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QSAR of the free radical scavenging potency of selected hydroxyanthraquinones

It is well known that anthraquinones are molecules with moderate, but not negligible antioxidative activity. Their chemical behaviour is influenced by different parameters such as thermodynamics, orbital and structural properties, and polarity of environment. To find dependence of antioxidant activity of fourteen selected anthraquinones on the physicochemical parameters, we developed one-, two- and three- descriptor mathematical models. In all quantitative structure–activity relationship models (QSAR), experimentally obtained ABTS values were used as dependent variables. One- descriptor model indicated that in methanol the best correlation give enthalpies that describe stable radical formation following single proton loss, and then transfer of electron. Unexpectedly, the best two-descriptor model shows the best dependence of the experimental results on the combination of the orbital and structural parameters. The best two-parameter model was improved by introducing one thermodynamical parameter, such as bond dissociation enthalpy. On that way the best three-descriptor model was obtained. It indicates that the best insight into the antioxidant capacity of a molecule can be obtained by pooling all types of parameters and influences in a mathematical model.

QSAR ; Anthraquinones ; ABTS ; Thermodynamical parameters ; Vicinal hydroxyl groups

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