Immunosuppressive effects of Echinodorus macrophyllus aqueous extract.

Echinodorus macrophyllus is a medicinal plant, popularly known in Brazil as "chapéu de couro", used to treat rheumatic diseases, which are usually characterized by exacerbated T and B lymphocyte response. We have evaluated the effects of the aqueous extract of Echinodorus macrophyllus (AEEm) on these cell functions, proliferation, and nitric oxide production. Mice treated orally for 7 days with AEEm had inhibited B cell antibody production (0.5mg/kg b.w.) and delayed type hypersensitivity (0.5 and 5mg/kg b.w.) mediated by T cells, reducing subcutaneous tissue leukocyte infiltration. AEEm inhibited, in vitro, NO production by stimulating J774 cells in a dose-dependent manner, with no cytotoxicity. We have demonstrated, for the first time, its immunosuppressive effect. This immunosuppressive effect supports a potential therapeutic use of AEEm to control exacerbated humoral and/or cellular immune response, as in autoimmune rheumatic diseases. However, it is important to be cautious about its indiscriminate popular use to avoid side effects, mainly in immunodeficiency diseases.