Antidepressant activity and toxicity of Hypericum foliosum aerial part

Hypericum foliosum Aiton (Guttiferae) is an endemic species of the Azores archipelago used on traditional medicine to treat skin diseases. Hypericum perforatum L. is an official antidepressant herbal drug. Preliminary chemical studies on the dried aerial part of H. foliosum showed the presence of the major classes of chemical compounds identified on H. perforatum, with the exception of hypericins [2]. A new acylphloroglucinol derivative with anti-Staphylococcal activity was also identified on H. foliosum [3]. The aim of this work was the evaluation of the potential antidepressant activity and chronic toxicity of an extract of the dried aerial part of H. foliosum.

A methanol extract of the dried aerial part of H. foliosum was prepared (Hf) and subsequently fractioned, the resulting fractions – petroleum ether and ethyl ether (Hf-lip) and methanol (Hf-me) – also being tested for antidepressant activity.

Antidepressant activity was evaluated in comparison with a methanol extract H. perforatum obtained in the same conditions (Hp) using fluoxetin (FLU) and imipramin (IMI) as reference antidepressant drugs. Two pharmacological models were applied: the forced swimming test (FST) and the tail suspension test (TST).

TST results showed a significant decrease in immobility times of mice treated with Hf total extract, although less pronounced then with FLU and IMI. Fractions Hf-lip and Hf-me also decreased immobility times, but in a lesser degree then the total extract (Hf) indicating a probable synergy between both fraction components. Hp extract had no significant effect on immobility times. FST only confirmed TST results for FLU and Hp.

Hf extract exhibited some signs of hepatic and renal toxicity but only in very large doses.

Acknowledgements: This work is supported by Laboratórios Medinfar S.A; We thank Prof. Rui Pinto for the help on the toxicity tests.

References: 1. Franco, A. (1984) Nova Flora de Portugal. Sociedade Astória.

2. Cachadinha, M. et al. (1994) Actas do II Simpósio da Associação Ibero-Macaronésica de Jardins Botânicos. Associação Ibero-Macaronésica de Jardins Botânicos, Horta, Açores.

3. Gibbons, S. et al. (2005) Phytochemistry 66:1472–1475.