An orally administered quinolinium molecule mitigates neuropathology of Alzheimer's disease through modulation of mitochondrial dysfunction and neuroinflammation.

Development of therapeutic options for Alzheimer's disease (AD) faces severe challenges. Only a few new anti-amyloid drugs based on monoclonal antibodies have been approved in recent years. Although the diversity of etiology and complexity of pathology make AD difficult to cure, these offer various molecular targets amenable for pharmaceutical interventions and disease modulation. In this study, we report an orally bioavailable quinolinium small molecule inhibitor, 88, to modulate neuropathologic changes in triple transgenic AD (3 × Tg-AD) mice. We have shown that 88 exhibited decent cerebral exposure, as compared with the forerunner quaternary isoquinolinium compound, 9Q, that we previously developed. In vivo studies revealed that 88 significantly mitigated cognitive deficits in 3 × Tg AD mice and decreased the amyloid burden as well as tau tangles in the hippocampus. Our data indicated that 88 treatments ameliorated the neuroinflammation via inhibiting glial activation and reducing cytokines IL-1β and IL-6. In vitro studies showed that 88 stabilized mitochondria membrane potential (MMP), decreased ROS generation, recovered respiratory function and ATP production in β-amyloid (Aβ)-induced PC12 cell model, suggesting mitigation of mitochondrial dysfunction. Such restored mitochondrial activity reduced the release of cytochrome c, which helped to prevent neuronal apoptosis both in vitro and in vivo. Our findings suggested that 88 could be useful in modulating AD, while the restoration of mitochondria functions and amelioration of neuroinflammation could be promising avenues for disease modulation.