Chemical Effects of Ionizing Radiations on Ceramide Digalactoside and Component Molecules

Abstract

Stearic acid, galactose and ceramide digalactoside have been y-irradiated in the solid state . Decarboxylation of stearic acid readily occurs to produce heptadecane (G=6-4) and traces of hexadecane . For stearic acid -G is 11 . 5 and for galactose is 14 ; the values are the same in air and in vacuo .Ceramide digalactoside on irradiation gives small amounts of penta and tridecane (G -9 x 10-$) . The -G values for disappearance of the stearyl and palmityl moieties are 0. 17 and 0 . 13 respectively . There is also evidence for breakdown of the trans olefinic double bond of the sphingosyl residue . Scission of the P-glycosidic bond results in the formation of galactose (G=1 .9). For the galactose residues -G is 3 . 7 .

Effect of UVA or UVB Irradiation on Cutaneous Lipids in Films or in Solution

“…According to several previous works (5,7), two major phenomena can be observed following UV irradiation: the hydrogenation of the double bond or the formation of new oxygenated compounds. For instance, the hydrogenation of unsaturation was observed in CER IIIa after UVA irradiation of the film, leading to the molecule at m/z 630.…”

“…These molecules, especially the unsaturated lipids, are sensitive to UV exposure (4). The effects of UV on lipids have been widely studied (5–7) and three major consequences were found: (1) β scission (fragmentation of the carbon chain), (2) hydrogenation of the double bond of unsaturated compounds and (3) formation of oxygenated entities from unsaturated lipids.…”