| Full text | |
| Author(s): |
de Almeida, Natalia E. C.
[1]
;
de Aguiar, Inara
[1]
;
de Zawadzki, Andressa
[1]
;
Cardoso, Daniel R.
[1]
Total Authors: 4
|
| Affiliation: | [1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
Total Affiliations: 1
|
| Document type: | Journal article |
| Source: | Journal of Physical Chemistry B; v. 118, n. 49, p. 14278-14287, DEC 11 2014. |
| Web of Science Citations: | 7 |
| Abstract | |
Hydroxyalkyl radicals have been reported to induce lipid oxidation as the key aspect of the pathogenesis of alcoholic fatty liver disease and are responsible for the alkylation and cleavage of DNA during the metabolism of a wide range of genotoxic compounds. However, relevant kinetic data for the oxidation of unsaturated lipids by 1-hydroxyethyl radical (HER) has not been reported. In this study, the rate constants for the reaction of unsaturated fatty acid methyl esters and sterols with HER have been determined using a competitive kinetic approach employing the spin-trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) as the competitive substrate. Polyunsaturated fatty acid methyl ester is shown to react with HER with an apparent second-order rate constant ranging from (3.7 +/- 0.1) x 10 L mol(-1) s(-1) for methyl linoleate to (2.7 +/- 0.2) x 107 L mol(-1) s(-1) for methyl docosahexanoate at 25.0 +/- 0.2 degrees C in ethanol. The apparent second-order rate constant for polyunsaturated fatty acid methyl ester oxidation by HER is dependent on the number of bisallylic hydrogen atoms rather than on the bond dissociation energy value for the weakest CH bond as determined by ab initio density functional theory calculations. Sterols displayed higher reactivity compared to unsaturated fatty acid methyl esters with apparent second-order rate constants of (2.7 +/- 0.1) x 10 and (5.2 +/- 0.1) x 10 L mol(-1) s(-1) at 25.0 +/- 0.2 degrees C in ethanol for cholesterol and ergosterol, respectively. Similar experiments with prenylflavonoids as potential herbal chemopreventive agents for preventing alcoholic liver diseases yield apparent second-order rate constants close to the diffusion control with k(app) values of (1.5 +/- 0.2) and (3.6 +/- 0.1) x 10 L mol(-1) s(-1) for 6-prenylnarigerin and xanthohumol at 25.0 +/- 0.2 degrees C in ethanol solution, respectively. Polyunsaturated lipids were revealed to be highly reactive oxidizable substrates toward HER-induced oxidation in biological systems leading to damage of membranes and sensitive structures. (AU) | |
| FAPESP's process: | 11/09273-4 - Reactivity of terpenes and prenylflavonoids towards radicals formed during the aging process of beer |
| Grantee: | Natália Ellen Castilho de Almeida |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 11/51555-7 - Bread and meat for the future |
| Grantee: | Daniel Rodrigues Cardoso |
| Support Opportunities: | Regular Research Grants |