© Georg Thieme Verlag Stuttgart · New York
Hyperforin Represents the Neurotransmitter Reuptake Inhibiting Constituent of Hypericum Extract
20 April 2007 (online)
Hydroalcoholic hypericum extract inhibits the synaptosomal uptake of serotonin, norepinephrine, and dopamine with about similar affinities and leads to a significant down-regulation of cortical (3-adrenoceptors and β-HT2-receptors after sub-chronic treatment of rats. While neither hypericine nor kaempferol did show any reuptake inhibiting properties, 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 200nmol/l. Moreover, a hyperforin-enriched (38 %) CO2 extract also leads to a significant β-receptor down-regulation after subchronic treatment. The data suggest hyperforin as the active principle of hypericum extracts in biochemical models of antidepressant activity.