Microwave-assisted synthesis of indoloquinoxaline derivatives as promising anti-alzheimer agents: DFT and molecular docking study

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline. One of the major pathological features of AD is the degeneration of cholinergic neurons and associated loss of acetylcholine (ACh), a key neurotransmitter involved in memory and cognition. Reduced ACh levels correlate with the severity of cognitive symptoms in AD. Thus, inhibition of acetylcholinesterase (AChE), the enzyme responsible for breaking down ACh, is a leading treatment strategy. This study aimed to synthesize and evaluate novel AChE inhibitors based on an indolo[2,3-b]quinoxaline scaffold. A series of indolo[2,3-b]quinoxaline derivatives were designed by molecular hybridization of indole and quinoxaline privileged structures. Microwave-assisted synthesis improved the efficiency of obtaining the desired compounds. In vitro screening identified several potent AChE inhibitors, with IC50 values down to 0.02 µM. The most active compounds contained electron-withdrawing groups like nitro and benzoyl moieties. DFT calculations provided insights into geometrical, thermal, and electronic properties of the compounds. FMO analysis revealed variations in HOMO and LUMO energies that impact reactivity. Molecular docking elucidated binding modes, highlighting the pi-pi, pi-H, and H-bonding interactions with key amino acids in the catalytic gorge of AChE. Overall, the indole-quinoxaline hybrids represent promising candidates for development of novel dual binding site AChE inhibitors and multifunctional anti-Alzheimer agents.