An addition compound of oxidized tocopherol and linoleic acid

Abstract

There is evidence that an addition compound of oxidized dl-alpha-tocopherol and linoleic acid is formed when the components are adsorbed in mixed monolayer on silica gel at a molecular ratio of 1:20, and subjected to heating in air at 80 C. A relatively nonpolar tocopheryl quinone is also formed in smaller amounts. These are the major tocopherol oxidation products isolated in this system and do not correspond to any known to the authors. The addition compound has about the same mobility as linoleic acid in most thin layer chromatography (TLC) and chromatographic systems, but can be isolated by successive chromatography on silica and gel filtration on Sephadex LH-20. It yields a single spot in TLC in several systems. The elemental analysis is reproducible and consistent with a simple addition compound of linoleic acid and bivalently oxidized tocopherol. The compound has a carboxyl group which can be esterified. The ester has about the same TLC mobility as methyl linoleate. The molecular weight of the ester is 722.6. The UV spectrumoshows a single peak, ETOH = 3000 A, E = 4.74. The IR max spectrum shows a very strong chroman ether band at 9.12 At, a strong methyl band at 7.24 At and carboxyl but no hydroxyl absorption. The NMR spectrum shows, in contrast to that of tocopherol, a reduction in aromatic methyl protons, a carboxyl proton exchangeable with deuterium oxide, but no hydroxyl proton. The compound does not reduce Emmerie-Engel reagent prior to treatment with concentrated hydriodic acid, nor do the ether-extractable products after such treatment. The present data are consistent with an addition product whose bridging group is a new chroman ring.

Phospholipase A2 of rat liver mitochondria in vitamin E deficiency

“…As Lucy (1972) has suggested, it is likely that the vitamin may decrease the availability of substrate by binding to the arachidonoyl residue, thus rendering them more resistant to hydrolysis. An oxidation product of a-tocopherol has been shown to form stable complexes with fatty acid residues of phosphatidylcholine (Porter et al, 1971). Alternately, vitamin E may be involved in maintenance of the fluidity of membrane bilayer that determines membrane conformation that, in turn, may keep the enzyme in an inactive form (Fourcans & Jain, 1974).…”

Model Study of Different Antioxidant Properties of α‐ and γ‐Tocopherol in Fats

“…The method used by Mayer et al 27 for the oxidation of a-T was modified as follows: a-COH (150 mg) dissolved in 10 ml diethyl ether was added to a solution of ferric chloride (450mg) in 20ml of 50% (v/v) aqueous methanol. The spirodimer (A2) derived from the a-COH was prepared as described by Porter et al 29 for the spirodimer obtained from a-T. The spirodimer (A2) derived from the a-COH was prepared as described by Porter et al 29 for the spirodimer obtained from a-T.…”