Tocotrienamines and tocopheramines: Reactions with radicals and metal ions
摘要:
The antioxidant activity of vitamin E (VE) homologs alpha, gamma and delta-tocotrienamines (4b-6b), never studied before, and alpha, gamma and delta-tocopheramines (4a-7a) was investigated by means of different total antioxidant capacity (TAC) tests. In all the test model systems, compounds 4a-7a and 4b-6b showed similar or higher TAC values than the parental vitamin E forms and their physiological metabolites. alpha-Homologs of VE amines showed markedly higher activity than the VE congeners in the TEAC test, which is tailored for liposoluble antioxidants, while gamma-homologs of the amine analogs showed higher activity in the FRAP tests. Kinetics analysis of the reaction with DPPH center dot showed higher second order rate k for 4a than for alpha-tocopherol (1a). alpha-Tocopherolquinone 1f was the common main oxidation product for both 1a and alpha-tocopheramine (4a) exposed to ferric ions or DPPH center dot, and the implied oxidative deamination of 4a was accompanied by a nitration reaction of phenolic substrates that were added to the reaction medium. Possible mechanisms of these reactions were studied. (C) 2011 Elsevier Ltd. All rights reserved.
The antioxidant activity of vitamin E (VE) homologs alpha, gamma and delta-tocotrienamines (4b-6b), never studied before, and alpha, gamma and delta-tocopheramines (4a-7a) was investigated by means of different total antioxidant capacity (TAC) tests. In all the test model systems, compounds 4a-7a and 4b-6b showed similar or higher TAC values than the parental vitamin E forms and their physiological metabolites. alpha-Homologs of VE amines showed markedly higher activity than the VE congeners in the TEAC test, which is tailored for liposoluble antioxidants, while gamma-homologs of the amine analogs showed higher activity in the FRAP tests. Kinetics analysis of the reaction with DPPH center dot showed higher second order rate k for 4a than for alpha-tocopherol (1a). alpha-Tocopherolquinone 1f was the common main oxidation product for both 1a and alpha-tocopheramine (4a) exposed to ferric ions or DPPH center dot, and the implied oxidative deamination of 4a was accompanied by a nitration reaction of phenolic substrates that were added to the reaction medium. Possible mechanisms of these reactions were studied. (C) 2011 Elsevier Ltd. All rights reserved.