Identification of cholesterol as a mouse skin lipid that reacts with nitrogen dioxide to yield a nitrosating agent, and of cholesteryl nitrite as the nitrosating agent produced in a chemical system from cholesterol

Abstract

The skin lipids of mice exposed to nitrogen dioxide (NO2) and mouse skin lipids exposed in vitro to NO2 contain nitrosating agents (NSAs), that react with amines to produce nitrosamines. This situation represents a potential hazard of exposure to NO2. A principal NSA precursor in mouse skin lipids was purified by thin-layer and high-performance liquid chromatography. Each fraction was assayed by bubbling in NO2 and determining NSA. The precursor was identified as cholesterol on the basis of its chromatographic behavior and spectral properties. In a chemical system, cholesterol reacted with NO2 to give 13% yields of an NSA, which was identified from its spectral properties as the previously known compound, cholesteryl-3-beta-nitrite. These findings and the chromatographic behavior of a major NSA in the skin lipids of NO2-exposed mice suggested that this NSA was cholesteryl nitrite.