Comparative Effects of Methylphenidate and Rosmarinic acid on AlCl3 Mouse Model of Alzheimer’s Disease

Abstract

Alzheimer’s disease (AD) is an irreparable progressive neurodegenerative disorder which develop gradually and leads to cognitive decline affecting memory, thinking and behavior. It is a multifactorial disease involving amyloidogenesis, neuroinflammation and oxidative stress as the predominant pathogenic events. There is currently no treatment to cure or halt the progression of neurodegenerative diseases. Donepezil is one of the FDA approved drugs for symptomatic treatment however accompanied with various side effects. The current study investigated the interaction potential of the Rosmarinic acid (RA), a bioactive compound of Rosmarinus officinalis, and Methylphenidate (MPH) with different target proteins crucially implicated in AD pathogenesis, in comparison to the standard drug, Donepezil. Docking results revealed that Donepezil has the highest and RA has a comparable binding affinity with the enzymes acetylcholinesterase (AChE), presenilin-1 (PSEN-1) and beta-secretase 1 (BACE1). RA has exhibited the strongest binding with pro inflammatory cytokines (IL6, TNF-α, NF-κB, p50) followed by MPH and then Donepezil. Donepezil and RA has the highest and almost similar binding affinity with the antioxidant enzymes (SOD1, SOD2, Prdx6). Furthermore, drug likeness analysis indicated that RA showed desirable drug like criteria. The overall results have shown that RA potentially target multiple pathways involved in AD pathogenesis and can be considered as a potential drug candidate to combat AD associated consequences and apathy. Moreover, in-vivo studies carried out on mouse models for AD to understand the potential outcomes of Donepezil, R. officinalis and MPH on memory, anxiety and depression through behavioral analysis. The animals were separated into eight groups (each with n=8). 2-Dimensional Gel Electrophoresis was carried out to assess the differential protein expression in AlCl3 + Abstract xv Donepezil, AlCl3 + R. officinalis and AlCl3 + MPH-treated groups compared to control and AlCl3-treated groups. Additionally, Western Blot was performed to compare protein acetylation and Congo red staining was performed for histological assessment. Donepezil, MPH and R. officinalis significantly improved memory in AlCl3 induced mice model. All the tested compounds showed comparable effects on cognition. R. officinalis significantly reduced depression in AlCl3-treated mice as compared to other treatment groups. Donepezil displayed the strongest anxiolytic like behavior followed by R. officinalis while MPH did not show significant anxiolytic effects in AD model. Furthermore, a marked difference in protein expression and protein acetylation was observed between control and diseased groups which was modified by drugs treatment. The results showed that Donepezil, MPH and R. officinalis have a significant role in modifying protein expression and protein acetylation in AlCl3 treated mice. Histopathological assessment showed that AlCl3 exposure led to the formation of amyloid beta plaques in hippocampus but none of the tested drugs caused significant reduction in amyloid burden at the selected doses. In conclusion, R. officinalis is best in treating all aspects of AD as it is a natural compound which would have minimal side effects. Additionally, these findings provide a preliminary data set of the targeted proteins crucial for AD therapeutics and can be helpful to uncover the complex molecular mechanisms encompassing AD pathology.