| Abstrakt: |
Inhibitory action of spatially hindered phenol antioxidants (AO) of ICHFAN groups, phenosan derivatives, containing ethanolamine, substituted by N- alkyl substituents R3 containing various carbon chains (from C2 to C 16) was investigated using two models, initiated oxidation of the homogenous methyl oleate (MO) solution in chlorbenzene, and a water-emulsive medium containing sodium dodecyl sulphate. ICHFANs act via two mechanisms: they react with peroxide radicals with the reaction rate constant of k7 = (0.59-1.06) x 10(4) (Mxc)(-1) and destroy hydroperoxides with formation of molecular products. The action of ICHFANs substantially depends on their chemical structure and oxidation conditions. In the lipidic solution, the ICHFANs effectively reduce MO oxidation; in comparable concentrations they exceed the action of the alpha-tocopherol, dibunol, phenosan K and its ether. The most effective AO is ICHFAN-10, which has the shortest substituent R3 (CH3). Elongation of R3 significantly reduced antioxidant activity. Behavior of the oxidation kinetics may be attributed to formation of micro-heterogeneous systems, with the participation of AO, in which OH phenol groups are oriented towards the nuclear of the micelle, limiting the possibility for their interaction with RO2* radicals. In the ICHFAN group, with the length of the R3 chain from C8H17 to C16H33, the periods of inhibition are increased proportionally to R3. The is explained by the insertion of such AO in the bilayer with internal orientation within hydrophobic radicals R3, and exposure of phenol OH groups to the external and internal micelle surfaces allowing them to destroy effectively RO2* radicals. During the oxidation in the water-emulsive medium, the inhibiting action of the corresponding ICHFAN is lower than in the homogenous solution, at that, the difference in the effectiveness of AO with different structures is reduced. This phenomenon is determined by the formation and stabilization with the presence of PAF micelles, in which the active OH-groups are located inside supramolecular structure. |
