Pyrrole-2,5-dione analogs as a promising antioxidant agents: microwave-assisted synthesis, bio-evaluation, SAR analysis and DFT studies/interpretation.

A new series of pyrrole analogs were developed via the microwave irradiation synthesis. Consequently, got a high yield of the products. As pyrroles are familiar for showing various biological properties, all obtained compounds were screened for their antioxidant properties, most of the compounds showing significant activity. In fact, the motifs 5e, 5g, 5h and 5m showed outstanding antioxidant properties. Further, to enlighten the biologically energetic behavior underlying the antioxidant activity, compounds DFT studies were performed. Noteworthy results have been attained and the structure activity relationship (SAR) was discussed with the support of this results. It was found that highly biological active compounds exhibited a low HOMO-LUMO energy gap (Eg) and the high Eg value compounds show very low/negligible or inactive antioxidant activities. In other cases, compounds containing high HOMO energy levels also provide high antioxidant activity. The thought-provoking point of our results is that theoretical descriptors of the HOMO-LUMO energy gap and the highest occupied molecular orbital energy are important descriptors in the bioorganic research to support the biological experiments.