J. Schwinn et al., THIYL RADICAL-INDUCED CIS TRANS-ISOMERIZATION OF METHYL LINOLEATE IN METHANOL AND OF LINOLEIC-ACID RESIDUES IN LIPOSOMES/, International journal of radiation biology, 74(3), 1998, pp. 359-365
Citations number
16
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging","Biology Miscellaneous","Nuclear Sciences & Tecnology
Purpose: To investigate the role of a thiol-containing biologically ac
tive compound in lipid peroxidation of membranes. Materials and method
s: Thiyl radicals were generated from 3-(2-mercaptoethyl)quinazoline-2
,4(1H,3H)-dione (MECH) using pulse radiolysis and gamma-radiolysis in
aqueous and alcoholic solutions saturated with N2O. The products were
analysed by H-1 NMR and by HPLC. Results: The thiyl radicals abstract
bisallylic hydrogens from [cis-9, cis-12]-methyl linoleate, yielding a
pentadienyl radical. In the absence of oxygen, a thiyl radical-induce
d cis/trans-isomerization leads to linoleic-type isomers. These chain-
type isomerization reactions can occur with the long living pentadieny
l radical, followed by a 'repair' reaction of the attached thiol, and
with the thiyl radical adduct with a double bond of the fatty acid res
idue. Conclusions: The results show that the mechanism of cis/trans-is
omerization is an integral part of the thiyl radical attack on polyuns
aturated fatty acids in homogeneous solutions and in bilayers.