Synthesis and antioxidant activity of sterically hindered bis-pyrocatechol thioethers

Abstract

A reaction of 3,5-di-tert-butyl-o-benzoquinone with 1,2- and 1,6-dithiols was used to obtain the corresponding bis-pyrocatechol thioethers; a comparative evaluation of their antioxidant activity was carried out. The synthesized thioethers, 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl)acetic acid, and 3,5-di-tert-butylpyrocatechol were studied in the reaction with diphenylpicrylhydrazyl radical. The influence of these compounds on the autooxidation process of oleic (cis-octadec-9-enoic) acid was studied. The antioxidant activity of bis-pyrocatechol thioethers was manifested in the reaction with diphenylpicrylhydrazyl radical in the process of autooxidation of oleic acid, which was confirmed by the experimental EC₅₀ values, the data on the number of transformed molecules of stable radical (ⁿDPPH), and the relative content of oleic acid hydroperoxides. Bis-pyrocatechol thioethers were found to exhibit the inhibitory activity in the course of oxidation of glutathione induced by 2,2’-azobis(2-amidinopropane) dihydrochloride.