Experimental and theoretical determination of the antioxidant properties of isoespintanol (2-isopropyl-3,6-dimethoxy-5-methylphenol)

The present study compares, theoretically and experimentally, the antioxidant power of isoespintanol (2-isopropyl-3,6-dimethoxy-5-methylphenol) isolated from the leaves of Oxandra cf. xylopioides, with its biosyntetic analogue thymol (2-isopropyl-5-methylphenol). Calculations based on the density functional theory at the B3LYP/6-311G(d,p) level allowed us to determine the O-H bond dissociation enthalpy (BDE), and the ionization potential (IP) of isoespintanol and thymol in the gas phase and in solution in water and in methanol. Computed Delta BDE and Delta IP values, and FRAP (Ferric Reducing Antioxidant Power) and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays have shown that isoespintanol is twice better antioxidant than thymol. (C) 2007 Elsevier B.V. All rights reserved.