Evaluation of synaptosomal uptake inhibition of most relevant constituentsof St. John's wort

In our previous investigations, we could demonstrate that extract preparati ons of Hypericum perforatum (St. John's wort, SJW) inhibit the uptake of se veral neurotransmitters (serotonin, norepinephrine, dopamine, GABA, L-gluta mate) in synaptosomal preparations of rodent brain. Hyperforin, the lipophi lic constituent, was identified as the main component responsible for these effects. The properties seen for hyperforin in these and other pharmacolog ical models present a plausible and logical explanation for the well docume nted antidepressive effects of SJW extract preparations in clinical studies . However, evidence for other active principles in SJW extract have been re ported [2,3] (See also communications by Misane & Ogren and Philippu in thi s issue). Accordingly, we tested various SJW extract preparations and all r elevant constituents as possible inhibitors of synaptosomal uptake of neuro transmitters. Two further components were found to be active in those model s. Adhyperforin, like hyperforin, showed a strong inhibiting profile in all uptake systems investigated. Moreover, we could observe a weak to moderate inhibiting profile for the oligomeric procyanidins fraction (OPC). Further investigations would have to clarify any possible contribution of these tw o constituents to the antidepressive effects of SJW extract seen in animal experiments and clinical trials.