Left ventricular noncompaction cardiomyopathy and short QT syndrome due to primary carnitine deficiency.

We report the case of a 13-year-old female patient presenting with presyncope and palpitations. Her electrocardiogram revealed an abbreviation of the rate-corrected QT interval with imaging showing significant left ventricular dysfunction. Carnitine levels were measured as part of her diagnostic workup, discovering a rare, reversible cause of short QT syndrome (SQTS) and associated cardiomyopathy-primary carnitine deficiency (PCD) caused by a homozygous mutation in the SLC22A5 gene, leading to an in-frame deletion mutation (NP_003051.1:p.Phe23del) affecting the organic cation transporter 2 (OCTN2) protein. Following the treatment with oral carnitine supplementation, her QT interval returned to within the normal range with significant improvement in left ventricular function.

Lenvatinib causes reduced expression of carnitine/organic cation transporter 2 and carnitine deficiency in the skeletal muscle of rats.

Lenvatinib, an oral tyrosine kinase inhibitor, is widely used to treat several types of advanced cancers but often causes muscular adverse reactions. Although carnitine supplementation may prevent these effects, the mechanism underlying lenvatinib-induced skeletal muscle impairment remains poorly understood. To this end, we aimed to investigate the impact of lenvatinib on carnitine disposition in rats. Once-daily administration of lenvatinib repeated for two weeks did not affect urinary excretion or serum concentration of carnitines throughout the treatment period but ultimately decreased the L-carnitine content in the skeletal muscle. The treatment decreased the expression of carnitine/organic cation transporter (OCTN) 2, a key transporter of carnitine, in skeletal muscle at the protein level but not at the mRNA level. In cultured C2C12 myocytes, lenvatinib inhibited OCTN2 expression in a dose-dependent manner at the protein level. Furthermore, lenvatinib dose-dependently decreased the protein levels of carnitine-related genes, adenosine triphosphate content, mitochondrial membrane potential, and markers of mitochondrial function in vitro. These results reveal the deleterious effects of lenvatinib on OCTN2 expression, carnitine content, and mitochondrial function in skeletal muscle that may be associated with muscle toxicity.

Wedelolactone protects against cisplatin-induced nephrotoxicity in mice via inhibition of organic cation transporter 2.

The balance of cisplatin uptake and efflux, mediated mainly by organic cation transporter 2 (OCT2) and multidrug and toxin extrusion 1 (MATE1), respectively, determines the renal accumulation and nephrotoxicity of cisplatin. Using transporter-mediated cellular uptake assay, we identified wedelolactone (WEL), a medicinal plant-derived natural compound, is a competitive inhibitor of OCT2 and a noncompetitive inhibitor of MATE1. Wedelolactone showed a selectivity to inhibit OCT2 rather than MATE1. Cytotoxicity studies revealed that wedelolactone alleviated cisplatin-induced cytotoxicity in OCT2-overexpressing HEK293 cells, whereas it did not alter the cytotoxicity of cisplatin in various cancer cell lines. Additionally, wedelolactone altered cisplatin pharmacokinetics, reduced kidney accumulation of cisplatin, and ameliorated cisplatin-induced acute kidney injury in the Institute of Cancer Research mice. In conclusion, these findings suggest a translational potential of WEL as a natural therapy for preventing cisplatin-induced nephrotoxicity and highlight the need for drug-drug interaction investigations of WEL with other treatments which are substrates of OCT2 and/or MATE1.

Population diversity of three variants of the SLC47A2 gene (MATE2-K transporter) in Mexican Mestizos and Native Americans.

