Hypericum extracts neurotransmitters

Muller WE, Singer A, Wonnemann M, Hafner U, Rolli M, Schafer C. (1998). Hyperforin represents the neurotransmitter reuptake inhibiting constituent of hypericum extract. Pharmacopsychia y. 31(suppl 1) 16-21. 

Rollie M, et al. Effects of hypericum extract LI 160 on neurotransmitter receptor binding and S5mapsomal uptake system. Pharmacopsychiatry 1995 28 207-210. Muller WE, Rollie M, Schafer C, et al. Effects of hypericum extract LI 160 in biochemical models of antidepressant activity. Pharmacopsychiatry 1997 30(suppl 2) 102-107. 

The exact mechanism of action responsible for St. John s wort s neurological effects is not known. Additionally, it is not known if any one chemical constituent is responsible for its activity or if it is a combination of multiple components. It is known that the extracts of H. perforatum appear to inhibit the synaptic uptake of several neurotransmitters including norepinephrine, serotonin (5-HT), and dopamine (3,11-13). Rats that were fed high doses of hypericum extracts standardized to flavonoids (50%), hypericin (0.3%), and... 

Other studies have shown that hypericum extracts inhibit in vitro the reuptake of monoamine neurotransmitters such as serotonin, dopamine and noradrenaline [10,87]. 

Amino acid neurotransmitter Constituents of hypericum also appear to have effects on amino acid neurotransmission, particularly GABA. Hypericin and a crude extract bind to GABAA and GABAB receptors (Cott 1997). Hyperforin also inhibits synaptosomal GABA reuptake in the low micromolar range (IC50 values of 0.05-0.10 ug/ml). Activity at GABAA benzodiazepine receptors was noted in extracts of four hy-... 

Assays with extracts devoid of hypericin but with a high content of hyperforin as well as assays with pure hyperforin demonstrated that this metabolite can modulate the function of various neurotransmitters involved in depression, being a potent inhibitor of serotonin, dopamine, noradrenaline and GABA uptake with almost equal potency. Moreover, results from clinical studies evidenced that the antidepressant efficacy of Hypericum preparations correlates with their content of hyperforin [6,87],... 

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