Free radical scavenging activity and mechanisms of amidoalkyl-2-naphthol derivative: a joint experimental and theoretical study

N-((4-Bromophenyl)(2-hydroxynaphthalen-1-yl)methyl)acetamide (BHMA) is a 1-amidoalkyl-2-naphthol derivative that has been reported to exhibit good acetylcholinesterase and α-glycosidase inhibitory activities. In the present paper, the free radical scavenging activity and mechanisms of BHMA were investigated using in vitro methods and quantum chemistry calculations. The molecular geometry of BHMA was first established using single-crystal X-ray diffraction analysis and was found to be nearly identical to that obtained theoretically. Then, the free radical scavenging activity of BHMA was evaluated by a series of in vitro assays including ABTS, phenanthroline and CUPRAC. After that, DFT (density functional theory)-based computational methods were used to study the main antioxidant mechanisms for all the possible sites of BHMA. As a result, BHMA was found to be a potent free radical scavenger with activity comparable to that of BHT and BHA. The OH bond was predicted to be more active for trapping free radicals than the NH/CH bonds. Hydrogen atom transfer and sequential proton loss electron transfer are, respectively, the dominant mechanisms in the gas phase and ethanol.