BACKGROUND: MATE2-K is an efflux transporter protein of organic cation expressed mainly in the kidney and encoded by the SLC47A2 gene. Different variants of this gene have shown an impact on the pharmacokinetics of various drugs, including metformin, which represents one of the most widely used drugs in treating type 2 diabetes. The SLC47A2 gene variants have been scarcely studied in Mexican populations, especially in Native American groups. For this reason, we analyzed the distribution of the variants rs12943590, rs35263947, and rs9900497 within the SLC47A2 gene in 173 Native Americans (Tarahumara, Huichol, Maya, Puerépecha) and 182 Mestizos (admixed) individuals from Mexico. METHODS AND RESULTS: Genotypes were determined through TaqMan probes (qPCR). The Hardy-Weinberg agreement was confirmed for all three SLC47A2 gene variants in all the Mexican populations analyzed. When worldwide populations were included for comparison purposes, for alleles and genotypes a relative interpopulation homogeneity was observed for rs35263947 (T allele; range 23.3-51.1%) and rs9900497 (T allele; range 18.6-40.9%). Conversely, heterogeneity was evident for rs12943590 (A allele, range 22.1-59.1%), where the most differentiated population was the Huichol, with high frequencies of the risk genotype associated with decreased response to metformin treatment (A/A = 40.9%). CONCLUSIONS: Although the SLC47A2 gene variants allow predicting favorable response to the metformin treatment in Mexican populations, the probable high frequency of ineffectiveness should be discarded in Huichols.

Polymorphisms in SLC44A1 are associated with cognitive improvement in children diagnosed with fetal alcohol spectrum disorder: an exploratory study of oral choline supplementation.

BACKGROUND: The essential nutrient choline provides one-carbon units for metabolite synthesis and epigenetic regulation in tissues including brain. Dietary choline intake is often inadequate, and higher intakes are associated with improved cognitive function. OBJECTIVE: Choline supplements confer cognitive improvement for those diagnosed with fetal alcohol spectrum disorder (FASD), a common set of neurodevelopmental impairments; however, the effect sizes have been modest. In this retrospective analysis, we report that genetic polymorphisms affecting choline utilization are associated with cognitive improvement following choline intervention. METHODS: Fifty-two children from the upper midwestern United States and diagnosed with FASD, ages 2-5 y, were randomly assigned to receive choline (500 mg/d; n = 26) or placebo (n = 26) for 9 mo, and were genotyped for 384 choline-related single nucleotide polymorphisms (SNPs). Memory and cognition were assessed at enrollment, study terminus, and at 4-y follow-up for a subset. RESULTS: When stratified by intervention (choline vs. placebo), 14-16 SNPs within the cellular choline transporter gene solute carrier family 44 member 1 (SLC44A1) were significantly associated with performance in an elicited imitation sequential memory task, wherein the effect alleles were associated with the greatest pre-/postintervention improvement. Of these, rs3199966 is a structural variant (S644A) and rs2771040 is a single-nucleotide variant within the 3' untranslated region of the plasma membrane isoform. An additive genetic model best explained the genotype associations. Lesser associations were observed for cognitive outcome and polymorphisms in flavin monooxygenase-3 (FMO3), methylenetetrahydrofolate dehydrogenase-1 (MTHFD1), fatty acid desaturase-2 (FADS2), and adiponectin receptor 1 (ADIPOR1). CONCLUSIONS: These SLC44A1 variants were previously associated with greater vulnerability to choline deficiency. Our data potentially support the use of choline supplements to improve cognitive function in individuals diagnosed with FASD who carry these effect alleles. Although these findings require replication in both retrospective and prospective confirmatory trials, they emphasize the need to incorporate similar genetic analyses of choline-related polymorphisms in other FASD-choline trials, and to test for similar associations within the general FASD population. This trial was registered at www.clinicaltrials.gov as NCT01149538.

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.

Carnitine promotes recovery from oxidative stress and extends lifespan in C. elegans.

Carnitine is required for transporting fatty acids into the mitochondria for ß-oxidation. Carnitine has been used as an energy supplement but the roles in improving health and delaying aging remain unclear. Here we show in C. elegans that L-carnitine improves recovery from oxidative stress and extends lifespan. L-carnitine promotes recovery from oxidative stress induced by paraquat or juglone and improves mobility and survival in response to H2O2 and human amyloid (Aß) toxicity. L-carnitine also alleviates the oxidative stress during aging, resulting in moderate but significant lifespan extension, which was dependent on SKN-1 and DAF-16. Long-lived worms with germline loss (glp-1) or reduced insulin receptor activity (daf-2) recover from aging-associated oxidative stress faster than wild-type controls and their long lifespans were not further increased by L-carnitine. A new gene, T08B1.1, aligned to a known carnitine transporter OCTN1 in humans, is required for L-carnitine uptake in C. elegans. T08B1.1 expression is elevated in daf-2 and glp-1 mutants and its knockdown prevents L-carnitine from improving oxidative stress recovery and prolonging lifespan. Together, our study suggests an important role of L-carnitine in oxidative stress recovery that might be important for healthy aging in humans.

