Magnoflorine improves cognitive deficits and pathology of Alzheimer's disease via inhibiting of JNK signaling pathway

BACKGROUND: Cognitive deficit is the main clinical feature of Alzheimer's disease (AD), and the massive death of neuronal cells is the leading cause of cognitive deficits. So, there is an urgent clinical need to discover effective drugs to protect brain neurons from damage in order to treat AD. Naturally-derived compounds have always been an important source of new drug discovery because of their diverse pharmacological activities, reliable efficacy and low toxicity. Magnoflorine is a quaternary aporphine alkaloid, which naturally exist in some commonly used herbal medicines, and has good anti-inflammatory and antioxidant effects. However, magnoflorine has not been reported in AD. HYPOTHESIS/PURPOSE: To investigate the therapeutic effect and mechanism of magnoflorine on AD. METHODS: Neuronal damage was detected by flow cytometry, immunofluorescence and western blotting. Oxidative stress was measured by detection of SOD and MDA, as well as JC-1 and reactive oxygen species (ROS) staining. The APP/PS1 mice were given drugs by intraperitoneal injection (I.P.) every day for one month, and then the new object recognition and Morris water maze were used to detect the cognitive ability of the mice. RESULTS: We demonstrated that magnoflorine reduced Aβ-induced PC12 cell apoptosis and intracellular ROS generation. Further studies found that magnoflorine significantly improved cognitive deficits and AD-type pathology. Most interestingly, the efficacy of magnoflorine was better than that of the clinical control drug donepezil. Mechanistically, based on RNA-sequencing analysis, we found that magnoflorine significantly inhibited phosphorylated c-Jun N-terminal kinase (JNK) in AD models. This result was further validated using a JNK inhibitor. CONCLUSION: Our results indicate that magnoflorine improves cognitive deficits and pathology of AD through inhibiting of JNK signaling pathway. Thus, magnoflorine may be a potential therapeutic candidate for AD.