Enzymatic Inactivation of W-NìtrosoCompounds in Murine Blood Plasma1

Murine blood plasma rapidly inactivates nitrosamides and nitrosocarbamates but not nitrosoureas. The mechanism of this inactivation in murine blood plasma has been investigated. The vast majority of activity (>97%) was inhibited by serine hydroxylase inhibitors. Also, 92% of the activity was inhibited by bis(pnitrophenyl)phosphate, a selective inhibitor of carboxy(esterases. Decomposition products formed after blood plasma action on Nethyl-N-nitrosoacetamide or W-methyl-A/-nitrosoethylcarbamate were separated and identified by gas chromatography. The products formed were consistent with a hydrolytic cleavage of the amidic bond. These observations are consistent with the idea that the major active faeton» in plasma is a carboxylester-