Synthesis, biological evaluation and molecular modeling studies of methyl indole-isoxazole carbohydrazide derivatives as multi-target anti-Alzheimer’s agents

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects the elderly population globally and there is an urgent demand for developing novel anti-AD agents. In this study, a new series of indole-isoxazole carbohydrazides were designed and synthesized. The structure of all compounds was elucidated using spectroscopic methods including FTIR, ¹H NMR, and ¹³C NMR as well as mass spectrometry and elemental analysis. All derivatives were screened for their acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activity. Out of all synthesized compounds, compound 5d exhibited the highest potency as AChE inhibitor with an IC₅₀ value of 29.46 ± 0.31 µM. It showed significant selectivity towards AChE, with no notable inhibition against BuChE. A kinetic study on AChE for compound 5d indicated a competitive inhibition pattern. Also, 5d exhibited promising BACE1 inhibitory potential with an IC₅₀ value of 2.85 ± 0.09 µM and in vitro metal chelating ability against Fe³⁺. The molecular dynamic studies of 5d against both AChE and BACE1 were executed to evaluate the behavior of this derivative in the binding site. The results showed that the new compounds deserve further chemical optimization to be considered potential anti-AD agents.