Design, Synthesis, in vitro biological evaluation and in silico molecular docking study of chloro substituted Benzimidazole-Thiazole hybrid derivatives as potential Anti-Alzheimer’s agents

In order to explore new acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitors, a series of benzimidazole-fused-thiazole bearing Schiff base derivatives (1–16) were designed and synthesized and further their precise structures were elucidated using various spectroscopic tools including 1H NMR, 13C NMR and HREI-MS. All the synthesized derivatives demonstrated better acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory potential with IC50 values ranging from 0.10 ± 0.10 µM to 11.60 ± 0.40 µM (against AChE) and 0.90 ± 0.10 µM to 22.10 ± 0.60 µM (BuChE) when the results were compared with Donepezil (IC50 = 2.16 ± 0.12 µM (against AChE) & 4.5 ± 0.11 µM (against BuChE) as standard inhibitor. Specifically, the analogues 4, 5, 11, 14 and 15 were identified to be significant potent, even more active than standard drug having IC50 values of 0.80 ± 0.10, 0.50 ± 0.10, 0.60 ± 0.10, 0.10 ± 0.10, 0.10 ± 0.10 µM (against AChE) and 2.40 ± 0.10, 1.10 ± 0.10, 1.30 ± 0.10, 0.90 ± 0.10 & 0.80 ± 0.10 µM (against BuChE) respectively. The structure–activity relationship (SAR) studies were carried out for all synthesized derivatives based on substitution pattern around aryl ring. Furthermore, the molecular docking approach was developed to explore the binding mode of interactions between most active scaffolds and active sites of targeted acetylcholinesterase and butyrylcholinesterase enzymes.