Tacripyrines (1-14) have been designed by combining an AChE inhibitor (tacrine) with a calcium antagonist such as nimodipine and are targeted to develop a multitarget therapeutic strategy to confront AD. Tacripyrines are selective and potent AChE inhibitors in the nanomolar range. The mixed type inhibition of hAChE activity of compound 11 (IC(50) 105 +/- 15 nM) is associated to a 30.7 +/- 8.6% inhibition of the proaggregating action of AChE on the Abeta and a moderate inhibition of Abeta self-aggregation (34.9 +/- 5.4%). Molecular modeling indicates that binding of compound 11 to the AChE PAS mainly involves the (R)-11 enantiomer, which also agrees with the noncompetitive inhibition mechanism exhibited by p-methoxytacripyrine 11. Tacripyrines are neuroprotective agents, show moderate Ca(2+) channel blocking effect, and cross the blood-brain barrier, emerging as lead candidates for treating AD.

Novel multifunctional compounds have been designed, synthesized, and evaluated as potential drugs for the treatment of Alzheimer's disease (AD). With an L-glutamic moiety as a suitable biocompatible linker, three pharmacophoric groups were joined: (1) an N-benzylpiperidine fragment selected to inhibit acetylcholinesterase by interacting with the catalytic active site (CAS), (2) an N-protecting group of the amino acid, capable of interacting with the acetylcholinesterase (AChE)-peripheral anionic site (PAS) and protecting neurons against oxidative stress, and (3) a lipophilic alkyl ester that would facilitate penetration into the central nervous system by crossing the blood-brain barrier. At submicromolar concentration, they inhibit AChE and butyrylcholinesterase (BuChE) of human origin, displace the binding of propidium iodide from the PAS of AChE, and could thus inhibit Abeta aggregation promoted by AChE. They also display neuroprotective properties against mitochondrial free radicals, show low toxicity, and could be able to penetrate into the CNS.

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