Abstract
It has been shown recently that the fraction IIIc of a crude extract of Hypericum perforatum, (St. John's wort) that contained both hypericin (1) and pseudohypericin (2), was remarkably active in the rats forced swimming test (FST) after Porsolt. However,
neither of the naphthodianthrones isolated from this fraction were sufficiently effective
when administered suspended in water. The solubility of 1 and 2 is remarkably increased in the presence of a fraction containing procyanidins, especially
procyanidin B2, which is present also in the active Hypericum fraction IIIc. The cooperative effect of procyanidins significantly increased the
in vivo effects of 1 and 2, which exhibited inverted U-shaped dose response curves, in the FST. The anti-immobility
effect of solubilized 1 and 2 was antagonized by the dopamine antagonist sulpiride. These data indicate that naphthodianthrones
are antidepressant constituents of H. perforatum and suggest that the dopaminergic system is involved in their action.
