Benzylpiperidine-Linked Diarylthiazoles as Potential Anti-Alzheimer's Agents: Synthesis and Biological Evaluation

A novel series of hybrid molecules were designed and synthesized by fusing the pharmacophoric features of cholinesterase inhibitor donepezil and diarylthiazole as potential multitarget-directed ligands for the treatment of Alzheimer's disease (AD). The compounds showed significant in vitro anticholinesterase (anti-ChE) activity, the most potent compound (44) among them showing the highest activity (IC50 value of 0.30 ± 0.01 μM) for AChE and (1.84 ± 0.03 μM) for BuChE. Compound 44 showed mixed inhibition of AChE in the enzyme kinetic studies. Some compounds exhibited moderate to high inhibition of AChE-induced Aβ1-42 aggregation and noticeable in vitro antioxidant and antiapoptotic properties. Compound 44 showed significant in vivo anti-ChE and antioxidant activities. Furthermore, compound 44 demonstrated in vivo neuroprotection by decreasing Aβ1-42-induced toxicity by attenuating abnormal levels of Aβ1-42, p-Tau, cleaved caspase-3, and cleaved PARP proteins. Compound 44 exhibited good oral absorption and was well tolerated up to 2000 mg/kg, po, dose without showing toxic effects.