Commercially available Hypericum perforatum extracts do not decrease immobility of rats in the forced swimming test.

There are controversial results of clinical trials on the antidepressant effects of Hypericum perforatum, while several preclinical studies describe antidepressant properties for Hypericum extracts. This study evaluates the antidepressant effect of two commercially available hydroalcoholic extracts of H. perforatum standardized to contain 0.3% hypericin in comparison to imipramine (IMI), in the forced swimming test (FST). Wistar rats were treated with different doses of two Hypericum extracts, of hypericin or of IMI and submitted to the FST. The experiments were videotape recorded to detail immobile and active behaviors of rats during the procedures. The imported extract tested and hypericin did not modify rats' behaviors in the test, while IMI, a classical antidepressant, significantly shortened immobility and prolonged climbing behavior during forced swimming. The locally produced Hypericum extract significantly increased immobility duration as compared to the controls at the same time as climbing efforts were decreased. Therefore, the two different commercially available Brazilian hydroalcoholic H. perforatum extracts did not show the expected effects in a screening test for antidepressant agents, on the contrary, one of the extracts promoted a depressant-like effect in rats. Therefore, these extracts available to the population differ from other Hypericum extracts. At which step of the production or commercialization chain these extracts probably lost their therapeutic potential remains to be evaluated.