title: Design, synthesis and biological evaluation of benzo[e][1,2,4]triazin-7(1H)-one and [1,2,4]-triazino[5,6,1-jk]carbazol-6-one derivatives as dual inhibitors of beta-amyloid aggregation and acetyl/butyryl cholinesterase.
abstract: Alzheimer's disease (AD) onset and progression are associated with the dysregulation of multiple and complex physiological processes and a successful therapeutic approach should therefore address more than one target. Two new chemical entities, the easily accessible heterocyclic scaffolds 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (benzotriazinone I) and 2-phenyl-6H-[1,2,4]triazino[5,6,1-jk]carbazol-6-one (triazafluoranthenone II), were explored for their multitarget-directed inhibition of beta-amyloid (Aβ) fibrillization and acetyl- (AChE) and/or butyryl- (BChE) cholinesterase, three valuable targets for AD therapy. Introduction of appropriate amine substituents at positions 6 and 5 on scaffold I and II, respectively, allowed the preparation of a series of compounds that were tested as Aβ(1-40) aggregation and cholinesterase inhibitors. Potent inhibitors of Aβ self-aggregation were discovered and among them benzotriazinone 7 exhibited an outstanding IC(50) equal to 0.37 μM. Compounds bearing a basic amine linked to the heterocyclic scaffold through a linear alkyl chain of varying length also afforded good ChE inhibitors. In particular, benzotriazinone 24 and triazafluoranthenone 38 were endowed with an interesting multiple activity, the former displaying IC(50) values of 1.4, 1.5 and 1.9 μM on Aβ aggregation and AChE and BChE inhibition, respectively, and the latter showing IC(50) values of 1.4 and an outstanding 0.025 μM in the Aβ aggregation and BChE inhibition, respectively. Benzotriazinone 24 and triazafluoranthenone 29, selected owing to their suitable aqueous solubility and Aβ aggregation inhibition, were submitted to a time course kinetic assay followed with thioflavin T (ThT) spectrofluorimetry, circular dichroism (CD) and transmission electron microscopy (TEM). Experimental data indicated that 24 acted at a low concentration ratio (10 μM 24 vs. 50 μM Aβ), stabilizing the unstructured Aβ peptide and inhibiting fibrillogenesis, and that 29 also acted as fibrillization inhibitor, but likely enhancing and stabilizing the β-sheet arrangement of Aβ to yield protofibrillar species as detected by TEM.
authors.affiliation: Dipartimento di Farmacia, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125 Bari, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Catto
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Berezin
authors.forename: Daniele
authors.initials: D
authors.lastname: Lo Re
authors.forename: Georgia
authors.initials: G
authors.lastname: Loizou
authors.forename: Marina
authors.initials: M
authors.lastname: Demetriades
authors.forename: Angelo
authors.initials: A
authors.lastname: De Stradis
authors.forename: Francesco
authors.initials: F
authors.lastname: Campagna
authors.forename: Panayiotis A
authors.initials: PA
authors.lastname: Koutentis
authors.forename: Angelo
authors.initials: A
authors.lastname: Carotti
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D002091:Butyrylcholinesterase / Q000097:blood / Q000378:metabolism*; D002800:Cholinesterase Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D004593:Electrophorus; D006736:Horses; D015394:Molecular Structure; D010446:Peptide Fragments / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D016229:Amyloid beta-Peptides; D002800:Cholinesterase Inhibitors; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); D000110:Acetylcholinesterase; D002091:Butyrylcholinesterase