| Recognition of the significance of lipids and lipid peroxidation to important pathological events has attracted increased interest in the autooxidation of biologically important molecules. The demonstration of the role of reactive oxygen radicals in many diseases and cell aging has resulted in an increasing need for antioxidant drugs to reinforce and to amplify natural defenses against free radicals. This research investigated a novel electrochemical method to initiate oxidation of free fatty acids as a preliminary screening method for potential antioxidant compounds.;In designing an aqueous medium that approximated physiological conditions and that was also suitable for electrochemical reactions, a detergent was necessary in order to solubilize the fatty acid substrate. Of the five detergents---sodium dodecyl sulfate, sodium deoxycholate, Tween 20, hexadecyltrimethylammonium bromide, octyl glucoside---studied, octyl glucoside was found to be the best detergent for electrochemistry at pH 7.4 of linoleic acid. Employing HPLC, LC-MS, 2nd derivative UV spectroscopy, and thin layer chromatography, it was determined that controlled-potential electrolysis of linoleic acid at +1.5 V yielded similar oxidation products to those observed under conditions of chemically induced oxidation via the Fenton reagent. Both electrochemical, and chemical modes of initiation of linoleic acid oxidation produced products which were identified as linoleic hydroperoxides.;Although less susceptible than linoleic acid to oxidation in aqueous medium, electrolysis of other polyunsaturated fatty acids, linolenic and arachidonic, produced HPLC profiles similar to those obtained with these fatty acids under chemical oxidation conditions.;Electrolysis at +1.5 V of linoleic acid in the presence of known antioxidant compounds was found to successfully predict the antioxidant behavior of the compounds under chemical oxidation conditions. Vitamin E, ascorbyl-6-palmitate, and Trolox were found to inhibit electrochemically induced and chemically induced oxidation of linoleic acid. Electrolysis of linoleic acid in the presence of ascorbic acid also predicted the concentration-dependent oxidant/antioxidant behavior of ascorbic acid observed during chemical oxidation of linoleic acid. Ascorbic acid at low concentrations was found to enhance the oxidation of linoleic acid under both electrochemical and chemical oxidation conditions, while at high concentrations, ascorbic acid was shown to inhibit both electrochemically-induced and chemically-induced oxidation of the fatty acid substrate. |
