Mechanism of action Hyperforin is believed to be the primary active constituent responsible for the antidepressant and anxiolytic properties of the extracts of St. John's wort. It acts as a reuptake inhibitor of monoamines, including serotonin, norepinephrine, dopamine, and of GABA and glutamate, with IC50 values of 0.05-0.10 mcg/ml for all compounds, with the exception of glutamate, which is in the 0.5 mcg/ml range. It appears to exert these effects by activating the transient receptor potential ion channel TRPC6. Activation of TRPC6 induces the entry of sodium and calcium into the cell which causes inhibition of monoamine reuptake.