10-Methoxyharmalan, a potent serotonin antagonist which affects conditioned behavior.

Abstract

10-Methoxyharmalan, an alkaloid obtained by the cyclodehydration of melatonin, itself a derivative of serotonin, is a more potent serotonin antagonist than harmaline and is only slightly less active than lysergic acid diethylamide. It has a similar, yet slightly greater, effect on behavior as that of harmaline and is the most potent serotonin derivative, so far tested, that affects the avoidance-escape behavioral reflex