Multifunctional edaravone‐N‐benzyl pyridinium derivatives: AChE inhibition kinetics, in vitro neuroprotective activities and BBB permeability studies

Abstract

Background: Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is mainly prevalent in the older population. Approximately fifty million people are diagnosed with dementia, with AD accounting for 60-70% of these cases. Amyloid beta (Aβ) is considered a pathological hallmark of AD. The shorter Aβ 25 -35 peptide fragments, formed from the amyloidogenic Aβ 1-40 peptide, plays a crucial role in the peptide's neurotoxic activity (Pike et al., 2002). Acetylcholinesterase (AChE) as well as oxidative stress have shown to trigger Aβ formation and aggregation (Belluti et al., 2011; Cheignon et al., 2018). Previously, we synthesized multifunctional edaravone-Nbenzyl pyridinium compounds that exhibited potent AChE inhibition and antioxidant activity as well as predicted to cross the blood-brain barrier (BBB) using in silico models (Zondagh et al., 2020). Method: Selected compounds were chosen to further investigate their AChE inhibitory kinetics, Aβ 25 -35 and MPP + attenuating ability, cytotoxicity and in vitro BBB permeability. The AChE inhibitory kinetics were determined using a modified Ellman's method. The data was analyzed, and a double-reciprocal Lineweaver-Burk plot was drawn. Mode of inhibition was determined from the Lineweaver-Burk plot. The compounds in vitro Aβ 25 -35 and MPP + attenuating activity and cytotoxicity at concentrations of 10 -100 µM was assessed on the SH-SY5Y cell line. The in vitro BBB permeability of the compounds were assessed on the b.End5 cell line. Result: All of the compounds exhibited mixed non-competitive -uncompetitive mode of AChE inhibition which correlate with previous molecular docking studies. Four of the five compounds exhibited no cytotoxic effects to the SH-SY5Y cell line, with some exhibiting proliferating effects. Compound 5a, 5e and 5j caused greater cell proliferation compared to the control at 10 μM. Most of the compounds exhibited significant activity at attenuating MPP + and Aβ 25 -35 . Compounds 5a, 5b and 5e exhibited the most promising attenuating affects over all concentrations. Compound 5e caused greater cell proliferation when compared to the control. Conclusion: These multifunctional compounds exhibited significant neuroprotective effects against neurotoxins, especially against Aβ 25 -35 . The compounds have shown promising activity as potential anti-Alzheimer's agents.