Design, synthesis, and evaluation of pyrano[3,2-c]coumarin derivatives for simultaneous targeting of amyloid-β42 and acetylcholinesterase in transgenic AD model of Drosophila.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder involving amyloid-β (Aβ) aggregation, cholinergic dysfunction, oxidative stress, mitochondrial impairment, and progressive neuronal loss. Consequently, the development of multi-target-directed ligands (MTDLs) capable of modulating multiple pathological pathways simultaneously has emerged as a promising therapeutic strategy. In this context, the present study describes the design, synthesis, and biological evaluation of a novel series of pyrano[3,2-c]coumarin derivatives 4a-n as dual Aβ42 and acetylcholinesterase (AChE) targeting anti-AD agents. Compounds 4a-n showed significant protection by inhibiting tissue specific Aβ42 aggregation in a transgenic AD model of Drosophila. In particular, compounds 4g and 4i were identified as potential lead compounds for targeting AD. These compounds inhibited endogenous Aβ42 aggregation and exhibited a significant rescue of eye phenotypes at respective effective concentrations (ECs) (4g, 46% rescue at EC = 250 µM and 4i, 65% rescue at EC = 50 µM). Furthermore, compounds 4g and 4i effectively reduced lipid-peroxidation, which was determined by assessing thiobarbituric acid reactive substances (TBARS) levels, at 25 and 50 µM, respectively, and reactive oxygen species (ROS). Compounds 4g and 4i also exhibited AChE inhibitory activity, with IC50 values of 0.02652 and 0.0268 µM, respectively. In silico molecular docking studies of 4i with Aβ42 (PDB ID: 1IYT) and AChE (PDB ID: 4EY4) also corroborated their anti-AD activity. Therefore, the present study indicated these compounds, especially 4i, could be promising lead candidates for AD drug development.