Catto_2012_Eur.J.Med.Chem_58C_84

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 Abeta 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 Abeta(1-40 aggregation and cholinesterase inhibitors Potent inhibitors of Abeta self-aggregation were discovered and among them benzotriazinone 7 exhibited an outstanding IC(50 equal to 0.37 muM 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 muM on Abeta aggregation and AChE and BChE inhibition respectively and the latter showing IC(50 values of 1.4 and an outstanding 0.025 muM in the Abeta aggregation and BChE inhibition respectively Benzotriazinone 24 and triazafluoranthenone 29 selected owing to their suitable aqueous solubility and Abeta 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 muM 24vs 50 muM Abeta stabilizing the unstructured Abeta peptide and inhibiting fibrillogenesis and that 29 also acted as fibrillization inhibitor but likely enhancing and stabilizing the beta-sheet arrangement of Abeta to yield protofibrillar species as detected by TEM.