A nitrosating agent from the reaction of atmospheric nitrogen dioxide (NO2) with methyl linoleate: comparison with a product from the skins of NO2-exposed mice.

We showed previously that exposure of mice to atmospheric nitrogen dioxide (NO2) leads to the formation of an ether-extractable nitrosating agent (NSA) in the skin, which produced N-nitrosomorpholine (NMOR) from morpholine in vitro but not in vivo (under our conditions). We now report that NO2 bubbled into hexane solutions of methyl linoleate (MLIN) produced a similar NSA that reacted with morpholine in dichloromethane solution to produce NMOR. The NSA yield increased sharply as MLIN concentration was raised, with a maximum 0.1% yield of NSA from MLIN. The NSA yield from MLIN was four times that from methyl oleate and seven times that from methyl stearate. The NSA derived from MLIN travelled on thin-layer chromatography more slowly than the main weight fraction; whereas TLC of NSA in the skin lipids of NO2-exposed mice and in untreated mouse skin lipids exposed in vitro to NO2 produced NSA that travelled more rapidly than the main weight fraction.