Rhein-Huprine Derivatives Reduce Cognitive Impairment, Synaptic Failure and Amyloid Pathology in AβPPswe/PS-1 Mice of Different Ages.

Alzheimer's disease (AD) is a neurodegenerative disorder in which the amyloid-β (Aβ) peptide plays a key role in synaptic impairment and memory decline associated with neuronal dysfunction and intra-neuronal accumulation of hyperphosphorylated tau protein. Two novel enantiopure rhein-huprine hybrids ((+)-1 and (-)-1) exhibit potent inhibitory effects against human acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), BACE-1 and both Aβ and tau antiaggregation activity in vitro and reduction on the amyloid precursor protein (APP) processing in vivo. Interestingly, in this work, we observed beneficial effects with both (+)- and (-)-1 in the reversion of the neuropathology presented in the AβPPswe/PS-1 Alzheimer´s model, including a reduction in the Aβ levels, tau phosphorylation and memory impairment with both treatments. Also, in young transgenic mice that present early symptoms of synaptic failure and memory loss, we found a protection of cognitive functions, including long-term potentiation (LTP) and a reduction of the neuro-inflammation by both (+)- and (-)-1. Furthermore, animals with an advanced disease (11month-old) present an exacerbate neurodegeneration that is reversed only with the dextrorotatory enantiomer. These studies indicated that rhein-huprine derivatives with multiple properties might have interesting therapeutic potential for AD.