Spectral monitoring of photoirradiated skin lipids: MS and IR approaches.
An investigation of the effects of UV(A) irradiation on the stratum corneum lipids was carried out in vitro on films. The modifications of their conformational order were studied by FTIR and the formation of new entities was detected by mass spectroscopy. The results show not only differences in behaviour of the three lipid classes (fatty acids (FA), ceramides (CER), and cholesterol), but also variation within a class, depending on the molecules structure. Upon UV(A) irradiation, beta scission occurs on all the components, saturated and unsaturated. Moreover, unsaturated FA or CER having a double bond on their FA moiety may become saturated or may be transformed into their free radical form. Unsaturated FA are more sensitive to UV(A) and lead more easily to oxygenated components than unsaturated CER. The chemical effects are irradiation dose dependent but do not deeply influence the supramolecular organisation of these lipids. The global conformation of the lipids stays in an orthorhombic state, a decrease of the packing density however is observed.
Merle
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C
Group Chimie Analytique de Paris-Sud EA 4041, IFR 141 School of Pharmacy, Univ. Paris-Sud, F. 92296 Châtenay-Malabry Cedex, France. chloe.merle@club-internet.fr
Laugel
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C
Baillet-Guffroy
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A
D002518:Ceramides / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods*; D010777:Photochemistry; D012867:Skin / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014466:Ultraviolet Rays
D002518:Ceramides; D005227:Fatty Acids; D005609:Free Radicals; D002784:Cholesterol