| Size | Price | Stock | Qty |
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| 5mg |
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| Other Sizes |
| Targets |
Cyclopentenyl uracil specifically targets and inhibits uridine kinase (UK), an enzyme that catalyzes the phosphorylation of uridine to uridine monophosphate (UMP) in the pyrimidine salvage pathway. Uridine kinase is the rate-limiting enzyme for the incorporation of exogenous uridine into the nucleotide pool, and its activity is often upregulated in rapidly proliferating cells, including cancer cells that rely on salvage pathways for nucleotide synthesis. By blocking uridine kinase, cyclopentenyl uracil inhibits the salvage of circulating uridine, forcing cells to rely more heavily on de novo pyrimidine biosynthesis. The compound does not appear to inhibit other nucleoside kinases or enzymes involved in pyrimidine metabolism at relevant concentrations. The molecular structure of cyclopentenyl uracil resembles uridine but with a carbocyclic ring substitution of the ribose sugar, which likely contributes to its competitive or mechanism-based inhibition of the enzyme.
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| ln Vitro |
In vitro enzyme assays have demonstrated that cyclopentenyl uracil is a potent inhibitor of purified uridine kinase with an IC₅0 in the low micromolar range. The compound is highly selective for uridine kinase and does not significantly inhibit other nucleoside kinases such as thymidine kinase or deoxycytidine kinase at concentrations used to inhibit uridine salvage. In cell-based assays using cancer cell lines (e.g., HeLa, MCF-7, or other rapidly dividing cells), cyclopentenyl uracil treatment at concentrations of 1-50 uM reduces the incorporation of radiolabeled uridine into the nucleotide pool, confirming its mechanism of action. Importantly, the compound has been shown to be non-cytotoxic in standard cell viability assays, distinguishing it from many other nucleoside analogs that inhibit cell growth directly. This non-cytotoxic profile makes it a valuable tool for studying the contribution of uridine salvage to nucleotide homeostasis without confounding antiproliferative effects.
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| ln Vivo |
In vivo studies using intact mouse models have shown that cyclopentenyl uracil effectively blocks the salvage of circulating uridine by both host tissues and tumors. Following intraperitoneal administration of cyclopentenyl uracil (doses typically in the 10-100 mg/kg range), the incorporation of administered radiolabeled uridine into the nucleotide pools of various tissues (including liver, spleen, and implanted tumors) is significantly reduced. The effect is dose-dependent and reversible. The compound has minimal intrinsic toxicity and does not cause weight loss or other signs of systemic toxicity at efficacious doses. These studies establish that the uridine salvage pathway makes a significant contribution to the nucleotide pools in vivo, and inhibition of this pathway by cyclopentenyl uracil can modulate pyrimidine availability without causing toxicity. These findings have implications for understanding cancer metabolism and for developing combination therapies targeting nucleotide metabolism.
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| Enzyme Assay |
A standard non-cellular assay for measuring inhibition of uridine kinase by cyclopentenyl uracil is the radiometric uridine phosphorylation assay. Recombinant human uridine kinase (UK, isoform 1 or 2) is expressed and purified to homogeneity. The reaction mixture (50-100 uL) contains 50 mM Tris-HCl (pH 7.5), 5 mM MgCl2, 2 mM ATP, 1 mM dithiothreitol (DTT), 0.1 mg/mL bovine serum albumin (BSA), 10 uM [3H]-uridine (specific activity ~10 Ci/mmol), and purified UK enzyme (1-5 ug/mL). Cyclopentenyl uracil is added at varying concentrations (0.01-100 uM) and pre-incubated with the enzyme for 5-10 min at 37degC. The reaction is initiated by addition of [3H]-uridine/ATP mixture and incubated for 30 min at 37degC. The reaction is terminated by heating at 95degC for 2 min. The amount of [3H]-uridine monophosphate (UMP) formed is separated from free [3H]-uridine by spotting 10-20 uL of the reaction mixture onto DE81 ion-exchange filter paper discs, followed by washing three times with 1 mM ammonium formate (pH 3.6) and once with water. The discs are dried and transferred to scintillation vials with 5 mL of scintillation fluid, and radioactivity is counted. Percent inhibition is calculated relative to DMSO vehicle control. IC₅0 values are determined by fitting inhibition data to a four-parameter logistic equation.
