Comprehensive evaluation of antioxidant properties of sterically hindered catechols with heterocyclic fragments, thioether or thione groups

Abstract

New sterically hindered catechols containing heterocyclic fragments (1,3,4-oxadiazole, 1,3,4-thiadiazole, pyrimidinyl, pyrazinyl) and thioether/thione groups were synthesized. Their electrochemical and antioxidant properties were studied in various model systems, including blood plasma, in comparison with the previously synthesized analogues and standard antioxidants (Trolox and ionol). Their electrochemical and structural features were studied using cyclic voltammetry, IR spectroscopy, NMR spectroscopy, high-resolution mass spectrometry, and X-ray diffraction analysis. The antioxidant properties of the synthesized compounds were assessed in vitro in model systems without additives or in the presence of blood plasma. The compounds were found to exhibit multidirectional activity depending on the structure and environmental conditions. The highest antiradical and reducing activities were demonstrated by the 6-trifluoromethyl-2-thiouracil derivative, which also shows an increase in the antioxidant effect in the presence of blood plasma.