HYPERFORIN REPRESENTS THE NEUROTRANSMITTER REUPTAKE INHIBITING CONSTITUENT OF HYPERICUM EXTRACT

Hydroalcoholic hypericum extract inhibits the synaptosomal uptake of s erotonin, norepinephrine, and dopamine with about similar affinities a nd leads to a significant down-regulation of cortical beta-adrenocepto rs and 5-HT2-receptors after subchronic treatment of rats. While neith er hypericine nor kaempferol did show any reuptake inhibiting properti es, hyperforin was identified as the unspecific reuptake inhibitor of hypericum extracts with half-maximal inhibitory concentrations for the three synaptosomal uptake systems mentioned above between 80 and 200 nmol/l. Moreover, a hyperforin-enriched (38%) CO2 extract also leads t o a significant P-receptor down-regulation after subchronic treatment. The data suggest hyperforin as the active principle of hypericum extr acts in biochemical models of antidepressant activity.