An LC-MS/MS- and hURAT1 cell-based approach for screening of uricosuric agents.

Urate anion exchanger 1 (URAT1) expressed in the proximal renal tubules is responsible for about 90% of the reabsorption of uric acid. URAT1 is identified as an important target of uricosuric drugs. Here we present an LC-MS/MS-based approach, combined with URAT1-transgenic MDCK cells, for the assessment of uric acid. Cell lysis was executed with 50 mM NaOH to release uric acid. 1,3-15N2 uric acid was employed as the internal standard. The harvested uric acid, along with the stable isotope-labeled uric acid, was analyzed by LC-MS/MS in multiple reactions monitoring and negative modes. Validation, i.e. determination of selectivity, precision, accuracy, extraction recovery, and matrix effect, and feasibility was evaluated by use of the approach developed. The linearity was observed in the range of 1.0-250 µM (r = 0.9960) with limit of detection of 50 nM and limit of quantitation of 200 nM. The precision and accuracy were found to be RSD ≤ 20% and 80-120% of the nominal value, respectively. Uric acid uptake showed concentration and time dependency in URAT1-transgenic cells. The observed inhibitory effects of three URAT1-targeted uricosuric drugs were consistent with those reported in literature. The stable isotope dilution-based approach was proven to be selective, sensitive, and convenient, which is a good in vitro model for URAT1-targeted drug candidate screening.

Engineering carboxylic acid reductase for selective synthesis of medium-chain fatty alcohols in yeast.

Medium-chain fatty alcohols (MCFOHs, C6 to C12) are potential substitutes for fossil fuels, such as diesel and jet fuels, and have wide applications in various manufacturing processes. While today MCFOHs are mainly sourced from petrochemicals or plant oils, microbial biosynthesis represents a scalable, reliable, and sustainable alternative. Here, we aim to establish a Saccharomyces cerevisiae platform capable of selectively producing MCFOHs. This was enabled by tailoring the properties of a bacterial carboxylic acid reductase from Mycobacterium marinum (MmCAR). Extensive protein engineering, including directed evolution, structure-guided semirational design, and rational design, was implemented. MmCAR variants with enhanced activity were identified using a growth-coupled high-throughput screening assay relying on the detoxification of the enzyme's substrate, medium-chain fatty acids (MCFAs). Detailed characterization demonstrated that both the specificity and catalytic activity of MmCAR was successfully improved and a yeast strain harboring the best MmCAR variant generated 2.8-fold more MCFOHs than the strain expressing the unmodified enzyme. Through deletion of the native MCFA exporter gene TPO1, MCFOH production was further improved, resulting in a titer of 252 mg/L for the final strain, which represents a significant improvement in MCFOH production in minimal medium by S. cerevisiae.

Primary carnitine deficiency - diagnosis after heart transplantation: better late than never!

BACKGROUND: Primary carnitine deficiency due to mutations in the SLC22A5 gene is a rare but well-treatable metabolic disorder that puts patients at risk for metabolic decompensations, skeletal and cardiac myopathy and sudden cardiac death. RESULTS: We report on a 7-year-old boy diagnosed with primary carnitine deficiency 2 years after successful heart transplantation thanks his younger sister's having been identified via expanded newborn screening during a pilot study evaluating an extension of the German newborn screening panel. CONCLUSION: As L-carnitine supplementation can prevent and mostly reverse clinical symptoms of primary carnitine deficiency, all patients with cardiomyopathy should be investigated for primary carnitine deficiency even if newborn screening results were unremarkable.

A proton-coupled organic cation antiporter is involved in the blood-brain barrier transport of Aconitum alkaloids.

