The behavioral activity profile of a therapeutically used alcoholic hypericum extract containing hyperforin (4.5%) in rodent models was compared with that of an experimental CO2 extract devoid of hypericines but highly enriched in hyperforin (38.8%). The antidepressant activities of 50, 150 and 300 mg/ kg/day of the alcoholic extract were similar to those of 5, 15 and 30 mg/kg/day respectively of the CO2 extract. The ethanol extract in the same dose range potentiated dopaminergic behavioral responses, whereas these effects were either absent or less pronounced in the CO2 extract treated groups. By contrast, serotoninergic effects of the CO2 extract were more pronounced than those of the alcoholic extract. These and various other observations made during the study confirm that although the antidepressant action of hypericum extracts depends on their hyperforin contents, their spectrums of central activity are due to other component(s). Our working hypothesis that hyperforin and serotoninergic mechanisms are involved in the therapeutically observed antidepressant activities of hypericum extracts is in agreement with these observations.

for his kind suggestions.Studies on the Cholinergic Receptor. 6.1 Synthesis and Muscarinic Activity of 2-Methyl-4-(2-dimethylaminoethyl)-l,3dioxolane Methiodide2

for helpful discussions. We are grateful to Miss Roberta Carraine for technical assistance with the bioassay, Miss Margaret Carroll and staff for elemental analyses, and Mr. Walter Hamill and staff for optical rotations.