ABCG2, OCT1, OCT2, OCTN1, and OCTN2 in the kidney of the hyperuricemic mice. Additionally, Siwu decoction remarkably reduced renal protein levels of NLRP3, ASC, Caspase-1, and IL-1β in the hyperuricemic mice. These results suggested that Siwu decoction exhibited anti-hyperuricemic and anti-inflammatory effects by inhibiting hepatic XOD activity, regulating renal organic ion transporter expression, and suppressing renal NLRP3 inflammasome activation, providing the evidence for its use in the treatment of hyperuricemia and associated kidney inflammation.

Effect of Zhusha Anshen pill, cinnabar, HgS, HgCl2 and MeHg on gene expression of renal transporters in mice / 中国中药杂志

<p><b>OBJECTIVE</b>To study the effect of Zhusha Anshen pill, cinnabar, HgS, HgCl2 and MeHg on the gene expression of renal transporters in mice.</p><p><b>METHOD</b>Healthy male mice were given equivalent physiological saline, Zhusha Anshen pill (1.8 g · kg(-1), containing 0.17 g · kg(-1) of mercury), cinnabar (0.2 g · kg(-1), containing 1.7 g · kg(-1) of mercury), high dose cinnabar (2 g · kg(-1), containing 1.7 g · kg(-1) of mercury), HgS (0.2 g · kg(-1), containing 0.17 g · kg(-1) of mercury), HgCl2 (0.032 g · kg(-1), containing 0. 024 g · kg(-1) of mercury), MeHg (0.026 g · kg(-1), containing 0.024 g · kg(-1) of mercury), once daily, for 30 d, measuring body mass gain. 30 days later, the mice were sacrificed. The mercury accumulation in kidneys was detected with atomic fluorescence spectrometer. Expressions of Oat1, Oat2, Oat3, Mrp2, Mrp4, Urat1 were detected with RT-PCR.</p><p><b>RESULT</b>Compared with the normal control group, a significant accumulation of Hg in kidney in HgCl2 and MeHg groups was observed (P <0.05), but these changes were not found in other groups. Compared with normal control group, mRNA expressions of Oat1 and Oat2 were evidently lower in HgCl2 and MeHg groups, but mRNA expressions of Mrp2 were apparently higher in HgCl2 group (P <0.05), mRNA expression of Mrp4 was significant higher in HgCl2 and MeHg groups, and mRNA expression of Urat1 was apparently lower in MeHg group.</p><p><b>CONCLUSION</b>HgCl2 and MeHg groups show significant difference from the normal group in mercury accumulation in kidneys and gene expression of kidney transporters, but with no difference between other groups and the normal group. Compared with HgCl2 and MeHg, cinnabar and its compounds could cause lower renal toxicity to mice.</p>

Inhibitory effect of medicinal plant-derived carboxylic acids on the human transporters hOAT1, hOAT3, hOATP1B1, and hOATP2B1 / 中国天然药物

A significant number of organic carboxylic acids have been shown to influence the absorption and distribution of drugs mediated by organic anion transporters (OATs). In this study, uptake experiments were performed to assess the inhibitory effects of cinnamic acid, ferulic acid, oleanolic acid, deoxycholic acid, and cynarin on hOAT1, hOAT3, hOATP1B1, and hOATP2B1. After a drug-drug interaction (DDI) investigation, cinnamic acid, ferulic acid, deoxycholic acid, and cynarin were found and validated to inhibit hOAT1 in a competitive manner, and deoxycholic acid was found to be an inhibitor of all four transporters. The apparent 50% inhibitory concentrations of cinnamic acid, ferulic acid, deoxycholic acid, and cynarin were estimated to be 133.87, 3.69, 90.03 and 6.03 μmol·L(-1) for hOAT1, respectively. The apparent 50% inhibitory concentrations of deoxycholic acid were estimated to be 9.57 μmol·L(-1) for hOAT3, 70.54 μmol·L(-1) for hOATP1B1, and 168.27 μmol·L(-1) for hOATP2B1. Because cinnamic acid, ferulic acid, and cynarin are ingredients of food or food additives, the present study suggests there are new food-drug interactions to be disclosed. In addition, deoxycholic acid may be used as a probe for studying the correlation of OATs and OATPs.

Wuling san ameliorates urate under-excretion and renal dysfunction in hyperuricemic mice / 中国天然药物

AIM@#The present study was undertaken to characterize the effects of Wuling San on urate excretion and renal function, and explore its possible mechanisms of action in hyperuricemic mice.@*METHODS@#Mice were administered with 250 mg·kg(-1) potassium oxonate by gavage once daily (10 animals/group) for seven consecutive days to develop a hyperuricemia model. Different doses of Wuling powder were orally initiated on the day 1 h after oxonate was given, separately. Allopurinol was used as a positive control. Serum and urine levels of uric acid and creatinine, and fractional excretion of uric acid (FEUA) were measured in hyperuricemic mice treated with Wuling San and allopurinol. Simultaneously, renal mRNA and protein levels of urate transporter 1 (mURAT1), glucose transporter 9 (mGLUT9), organic anion transporter 1 (mOAT1), as well as organic cation/carnitine transporters mOCT1, mOCT2 and mOCTN2, were assayed by semi-quantitative RT-PCR and Western blot methods, respectively.@*RESULTS AND CONCLUSION@#Compared to the hyperuricemia control group, Wuling San significantly reduced serum uric acid and creatinine levels, increased 24 h urate and creatinine excretion, and FEUA in hyperuricemic mice, exhibiting its ability to enhance urate excretion and improve kidney function. Wuling San was found to down-regulate mRNA and protein levels of mURAT1 and mGLUT9, as well as up-regulate mOAT1 in the kidney of hyperuricemic mice. Moreover, Wuling San up-regulated renal mRNA and protein levels of mOCT1, mOCT2 and mOCTN2, leading to kidney protection in this model.

