Reactivity of tert-butylperoxyl radical with some phenylthiazolidine derivatives and probucol

The hybrid molecule phenylthiazolidine derivatives and probucol were kinetically examined as antioxidants (AOs) in scavenging tert-butylperoxyl radical (t-BuOO^•) with comparable to the reference AO, butylated hydroxytoluene (BHT). The anti-t-BuOO^• reactivity of phenylthiazolidine derivatives and probucol was established using the direct kinetic electron paramagnetic resonance (EPR) technique with pulse reactant injection. Absolute values of the bimolecular reaction rate constants and antiradical capacities of the studied compounds were measured from −63 to 0°C. The main antiperoxylradical sites of the compounds under study were revealed.

High removal ability of t-BuOO^• by (2-(4-hydroxyphenyl)thiazolidine), 4-[thiazolidin-2-yl]benzene-1,2-diol, 2-(4-hydroxyphenyl)thiazolidine-4-carboxylic acid and probucol was connected with the reaction of hydrogen atom abstraction from phenolic OH group.

Weaker antiperoxylradical reactivity of 2-phenylthiazolidine was connected with the slower reaction of hydrogen atom abstraction from benzylic C–H bond in reference to nitrogen and sulfur atoms compared with the phenolic OH group. It is found that sulfide groups had much weaker participation in antiperoxylradical reactivity of the studied compounds. It is concluded that removal of alkylperoxyl radicals by oxidizable phenylthiazolidine derivatives and probucol may partially account for biological activity of their compounds.