Effects of some Hypericum reflexum L. fil. extracts in the forced swimming test in mice

We previously reported that the infusion and the methanol extract from the aerial parts of Hypericum reflexum L. fil., an endemic species of the Canary Islands, showed antidepressant activity in mice [1, 2]. Preliminary phytochemical analysis carried out with the methanol extract of this species reveals the presence of flavonoids, tannins, saponins and anthraquinones. The presence of hypericin could not be detected in the crude methanol extract. On the basis of these results, the present study was undertaken to evaluate the antidepressant activity of the aqueous, butanol and chloroform fractions obtained from the methanol extract of this plant on the forced swimming test in mice. Also the effects of these fractions on locomotor activity, body temperature and sleep potentiation were evaluated. Student's t-test was used to verify the statistical significance.

The fractions under study (500mg/kg p.o.) did not have a significant effect on the spontaneous motor activity, with the exception of the butanol fraction which significantly reduced this activity by 32.81% at the first hour after administration. Furthermore, only the chloroform fraction produced a slight but significant hypothermia, being maintained up to the second hour after administration. Moreover, none of the different fractions assayed significantly prolonged pentobarbital induced sleeping time. In the forced swimming test, it was found that the butanol and chloroform fractions (500mg/kg p.o.) significantly shortened the immobility time of mice by 17.05 and 22.83%, respectively. It could be concluded that the butanol and chloroform fractions assayed have a certain antidepressant activity in the forced swimming test.

Acknowledgements: Consejería de Educación, Cultura y Deportes del Gobierno de Canarias (PI2000/105) project, Caja Canarias- University of La Laguna.

References: 1. Sánchez-Mateo, C.C. et al. (2002), J. Ethnopharmacol. 79: 119–127. 2. Prado, B. et al. (2002), Phytother. Res. 16: 740–744.