ETHNOPHARMACOLOGICAL RELEVANCE: The herbs of Aconitum are the essential Traditional Chinese medicine and have played an indispensable role in many Asian countries for thousands of years to treat critical illnesses, and chronic, stubborn diseases. However, Aconitum may induce severe neurotoxicity and even death. So far the mechanism of Aconitum penetrating the blood-brain barrier (BBB) is still unclear. AIM OF THE STUDY: To determine whether influx transporters contribute to the brain uptake of the highly toxic alkaloids in Aconitum including aconitine (AC), mesaconitine (MA) and hypaconitine (HA). MATERIALS AND METHODS: The uptake of AC, MA and HA was characterized using in vitro hCMEC/D3 model and in situ mouse brain perfusion. In hCMEC/D3 cells, the effect of incubation temperature, time, initial drug concentration, energy (NaN3), extracellular and intracellular pH (FCCP and NH4Cl), the prototypical substrates/inhibitors of known organic cation transporting carriers and trans-stimulation (pre-incubating with pyrilamine and diphenhydramine) on the cellular uptake were studied. In addition, the effect of silencing OCTN1, OCTN2 and PMAT by specific siRNA was investigated. In mice, the contribution of the proton-coupled antiporter on the brain uptake of Aconitum was investigated by chemical inhibition. RESULTS: In hCMEC/D3 cells, AC, MA and HA were each taken up in a temperature-, time- and concentration-dependent manner, which were reduced by NaN3 and FCCP. Regulation of extracellular and intracellular pH as well as trans-stimulation studies showed that AC, MA and HA were transported by a proton-coupled antiporter expressed at the plasma membrane that could also transport pyrilamine and diphenhydramine. Each uptake was markedly inhibited by various cationic drugs, but insensitive to the prototypical substrates/inhibitors of identified organic cation transporting carriers, such as OCTs, PMAT, MATEs and OCTNs. In addition, silence of OCTN1, OCTN2 and PMAT had no significant inhibitory effect on the uptake of AC, MA and HA. In mice, the brain uptake of each alkaloid measured by in situ brain perfusion was suppressed by diphenhydramine when the transport capacity of P-gp/Bcrp at the BBB was chemically inhibited. CONCLUSIONS: A novel proton-coupled organic cation antiporter plays a predominant role in the blood to brain influx of AC, MA and HA at the BBB, and thus affect the safety of Aconitum species.

An in vitro study on interaction of anisodine and monocrotaline with organic cation transporters of the SLC22 and SLC47 families.

Current study systematically investigated the interaction of two alkaloids, anisodine and monocrotaline, with organic cation transporter OCT1, 2, 3, MATE1 and MATE2-K by using in vitro stably transfected HEK293 cells. Both anisodine and monocrotaline inhibited the OCTs and MATE transporters. The lowest IC50 was 12.9 µmol·L-1 of anisodine on OCT1 and the highest was 1.8 mmol·L-1 of monocrotaline on OCT2. Anisodine was a substrate of OCT2 (Km = 13.3 ± 2.6 µmol·L-1 and Vmax = 286.8 ± 53.6 pmol/mg protein/min). Monocrotaline was determined to be a substrate of both OCT1 (Km = 109.1 ± 17.8 µmol·L-1, Vmax = 576.5 ± 87.5 pmol/mg protein/min) and OCT2 (Km = 64.7 ± 14.8 µmol·L-1, Vmax = 180.7 ± 22.0 pmol/mg protein/min), other than OCT3 and MATE transporters. The results indicated that OCT2 may be important for renal elimination of anisodine and OCT1 was responsible for monocrotaline uptake into liver. However neither MATE1 nor MATE2-K could facilitate transcellular transport of anisodine and monocrotaline. Accumulation of these drugs in the organs with high OCT1 expression (liver) and OCT2 expression (kidney) may be expected.

Relationship of MATE1 Inhibition and Cytotoxicity in Nephrotoxicity: Application for Safety Evaluation in Early Drug Discovery.

