A THEORETICAL STUDY ON TAUTOMERISM AND FREE RADICAL SCAVENGING ACTIVITY OF CURCUMIN AND ITS DERIVATIVES IN DIFFERENT SOLVENTS

Theoretical calculations employing DFT methods are carried out to find the stability of curcumin and some of its derivatives in terms of diketo/enol tautomerism in a number of solvents. The results confirm that the enol form is more stable than the diketo form, independently of the solvent type. In order to quantitative assessment of antioxidant properties of studied species, the reactions of curcumin and its derivatives with the hydroxyl radical (OH•) are also investigated in different liquid solutions. Calculations show that curcumin is a good antioxidant and the abilities of other derivatives to scavenge free radicals are comparable with curcumin in all studied liquid solutions.