Showing papers on "Xanthine published in 2022"
TL;DR: In this article , the authors applied untargeted metabolomics (LOD, 1.08-35.60 μg L-1; LOQ, 2.54-90.2%) and proteomics methods by UHPLC-Q-Orbitrap HRMS to investigate the metabolic pathways and nutritional quality of goat milk contaminated with sodium perchlorate.
23 citations
TL;DR: In this article , an ultrabright lysozyme-functionalized 5-methyl-2-thiouracil gold nanoclusters with yellow emission were rationally designed and synthesized based on [email protected] by making the NC shell modified with the lyso enzyme.
Abstract: Making the gold-thiolate shell rigid is an appealing and efficient strategy for improving the fluorescence of gold nanoclusters (GNCs). In this study, ultrabright lysozyme-functionalized 5-methyl-2-thiouracil gold nanoclusters ([email protected]) with yellow emission were rationally designed and synthesized based on [email protected] by making the NC shell modified with the lysozyme. The resultant [email protected] exhibited a remarkable luminescence efficiency, high stability, and water-solubility. By combining [email protected] with iron-doped carbon-nanosheet (Fe/C NS) that mimicked peroxidase-like activity, a novel fluorescent nanoprobe was developed for the determination of xanthine. Under the catalysis of xanthine oxidase (XOD), hydrogen peroxide (H2O2) was produced during the oxidation of xanthine. In the presence of H2O2, Fe/C NS can effectively catalyze H2O2 to generate reactive oxygen species (ROS) and subsequently catalyze p-phenylenediamine (PPD) to form its oxidized product (PPDox), thereby quenching the fluorescence of [email protected] at 550 nm via fluorescence resonance energy transfer (FRET). Coupling the peroxidase-like activity of Fe/C NS and XOD cascade reactions, the proposed sensing platform based on [email protected] and Fe/C NS can realize the quantitative analysis of xanthine in the range from 0.5 to 400 µmol L−1, affording a low detection limit of 0.23 µmol L−1. In addition, this study provided satisfactory results for monitoring the xanthine content of real samples.
15 citations
TL;DR: In this paper , the authors examined the crystal morphology of guanine and found no correlation between the biogenic crystal morphology and dopant content and concluded that dopants do not influence the crystal shape.
Abstract: Highly reflective crystals of the nucleotide base guanine are widely distributed in animal coloration and visual systems. Organisms precisely control the morphology and organization of the crystals to optimize different optical effects, but little is known about how this is achieved. Here we examine a fundamental question that has remained unanswered after over 100 years of research on guanine: what are the crystals made of? Using solution-state and solid-state chemical techniques coupled with structural analysis by powder XRD and solid-state NMR, we compare the purine compositions and the structures of seven biogenic guanine crystals with different crystal morphologies, testing the hypothesis that intracrystalline dopants influence the crystal shape. We find that biogenic “guanine” crystals are not pure crystals but molecular alloys (aka solid solutions and mixed crystals) of guanine, hypoxanthine, and sometimes xanthine. Guanine host crystals occlude homogeneous mixtures of other purines, sometimes in remarkably large amounts (up to 20% of hypoxanthine), without significantly altering the crystal structure of the guanine host. We find no correlation between the biogenic crystal morphology and dopant content and conclude that dopants do not dictate the crystal morphology of the guanine host. The ability of guanine crystals to host other molecules enables animals to build physiologically “cheaper” crystals from mixtures of metabolically available purines, without impeding optical functionality. The exceptional levels of doping in biogenic guanine offer inspiration for the design of mixed molecular crystals that incorporate multiple functionalities in a single material.
14 citations
TL;DR: Results demonstrated that L. paracasei MJM60396 can prevent hyperuricemia in multiple ways by absorbing purines, decreasing UA synthesis by suppressing xanthine oxidase, and increasing UA excretion by regulating urate transporters.