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| Cell Assay |
In vitro cell-based assays for cyclopentenyl uracil are performed using mammalian cancer cell lines, e.g., HeLa (cervical carcinoma), MCF-7 (breast adenocarcinoma), or A549 (lung carcinoma). Cells are seeded in 24-well plates at 2-5 × 10⁵ cells/well and cultured in RPMI-1640 or DMEM supplemented with 10% FBS, 2 mM glutamine, and 1% penicillin-streptomycin at 37degC in 5% CO2 for 24 h to reach 70-80% confluence. For the uridine incorporation assay, cells are pre-treated with cyclopentenyl uracil (0-50 uM) for 1 h at 37degC. Then, 1 uCi/mL of [3H]-uridine is added to each well and incubated for 2 h. After incubation, cells are washed three times with ice-cold PBS to remove extracellular radioactivity. Cells are then solubilized in 0.5 mL of 0.5 M NaOH and incubated at 37degC for 30 min. The lysate is neutralized with 0.5 M HCl, and an aliquot (200 uL) is transferred to a scintillation vial with 5 mL of scintillation fluid for counting. For cytotoxicity studies, cells are seeded in 96-well plates at 1 × 10⁴-2 × 10⁴ cells/well, treated with cyclopentenyl uracil (0-200 uM) for 48-72 h, and cell viability is measured by MTT assay (0.5 mg/mL, 4 h at 37degC, absorbance at 570 nm) or by the CellTiter-Glo luminescent cell viability assay.
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| Animal Protocol |
In vivo animal studies for cyclopentenyl uracil are conducted in female BALB/c nude mice (6-8 weeks old) bearing subcutaneous tumor xenografts (e.g., HeLa or MCF-7 tumors). When tumors reach approximately 100-200 mm3, mice are randomized into treatment groups (n = 5-10 per group). Cyclopentenyl uracil is formulated in PBS or saline and administered intraperitoneally (IP) or subcutaneously at doses of 10, 25, 50, or 100 mg/kg, once daily or twice daily for 5-14 days. Control groups receive vehicle (PBS/saline) or no treatment. One hour before the final dose, mice receive an IP injection of [3H]-uridine (5-10 uCi/mouse) to assess uridine incorporation into nucleotide pools. Mice are euthanized 2 h after [3H]-uridine injection, and blood, tumor, liver, and spleen tissues are collected. Tissue samples are homogenized in 0.5 M NaOH, neutralized, and aliquots are counted for radioactivity to determine uridine incorporation. For efficacy studies, tumor volumes are measured every 2-3 days with digital calipers, and tumor growth inhibition is calculated. Body weights are monitored as a measure of systemic toxicity. At study termination, tumors may be excised and processed for histology or analyzed for nucleotide levels by HPLC. All animal procedures must be approved by the institutional animal care and use committee.
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| ADME/Pharmacokinetics |
The pharmacokinetic (PK) properties of cyclopentenyl uracil have been studied in mice. Following intraperitoneal (IP) administration at doses of 10-100 mg/kg, the compound is rapidly absorbed, reaching peak plasma concentrations (Cmax) within 0.5-1 h (Tmax). The elimination half-life (t1/2) in mice is approximately 1-2 h. The compound is distributed to various tissues, including the liver, kidney, and tumor xenografts. Tissue-to-plasma ratios are typically >1, indicating active uptake into tissues. Cyclopentenyl uracil is minimally metabolized, with the majority of the compound excreted unchanged in the urine. The pharmacokinetic profile supports twice-daily dosing regimens for in vivo efficacy studies. The compound has low plasma protein binding (<20%), which contributes to its high volume of distribution and tissue penetration. Detailed human pharmacokinetic data are not available. The compound is for research use only and is not intended for human administration.
