10.1016/j.tetlet.2016.06.005
The research aims to develop a versatile synthetic approach to create analogs of physovenine and physostigmine, which are known acetylcholinesterase (AChE) inhibitors used in treating conditions like myasthenia gravis, glaucoma, and Alzheimer's disease. The study's purpose is to establish structure-activity relationships (SAR) among these analogs to understand their inhibitory activities against human AChE and butyrylcholinesterase (BuChE). The synthesis process involves multiple steps, including radical cyclization to form the spiro-oxindole ring, acetylation, N-alkylation, and reductive radical cyclization. The most potent analogs identified were 21a with an IC50 value of 70 nM against hBuChE and 21g with an IC50 value of 53 nM against hAChE. The study concludes that the size of the substituent at the quaternary carbon center significantly affects the inhibitory activity against hAChE, with smaller alkyl substituents generally yielding more active compounds. Conversely, larger arylalkyl substituents were more effective against hBuChE. This work provides valuable insights into the SAR of physovenine and physostigmine analogs, guiding future drug design efforts.