Abstract: Hyperuricemia is a metabolic disorder caused by increased uric acid (UA) synthesis or decreased UA excretion. Changes in eating habits have led to an increase in the consumption of purine-rich foods, which is closely related to hyperuricemia. Therefore, decreased purine absorption, increased UA excretion, and decreased UA synthesis are the main strategies to ameliorate hyperuricemia. This study aimed to screen the lactic acid bacteria (LAB) with purine degrading ability and examine the serum UA-lowering effect in a hyperuricemia mouse model. As a result, Lacticaseibacillus paracasei MJM60396 was selected from 22 LAB isolated from fermented foods for 100% assimilation of inosine and guanosine. MJM60396 showed probiotic characteristics and safety properties. In the animal study, the serum uric acid was significantly reduced to a normal level after oral administration of MJM60396 for 3 weeks. The amount of xanthine oxidase, which catalyzes the formation of uric acid, decreased by 81%, and the transporters for excretion of urate were upregulated. Histopathological analysis showed that the damaged glomerulus, Bowman’s capsule, and tubules of the kidney caused by hyperuricemia was relieved. In addition, the impaired intestinal barrier was recovered and the expression of tight junction proteins, ZO-1 and occludin, was increased. Analysis of the microbiome showed that the relative abundance of Muribaculaceae and Lachnospiraceae bacteria, which were related to the intestinal barrier integrity, was increased in the MJM60396 group. Therefore, these results demonstrated that L. paracasei MJM60396 can prevent hyperuricemia in multiple ways by absorbing purines, decreasing UA synthesis by suppressing xanthine oxidase, and increasing UA excretion by regulating urate transporters.
13 citations
TL;DR: It is found that the lighter the fermentation, the greater the potential for inhibiting the production of uric acid, and the inhibitory effects of polyphenols rich in lightly fermented tea were significantly stronger than caffeine rich in highly fermented tea.
Abstract: Background The health benefits of tea are as diverse including the reduction of uric acid levels. Xanthine oxidase is the most directly mediated enzyme in the production of uric acid. Objective To explore the inhibitory effects of different teas and its main bioactive components on the production of uric acid. Design Experimental study. The experiments were conducted in vitro using human immortalized normal liver cell line HL-7702 (L-02). Results The inhibition of the xanthine oxidase activities and the expression level of xanthine dehydrogenase mRNA stimulated in the hyperuric hepatocyte cell model showed that the unfermented green tea and th1e lightly fermented yellow tea, white tea, and oolong tea significantly stronger than the highly fermented black tea and dark tea. The main bioactive compound, gallic acid, showed the strongest inhibitory effect on uric acid production, followed by tea polyphenols and theaflavins. Discussion All teas exhibited significant inhibition of xanthine oxidase activities, and the degree of fermentation of tea may be inversely proportional to its ability to inhibit the production of uric acid. Compared with tea polyphenols rich in tea, gallic acid may be a more potential uric acid-lowering component. Conclusion In this article, we first compared the effects of six traditional Chinese tea made from a single variety in stabilizing the synthesis of uric acid and found that the lighter the fermentation, the greater the potential for inhibiting the production of uric acid. Furthermore, we analyzed the inhibitory effects of its main biochemical active ingredients and found that the inhibitory effects of polyphenols rich in lightly fermented tea were significantly stronger than caffeine rich in highly fermented tea. Our findings will be helpful for people to choose a proper tea for alleviating hyperuricemia and provide a scientific basis for uric acid-lowering tea processing.
12 citations
17 Mar 2022
9 citations
TL;DR: In this paper, a 3D organoid culture system for mimicking hyperuricemia in vitro was established using cultured human liver organoids, which can be generated from single hepatocytes and passaged for several months, retaining key morphological features, functional purine metabolism and global gene expression profile.
7 citations
TL;DR: In this article , a 3D organoid culture system for mimicking hyperuricemia in vitro was established using cultured human liver organoids, which can be generated from single hepatocytes and passaged for several months, retaining key morphological features, functional purine metabolism and global gene expression profile.
