Evaluation of the antioxidant activity for 2,3-dihydroquinazolin-4(1H)-one and derivatives. An experimental and theoretical study

Abstract

2,3-dihydroquinazoline-4(1H)-one (DHQ) is an important building block in drug design with several biological properties. The antioxidant activity of three DHQ-derivatives was assessed using ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and ORAC (oxygen radical absorbance capacity) tests, indicating that these compounds have antioxidant properties. Theoretical calculations were carried out to establish a possible explanation for antioxidant properties through thermodynamic parameters and molecular structure characteristics. Ionization energy, bond dissociation enthalpy, electron affinity, and electrophilic index indicate that DHQs have antioxidant characteristics by similar mechanisms as those established for polyphenols. Determined activities can be elucidated through energy values for frontier orbitals since the molecule with the less antioxidant activity for both assays possess a positive electron affinity and the highest electrophilic index, indicating it is more likely to attract electrons instead of donating them for radical scavenging.