Alvin Felmeister

Identification of cholesteryl nitrate as a product of the reaction between NO2 and cholesterol monomolecular films

Abstract The effects of exposure of monomolecular films of cholesterol, dihydrocholesterol, 5-cholesten-3-one, 7-hydroxycholesterol, and 7-ketocholesterol to air and NO2 were studied. Whereas exposure to air resulted in expansion of the films in all cases, exposure to NO2 resulted in condensation of all of the films with the exception of 5-cholesten-3-one. The expansion effects were determined to be the result of the formation of various autoxidation products of cholesterol. The condensation effects were caused by the formation and subsequent desorption of cholesteryl nitrate. Identification of the products was based on surface pressure-surface area and thin layer chromatographic evidence.

Interactions of gaseous air pollutants with egg lecithin and phosphatidyl ethanolamine monomolecular films

Abstract The interaction of egg lecithin and phosphatidyl ethanolamine monomolecular films with nitrogen dioxide containing atmospheres was studied. The extent of interaction of nitrogen dioxide with the phospholipids studied increased with increasing unsaturation of the phospholipid and with decreasing initial surface pressure of the film. Nitrogen dioxide, in both the gas phase above the film and liquid phase below the film, was found to interact with the phospholipids.

Interaction of nitrogen dioxide with cholesterol-lecithin mixed monolayers.

Abstract The interaction of NO 2 with cholesterol-dipalmitoyl lecithin and cholesterolegg lecithin mixed monomolecular films was studied. Both lecithins inhibited the NO 2 -induced loss of cholesterol from the films, and the degree of inhibition was directly related to the mole fraction of these lipids in the film. The dipalmitoyl lecithin was more efficient in producing this inhibition, apparently because of its greater tendency to associate with the NO 2 -cholesterol reaction products. A method is presented to calculate the percentage apparent loss of cholesterol from the mixed films after exposure to NO 2 .

The interaction of nitrogen dioxide with monomolecular films of cholesterol, dihydrocholesterol, and cholesteryl acetate

Abstract The interaction of NO2 with monomolecular films of cholesterol, dihydrocholesterol, and cholesteryl acetate was studied. It appears that two different and relatively independent reactions occur in the presence of NO2. One reaction involves the 3-hydroxy group and leads to products which tend to be desorbed from the surface. The other reaction involves the 5,6 double bond and leads to products which remain on the surface, and which occupy a larger area per molecule than the non-reacted molecule. Thus, the orientation of cholesterol at a gas/ water interface, which is a function of surface pressure, influences both the rate of reaction and the reaction products in the presence of NO2.