7 citations
TL;DR: Some riboswitches can diversify their ligand-sensing and gene-control functions without the need to evolve entirely novel structures, which highlights a capability that could have also been exploited by ancient forms of life during the RNA World.
Abstract: Significance Numerous purines and their metabolic derivatives must be monitored for proper control of relevant metabolic pathways. In certain bacteria, some metabolic steps related to purine production or degradation are catalyzed by proteins whose production is under direct regulatory control by purine-sensing riboswitches. Four riboswitch classes selective for guanine, adenine, and 2′-deoxyguanosine (two classes) reported previously exploit a common architecture involving a three-stem junction. Here, we describe three additional classes based on this same scaffold that sense xanthine, guanine, or 2′-deoxyguanosine. Thus, some riboswitches can diversify their ligand-sensing and gene-control functions without the need to evolve entirely novel structures, which highlights a capability that could have also been exploited by ancient forms of life during the RNA World.
7 citations
TL;DR: In this paper , a new design of biosensor based on polymeric nano(bio)composite has been proposed for the selective detection of xanthine to be used in the clinical analysis as well as food quality control.
7 citations
TL;DR: In this article , a series of new xanthine derivatives derived from the natural xanthines or methylxanthines would be rich resources and possess high potentials to afford new active pesticidal molecules.
Abstract: BACKGROUND
The design and discovery of novel pesticidal agents according to bioactive natural products are an important aspect in agrochemical innovations. New xanthine derivatives derived from the natural xanthine or methylxanthines would be rich resources and possess high potentials to afford new active pesticidal molecules. Herein novel xanthine derivatives were designed through a strategy of combining methylxanthine caffeine skeleton with acrylamide or acrylate motif of cinnamic acid derivatives.
RESULTS
A series of novel (E)-3-(1,3,7-trimethyl-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-8-yl)acrylic acid derivatives, that is, caffeine-(E)-acrylamides and caffeine-(E)-acrylates were synthesized and confirmed via melting points, 1 H NMR, 13 C NMR and HRMS. The single crystal of compound I12 was obtained to illustrate a trans-configuration of the vinyl double bond. Preliminary insecticidal evaluations displayed that some of the compounds had favorable insecticidal potentials against Mythimna separata Walker at 200 mg·L-1 . Some of the compounds exhibited excellent insecticidal activity against Plutella xylostella L. at low test concentrations, e.g. I18 and I24 with LC50 value of 0.0435 mg·L-1 and 0.0133 mg·L-1 respectively were found more potent than insecticide control triflumuron. The structure-activity relationship (SAR) analysis was also given in detail.
CONCLUSION
Compounds I12, I18, I24 and I26 generated from the integration of natural methylxanthine (caffeine) and acrylate moieties could be novel insecticidal leading compounds for further structural optimization. The SAR analysis may bring a new inspiration to the extensive deep investigations on new xanthine derivatives in agrochemical area.
TL;DR: In this article , the authors used molecular docking, fluorescence quenching, circular dichroism spectroscopy and molecular dynamics simulations to identify potential inhibitors against xanthine oxidase from a library of pickled radish compounds.
TL;DR: In-vitro and in-silico results divulge that phenolic compounds have a strong potential to lower uric acid levels via interacting with the XO enzyme and can be used to combat hyperuricemia.
Abstract: This project was designed to explore the xanthine oxidase (XO) inhibitory mechanism of eight structurally diverse phenolic compounds [quercetin: C1, quercetin-3-rhamnoside: C2, 4, 5-O-dicaffeoylquinic acid: C3, 3, 5-O-dicaffeoylquinic acid: C4, 3, 4-O-di-caffeoylquinic acid: C5, 4-O-caffeoylquinic acid (C6), 3-O-caffeoylquinic acid: C7, and caffeic acid: C8]. For this purpose, in-vitro and different computational methods were applied to determine the xanthine oxidase (XO) inhibitory potential of eight structurally diverse phenolic compounds. The results revealed that phenolic compounds (C1–C8) possess strong to weak XO inhibitory activity. These results were further confirmed by atomic force microscopy (AFM) and 1H NMR analysis. Furthermore, computational study results revealed that phenolic compounds (C1–C8) bind with the surrounding amino acids of XO at the molybdenum (MO) site. These in-vitro and in-silico results divulge that phenolic compounds have a strong potential to lower uric acid levels via interacting with the XO enzyme and can be used to combat hyperuricemia.
