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  Efficacy of St. John's wort extract standardized to hyperforin

To investigate the potential role of the constituent hyperforin in the antidepressant activity of St. John's wort (Hypericum perforatum L., Clusiaceae), researchers compared the effects of two different St. John's wort extracts and placebo in 147 patients with mild or moderate depression [Laakman et al., 1998]. The two St. John's wort extracts used in the study were standardized to either 5 percent or 0.5 percent hyperforin. Hyperforin is naturally present in St. John's wort in larger amounts than hypericin, the marker compound to which most St. John's wort extracts are now standardized.

During the course of the randomized, double-blind study, subjects received six weeks of treatment with either placebo, the 5 percent hyperforin extract at a daily dose of 300 mg, or the 0.5 percent hyperforin extract at a daily dose of 300 mg. Results were assessed with the Hamilton Depression Scale (HAMD), the Clinical Global Impression scale, and the von Zerssen Depression Self-Rating Scale. According to the results, the 5 percent hyperforin extract was significantly more effective than placebo in alleviating symptoms of depression. No significant superiority over placebo could be demonstrated with the 0.5 percent hyperforin extract.

Side effects were reported by 28.6 percent of the subjects in each of the St. John's wort groups and by 30 percent of placebo subjects. The most frequent adverse effect was headache, which occurred only in the placebo group. Side effects reported by patients taking St. John's wort included bronchitis, flu-like symptoms, and cough.

The two St. John's wort extracts utilized in the trial were both manufactured by Dr. Willmar Schwabe Pharmaceuticals of Germany. The investigators concluded that the Hypericum extract standardized to 5 percent hyperforin was "an effective option in the treatment of mildly or moderately depressed patients, which avoids the well-known side effects of other antidepressant agents like tricyclics or SSRIs" as well as the abuse potential of benzodiazepine drugs. Although it is highly unlikely that any one compound is responsible for the antidepressant effectiveness of St. John's wort, one laboratory study showed that hyperforin inhibited uptake of serotonin, dopamine, noradrenaline, gamma-aminobutyric acid (GABA), and L-glutamate [Chatterjee et al., 1998].

- Evelyn Leigh, HRF

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[Chatterjee SS, Bhattacharya SK, Wonnemann M, et al. Hyperforin as a possible antidepressant component of Hypericum extracts. Life Sciences 1998; 63(6): 499-510.

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Laakmann G, Schule C, Baghai T, et al. St. John's wort in mild to moderate depression: the relevance of hyperforin for the clinical efficacy. Pharmacopsychiat 1998; 31(suppl): 54-59.]

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