The four known cactus alkaloids—anhalamine, anhalidine, anhalonidine, and pellotine—were synthesized from mescaline using new, straightforward chemical procedures. The work presents simple synthetic routes to these alkaloids, which are naturally occurring compounds found in cacti.
Mescaline and two of its analogs, anhalinine and a methylenemescaline trimer, block neuromuscular transmission in frog muscle and affect rat brain tissue. The compounds reduce both directly and nerve-evoked muscle twitches, with a stronger effect on nerve-evoked responses. They decrease the size of endplate potentials, reduce the amount of acetylcholine released per nerve impulse, hyperpolarize the resting membrane potential, and lengthen the action potential. At concentrations that block transmission, they do not displace alpha-bungarotoxin binding to nicotinic receptors, indicating the block is not due to receptor antagonism. The findings suggest mescaline and its analogs inhibit transmission primarily by reducing acetylcholine release and also by altering potassium conductance.