TL;DR: In this article , a green and cost-effective technique for the preparation of silver nanoparticles stabilized with cinnamon phytochemicals (CIN-AgNPs) as H2O2 and xanthine nonozyme is described.
TL;DR: In this article , a universal ratiometric fluorescence and colorimetric dual-mode sensing platform for detecting hydrogen peroxide (H2O2) and related metabolites in human fluid was constructed based on iron and nitrogen co-doped carbon dots (Fe/N-CDs).
TL;DR: In this article , a simple, all-in-one injection hydrophilic interaction liquid chromatography-tandem mass spectrometry method was developed for simultaneous determination of 20 metabolites: adenine, adenosine, deoxyadenosine and inosine.
TL;DR: The effects of changes of VNAs in the plasma of CRC patients (especially NDMA and NPYR) on the progression of CRC should attract attention.
TL;DR: In this paper , the in vitro inhibitory effect of water extract of the flower bud of Sophora japonica (WESJ) on Xanthine oxidase (XOD) was investigated by ultraviolet spectrophotometry.
Abstract: Hyperuricemia (HUA) is a metabolic condition caused by excessive production or low excretion of uric acid (UA) in the body. Xanthine oxidase (XOD) is the key enzyme in the process of metabolism purines to generate UA. In this study, the in vitro inhibitory effect of water extract of the flower bud of Sophora japonica (WESJ) on XOD was investigated by ultraviolet spectrophotometry. A mice model of HUA was constructed to explore the effect of WESJ on UA levels and the mechanism of action on renal function. Based on Box–Behnken design, the optimal extraction process of WESJ was determined to extract Sophora japonica twice with 8 times of water, 0.5 h each time. Pharmacological results showed that low, medium, and high doses of WESJ (200, 400, 600 mg/kg) could significantly reduce serum UA level, inhibit the activity of XOD in blood and liver, and have a protective effect on kidney damage caused by high UA. Through UPLC-Q-TOF-MS/MS analysis, 214 compounds were identified in WESJ, including flavonoids, polyphenols, triterpenoids, organic acids, and others. The rat serum of WESJ was analyzed, and 23 prototype components entering the blood were identified, including 15 flavonoids and polyphenols, which may be the main bioactive components. In conclusion, flavonoids and polyphenols in WESJ may reduce the level of UA and alleviate kidney damage by inhibiting the activity of XOD. WESJ is expected to be used as a plant-based food and dietary supplement for the treatment of HUA.
TL;DR: In this article , a mutant with early leaf senescence and reduced tillering was identified, and the mutation of ESL1 led to decreases in allantoin, allantoate, and ABA contents.
Abstract: Xanthine dehydrogenase, a member of the molybdenum enzyme family, participates in purine metabolism and catalyzes the generation of ureides from xanthine and hypoxanthine. However, the mechanisms by which xanthine dehydrogenase affects rice growth and development are poorly understood. In the present study, we identified a mutant with early leaf senescence and reduced tillering that we named early senescence and less-tillering 1 (esl1). Map-based cloning revealed that ESL1 encodes a xanthine dehydrogenase, and it was expressed in all tissues. Chlorophyll content was reduced and chloroplast maldevelopment was severe in the esl1 mutant. Mutation of ESL1 led to decreases in allantoin, allantoate, and ABA contents. Further analysis revealed that the accumulation of reactive oxygen species in esl1 resulted in decreased photosynthesis and impaired chloroplast development, along with increased sensitivity to abscisic acid and abiotic stresses. Ttranscriptome analysis showed that the ESL1 mutation altered the expression of genes involved in the photosynthesis process and reactive oxygen species metabolism. Our results suggest that ESL1 is involved in purine metabolism and the induction of leaf senescence. These findings reveal novel molecular mechanisms of ESL1 gene-mediated plant growth and leaf senescence.
