Exploring the physicochemical properties of the integration of Tristearoyl uridine in Langmuir monolayers: An approach to cell membrane modeling for prodrugs.

Understanding the mechanisms by which drugs interact with cell membranes is crucial for unraveling the underlying biochemical and biophysical processes that occur on the surface of these membranes. Our research focused on studying the interaction between an ester-type derivative of tristearoyl uridine and model cell membranes composed of lipid monolayers at the air-water interface. For that, we selected a specific lipid to simulate nontumorigenic cell membranes, namely 1,2-dihexadecanoyl-sn-glycero-3-phospho-l-serine. We noted significant changes in the surface pressure-area isotherms, with a noticeable shift towards larger areas, which was lower than expected for ideal mixtures, indicating monolayer condensation. Furthermore, the viscoelastic properties of the interfacial film demonstrated an increase in both the elastic and viscous parameters for the mixed film. We also observed structural alterations using vibrational spectroscopy, which revealed an increase in the all-trans to gauche conformers ratio. This confirmed the stiffening effect of the prodrug on the lipid monolayer. In summary, this study indicates that this lipophilic prodrug significantly impacts the lipid monolayer's thermodynamic, rheological, electrical, and molecular characteristics. This information is crucial for understanding how the drug interacts with specific sites on the cellular membrane. It also has implications for drug delivery, as the drug's passage into the cytosol may involve traversing the lipid bilayer.

Molnupiravir increases SARS-CoV-2 genome diversity and complexity: A case-control cohort study.

Molnupiravir, an oral direct-acting antiviral effective in vitro against SARS-CoV-2, has been largely employed during the COVID-19 pandemic, since December 2021. After marketing and widespread usage, a progressive increase in SARS-CoV-2 lineages characterized by a higher transition/transversion ratio, a characteristic signature of molnupiravir action, appeared in the Global Initiative on Sharing All Influenza Data (GISAID) and International Nucleotide Sequence Database Collaboration (INSDC) databases. Here, we assessed the drug effects by SARS-CoV-2 whole-genome sequencing on 38 molnupiravir-treated persistently positive COVID-19 outpatients tested before and after treatment. Seventeen tixagevimab/cilgavimab-treated outpatients served as controls. Mutational analyses confirmed that SARS-CoV-2 exhibits an increased transition/transversion ratio seven days after initiation of molnupiravir. Moreover we observed an increased G->A ratio compared to controls, which was not related to apolipoprotein B mRNAediting enzyme, catalytic polypeptide-like (APOBEC) activity. In addition, we demonstrated for the first time an increased diversity and complexity of the viral quasispecies.

In Vitro Transcribed mRNA Immunogenicity Induces Chemokine-Mediated Lymphocyte Recruitment and Can Be Gradually Tailored by Uridine Modification.

Beyond SARS-CoV2 vaccines, mRNA drugs are being explored to overcome today's greatest healthcare burdens, including cancer and cardiovascular disease. Synthetic mRNA triggers immune responses in transfected cells, which can be reduced by chemically modified nucleotides. However, the side effects of mRNA-triggered immune activation on cell function and how different nucleotides, such as the N1-methylpseudouridine (m1Ψ) used in SARS-CoV2 vaccines, can modulate cellular responses is not fully understood. Here, cellular responses toward a library of uridine-modified mRNAs are investigated in primary human cells. Targeted proteomics analyses reveal that unmodified mRNA induces a pro-inflammatory paracrine pattern marked by the secretion of chemokines, which recruit T and B lymphocytes toward transfected cells. Importantly, the magnitude of mRNA-induced changes in cell function varies quantitatively between unmodified, Ψ-, m1Ψ-, and 5moU-modified mRNA and can be gradually tailored, with implications for deliberately exploiting this effect in mRNA drug design. Indeed, both the immunosuppressive effect of stromal cells on T-cell proliferation, and the anti-inflammatory effect of IL-10 mRNA are enhanced by appropriate uridine modification. The results provide new insights into the effects of mRNA drugs on cell function and cell-cell communication and open new possibilities to tailor mRNA-triggered immune activation to the desired pro- or anti-inflammatory application.

