Icariin: A Special Antioxidant To Protect Linoleic Acid against Free-Radical-Induced Peroxidation in Micelles
- 21 April 2006
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 110 (19), 6372-6378
- https://doi.org/10.1021/jp053998z
Abstract
The objective in this work is to determine the antioxidant capacity and effectiveness of icariin (2-(4‘-methoxylphenyl)-3-rhamnosido-5-hydroxyl-7-glucosido-8-(3‘-methyl-2-butylenyl)-4-chromanone), the major component in herba epimedii being used widely in traditional Chinese medicine for the treatment of artherosclerosis and neuropathy, in which 2,2‘-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced peroxidation of linoleic acid (LH) in sodium dodecyl sulfate (SDS) acts as the experimental system. By containing an intramolecular hydrogen bond, icariin protects LH against AAPH-induced peroxidation of LH only in SDS, an anionic micelle. The number of trapping peroxyl radicals (LOO•), n, by icariin is just 0.0167 whereas α-tocopherol (TOH) and l-ascorbyl-6-laurate (VC-12) are 2.14 and 1.25, respectively, with reference to the n of 6-hydroxyl-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), 2.00. This is also related to how the intramolecular hydrogen bond enhances the bond dissociation enthalpy (BDE) of O−H in icariin. However, calculation of the inhibition rate constant, kinh, a kinetic parameter to describe the reaction between the antioxidant and LOO•, results in a kinh of icariin at about one magnitude larger than those of Trolox, TOH, and VC-12. This fact reveals that, by the view of kinetics, icariin is an antioxidant with much higher effectiveness. In addition, the antioxidant capacities of icariin used together with other antioxidants have been determined and the results indicate that the n of icariin decreases markedly while the n values of Trolox and TOH increase, even if the n of icariin is a negative value in the presence of VC-12. Furthermore, an analysis of kinh in this case reveals that the kinhicariin increases nearly one magnitude with the decrease of kinhTrolox and no remarkable change occurs for kinhTOH. The negative value of kinhicariin in the presence of VC-12 can be regarded as the icariin functions as a prooxidant that can be rectified by VC-12 effectively. These findings implicate that the evaluation of antioxidant activity should not only focus on an n value, a thermodynamic possibility, but kinh and the charge property of the micelle should be also taken into account. To some extent, the latter factors are more important than the thermodynamic possibility.Keywords
This publication has 31 references indexed in Scilit:
- Kinetic study on the prooxidative effect of vitamin C on the autoxidation of glycerol trioleate in micellesJournal of Physical Organic Chemistry, 2006
- Effects of garcinol on free radical generation and NO production in embryonic rat cortical neurons and astrocytesBiochemical and Biophysical Research Communications, 2005
- The Chemistry behind Antioxidant Capacity AssaysJournal of Agricultural and Food Chemistry, 2005
- Influence of Pb(II) on the Radical Properties of Humic Substances and Model CompoundsThe Journal of Physical Chemistry A, 2005
- Bond Dissociation Energies of the N−H Bond and Rate Constants for the Reaction with Alkyl, Alkoxyl, and Peroxyl Radicals of Phenothiazines and Related CompoundsJournal of the American Chemical Society, 1999
- Antioxidant effect of coumarin derivatives on free radical initiated and photosensitized peroxidation of linoleic acid in micellesJournal of the Chemical Society, Perkin Transactions 2, 1999
- Retinoic Acid-Dependent Stimulation of 2,2‘-Azobis(2-amidinopropane)-Initiated Autoxidation of Linoleic Acid in Sodium Dodecyl Sulfate Micelles: A Novel Prooxidant Effect of Retinoic AcidChemical Research in Toxicology, 1998
- Radical-Initiated Lipid Peroxidation in Low Density Lipoproteins: Insights Obtained from Kinetic ModelingChemical Research in Toxicology, 1996
- 1992 Syntex Award Lecture Model biomembranes: quantitative studies of peroxidation, antioxidant action, partitioning, and oxidative stressCanadian Journal of Chemistry, 1993
- Autoxidation of a model membrane. A comparison of the autoxidation of egg lecithin phosphatidylcholine in water and in chlorobenzeneJournal of the American Chemical Society, 1980