Free radical scavenging activity of caffeine's metabolites
Article first published online: 3 APR 2012
Copyright © 2012 Wiley Periodicals, Inc.
International Journal of Quantum Chemistry
Special Issue: Mexican Theoretical Physical Chemistry Meetings
Volume 112, Issue 21, pages 3472–3478, 5 November 2012
How to Cite
León-Carmona, J. R. and Galano, A. (2012), Free radical scavenging activity of caffeine's metabolites. Int. J. Quantum Chem., 112: 3472–3478. doi: 10.1002/qua.24084
- Issue published online: 18 SEP 2012
- Article first published online: 3 APR 2012
- Manuscript Accepted: 15 FEB 2012
- Manuscript Revised: 13 FEB 2012
- Manuscript Received: 24 JAN 2012
- reactive oxygen species;
- branching ratios
The reactions of caffeine's main metabolites [paraxanthine, theobromine, theophylline, and 1-methylxanthine] with •OH, •OCH3, •OOH, and •OOCH3, in nonpolar and polar environments, have been studied using the density functional theory. Different mechanisms of reaction have been taken into account and their relative importance on the antioxidant activity of these compounds has been assessed. The free radical scavenging activity of the studied metabolites was found to be excellent for •OH, moderate for •OCH3, and negligible for peroxy radicals. The results from the present work indicate that the antioxidant activity of caffeine in our body remains almost the same when metabolized to paraxanthine, theobromine, theophylline, and 1-methylxanthine, while it is increased after being metabolized to 1-methyluric acid. In addition, the polarity of the environment was found to affect the overall reactivity of the studied compounds, to influence the relative importance of the different mechanisms and channels of reaction, and to have negligible effects on the relative scavenging activity of the studied compounds (theobromine > paraxanthine ≈ theophylline ≈ 1-methylxanthine). The studied metabolites were found to be better scavengers in nonpolar media than in aqueous solution. © 2012 Wiley Periodicals, Inc.