Clinical activity, pharmacokinetics, and pharmacodynamics of oral hypomethylating agents for myelodysplastic syndromes/neoplasms and acute myeloid leukemia: A multidisciplinary review.

OBJECTIVE: To review the pharmacokinetic (PK)-pharmacodynamic (PD) profiles, disease setting, dosing, and safety of oral and parenteral hypomethylating agents (HMAs) for the treatment of myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML), and to provide a multidisciplinary perspective on treatment selection and educational needs relating to HMA use. DATA SOURCES: Clinical and real-world data for parenteral decitabine and azacitidine and two oral HMAs: decitabine-cedazuridine (DEC-C) for MDS and azacitidine (CC-486) for AML maintenance therapy. DATA SUMMARY: Differences in the PK-PD profiles of oral and parenteral HMA formulations have implications for their potential toxicities and planned use. Oral DEC-C (decitabine 35 mg and cedazuridine 100 mg) has demonstrated equivalent systemic area under the concentration-time curve (AUC) exposure to a 5-day regimen of intravenous (IV) decitabine 20 mg/m2 and showed no significant difference in PD. The AUC equivalence of oral DEC-C and IV decitabine means that these regimens can be treated interchangeably (but must not be substituted within a cycle). Oral azacitidine has a distinct PK-PD profile versus IV or subcutaneous azacitidine, and the formulations are not bioequivalent or interchangeable owing to differences in plasma time-course kinetics and exposures. Clinical trials are ongoing to evaluate oral HMA combinations and novel oral HMAs, such as NTX-301 and ASTX030. CONCLUSIONS: Treatment with oral HMAs has the potential to improve quality of life, treatment adherence, and disease outcomes versus parenteral HMAs. Better education of multidisciplinary teams on the factors affecting HMA treatment selection may help to improve treatment outcomes in patients with MDS or AML.

Protective Effect of Uridine on Structural and Functional Rearrangements in Heart Mitochondria after a High-Dose Isoprenaline Exposure Modelling Stress-Induced Cardiomyopathy in Rats.

The pyrimidine nucleoside uridine and its phosphorylated derivates have been shown to be involved in the systemic regulation of energy and redox balance and promote the regeneration of many tissues, including the myocardium, although the underlying mechanisms are not fully understood. Moreover, rearrangements in mitochondrial structure and function within cardiomyocytes are the predominant signs of myocardial injury. Accordingly, this study aimed to investigate whether uridine could alleviate acute myocardial injury induced by isoprenaline (ISO) exposure, a rat model of stress-induced cardiomyopathy, and to elucidate the mechanisms of its action related to mitochondrial dysfunction. For this purpose, a biochemical analysis of the relevant serum biomarkers and ECG monitoring were performed in combination with transmission electron microscopy and a comprehensive study of cardiac mitochondrial functions. The administration of ISO (150 mg/kg, twice with an interval of 24 h, s.c.) to rats caused myocardial degenerative changes, a sharp increase in the serum cardiospecific markers troponin I and the AST/ALT ratio, and a decline in the ATP level in the left ventricular myocardium. In parallel, alterations in the organization of sarcomeres with focal disorganization of myofibrils, and ultrastructural and morphological defects in mitochondria, including disturbances in the orientation and packing density of crista membranes, were detected. These malfunctions were improved by pretreatment with uridine (30 mg/kg, twice with an interval of 24 h, i.p.). Uridine also led to the normalization of the QT interval. Moreover, uridine effectively inhibited ISO-induced ROS overproduction and lipid peroxidation in rat heart mitochondria. The administration of uridine partially recovered the protein level of the respiratory chain complex V, along with the rates of ATP synthesis and mitochondrial potassium transport, suggesting the activation of the potassium cycle through the mitoKATP channel. Taken together, these results indicate that uridine ameliorates acute ISO-induced myocardial injury and mitochondrial malfunction, which may be due to the activation of mitochondrial potassium recycling and a mild uncoupling leading to decreased ROS generation and oxidative damage.

Uridine as a Regulator of Functional and Ultrastructural Changes in the Brain of Rats in a Model of 6-OHDA-Induced Parkinson's Disease.