Accumulation of toxic endogenous and/or exogenous substances can trigger tissue injury. Multidrug and toxin extrusion proteins (MATEs) are transporters at renal proximal tubules involved in the secretion of hydrophilic substances into urine. Multidrug and toxin extrusion protein inhibition can lead to nephrotoxicity via accumulation of toxic substances; however, case studies demonstrating causality are rare, except for drug-drug interaction studies. To explore the involvement of MATE inhibition in nephrotoxicity, MATE1 inhibition, cytotoxicity, and mitochondrial toxicity (MT) of 38 in-house compounds that showed toxicity were assessed in in vivo safety evaluations using rats, dogs, and monkeys and compared considering unbound exposures at minimal steady-state concentration (C24h,u) between nephrotoxicity positive and negative compounds. Logarithmic-corrected means of C24h,u normalized by MATE1 IC50 or cytotoxicity EC50 (C24h,u/IC50 and C24h,u/EC50) were higher for nephrotoxic compounds. An exposure cutoff of C24h,u/IC50 > 0.01 filtered nephrotoxicity with a 54% positive predictive value. Of 7 cases filtered with this cutoff, all the cases showed pathological changes at renal proximal tubules expressing MATE1. Furthermore, all cases with > 0.01 reliable exposure for MATE1 inhibition and cytotoxicity exhibited nephrotoxicity. Although compounds potent for MATE1 inhibition and cytotoxicity without and with MT (potentials of 10, 30, and 40 µM, respectively) were correctly classified as nephrotoxic by evaluation of in vitro potency alone, without considering exposures, these results suggest that MATE1 inhibition potency and cytotoxicity can be used to assess nephrotoxicity, especially at proximal tubules, and could be used for safety assessment in early drug discovery.

Increased expression of SLC46A3 to oppose the progression of hepatocellular carcinoma and its effect on sorafenib therapy.

Hepatocellular carcinoma (HCC) prognosis remains dismal due to postsurgical recurrence and distant metastasis. Therefore, novel prognostic biomarkers and therapeutic targets for HCC therapy are urgently needed to improve the survival of liver cancer patients. Our evidence suggests that SLC46A3 (the gene solute carrier family 46 (sodium phosphate), member 3) is a member of the SLC46 family and has a potential role in the progression and treatment of HCC. The objective of the present study was to estimate the expression pattern and biological function of SLC46A3 in the progression of HCC, which may serve as a promising biomarker for diagnosis and therapy. In order to determine the expression pattern of SLC46A3 in HCC, several public HCC databases and tissue chips were used to examine 129 sets of primary HCC and non-tumor adjacent tissues from patients who had undergone surgery. The expression of SLC46A3 in 80 sets of HCC and non-tumor adjacent tissues were then compared by RT-PCR and Western Blot. The proliferation, invasion, migration and sphere-forming abilities of SLC46A3 knock-down and overexpressing cell lines were evaluated and the expression of related molecules in the epithelial mesenchymal transition (EMT) were detected by RT-PCR, western blot and immunofluorescence assay. The IC50 value was used to evaluate the effect of SLC46A3 on sorafenib resistance. A lung metastasis model of mice HCC was constructed to test the potential effect of SLC46A3 on cancer metastasis and a subcutaneous xenografted tumor mice model was designed to verify the effect of SLC46A3 on the resistance of HCC cell lines to sorafenib. The expression of SLC46A3 was down-regulated in 83.2% of human HCC tissues compared to non-tumor adjacent tissues. Tumors that expressed low levels of SLC46A3 had more aggressive phenotypes, and patients with these tumors had shorter survival times after surgery compared to patients whose tumors expressed high levels of SLC46A3. Hepatocellular carcinoma cell lines that stably overexpressed SLC46A3 inhibited the levels of migration and invasion compared with control HCC cells, and formed smaller xenograft tumors with more metastases in mice compared with HCC cells that did not overexpress SLC46A3. In addition, overexpression of SLC46A3 obviously inhibited epithelial-to-mesenchymal transition-activating transcription factors such as N-cadherin and Vimentin. Furthermore, descended of IC50 showed that overexpressed SLC46A3 could reduce sorafenib resistance and improve drug response in vivo and in vitro. In conclusion, increased expression of SLC46A3 could favor a better clinical prognosis for patients with HCC, ameliorate sorafenib resistance, and improve drug response. SLC46A3 might serve as a potential prognostic biomarker and therapeutic target in HCC.

