In-vitro evaluation studies of 7-chloro-4-aminoquinoline Schiff bases and their copper complexes as cholinesterase inhibitors.

Alzheimer's disease (AD) is one of the most common age-related neurodegenerative disorders. Aggregation of amyloid-ß peptide into extracellular plaques with incorporation of metal ions, such as Cu2+, and reduction of the neurotransmitter acetylcholine levels are among the factors associated to the AD brain. Hence, a series of 7-chloro-4-aminoquinoline Schiff bases (HLa-e) were synthesized and their cytotoxicity and anti-cholinesterase activity, assessed for Alzheimer's disease. The intrinsic relationship between Cu2+ and the amyloidogenic plaques encouraged us to investigate the chelating ability of HLa-e. Dimeric tetracationic compounds, [Cu2(NHLa-e)4]Cl4, containing quinoline protonated ligands were isolated from the reactions with CuCl2·2H2O and fully characterized in the solid state, including an X ray diffraction study, whereas EPR data showed that the complexes exist as monomers in DMSO solution. The inhibitory activity of all compounds was evaluated by Ellman's spectrophotometric method in acetylcholinesterase (AChE) from Electrophorus electricus and butyrylcholinesterase (BChE) from equine serum. HLa-e and [Cu(NHLd)2]Cl2 were selective for AChE (IC50 = 4.61-9.31 µM) and were not neurotoxic in primary brain cultures. Docking and molecular dynamics studies of HLa-e inside AChE were performed and the results suggested that these compounds are able to bind inside AChE similarly to other AChE inhibitors, such as donepezil. Studies of the affinity of HLd for Cu2+ in DMSO/HEPES at pH 6.6 and pH 7.4 in µM concentrations showed formation of analogous 1:2 Cu2+/ligand complexes, which may suggest that in the AD-affected brain HLd may scavenge Cu2+ and the complex, also inhibit AChE.

A molecular dynamics study of components of the ginger (Zingiber officinale) extract inside human acetylcholinesterase: implications for Alzheimer disease.

Components of ginger (Zingiber officinale) extracts have been described as potential new drug candidates against Alzheimer disease (AD), able to interact with several molecular targets related to the AD treatment. However, there are very few theoretical studies in the literature on the possible mechanisms of action by which these compounds can work as potential anti-AD drugs. For this reason, we performed here docking, molecular dynamic simulations and mmpbsa calculations on four components of ginger extracts former reported as active inhibitors of human acetylcholinesterase (HssAChE), and compared our results to the known HssAChE inhibitor and commercial drug in use against AD, donepezil (DNP). Our findings points to two among the compounds studied: (E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hept-4-en-3-on and 1-(3,4-dihydroxy-5-methoxyphenyl)-7-(4-hydroxy-3- ethoxyphenyl) heptane-3,5-diyl diacetate, as promising new HssAChE inhibitors that could be as effective as DNP. We also mapped the binding of the studied compounds in the different binding pockets inside HssAChE and established the preferred interactions to be favored in the design of new and more efficient inhibitors.