Isolation and characterization of 5-carbamoylmethyluridine and 5-carbamoylmethyl-2-thiouridine from human urine

Two new modified uracil nucleosides, 5-carbamoylmethyuridine (ncm(5)U, I) and 5-carbamoylmethyl-2-thiouridine (ncm(5)s(2)U, II) were isolated from a 24 hr collection of a normal human urine. The structures were assigned on the basis of UV, NMR and mass spectral data and confirmed by comparison of the spectral data and HPLC mobilities with those of authentic samples. On the basis of experimental data it appears possible that 5-carbamoylmethyl-2-thio-uridine (ncm(5)s(2)U, II) may be a degradation product produced from a labile precursor by the chemical treatments during the isolation procedure. However, the other nucleoside (ncm(5)U,I) certainly appears to be of metabolic origin and was also found in the urines of one chronic myelogenous leukemia and one lung carcinoma patient.