DFT study and radical scavenging activity of 2-phenoxypyridotriazolo pyrimidines by DPPH, ABTS, FRAP and reducing power capacity

The target 2-phenoxy[3,2-e][1,2,4]triazolo[1,5-a]pyrimidines (1–6) was previously synthesized and fully characterized. In the present study, the antioxidant activity of compounds 1–6 was evaluated using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power, 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and reducing power capacity assays. The findings showed that at fifth of the used concentration (0.1 mg/mL), six of the examined pyridotriazolopyrimidines (6d–6h) are superior to the compounds as they displayed the highest capacity to scavenge DPPH, ABTS and free radicals when compared to the standard agent, butylated hydroxytoluene. Theoretical calculations based on density functional theory study together with structural modifications of the targets provided valuable clarifications regarding the requirements to synthesize more active target compounds against free radicals.