O-Hydroxyl- or o-amino benzylamine-tacrine hybrids: Multifunctional biometals chelators, antioxidants, and inhibitors of cholinesterase activity and amyloid-β aggregation

A series of hybrid molecules were synthesised by reacting N-(aminoalkyl)tacrine with salicylic aldehyde or derivatives of 2-aminobenzaldehyde. All of the hybrids are potential biometal chelators, and in addition, most of them were better antioxidants and inhibitors of cholinesterases and amyloid-β (Aβ) aggregation than the lead compound tacrine. Compound 7c has the potential to be a candidate for AD therapy: it is a much better inhibitor of acetylcholinesterase (AChE) than tacrine (IC50: 0.55 nM vs 109 nM), has good biometal chelation ability, is able to inhibit Aβ aggregation and has moderate antioxidant activity (1.22 Trolox equivalents).