TL;DR: In this paper , a series of cyclic dinuclear Au(I) N-heterocyclic carbene complexes based on xanthine and benzimidazole ligands has been synthesized and characterized by various methods, including X-ray diffraction.
Abstract: With the aim to improve the design of metal complexes as stabilizers of noncanonical DNA secondary structures, namely, G-quadruplexes (G4s), a series of cyclic dinuclear Au(I) N-heterocyclic carbene complexes based on xanthine and benzimidazole ligands has been synthesized and characterized by various methods, including X-ray diffraction. Fluorescence resonance energy transfer (FRET) and CD DNA melting assays unraveled the compounds’ stabilization properties toward G4s of different topologies of physiological relevance. Initial structure–activity relationships have been identified and recognize the family of xanthine derivatives as those more selective toward G4s versus duplex DNA. The binding modes and free-energy landscape of the most active xanthine derivative (featuring a propyl linker) with the promoter sequence cKIT1 have been studied by metadynamics. The atomistic simulations evidenced that the Au(I) compound interacts noncovalently with the top G4 tetrad. The theoretical results on the Au(I) complex/DNA Gibbs free energy of binding were experimentally validated by FRET DNA melting assays. The compounds have also been tested for their antiproliferative properties in human cancer cells in vitro, showing generally moderate activity. This study provides further insights into the biological activity of Au(I) organometallics acting via noncovalent interactions and underlines their promise for tunable targeted applications by appropriate chemical modifications.
TL;DR: In this article , mycotoxin alternariol (AOH), a dibenzo-α-pyrone derivative, had strong inhibitory activity on XO, and the IC50 value was 0.23 ± 0.01 μM.
TL;DR: In this article , a rat model with the genetic ablation of the Xdh gene on the Dahl salt-sensitive rat background (SSXdh−/−) was created to explore how hypouricemia can lead to kidney damage.
TL;DR: In this article , a nickel-catalyzed C-H heteroarylation of arenes has been described using a removable oxazoline-aniline derived directing group.
TL;DR: In this paper , an ultraviolet (UV)-treated liquid crystal (LC)-based optical sensor for monitoring the xanthine (Xn) levels is presented, which is based on the orientation change of UV-treated 4-cyano-4-4′-pentylbiphenyl (5CB) by the pH-dependent adsorption and desorption of CB at the aqueous-5CB interface.
Abstract: We report an ultraviolet (UV)-treated liquid crystal (LC)-based optical sensor for monitoring the xanthine (Xn) levels. The sensing mechanism is based on the orientation change of UV-treated 4-cyano-4′-pentylbiphenyl (5CB) by the pH-dependent adsorption and desorption of 4-cyano-4′-biphenylcarboxylate (CB) at the aqueous-5CB interface. The areal density of CB adsorbed at the interface has an effect on the orientation of the LCs and depends on the pH of the solutions. When the pH levels increased, the optical image of the UV-treated 5CB appeared dark due to the self-assembled CB at the interface. When the pH levels decreased, the optical image appeared bright due to the desorption of CB from the interface to the aqueous phase. Xanthine oxidase (XO) catalyzes the Xn degradation reaction, forming uric acid and hydrogen peroxide. These acidic products contribute to decreasing pH levels and the tilted ordering of 5CB. A transition from the homeotropic to tilted orientation as the Xn concentration increased was visible as a change from dark to bright images under a polarizing microscope. This pH-driven optical sensor had low detection limits of 1.733 pM in the phosphate-buffered saline and could be applicable in human urine and spoiled fish.
