Evaluation of 4-methylpiperidine analogs of hemicholinium-3.

A series of substituted piperidine analogs of hemicholinium-3 was evaluated for their ability to inhibit neuromuscular transmission, to decrease acetylcholine content of caudate slices, to inhibit choline acetyltransferase activity, and to produce toxicity. Quaternary and tertiary amine derivatives of 4-methyl- and 4-hydroxyl-substituted piperidine analogs containing beta-carbonyl or beta-hydroxyl substitutions in the phenylethyl spacing moiety were tested. 4-Methyl piperidine derivatives maintained potent hemicholinium-3 like activity. Reduction of activity was seen with the 4-hydroxyl piperidine analogs. Compounds with beta-hydroxyl substitution were more potent than those with beta-carbonyl substitution. The tertiary amine, 4-methyl piperidine derivative with a hydroxyl group on the beta-carbon of the ethyl side chain also possessed hemicholinium-3 like activity. However, tertiary amine analogs were substantially less potent than hemicholinium-3 or their quaternary amine analogs.