Mangiferin promotes uric acid excretion and kidney function improvement and modulates related renal transporters in hyperuricemic mice / 药学学报

The effects of mangiferin on uric acid excretion, kidney function and related renal transporters were investigated in hyperuricemic mice induced by potassium oxonate. Mice were divided into normal control group, and 5 hyperuricemic groups with model control, 50, 100, and 200 mg x kg(-1) mangiferin, and 5 mg x kg(-1) allopurinol. Mice were administered by gavage once daily with 250 mg x kg(-1) potassium oxonate for seven consecutive days to create the model. And 3 doses of mangiferin were orally initiated on the day 1 h after potassium oxonate was given, separately. Serum uric acid, creatinine and urea nitrogon levels, as well as urinary uric acid creatinine levels were measured. Mouse uromodulin (mUMOD) levels in serum, urine and kidney were determined by ELISA method. The mRNA and protein levels of related renal transporters were assayed by RT-PCR and Western blotting methods, respectively. Compared to model group, mangiferin significantly reduced serum uric acid, creatinine and urea nitrogon levels, increased 24 h uric acid and creatinine excretion, and fractional excretion of uric acid in hyperuricemic mice, exhibiting uric acid excretion enhancement and kidney function improvement. Mangiferin was found to down-regulate mRNA and protein levels of urate transporter 1 (mURAT1) and glucose transporter 9 (mGLUT9), as well as up-regulate organic anion transporter 1 (mOAT1) in the kidney of hyperuricemic mice. These findings suggested that mangiferin might enhance uric acid excretion and in turn reduce serum uric acid level through the decrease of uric acid reabsorption and the increase of uric acid secretion in hyperuricemic mice. Moreover, mangiferin remarkably up-regulated expression levels of renal organic cation and carnitine transporters (mOCT1, mOCT2, mOCTN1 and mOCTN2), increased urine mUMOD levels, as well as decreased serum and kidney mUMOD levels in hyperuricemic mice, which might be involved in mangiferin-mediated renal protective action.

Effects of Increased Uric Acid Intake on the Abundance of Urate-anion exchanger and Organic Anion Transporter Proteins in the Rat Kidney

Renal handling of uric acid mainly occurs in the proximal tubule, and bidirectional transport of urate may involve apical absorption via the urate-anion exchanger (URAT1) and basolateral uptake via organic anion transporters (OAT1 and OAT3). In rat kidneys, we investigated whether the protein abundance of URAT1, OAT1, and OAT3 is affected by the increase in uric acid intake. Male Sprague-Dawley rats were randomly divided into control and uric acid-supplemented groups, and uric acid-supplemented rats were given 0.75 g of uric acid per 180 g body weight per day for 8 days. After the animal experiment, kidneys were harvested and semi-quantitative immunoblotting was carried out from cortical homogenates using polyclonal peptide-derived antibodies to URAT1, OAT1, and OAT3. Serum uric acid level showed an increasing tendency (p=0.055) in the uric acid-supplemented rats (2.60+/- 0.27 mg/dL) compared with control rats (1.97+/-0.29 mg/dL), whereas urinary uric acid excretion was not significantly different between the uric acid-supplemented rats (3.27+/-0.40 mg/d) and control rats (2.61+/-0.34 mg/d). URAT1 protein abundance in cortical homogenates was not significantly different between the uric acid-supplemented rats (132+/-14%) and control rats (100+/-7%). However, OAT1 protein abundance was significantly (p<0.05) increased in the uric acid-supplemented rats (148+/-13%) compared with the control rats (100+/-8%). OAT3 protein abundance was not significantly different between the uric acid-supplemented rats (131+/-12%) and control rats (100+/-17%). In conclusion, OAT1 may have a regulatory role in response to the increase in uric acid intake in the rat kidney. The up-regulation of OAT1 would exert stimulation of urinary uric acid excretion and might contribute to protection from hyperuricemia.

Co-localization and interaction of organic anion transporter 1 with caveolin-2 in rat kidney

The organic anion transporters (OAT) have recently been identified. Although the some transport properties of OATs in the kidney have been verified, the regulatory mechanisms for OAT's functions are still not fully understood. The rat OAT1 (rOAT1) transports a number of negatively charged organic compounds between the cells and their extracellular milieu. Caveolin (Cav) also plays a role in membrane transport. Therefore, we investigated the protein-protein interactions between rOAT1 and caveolin-2. In the rat kidney, the expressions of rOAT1 mRNA and protein were observed in both the cortex and the outer medulla. With respect to Cav-2, the expressions of mRNA and protein were observed in all portions of the kidney (cortex < outer medulla = inner medulla). The results of Western blot analysis using the isolated caveolae-enriched membrane fractions or the immunoprecipitates by respective antibodies from the rat kidney showed that rOAT1 and Cav-2 co-localized in the same fractions and they formed complexes each other. These results were confirmed by performing confocal microscopy with immunocytochemistry using the primary cultured renal proximal tubular cells. When the synthesized cRNA of rOAT1 along with the antisense oligodeoxynucleotides of Xenopus Cav-2 were co-injected into Xenopus oocytes, the [14C]p-aminohippurate and [3H]methotrexate uptake was slightly, but significantly decreased. The similar results were also observed in rOAT1 over-expressed Chinese hamster ovary cells. These findings suggest that rOAT1 and caveolin-2 are co-expressed in the plasma membrane and rOAT1's function for organic compound transport is upregulated by Cav-2 in the normal physiological condition.