TL;DR: NAY significantly reduced the level of UA in hyperuricemia mice and cells by inhibiting xanthine oxidase activity and reduced the levels of TNF-α, IL-6, and other inflammatory factors in serum and kidney of mice.
Abstract: Objective: To observe the antioxidative effects of N-(9,10-anthraquinone-2-ylcarbonyl) xanthine oxidase inhibitors (NAY) in vitro and in vivo models of hyperuricemia and explore the mechanism. Methods: A classical experimental method of acute toxicity and a chronic toxicity test were used to compare the toxic effects of different doses of NAY in mice. The hyperuricemia mouse model was established by gavage of potassium oxonate in vivo. After treatment with different doses of NAY (low dose: 10 mg/kg, medium dose: 20 mg/kg, and high dose: 40 mg/kg) and allopurinol (positive drug, 10 mg/kg), observe the levels of uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) in urine and serum, respectively, and detect the activities of xanthine oxidase in the liver. The hyperuricemia cell model was induced by adenosine and xanthine oxidase in vitro. The cells were given different doses of NAY (50, 100, and 200 μmol/L) and allopurinol (100 μmol/L). Then the culture supernatant UA level of the medium was measured. The next step was to detect the xanthine oxidase activity in the liver and AML12 cells, and the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), and NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammatory factors in the kidney and serum of mice. Western blot was used to detect xanthine oxidase protein expression in mouse liver tissue and AML12 cells, ASC, Caspase-1, NLRP3, GLUT9, OAT1, and OAT3 protein expression in mouse kidney tissue and HK-2 cells. Hematoxylin–eosin staining was used to stain the liver and kidney tissues of mice and observe the tissue lesions. Results: NAY had little effect on blood routine and biochemical indexes of mice, but significantly reduced the serum UA level. NAY significantly reduced the level of UA in hyperuricemia mice and cells by inhibiting xanthine oxidase activity and reduced the levels of TNF-α, IL-6, and other inflammatory factors in serum and kidney of mice. NAY can inhibit inflammation by inhibiting the NLRP3 pathway. In addition, NAY can downregulate GLUT9 protein expression and upregulate OAT1 and OAT3 protein expression to reduce the UA level by promoting UA excretion and inhibiting UA reabsorption. Conclusion: These findings suggested that NAY produced dual hypouricemic actions. On the one hand, it can inhibit the formation of UA by inhibiting xanthine oxidase inhibitors activity, and on the other hand, it can promote the excretion of UA by regulating the UA transporter. It provides new ideas for the development of hyperuricemia drugs in the future.
TL;DR: A new type of fluorescent probe Rhodol-OAc, which had good water solubility, high selectivity and sensitivity to H2O2, low cytotoxicity, excellent mitochondrial targeting ability, etc, was successfully applied in the imaging of exogenous and endogenous H 2O2 in living cells.
Abstract: Hydrogen peroxide (H2O2) is a main member of reactive oxygen species (ROS) in cells that has a significant impact on various physiological and pathological processes of organisms. Here, we designed and synthesized a new type of fluorescent probe Rhodol-OAc for the specific detection of H2O2. The probe had good water solubility, high selectivity and sensitivity to H2O2, low cytotoxicity, excellent mitochondrial targeting ability, etc. It was successfully applied in the imaging of exogenous and endogenous H2O2 in living cells. In addition, theoretical calculations were carried out to clarify the luminescence mechanism of the probe. More importantly, we successfully applied the probe to indirectly detect xanthine and glucose, the metabolism of which generates H2O2, and achieved satisfactory results.
TL;DR: Male uricase-deficient rats’ UA metabolism is similar to that of men, and these animals are a sensitive model for studying hyperuricemia.