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.

Genome-wide analysis of the MATE gene family in potato.

The multidrug and toxic compound extrusion (MATE) protein family is a newly discovered family of secondary transporters that extrude metabolic waste and a variety of antibiotics out of the cell using an electrochemical gradient of H+ or Na+ across the membrane. The main function of MATE gene family is to participate in the process of plant detoxification and morphogenesis. The genome-wide analysis of the MATE genes in potato genome was conducted. At least 48 genes were initially identified and classified into six subfamilies. The chromosomal localization of MATE gene family showed that they could be distributed on 11 chromosomes except chromosome 9. The number of amino acids is 145-616, the molecular weight of proteins is 15.96-66.13 KD, the isoelectric point is 4.97-9.17, and they were located on the endoplasmic reticulum with having 4-13 transmembrane segments. They contain only two parts of the exons and UTR without introns. Some members of the first subfamily of potato MATE gene family are clustered with At2g04070 and they may be related to the transport of toxic compounds such as alkaloids and heavy metal. The function of the members of the second subfamily may be similar to that of At3g23560, which is related to tetramethylammonium transport. Some members of the third subfamily are clustered with At3g59030 and they may be involved in the transport of flavonoids. The fifth subfamily may be related to the transport of iron ions. The function of the sixth subfamily may be similar to that of At4g39030, which is related to salicylic acid transport. There are three kinds of conserved motifs in potato MATE genes, including the motif 1, motif 2, and motif 3. Each motif has 50 amino acids. The number of each motif is different in the gene sequence, of which 45 MATE genes contain at least a motif, but there is no motif in ST0015301, ST0045283, and ST0082336. These results provide a reference for further research on the function of potato MATE genes.

DKB114, A Mixture of Chrysanthemum Indicum Linne Flower and Cinnamomum Cassia (L.) J. Presl Bark Extracts, Improves Hyperuricemia through Inhibition of Xanthine Oxidase Activity and Increasing Urine Excretion.

Chrysanthemum indicum Linne flower (CF) and Cinnamomum cassia (L.) J. Presl bark (CB) extracts have been used as the main ingredients in several prescriptions to treat the hyperuricemia and gout in traditional medicine. In the present study, we investigated the antihyperuricemic effects of DKB114, a CF, and CB mixture, and the underlying mechanisms in vitro and in vivo. DKB114 markedly reduced serum uric acid levels in normal rats and rats with PO-induced hyperuricemia, while increasing renal uric acid excretion. Furthermore, it inhibited the activity of xanthine oxidase (XOD) in vitro and in the liver in addition to reducing hepatic uric acid production. DKB114 decreased cellular uric acid uptake in oocytes and HEK293 cells expressing human urate transporter (hURAT)1 and decreased the protein expression levels of urate transporters, URAT1, and glucose transporter, GLUT9, associated with the reabsorption of uric acid in the kidney. DKB114 exerts antihyperuricemic effects and uricosuric effects, which are accompanied, partially, by a reduction in the production of uric acid and promotion of uric acid excretion via the inhibition of XOD activity and reabsorption of uric acid. Therefore, it may have potential as a treatment for hyperuricemia and gout.

Organic solute carrier 22 (SLC22) family: Potential for interactions with food, herbal/dietary supplements, endogenous compounds, and drugs.

Many drugs, hormones, components of herbal medicines, environmental pesticides and toxins are Solute Carrier family 22 (SLC22) substrates. The last twenty years has seen great progress in determining SLC22 tissue expression profiles, membrane localization, energetics, substrate profiles and biopharmaceutical significance. However, much still remains to be answered in terms of SLC22 family member's roles in 'normal' physiology as compared to pathophysiological states, as well as in drug interactions that impact pharmacokinetics, efficacy and toxicity. This review begins with a brief synopsis of SLC22 family discovery, function and tissue expression. Subsequent sections provide examples establishing a role for SLC22 transporters in food-drug, herbal supplement-drug, endogenous substrate-drug and drug-drug interactions.

