CATALYTIC ANTIOXIDANT ACTIVITY OF DIARYL TELLURIDES IN A TWO-PHASE LIPID PEROXIDATION MODEL

摘要

Diaryl tellurides, diaryl sulfides, ebselen, probucol, BHT, trolox, and vitamin E were assessed for their capacity to inhibit ate-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system containing N-acetylcysteine as a thiol reducing agent in the aqueous phase. The progress of peroxidation in the organic layer was monitored by HPLC with UV detection, and the inhibited rate of peroxidation, R(inh), and the duration of the inhibited phase, T-inh, were determined. In catalytic amounts (40 mu M), both phenolic and nonphenolic diaryl tellurides efficiently inhibited peroxidation in the chlorobenzene layer until the thiol reducing agent in the aqueous phase had been completely oxidized to the corresponding disulfide. Although efficient, trolox and vitamin E offered antioxidant protection only on a stoichiometric basis. BHT, probucol, and ebselen all showed poor antioxidant capacity under the conditions used. Some phenolic diaryl sulfides were moderately efficient inhibitors, with the antioxidant protection enduring for a considerable time without consumption of N-acetylcysteine in the aqueous phase. It is proposed that the diaryl tellurides act as hydrogen atom and/or electron donors toward peroxyl radicals. Further oxidation/hydrolysis probably provides tellurium(IV) dihydroxides, which can recycle to the active antioxidant through reduction by N-acetylcysteine at the water/chlorobenzene interphase. [References: 39]