Studies on the metabolism of thymine and 6-azathymine

Abstract

The administration of 6-azathymine to the mouse led to the urinary elimination not only of free azathymine, but also of various metabolites of it. Of these metabolites, two have been identified: (a) the ribonucleoside, (b) a side-chain oxidation product of azathymine, tentatively identified as 5-hydroxymethyl-6-azauracil (6-hydroxymethyl as-triazine-3:5-(2H:4H)-dione). Other metabolic derivatives of azathymine were produced, but their nature has not been established conclusively. The administration of azathymine also resulted in the excretion of relatively large amounts of free uracil. Following the administration of 6-azathymine-5- 14C to mice, radioactivity was found in all tissues investigated, not only in the form of free azathymine, but also as metabolic derivatives. A study of the influence of mouse liver slices or homogenates on radioactive azathymine and thymine indicated that each of these compounds is converted to the corresponding ribonucleoside and, to a lesser degree, to the analogous 2'-deoxyribonucleoside.