Using a model of Parkinson's disease (PD) induced by the bilateral injection of neurotoxin 6-hydroxydopamine (6-OHDA) into rat brain substantia nigra (SN), we showed uridine to exert a protective effect associated with activation of the mitochondrial ATP-dependent potassium (mitoK-ATP) channel. Injection of 4 µg neurotoxin evoked a 70% decrease in the time the experimental animal spent on the rod in the RotaRod test, an increase in the amount of lipid peroxides in blood serum and cerebral-cortex mitochondria and the rate of reactive oxygen species formation, and a decrease in Ca2+ retention in mitochondria. Herewith, lymphocytes featured an increase in the activity of lactate dehydrogenase, a cytosolic enzyme of glycolysis, without changes in succinate-dehydrogenase activity. Structural changes occurring in the SN and striatum manifested themselves in the destruction of mitochondria, degeneration of neurons and synapses, and stratification of myelin sheaths in them. Subcutaneous injections of 30 µg/kg uridine for 22 days restored the neurotoxin-induced changes in these parameters to levels close to the control. 5-Hydroxydecanoate (5 mg/kg), a specific mitoK-ATP channel inhibitor, eliminated the beneficial effect of uridine for almost all characteristics tested, indicating the involvement of the mitoK-ATP channel in the protective effect of uridine. The mechanism of the protective effect of uridine and its therapeutic applications for the prevention and treatment of PD are discussed.

Uridine Derivatives: Synthesis, Biological Evaluation, and In Silico Studies as Antimicrobial and Anticancer Agents.

Nucleoside analogs are frequently used in the control of viral infections and neoplastic diseases. However, relatively few studies have shown that nucleoside analogs have antibacterial and antifungal activities. In this study, a fused pyrimidine molecule, uridine, was modified with various aliphatic chains and aromatic groups to produce new derivatives as antimicrobial agents. All newly synthesized uridine derivatives were analyzed by spectral (NMR, FTIR, mass spectrometry), elemental, and physicochemical analyses. Prediction of activity spectra for substances (PASS) and in vitro biological evaluation against bacteria and fungi indicated promising antimicrobial capability of these uridine derivatives. The tested compounds were more effective against fungal phytopathogens than bacterial strains, as determined by their in vitro antimicrobial activity. Cytotoxicity testing indicated that the compounds were less toxic. In addition, antiproliferative activity against Ehrlich ascites carcinoma (EAC) cells was investigated, and compound 6 (2',3'-di-O-cinnamoyl-5'-O-palmitoyluridine) demonstrated promising anticancer activity. Their molecular docking against Escherichia coli (1RXF) and Salmonella typhi (3000) revealed notable binding affinities and nonbonding interactions in support of this finding. Stable conformation and binding patterns/energy were found in a stimulating 400 ns molecular dynamics (MD) simulation. Structure-activity relationship (SAR) investigation indicated that acyl chains, CH3(CH2)10CO-, (C6H5)3C-, and C2H5C6H4CO-, combined with deoxyribose, were most effective against the tested bacterial and fungal pathogens. Pharmacokinetic predictions were examined to determine their ADMET characteristics, and the results in silico were intriguing. Finally, the synthesized uridine derivatives demonstrated increased medicinal activity and high potential for future antimicrobial/anticancer agent(s).

Effects of uridine and nucleotides on hemostasis parameters.

Several purinergic receptors have been identified on platelets which are involved in hemostatic and thrombotic processes. The aim of the present study was to investigate the effects of uridine and its nucleotides on platelet aggregation and hemostasis in platelet-rich plasma (PRP) and whole blood. The effects of uridine, UMP, UDP, and UTP at different final concentrations (1 to 1000 µM) on platelet aggregation were studied using an aggregometer. In PRP samples, platelet aggregation was induced by ADP, collagen and epinephrine 3 min after addition of uridine, UMP, UDP, UTP and saline (as a control). All thromboelastogram experiments were performed at 1000 µM final concentrations of uridine and its nucleotides in whole blood. UDP and UTP were also tested in thromboelastogram with PRP. Our results showed that UDP, and especially UTP, inhibited ADP- and collagen-induced aggregation in a concentration-dependent manner. In whole blood thromboelastogram experiments, UDP stimulated clot formation while UTP suppressed clot formation. When thromboelastogram experiments were repeated with PRP, UTP's inhibitory effect on platelets was confirmed, while UDP's stimulated clot forming effect disappeared. Collectively, our data showed that UTP inhibited platelet aggregation in a concentration-dependent manner and suppressed clot formation. On the other hand, UDP exhibited distinct effects on whole blood or PRP in thromboelastogram. These data suggest that the difference on effects of UTP and UDP might have arisen from the different receptors that they stimulate and warrant further investigation with regard to their in vivo actions on platelet aggregation and hemostasis.

