No abstract

A series of multitarget-directed resveratrol derivatives was designed and synthesized for the treatment of Alzheimer's disease (AD). In vitro studies indicated that most of the target compounds exhibit significant inhibition of self-induced β-amyloid (Aβ) aggregation and Cu(II)-induced Aβ1-42 aggregation and acted as potential antioxidants and biometal chelators. In particular, compounds 5d and 10d are potential lead compounds for AD therapy (5d, IC50 = 7.56 μM and 10d, IC50 = 6.51 μM for self-induced Aβ aggregation; the oxygen radical absorbance capacity assay using fluorescein (ORAC-FL) values are 4.72 and 4.70, respectively). Moreover, these compounds are capable of disassembling the highly structured Aβ fibrils generated by self- and Cu(II)-induced Aβ aggregation. Furthermore, 5d crossed the blood-brain barrier (BBB) in vitro and did not exhibit any acute toxicity in mice at doses of up to 2000 mg/kg. Taken together, the data indicate that 5d is a very promising lead compound for AD.

A novel series of compounds obtained by fusing the cholinesterase inhibitor donepezil and the antioxidant ebselen were designed as multi-target-directed ligands against Alzheimer's disease. An in vitro assay showed that some of these molecules did not exhibit highly potent cholinesterase inhibitory activity but did have various other ebselen-related pharmacological effects. Among the molecules, compound 7d, one of the most potent acetylcholinesterase inhibitors (IC50 values of 0.042 μM for Electrophorus electricus acetylcholinesterase and 0.097 μM for human acetylcholinesterase), was found to be a strong butyrylcholinesterase inhibitor (IC50 = 1.586 μM), to possess rapid H2O2 and peroxynitrite scavenging activity and glutathione peroxidase-like activity (ν0 = 123.5 μM min(-1)), and to be a substrate of mammalian TrxR. A toxicity test in mice showed no acute toxicity at doses of up to 2000 mg/kg. According to an in vitro blood-brain barrier model, 7d is able to penetrate the central nervous system.

A novel series of clioquinol-moracin hybrids were designed and synthesized by fusing the pharmacophores of clioquinol and moracin M, and their activities as multitarget-directed ligands against Alzheimer's disease were evaluated. Biological activity results demonstrated that these hybrids possessed significant inhibitory activities against phosphodiesterase 4D (PDE4D) and Aβ aggregation as well as remarkable antioxidant effects and excellent blood-brain barrier permeability. The optimal compound, 18d (WBQ5187), exhibited excellent PDE4D inhibitory potency (IC50 = 0.32 μM), significant antioxidant effects, appropriate biometal chelating functions, and interesting properties that modulated self- and metal-induced Aβ aggregation. Two-dimensional NMR studies revealed that 18d had significant interactions with Aβ1-42 at the R5, H6, H14, Q15, and F20 residues. Furthermore, this typical hybrid possessed preeminent neuroprotective effects against inflammation in microglial cells. Most importantly, oral administration of 18d·HCl demonstrated marked improvements in cognitive and spatial memory in a rat model of Alzheimer's disease and protected hippocampal neurons from necrosis.

A novel series of benzylideneindanone derivatives were designed, synthesized, and evaluated as multitarget-directed ligands against Alzheimer's disease. The in vitro studies showed that most of the molecules exhibited a significant ability to inhibit self-induced β-amyloid (Aβ(1-42)) aggregation (10.5-80.1%, 20 μM) and MAO-B activity (IC(50) of 7.5-40.5 μM), to act as potential antioxidants (ORAC-FL value of 2.75-9.37), and to function as metal chelators. In particular, compound 41 had the greatest ability to inhibit Aβ(1-42) aggregation (80.1%), and MAO-B (IC(50) = 7.5 μM) was also an excellent antioxidant and metal chelator. Moreover, it is capable of inhibiting Cu(II)-induced Aβ(1-42) aggregation and disassembling the well-structured Aβ fibrils. These results indicated that compound 41 is an excellent multifunctional agent for the treatment of AD.