NO-donor thiacarbocyanines as multifunctional agents for Alzheimer's disease

Some symmetrical and unsymmetrical thiacarbocyanines bearing NO-donor nitrooxy and furoxan moieties were synthesized and studied as candidate anti-Alzheimer's drugs. All products activated soluble guanylate cyclase (sGC) in a dose-dependent manner, depending on the presence in their structures of NO-donor groups. None displayed toxicity when tested at concentrations below 10 μM on human brain microvascular endothelial cells (hCMEC/D3). Some products were capable of inhibiting amyloid β-protein (Aβ) aggregation, with a potency in the low μM concentration range, and of inhibiting aggregation of human recombinant tau protein in amyloid fibrils when incubated with the protein at 1 μM concentration. Nitrooxy derivative 21 and furoxan derivative 22 were selected to investigate synaptic plasticity. Both products, tested at 2 μM concentration, counteracted the inhibition of long-term potentiation (LTP) induced by Aβ42 in hippocampal brain slices.