Recognition and release of uridine and hCNT3: From multivariate interactions to molecular design.

As a vital target for the development of novel anti-cancer drugs, human concentrative nucleoside transporter 3 (hCNT3) has been widely concerned. Nevertheless, the lack of a comprehensive understanding of molecular interactions and motion mechanism has greatly hindered the development of novel inhibitors against hCNT3. In this paper, molecular recognition of hCNT3 with uridine was investigated with molecular docking, conventional molecular dynamics (CMD) simulations and adaptive steered molecular dynamics (ASMD) simulations; and then, the uridine derivatives with possibly highly inhibitory activity were designed. The result of CMD showed that more water-mediated H-bonds and lower binding free energy both explained higher recognition ability and transported efficiency of hCNT3. While during the ASMD simulation, nucleoside transport process involved the significant side-chain flip of residues F321 and Q142, a typical substrate-induced conformational change. By considering electronegativity, atomic radius, functional group and key H-bonds factors, 25 novel uridine derivatives were constructed. Subsequently, the receptor-ligand binding free energy was predicted by solvated interaction energy (SIE) method to determine the inhibitor c8 with the best potential performance. This work not only revealed molecular recognition and release mechanism of uridine with hCNT3, but also designed a series of uridine derivatives to obtain lead compounds with potential high activity.

Amauroderma rugosum Extract Suppresses Inflammatory Responses in Tumor Necrosis Factor Alpha/Interferon Gamma-Induced HaCaT Keratinocytes.

Keratinocytes form the physical barrier of the skin and play an important role in the inflammatory process. Amauroderma rugosum is an edible mushroom; however, its pharmacological properties have seldom been studied. Although the anti-inflammatory effect of the organic solvent extract of Amauroderma rugosum has been previously reported, it is not known whether the aqueous extract has a similar effect. In addition, the effect of Amauorderma rugosum extract on skin has never been explored. Therefore, the objectives of the present study were to evaluate the anti-inflammatory effects of the aqueous extract of Amauroderma rugosum on HaCaT keratinocytes, to explore its mechanisms of action, and to study the possible active ingredients involved. The results showed that the aqueous extract of Amauroderm rugosum at a concentration of 1.5 mg/mL was non-toxic to HaCaT cells and inhibited the release of cytokine interleukin-1ß, and chemokines interleukin-8 and monocyte chemoattractant protein-1 in tumor necrosis factor (TNF)-α- and interferon (IFN)-γ-stimulated HaCaT cells. Amauroderma rugosum extract reduced the intracellular levels of reactive oxygen species. In addition, Amauroderma rugosum extract reduced the total protein expression of nuclear factor-kappa B (NF-κB) and B-cells inhibitor alpha in HaCaT keratinocytes and inhibited the phosphorylation of mitogen-activated protein kinase kinase (MEK) 1/2, extracellular signal-regulated kinase (ERK) 1/2, protein kinase B (Akt), and mammalian target of rapamycin (mTOR) in TNF-α- and INF-γ-stimulated HaCaT keratinocytes. Chemical analysis revealed that the aqueous extract of Amauroderma rugosum contains polysaccharides, triterpenes, and phenolic compounds. Anti-inflammatory compounds, such as gallic acid, guanosine, and uridine, were also present. The anti-inflammatory effect of Amauroderma rugosum could be mimicked by a combination of gallic acid, guanosine, and uridine. In conclusion, our study suggests that the aqueous extract of Amauroderma rugosum exerts anti-inflammatory effects on keratinocytes through its antioxidant and inhibitory effects on MEK/ERK-, Akt/mTOR-, and NF-κB-dependent signaling pathways.

A druggable addiction to de novo pyrimidine biosynthesis in diffuse midline glioma.