Abstract: The aim of this study was to provide a sensitive model animal for studying hyperuricemia. Male uricase-deficient rats, named Kunming-DY rats, were raised for 130 days, or orally administered with purines and other chemicals. Serum uric acid (SUA) in the animals was assayed, and the UA level in their organs and their 24-h excretion was determined. Genes in the jejunum, ileum, kidney and liver related to UA synthesis and transportation were detected by quantitative RNA sequencing. Uricase-deficient rats have a high level of SUA and are sensitive to xanthine, adenosine, inosine, allopurinol, and alcohol. Besides, the high level of SUA in male uricase-deficient rats was stable, much higher than that in wild-type rats but similar to that in men. The distribution pattern of UA in uricase-deficient rats’ organs was different from that in wild-type rats. The kidney, liver, and small intestine were the top three organs where UA distributed, but the UA in the small intestine, colon, lung, thymus, and brain was less affected by uricase deficiency, indicating that these organs are constitutive distribution organs in UA. The 24-h UA excreted by a uricase-deficient rat was about five times higher than that excreted by a wild-type rat. However, the 24-h UA excreted through feces was not significantly changed. Both the urine volume and UA in uricase-deficient rats significantly increased, and more than 90% of UA was excreted via urine. The expression of xanthine dehydrogenase was not upregulated. Some genes of transporter associated with uric acid excretion in the kidney were significantly regulated, though not sufficient to explain the increase in SUA. In conclusion, male uricase-deficient rats’ UA metabolism is similar to that of men. The elevation of SUA in uricase-deficient rats is caused by uricase deficiency, and uricase-deficient rats are a sensitive model for studying hyperuricemia.
TL;DR: This study represents the first attempt to bring together site-directed mutagenesis reports and the latest cryo-EM structure of an antagonist bound to TRPA1, and suggests that the core moiety of HC-030031 binds to a pocket formed by the TRP-like domain and the pre-S1, S4, S5 helices of one subunit.
Abstract: TRPA1 is a transmembrane cation channel, one of the most promising targets in the context of respiratory diseases. Its general structure has already been experimentally resolved, but the binding site of TRPA1 antagonists such as HC-030031, a model methylxanthine derivative, remains unknown. The present study aimed to determine the potential binding site of xanthine antagonists and to describe their binding mode, using a molecular modeling approach. This study represents the first attempt to bring together site-directed mutagenesis reports and the latest cryo-EM structure of an antagonist bound to TRPA1. Our research suggests that the core moiety of HC-030031 binds to a pocket formed by the TRP-like domain and the pre-S1, S4, S5 helices of one subunit. The structure, determined by cryo-EM, shows interactions of a core hypoxanthine moiety in the same area of the binding site, sharing the interaction of xanthine/hypoxanthine with Trp-711. Moreover, the predicted binding mode of HC-030031 assumes interaction with Asn-855, a residue demonstrated to be important for HC-030031 recognition in site-directed mutagenesis studies. Our model proved to be advantageous in a retrospective virtual screening benchmark; therefore, it will be useful in research on new TRPA1 antagonists among xanthine derivatives and their bioisosteres.
TL;DR: The clone of Slc23a4-paralog SLC23A3 from the human kidney is confirmed to be a hypoxanthine transporter in the human kidneys and its transport activity is investigated.
Abstract: Abstract LLC-PK1 renal cells show Na+-dependent and Na+-independent hypoxanthine uptake. While the latter is inhibited by adenine, neither are inhibited by xanthine. In rats, intestinal Na+-dependent hypoxanthine transporter Slc23a4 is not expressed in the kidney, and its action is inhibited by xanthine. This study aimed to clone Slc23a4-paralog SLC23A3 from the human kidney and investigate its hypoxanthine transport activity. We observed Na+-dependent 10 nM [3H]-hypoxanthine uptake in SLC23A3 RNA-injected Xenopus oocytes. Moreover, 100 μM xanthine did not inhibit Na+-independent 300 nM [3H]-hypoxanthine uptake, whereas 100 μM adenine did. These results confirm that SLC23A3 is a hypoxanthine transporter in the human kidney.