This water-soluble ribonucleoside (FWfree-acid = 288.21 g/mol; CAS 314-50- 1; lmax of 267 nm in 0.1 N HCl (e = 9570 cm–1M–1; another report lists 9800) and 265 nm in 0.1 N methanolic NaOH (e = 8960 cm–1M–1; another report lists 7800)), first observed in Neurospora crassa, is also foound in the urine of cancer patients treated with 6-azauridine, Orotidine is most likely formed from OMP, its 5’-monophosphate ester and the direct precursor of UMP. Orotidine is readily hydrolyzed in dilute mineral acids. Target(s): orotate phosphoribosyltransferase; orotidine-5’-phosphate decarboxylase.