Diffuse midline glioma (DMG) is a uniformly fatal pediatric cancer driven by oncohistones that do not readily lend themselves to drug development. To identify druggable targets for DMG, we conducted a genome-wide CRISPR screen that reveals a DMG selective dependency on the de novo pathway for pyrimidine biosynthesis. This metabolic vulnerability reflects an elevated rate of uridine/uracil degradation that depletes DMG cells of substrates for the alternate salvage pyrimidine biosynthesis pathway. A clinical stage inhibitor of DHODH (rate-limiting enzyme in the de novo pathway) diminishes uridine-5'-phosphate (UMP) pools, generates DNA damage, and induces apoptosis through suppression of replication forks-an "on-target" effect, as shown by uridine rescue. Matrix-assisted laser desorption/ionization (MALDI) mass spectroscopy imaging demonstrates that this DHODH inhibitor (BAY2402234) accumulates in the brain at therapeutically relevant concentrations, suppresses de novo pyrimidine biosynthesis in vivo, and prolongs survival of mice bearing intracranial DMG xenografts, highlighting BAY2402234 as a promising therapy against DMGs.

Characterisation of P2Y receptor subtypes mediating vasodilation and vasoconstriction of rat pulmonary artery using selective antagonists.

Pulmonary vascular tone is modulated by nucleotides, but which P2 receptors mediate these actions is largely unclear. The aim of this study, therefore, was to use subtype-selective antagonists to determine the roles of individual P2Y receptor subtypes in nucleotide-evoked pulmonary vasodilation and vasoconstriction. Isometric tension was recorded from rat intrapulmonary artery rings (i.d. 200-500 µm) mounted on a wire myograph. Nucleotides evoked concentration- and endothelium-dependent vasodilation of precontracted tissues, but the concentration-response curves were shallow and did not reach a plateau. The selective P2Y2 antagonist, AR-C118925XX, inhibited uridine 5'-triphosphate (UTP)- but not adenosine 5'-triphosphate (ATP)-evoked relaxation, whereas the P2Y6 receptor antagonist, MRS2578, had no effect on UTP but inhibited relaxation elicited by uridine 5'-diphosphate (UDP). ATP-evoked relaxations were unaffected by the P2Y1 receptor antagonist, MRS2179, which substantially inhibited responses to adenosine 5'-diphosphate (ADP), and by the P2Y12/13 receptor antagonist, cangrelor, which potentiated responses to ADP. Both agonists were unaffected by CGS1593, an adenosine receptor antagonist. Finally, AR-C118925XX had no effect on vasoconstriction elicited by UTP or ATP at resting tone, although P2Y2 receptor mRNA was extracted from endothelium-denuded tissues using reverse transcription polymerase chain reaction with specific oligonucleotide primers. In conclusion, UTP elicits pulmonary vasodilation via P2Y2 receptors, whereas UDP acts at P2Y6 and ADP at P2Y1 receptors, respectively. How ATP induces vasodilation is unclear, but it does not involve P2Y1, P2Y2, P2Y12, P2Y13, or adenosine receptors. UTP- and ATP-evoked vasoconstriction was not mediated by P2Y2 receptors. Thus, this study advances our understanding of how nucleotides modulate pulmonary vascular tone.

Mitochondrial Homeostasis and Mast Cells in Experimental Hepatic Ischemia-Reperfusion Injury of Rats.

BACKGROUND: Ischemia-reperfusion injury is a histopathological event and is an important cause of morbidity and mortality after hepatobiliary surgery. We aimed to investigate the protective effect of uridine on hepatic ischemia-reperfusion injury in rats. METHODS: The animals were divided into 4 groups (n = 8): group I (control), group II: ischemia-reperfusion (30 minutes ischemia and 120 minutes reperfusion), group III: ischemia-reperfusion+uridine (at the beginning of reperfusion), and group IV: ischemia-reperfusion+uridine (5 minutes before ischemia-reperfusion). Uridine was administered a single dose of 30 mg/kg IV. The 3 elements of the hepatoduodenal ligament (hepatic artery, portal vein, and biliary tract) were obliterated for 30 minutes. Then hepatic reperfusion was achieved for 120 minutes. RESULTS: In the ischemia-reperfusion group, both liver tissues and serum chymase activity and high-temperature requirement A2 levels were higher. Severe central vein dilatation and congestion, widening sinusoidal range, diffuse necrotic hepatocytes and dense erythrocyte accumulation in sinusoids, and strongly inducible nitric oxide synthase expression were seen in the ischemia-reperfusion group. A clear improvement was seen in both uridine co-administration and pretreatment groups. CONCLUSION: Our results revealed that uridine limits the development of liver damage under conditions of ischemia-reperfusion, thus contributing to an increase in hepatocyte viability.

