Alkyl beta-carboline-3-carboxylate derivatives (e.g. beta-CCM and beta
-CCB), known to interact with the central benzodiazepine receptor, wer
e quaternized at the N-2 position using methyl iodide. The products st
rongly inhibited acetylcholinesterase in vitro and displayed affinitie
s for muscarinic receptors in the micromolar range.