Reactivity of Thiyl Radicals Generated from Thiomethoxide and Dimethyldisulfide in Microheterogeneous Media

Abstract: Sodium thiomethoxide and dimethyldisulfide will be shown to be convenient sources of methyl thiyl radicals for effecting the cis-trans double bond isomerization of oleic acid to elaidic acid residues arranged in phospholipid bilayers of the microheterogeneous aqueous environment of liposomes. The methods used for methyl thiyl radical generation encompass radiolytic and photochemical meth-ods. The convenience of these methyl thiyl radical sources will be interpreted in terms of the turn-over numbers in the radical chain cis-trans isomerization reaction of unsaturated lipids. Keywords: Methyl thiyl radicals, Sodium thiomethoxide, Dimethyldisulfide, cis-trans isomerization. INTRODUCTION Thiyl radicals have been extensively studied in the context of free radical double bond isomerization. Fig. ( 1 ) shows the reaction mechanism of free thiyl radical RS• double bond isomerization that consists of a reversible addition of radical RS• to the double bond. The regeneration of the double bond is obtained by -elimination of RS• and the result is in favor of the

[1]  A. Scaloni,et al.  Human serum albumin modifications associated with reductive radical stress. , 2011, Molecular bioSystems.

[2]  A. Scaloni,et al.  The reductive desulfurization of Met and Cys residues in bovine RNase A is associated with trans lipids formation in a mimetic model of biological membranes. , 2008, Journal of proteome research.

[3]  C. Chatgilialoglu,et al.  One-electron reduction of methanesulfonyl chloride. The fate of MeSO2Cl(.)(-) and MeSO2(.) intermediates in oxygenated solutions and their role in the cis-trans isomerization of mono-unsaturated fatty acids. , 2007, Journal of the American Chemical Society.

[4]  C. Chatgilialoglu,et al.  The sulfhydryl radical (HS(.)/S(.-)): a contender for the isomerization of double bonds in membrane lipids. , 2007, Angewandte Chemie.

[5]  P. Wardman,et al.  Trans-fatty acids and radical stress: what are the real culprits? , 2006, Bioorganic & medicinal chemistry.

[6]  C. Chatgilialoglu,et al.  Geometrical trans Lipid Isomers: A New Target for Lipidomics , 2005, Chembiochem : a European journal of chemical biology.

[7]  C. Chatgilialoglu,et al.  Trans lipids: the free radical path. , 2005, Accounts of chemical research.

[8]  L. Landi,et al.  Regioselective cis-trans isomerization of arachidonic double bonds by thiyl radicals: the influence of phospholipid supramolecular organization. , 2004, Journal of the American Chemical Society.

[9]  P. Moore,et al.  Hydrogen sulfide: from the smell of the past to the mediator of the future? , 2003, Trends in pharmacological sciences.

[10]  L. Landi,et al.  Arachidonate geometrical isomers generated by thiyl radicals: the relationship with trans lipids detected in biological samples. , 2002, Free radical biology & medicine.

[11]  C. Chatgilialoglu,et al.  The kinetics of thiyl radical-induced reactions of monounsaturated fatty acid esters. , 2002, Journal of the American Chemical Society.

[12]  L. Landi,et al.  Cis-trans isomerization of polyunsaturated fatty acid residues in phospholipids catalyzed by thiyl radicals. , 2001, Journal of the American Chemical Society.

[13]  H. Sies,et al.  Glutathione and its role in cellular functions. , 1999, Free radical biology & medicine.

[14]  N. Kruger,et al.  Nitrogen dioxide induces cis-trans-isomerization of arachidonic acid within cellular phospholipids. Detection of trans-arachidonic acids in vivo. , 1999, The Journal of biological chemistry.

[15]  C. Record,et al.  Blood and brain concentrations of mercaptans in hepatic and methanethiol induced coma. , 1984, Gut.

[16]  O. Strausz,et al.  Reaction of hydrogen atoms with dimethyldisulfide , 1980 .

[17]  A. Konings,et al.  Protection of liposomal lipids against radiation induced oxidative damage. , 1979, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[18]  M. Matsuda,et al.  Flash Photolysis Study on the Addition Reaction of Alkylthiyl Radical to Olefins , 1978 .

[19]  J. Spinks,et al.  Introduction to Radiation Chemistry , 1964 .

[20]  C. Chatgilialoglu,et al.  Radiation chemical studies of methionine in aqueous solution: understanding the role of molecular oxygen. , 2010, Chemical research in toxicology.