Suppressive effects of isorhynchophylline on 5-HT2A receptor function in the brain: behavioural and electrophysiological studies.
European journal of pharmacology July 11, 2005 Kinzo Matsumoto, Ryo Morishige, Yukihisa Murakami et al.
Isorhynchophylline, a compound from Uncaria plants used in traditional Chinese medicine, preferentially blocks 5-HT2A receptors in the brain, likely through competitive antagonism. In mice, it dose-dependently reduced 5-HT2A-mediated head-twitch responses without affecting 5-HT1A or 5-HT2C behaviors. A related alkaloid, isocorynoxeine, had similar effects, while stereoisomers did not, indicating the oxindole moiety's configuration is essential for this activity.