Tetrahydrouridine is a competitive, reversible inhibitor of cytidine deaminase (Ki values = 54 and 240 nM for human and E. coli enzymes, respectively).Its use, alone or in combination with the DNA methyltransferase inhibitor 5-fluoro-2'-deoxycytidine, is being evaluated in animal models and clinical trials for diseases, including cancer and mitochondrial DNA depletion syndrome.
Tetrahydrouridine is supplied as a crystalline solid. A stock solution may be made by dissolving the tetrahydrouridine in the solvent of choice. Tetrahydrouridine is soluble in organic solvents such as DMSO and dimethyl formamide, which should be purged with an inert gas. The solubility of tetrahydrouridine in these solvents is approximately 10 and 16 mg/ml, respectively.
Further dilutions of the stock solution into aqueous buffers or isotonic saline should be made prior to performing biological experiments. Ensure that the residual amount of organic solvent is insignificant, since organic solvents may have physiological effects at low concentrations. Organic solvent-free aqueous solutions of tetrahydrouridine can be prepared by directly dissolving the crystalline solid in aqueous buffers. The solubility of tetrahydrouridine in PBS, pH 7.2, is approximately 5 mg/ml. We do not recommend storing the aqueous solution for more than one day.
Tetrahydrouridine is a competitive, reversible inhibitor of cytidine deaminase (Ki values = 54 and 240 nM for human and E. coli enzymes, respectively). Its use, alone or in combination with the DNA methyltransferase inhibitor 5-fluoro-2’-deoxycytidine, is being evaluated in animal models and clinical trials for diseases, including cancer and mitochondrial DNA depletion syndrome.
3,4,5,6-Tetrahydrouridine, is a derivative of Uridine (U829910). Tetrahydrouridine (THU), is a potent inhibitor of cytidine. It inhibits cell proliferation through cell cycle regulation regardless of cytidine deaminase expression levels deaminase (CDA), and thus can be used as a potential and promising treatment for tumors with highly expressed CDA.
Administration of 167 mg/kg Tetrahydrouridine (THU) followed by 1.0 mg/kg DAC results in death in one male and eight females. Animals surviving to scheduled termination are generally asymptomatic with no treatment related effects observed in body weights, food consumption, clinical chemistry and urinalysis for a treatment up to 1.0 mg/kg DAC in combination with 167 mg/kg Tetrahydrouridine in animals[2].
[1] B A CHABNER. Purification and properties of cytidine deaminase from normal and leukemic granulocytes.[J]. Journal of Clinical Investigation, 1974, 53 3: 922-931. DOI:
10.1172/jci107633[2] R M COHEN R W. Cytidine deaminase from Escherichia coli. Purification, properties and inhibition by the potential transition state analog 3,4,5,6-tetrahydrouridine.[J]. The Journal of Biological Chemistry, 1971, 246 24: 7561-7565.
[3] OSCAR ALCAZAR. Epigenetic regulation by decitabine of melanoma differentiation in vitro and in vivo?[J]. International Journal of Cancer, 2011, 131 1: 18-29. DOI:
10.1002/ijc.26320