Aging affects the biological activity of fibroblast growth factor (FGF) in gastric epithelial cell, which is partially rescued by uridine.

Aging has become an irreversible trend in the world, the health problems caused by aging cannot be ignored. The physiological functions of human body begin to decline with aging, the decline of gastrointestinal function caused by aging is an important problem that needs to be resolved. In this work, we evaluated the anti-aging effect of uridine in the senescent gastric epithelial cell model, and found that the aging level of gastric epithelial cell was significantly down-regulated by uridine treatment, uridine could obviously down-regulate the ratio of the SA-ß-gal-positive senescent cells. Furthermore, aging-related marker molecules (such as p16 and p21) were also significantly down-regulated under uridine treatment. Additionally, the levels of inflammation and oxidative stress were also significantly reduced by uridine treatment. Next, our further studies the effect of aging on FGF activity on gastric epithelial cell, and found that FGF/FGFR-mediated signaling pathways were significantly down-regulated. However, uridine treatment can not only alleviate the senescence of gastric epithelial cell, but also can partially restore the sensitivity of FGF signaling. Taken together, the current work indicates that uridine shows a good anti-aging effect, which lays a solid foundation for the related research in this filed.

A sensitive and less cytotoxic assay for identification of proliferating T cells based on bioorthogonally-functionalized uridine analogue.

Quantitative detection of T cell proliferation is an important readout in immunology research, as it is one of the hallmarks of T cell activation. Fluorescence-based methods for T cell proliferation mostly rely on the usage of probes that non-specifically conjugate to free primary amine groups in cells. Each cell division then results in a two-fold dilution of the probes which is detectable with flow cytometry. However, questions have been raised about cytotoxicity of these dilution-based T cell proliferation probes and they potentially affect T cell activation. An alternative assay relies on the incorporation of the uridine analog BrdU in the DNA of dividing T cells that can be detected with an antibody, but this requires harsh fixation and denaturation conditions. Recently, a new assay for detection of cell proliferation has been developed, based on the incorporation of the bioorthogonally-functionalized uridine analog 5-ethynyl-2'-deoxyuridine (EdU). Goal of this study was to compare the sensitivity and cytotoxicity of the EdU assay with a widely-used dilution-based T cell proliferation probe, CellTrace Far Red. We found that, compared to the dilution-based probe, the EdU-based assay better preserves T cell viability, is more sensitive for detecting T cell proliferation, and allows for better discernable interferon gamma responses.

Uridine relieves MSCs and chondrocyte senescence in vitvo and exhibits the potential to treat osteoarthritis in vivo.

Osteoarthritis (OA) is a degenerative disease of extremely high incidence in the elderly. Therefore, anti-aging may be an important prerequisite for treating OA. The senescence of chondrocytes and mesenchymal stem cells (MSCs) is one of the important factors that causes OA. Here, the effect of uridine (which is a functional food derived from plants or animals) on senescence of chondrocytes and MSCs was evaluated in in vivo and in vitro experiments. For this, we established the senescence model of chondrocyte and MSCs in vitro, and established the OA model in vivo, and a series of experiments (such as CLSM, ELISA, Western blot, etc.) were conducted to evaluate the effect of uridine on chondrocyte and MSCs senescence. The results showed that uridine could alleviate chondrocyte and MSCs senescence in vitro by evaluating a series of aging markers. Furthermore, uridine could also relieve OA in vivo. In summary, in the present work, we found that uridine can alleviate chondrocyte and MSCs senescence in in vitro and in vivo experiments. Uridine has shown great potential in the treatment of OA in vivo, suggesting that uridine could be used to treat and prevent OA induced by aging, and has potential clinical applications in future.

