Synthesis, DFT Calculations, and In Vitro Antioxidant Study on Novel Carba-Analogs of Vitamin E.
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ABSTRACT: Vitamin E is the most active natural lipophilic antioxidant with a broad spectrum of biological activity. ?-Tocopherol (?-T), the main representative of the vitamin E family, is a strong inhibitor of lipid peroxidation as a chain-breaking antioxidant. Antioxidant and antiradical properties of vitamin E result from the presence of a phenolic hydroxyl group at the C-6 position. Due to stereoelectronic effects in the dihydropyranyl ring, the dissociation enthalpy for phenolic O-H bond (BDEOH) is reduced. The high chain-breaking reactivity of ?-T is mainly attributed to orbital overlapping of the 2p-type lone pair on the oxygen atom (O1) in para position to the phenolic group, and the aromatic ?-electron system. The influence of the O1 atom on the antioxidant activity of vitamin E was estimated quantitatively. The all-rac-1-carba-?-tocopherol was synthesized for the first time. Along with model compounds, 1-carba-analog of Trolox and its methyl ester were screened for their in vitro antioxidant activity by inhibition of styrene oxidation, and for the radical-reducing properties by means of 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging assay. To study the antioxidant activity, density functional theory (DFT) was also applied. Reaction enthalpies related to HAT (hydrogen atom transfer), SET-PT (sequential electron transfer-proton transfer), and SPLET (sequential proton loss-electron transfer) mechanisms were calculated.
SUBMITTER: Baj A
PROVIDER: S-EPMC6943657 | biostudies-literature | 2019 Nov
REPOSITORIES: biostudies-literature
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