Effect and mechanism of dioscin from Dioscorea spongiosa on uric acid excretion in animal model of hyperuricemia.

ETHNOPHARMACOLOGY RELEVANCE: Dioscin, a spirostane glycoside, the rhizoma of Dioscorea septemloba (Diocoreacea) is used for diuresis, rheumatism, and joints pain. Given the poor solubility and stability of Dioscin, we proposed a hypothesis that Dioscin's metabolite(s) are the active substance(s) in vivo to contribute to the reducing effects on serum uric acid levels. AIM OF THE STUDY: The aim of this study is to identify the active metabolite(s) of Dioscin in vivo and to explore the mechanism of its antihyperuricemic activity. MATERIALS AND METHODS: After oral administration of Dioscin in potassium oxonate (PO) induced hyperuricemia rats and adenine-PO induced hyperuricemia mice models, serum uric acid and creatinine levels, clearance of uric acid and creatinine, fractional excretion of uric acid, and renal pathological lesions were determined were used to evaluate the antihyperuricemic effects. Renal glucose transporter-9 (GLUT-9) and organic anion transporter-1 (OAT-1) expressions were analyzed by western blotting method. Renal uric acid excretion was evaluated using stably urate transporter-1 (URAT-1) transfected human epithelial kidney cell line. Intestinal uric acid excretion was evaluated by measuring the transcellular transport of uric acid in HCT116 cells. RESULTS: In hyperuricemia rats, both 25 and 50mg/kg of oral Dioscin decreased serum uric acid levels over 4h. In the hyperuricemia mice, two weeks treatment of Dioscin significantly decreased serum uric acid and creatinine levels, increased clearance of uric acid and creatinine, increased fractional excretion of uric acid, and reduced renal pathological lesions caused by hyperuricemia. In addition, renal GLUT -9 was significantly down-regulated and OAT-1 was up-regulated in Dioscin treated hyperuricemia mice. Dioscin's metabolite Tigogenin significantly inhibited uric acid re-absorption via URAT1 from 10 to 100µM. Diosgenin and Tigogenin increased uric acid excretion via ATP binding cassette subfamily G member 2 (ABCG2). CONCLUSION: Decreasing effect of Dioscin on serum uric acid level and enhancing effect on urate excretion were confirmed in hyperuricemia animal models. Tigogenin, a metabolite of Dioscin, was identified as an active substance with antihyperuricemic activity in vivo, through inhibition of URAT1 and promotion of ABCG2.

Two MATE Transporters with Different Subcellular Localization are Involved in Al Tolerance in Buckwheat.

Buckwheat (Fagopyrum esculentum) shows high tolerance to aluminum (Al) toxicity, but the molecular mechanisms responsible for this high Al tolerance are still poorly understood. Here, we investigated the involvement of two MATE (multi-drug and toxic compound extrusion) genes in Al tolerance. Both FeMATE1 and FeMATE2 showed efflux transport activity for citrate, but not for oxalate when expressed in Xenopus oocytes. A transient assay with buckwheat leaf protoplasts using green fluorescent protein (GFP) fusion showed that FeMATE1 was mainly localized to the plasma membrane, whereas FeMATE2 was localized to the trans-Golgi and Golgi. The expression of FeMATE1 was induced by Al only in the roots, but that of FeMATE2 was up-regulated in both the roots and leaves. Furthermore, the expression of both genes only responded to Al toxicity, but not to other stresses including low pH, cadmium (Cd) and lanthanum (La). Heterologous expression of FeMATE1 or FeMATE2 in the Arabidopsis mutant atmate partially rescued its Al tolerance. Expression of FeMATE1 also partially recovered the Al-induced secretion of citrate in the transgenic lines, whereas expression of FeMATE2 did not complement the citrate secretion. Further physiological analysis showed that buckwheat roots also secreted citrate in addition to oxalate in response to Al in a dose-responsive manner. Taken together, our results indicate that FeMATE1 is involved in the Al-activated citrate secretion in the roots, while FeMATE2 is probably responsible for transporting citrate into the Golgi system for the internal detoxification of Al in the roots and leaves of buckwheat.