Uridine treatment prevents myocardial injury in rat models of acute ischemia and ischemia/reperfusion by activating the mitochondrial ATP-dependent potassium channel.

The effect of uridine on the myocardial ischemic and reperfusion injury was investigated. A possible mechanism of its cardioprotective action was established. Two rat models were used: (1) acute myocardial ischemia induced by occlusion of the left coronary artery for 60 min; and (2) myocardial ischemia/reperfusion with 30-min ischemia and 120-min reperfusion. In both models, treatment with uridine (30 mg/kg) prevented a decrease in cell energy supply and in the activity of the antioxidant system, as well as an increase in the level of lipid hydroperoxides and diene conjugates. This led to a reduction of the necrosis zone in the myocardium and disturbances in the heart rhythm. The blocker of the mitochondrial ATP-dependent potassium (mitoKATP) channel 5-hydroxydecanoate limited the positive effects of uridine. The data indicate that the cardioprotective action of uridine may be related to the activation of the mitoKATP channel. Intravenously injected uridine was more rapidly eliminated from the blood in hypoxia than in normoxia, and the level of the mitoKATP channel activator UDP in the myocardium after uridine administration increased. The results suggest that the use of uridine can be a potentially effective approach to the management of cardiovascular diseases.

Anti-Apoptotic and Anti-Oxidant Effects of Systemic Uridine Treatment in an Experimental Model of Sciatic Nerve Injury.

AIM: To investigate the anti-apoptotic and anti-oxidant effects of systemic uridine treatment in a rat model of sciatic nerve injury. MATERIAL AND METHODS: Thirty-two adult male rats were equally randomized to Sham, Control, U100, and U500 groups. Sham rats received a sham operation by exposing the right sciatic nerve without transection, while those in the Control, U100, and U500 groups underwent right sciatic nerve transection followed by immediate primary anostomosis. Sham and Control groups received saline (0.9% NaCl) injections intraperitoneally (i.p.), while U100 and U500 groups received 100 mg/kg and 500 mg/kg uridine injections (i.p.), respectively, once a day for 7 days after the surgery. Rats in all the groups were sacrificed on the eighth day; sciatic nerve samples were analyzed for apoptosis by Western Blotting and for oxidation parameters including myeloperoxidase (MPO), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) by Enzyme-Linked Immunosorbent Assay (ELISA). RESULTS: Uridine treatment at the dose of 500 mg/kg significantly decreased as apoptosis determined by Caspase-3/Actin ratio and exhibited significant anti-oxidant effects as determined by decreased levels of MPO and MDA as well as increased levels of SOD, GPx, and CAT compared to controls. Uridine at 100 mg/kg was only found to decrease the Caspase-3/Actin ratio, although it significantly decreased MDA and increased CAT levels compared to controls. CONCLUSION: Treatment with uridine reduces apoptosis and oxidation in a rat model of sciatic nerve injury dose-dependently. Thus, uridine may be beneficial in peripheral nerve regeneration by exhibiting anti-apoptotic and anti-oxidant effects.

Bisubstrate Ether-Linked Uridine-Peptide Conjugates as O-GlcNAc Transferase Inhibitors.

The O-linked ß-N-acetylglucosamine (O-GlcNAc) transferase (OGT) is a master regulator of installing O-GlcNAc onto serine or threonine residues on a multitude of target proteins. Numerous nuclear and cytosolic proteins of varying functional classes, including translational factors, transcription factors, signaling proteins, and kinases are OGT substrates. Aberrant O-GlcNAcylation of proteins is implicated in signaling in metabolic diseases such as diabetes and cancer. Selective and potent OGT inhibitors are valuable tools to study the role of OGT in modulating a wide range of effects on cellular functions. We report linear bisubstrate ether-linked uridine-peptide conjugates as OGT inhibitors with micromolar affinity. In vitro evaluation of the compounds revealed the importance of donor substrate, linker and acceptor substrate in the rational design of bisubstrate analogue inhibitors. Molecular dynamics simulations shed light on the binding of this novel class of inhibitors and rationalized the effect of amino acid truncation of acceptor peptide on OGT inhibition.