Quaternary pilocarpine derivatives as potential acetylcholine antagonists. 2. Alterations in the lactone and...

In order to investigate the chemical behavior of pilocarpine, as well as the factors which determine its pharmacological activity, systematic and specific structural changes involving the lactone and imidazole moieties have been performed. Series of model compounds with cyclic or open-chain structures and a variety of N-3 bonded chains obtained from previously prepared anticholinergic derivatives of pilocarpine have been synthesized. The changes included N-3 chains of different lengths with an acetylcholine-like structure, the introduction of nucleophilic groups such as ketoxime, hydroxamic, or both at the side chain, or following hydroxylaminolysis of the lactone, respectively. Specific structural alterations could be obtained by reacting with free hydroxylamine under carefully controlled conditions, and the existence of syn and anti isomers was disclosed in certain cases. The new groups in the pilocarpine derivatives influenced their degree of antagonism to acetylcholine. Several compounds displayed some antidotal activity.