Design and synthesis of novel tetrahydronephthalene-1-amine based analogues as cholinesterase inhibitors

Inhibiting cholinesterase (ChE) such as AChE and BChE is thought to be one of the most effective treatments for Alzheimer’s disease (AD) and dementia. In the present work, a new facile method for (1S,4S)-4-(3,4-dichlorophenyl)-n-methyl-1,2,3,4-tetrahydronaphthalen-1-amine based analogues 4 (a–p) in good yield (66–93 %) were synthesized by refluxing demethylsertraline (2) with different aldehydes and ketones 3 (a–p). The newly synthesized analogues 4 (a–p) were characterized by physical and spectroscopic techniques for instance FTIR, LR-MS and HR-MS. The synthesized demethylsertraline based analogues 4 (a–p) were examined for their biological activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). In case of AChE activity, electron donating substituents have shown more inhibition as 4–hydroxyphenyl– (4b, IC₅₀, 0.98 ± 0.99 µM) and 3,4–dimethoxyyphenyl– (4c, IC₅₀, 1.0 ± 0.98 µM) and exhibited excellent binding affinity. In case of BChE activity, 4e consisting of electron withdrawing substituent has shown potent inhibition (1.26 ± 0.34 µM). Similarly, 4i and 4n depicted good inhibition with IC₅₀ values 1.66 ± 0.78 µM and 1.66 ± 0.98 µM respectively as they possess weakly donating substituents. The structure activity relationship of BChE inhibition has shown opposite trend than AChE inhibition. It has been scrutinized that strong electron donating substituent decrease the BChE inhibitory activities whereas electron withdrawing groups greatly enhance the enzyme inhibition activity. In silico study of the synthesized compounds 4 (a–p) of the series was carried out. Compound 4b demonstrated excellent interaction with AChE compare with Eserine (standard) with a score of 6228 and an ACE value of –101.33 kcal/mol. Compound 4e demonstrated potent interaction with BChE compare with Eserine (standard) with a score of 6028 and ACE value of –258.53 kcal/mol. Compound 4b has the potential to serve as a lead molecule in medication development for Alzheimer’s disease treatment.