Synthesis and evaluation of clioquinol-rolipram/roflumilast hybrids as multitarget-directed ligands for the treatment of Alzheimer's disease.

Considering the importance of PDE4D inhibition and the modulation of biometals in Alzheimer's disease (AD) therapeutics, we have designed, synthesized and evaluated a series of new clioquinol-rolipram/roflumilast hybrids as multitarget-directed ligands for the treatment of AD. In vitro studies demonstrated that some of the molecules processed remarkable inhibitory activity against phosphodiesterase 4D (PDE4D), strong intracellular antioxidant capacity, potent inhibition of metal-induced aggregation of Aβ, and potential blood-brain barrier permeability. Compound 7a demonstrated significant improvement in cognitive and spatial memory in an Aβ25-35-induce mouse model in Morris water-maze test (MWM). These results indicate that compound 7a is a promising multifunctional candidate that is worthy of further study.