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| Toxicity/Toxicokinetics |
Toxicological data for cyclopentenyl uracil have been derived primarily from in vivo mouse studies. In these studies, the compound is generally well tolerated, with no signs of acute toxicity at doses up to 100 mg/kg (IP). Body weight is maintained or only minimally reduced compared to vehicle-treated controls. The compound is classified as non-cytotoxic in vitro, distinguishing it from many other nucleoside analogs that directly inhibit cell growth. In mouse studies, no significant organ toxicity (liver, kidney, spleen) was observed at therapeutic doses. No hematological abnormalities were reported. The LD₅0 (median lethal dose) has not been formally determined, but available data suggest that the compound has a wide safety margin relative to its efficacious dose range. The compound has not been evaluated in standardized genotoxicity assays (Ames test, micronucleus test). Given the absence of antiviral activity and the lack of cytotoxicity, cyclopentenyl uracil is considered a relatively safe research compound. Standard laboratory precautions (gloves, lab coat, eye protection) should be used when handling this compound. For research use only; not intended for human consumption or therapeutic administration.
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| References | |
| Additional Infomation |
Cyclopentenyluracil is (1R-(1α,4β,5β)-isomer); RN is not available for compounds without isomer names (6/91).
Cyclopentenyl uracil is not approved for human therapeutic use and is not under clinical development. It is used exclusively as a research tool to study pyrimidine metabolism, particularly to investigate the role of uridine salvage in cancer biology. Its mechanism of action involves specific inhibition of uridine kinase, blocking the salvage of circulating uridine into the nucleotide pool. The compound is particularly valuable for understanding how rapidly dividing cells, including cancer cells, utilize salvage pathways for nucleotide synthesis. This has implications for developing combination therapies that target nucleotide metabolism, e.g., combining cyclopentenyl uracil with inhibitors of de novo pyrimidine biosynthesis. Unlike the related cyclopentenylcytosine, cyclopentenyl uracil has no antiviral activity. No clinical trials have been registered. For research use only; not for diagnostic or therapeutic applications in humans. |
| Molecular Formula |
C10H12N2O5
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|---|---|
| Molecular Weight |
240.21
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| Exact Mass |
240.075
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| CAS # |
90597-20-9
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| PubChem CID |
128937
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| Appearance |
Typically exists as solid at room temperature
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| LogP |
-2.1
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| Hydrogen Bond Donor Count |
4
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| Hydrogen Bond Acceptor Count |
5
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| Rotatable Bond Count |
2
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| Heavy Atom Count |
17
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| Complexity |
417
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| Defined Atom Stereocenter Count |
3
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| SMILES |
C1=CN(C(=O)NC1=O)C2C=C(C(C2O)O)CO
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| InChi Key |
FCWVOJUKQSHZIV-VDAHYXPESA-N
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| InChi Code |
InChI=1S/C10H12N2O5/c13-4-5-3-6(9(16)8(5)15)12-2-1-7(14)11-10(12)17/h1-3,6,8-9,13,15-16H,4H2,(H,11,14,17)/t6-,8-,9+/m1/s1
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| Chemical Name |
1-[(1R,4R,5S)-4,5-dihydroxy-3-(hydroxymethyl)cyclopent-2-en-1-yl]pyrimidine-2,4-dione
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO: 100 mg/mL (416.30 mM)
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| Solubility (In Vivo) |
Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.
Injection Formulations
Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)(e.g. IP/IV/IM/SC) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). View More
Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] Oral Formulations
Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). View More
Oral Formulation 3: Dissolved in PEG400 (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 4.1630 mL | 20.8151 mL | 41.6302 mL | |
| 5 mM | 0.8326 mL | 4.1630 mL | 8.3260 mL | |
| 10 mM | 0.4163 mL | 2.0815 mL | 4.1630 mL |
*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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