Theoretical study on the investigation of antioxidant properties of some hydroxyanthraquinones

ABSTRACT

Anthraquinones are located in an important class of natural compounds having antioxidant properties. Quantum chemical calculations based on the density functional theory were employed to study the relationship between the structure and the antioxidant activity of four hydroxyanthraquinones. The solvation effects on the antioxidant activity were taken into account by using the conductor-like polarisable continuum model with different dielectric constants (ε = 2.25, C₆H₆; ε = 78.39, H₂O). The three antioxidant action mechanisms, hydrogen atom transfer (HAT), single electron transfer-proton transfer and sequential proton loss electron transfer (SPLET) were elucidated. The reaction enthalpies related to the steps in these mechanisms were computed in gas phase and solvents. The calculated results are in line with experimental values. The results showed that HAT was the most favourable mechanism for describing the antioxidant activity of hydroxyanthraquinones in the gas phase and in benzene, whereas in aqueous solution, SPLET represented the most thermodynamically plausible reaction pathway.

KEYWORDS:

• Antioxidant mechanism
• hydroxyanthraquinones
• radical-scavenging
• density functional theory
• antioxidant descriptors

Acknowledgments

This research was made possible by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). This work is supported by The Scientific Research Project Fund of Cumhuriyet University under the project number F-453.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

Scientific Research Project Fund of Cumhuriyet University [project number F-453].