CHIH-DFT study of the electronic properties and chemical reactivity of quercetin

Quercetin is one of the most abundant flavonoids in vegetal tissues and presents high antioxidant activity. It is known that it exerts its antioxidant activity through the capacity to donate protons and electrons to inhibit reactive oxygen species (ROS) that act like free radicals. As the biological activity of the flavonoids is governed mainly by electronic interactions with biomolecules, the study of the electronic and reactivity properties in the molecule of quercetin is considered to be very important. For the calculation of the electronic properties and reactivity, we used the CHIH-DFT model chemistry. The results show that quercetin is a relatively polar molecule, soluble in water, and which presents diamagnetic properties in its basal state, in addition to an aromatic character. It presents a greater tendency to give electrons than to attract them, which confirms its antioxidant capacity. The more important reactive sites, that can be related to the antioxidant properties, are located mainly in rings B and C. (c) 2004 Elsevier B.V. All rights reserved.