Tacrine is a drug used in the treatment of Alzheimer's disease as a cognitive enhancer and inhibitor of the enzyme acetylcholinesterase (AChE). However, its clinical application has been restricted due to its poor therapeutic efficacy and high prevalence of detrimental effects. An attempt was made to understand the molecular mechanisms that underlie tacrine and its analogues influence over neurotherapeutic activity by focusing on modulation of neurogenesis, neuroinflammation, endoplasmic reticulum stress, apoptosis, and regulatory role in gene and protein expression, energy metabolism, Ca2+ homeostasis modulation, and osmotic regulation. Regardless of this, analogues of tacrine are considered as a model inhibitor of cholinesterase in the therapy of Alzheimer's disease. The variety both in structural make-up and biological functions of these substances is the main appeal for researchers' interest in them. A new paradigm for treating neurological diseases is presented in this review, which includes treatment strategies for Alzheimer's disease, as well as other neurological disorders like Parkinson's disease and the synthesis and biological properties of newly identified versatile tacrine analogues and hybrids. We have also shown that these analogues may have therapeutic promise in the treatment of neurological diseases in a variety of experimental systems.
The search for new treatments for Alzheimer's disease (AD) has led to the exploration of plant-based drugs as potential options. Acetylcholinesterase (AChE) inhibitors are widely used as anti-AD medications. This study aimed to investigate the inhibitory mechanism of girinimbine, a constituent of Murraya koenigii, on AChE. AChE inhibition was assessed by in vitro experiments using the modified Ellman method, as well as in silico molecular docking and molecular dynamic simulation. The results were compared to those of the well-known anti-AChE agents tacrine and propidium iodide. Girinimbine, propidium, and tacrine at concentrations of 3.8X10-5M, 1.1x10-5M, and 6.1x10-7M showed percentages of inhibition percentages of 35.6%, 28.2%, and 76.6%, respectively. The docking and molecular dynamics simulation analyses indicated that girinimbine exhibited a higher binding affinity to AChE compared to propidium and tacrine. This finding was further confirmed by the docking, root mean square deviation (RMSD), root mean square fluctuation (RMSF), and radius of rotation analyses. In conclusion, M. koenigii girinimbine shows promise as an acetylcholinesterase inhibitor for Alzheimer's disease. Further research, including in vivo studies and clinical trials, is needed to explore its potential as a plant-based drug candidate for AD treatment.