Scientific article

Theoretical parameters to characterize antioxidants - Part 2 - The cases of melatonin and carvedilol

Published inHelvetica chimica acta, vol. 81, no. 7, p. 1337-1348
Publication date1998

This theoretical study focuses on two indole derivatives, melatonin (1) and carvedilol (8), with the objective of improving our understanding of the molecular mechanisms underlying their radical-scavenging activity. Quantum-mechanical calculations were carried out using the AMI semi-empirical method, some results being confirmed by nb initio (3-21G) calculations. The quantum-chemical descriptor Delta H-ox (relative adiabatic oxidation potential) and the shape of the SOMO (singly occupied molecular orbital) indicate that the stabilization of its radical cation can partially explain the well-documented antioxidant efficacy of melatonin. This stabilization may result from electrostatic interactions and from a hyperconjugative effect existing in a Family of conformers of the melatonin radical cation having the side chain almost perpendicular to the plane of the aromatic rings. Furthermore, 6-hydroxymelatonin (7) appears to be a better free-radical scavenger than melatonin (1) in agreement with experimental results. According to the theoretical parameters Delta H-ox and Delta H-abs (relative bond dissociation enthalpy), carvedilol (8) is not a good antioxidant, in contrast to its ring-hydroxylated metabolites whose powerful antioxidant effects are explained by the formation of an oxyl radical stabilized by delocalization over the carbazole nucleus

Affiliation Not a UNIGE publication
Citation (ISO format)
MIGLIAVACCA, E. et al. Theoretical parameters to characterize antioxidants - Part 2 - The cases of melatonin and carvedilol. In: Helvetica chimica acta, 1998, vol. 81, n° 7, p. 1337–1348. doi: 10.1002/hlca.19980810544
ISSN of the journal0018-019X

Technical informations

Creation08/06/2010 10:46:49 AM
First validation08/06/2010 10:46:49 AM
Update time03/14/2023 3:56:26 PM
Status update03/14/2023 3:56:26 PM
Last indexation10/18/2023 10:55:26 AM
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack