title: Geometrical isomerism of monounsaturated fatty acids: thiyl radical catalysis and influence of antioxidant vitamins.
abstract: Thiyl radicals generated either from thiols or disulfides act as the catalyst for the cis-trans isomerization of a variety of monounsaturated fatty acid methyl esters in homogeneous solution. Similar results have also been obtained using alpha-lipoic acid and its reduced form. The effectiveness of the isomerization processes in the presence of the most common antioxidants has been addressed. The ability of thiyl radical scavenging was found to increase along the series alpha-tocopherol < ascorbic acid < all-trans retinol. The cis-trans isomerization of fatty acid residues in multilamellar vesicles of dioleoyl phosphatidyl choline by thiyl radical, in the absence and presence of the various antioxidants, has also been studied in detail. The influence of the isomerization process on the phospholipid bilayer has been tested by permeability measurements of vesicles and it is clearly shown that trans fatty acid-containing membranes have intermediate properties between those formed by all-cis and saturated components. This study contributes to the understanding of radical processes that can alter or protect the naturally occurring cis geometry of unsaturated lipids in cell membranes and demonstrates a new role of essential antioxidants.
authors.affiliation: ISOF, Consiglio Nazionale delle Ricerche, Bologna, Italy. chrys@area.bo.cnr.it
authors.forename: Chryssostomos
authors.initials: C
authors.lastname: Chatgilialoglu
authors.forename: Laura
authors.initials: L
authors.lastname: Zambonin
authors.forename: Alessio
authors.initials: A
authors.lastname: Altieri
authors.forename: Carla
authors.initials: C
authors.lastname: Ferreri
authors.forename: Quinto G
authors.initials: QG
authors.lastname: Mulazzani
authors.forename: Laura
authors.initials: L
authors.lastname: Landi
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D002384:Catalysis / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects; D005609:Free Radicals / Q000737:chemistry*; D005720:Gamma Rays; D007536:Isomerism; D009829:Oleic Acids / Q000737:chemistry; D010084:Oxidation-Reduction / Q000528:radiation effects; D010782:Photolysis / Q000528:radiation effects; D013997:Time Factors; D014815:Vitamins / Q000494:pharmacology*; D020002:tert-Butyl Alcohol
chemical_list: D000975:Antioxidants; D005229:Fatty Acids, Monounsaturated; D005609:Free Radicals; D009829:Oleic Acids; D014815:Vitamins; C005576:methyl oleate; D020002:tert-Butyl Alcohol