Anti-inflammatory activity of the extract, fractions and amides from the leaves of Piper ovatum Vahl (Piperaceae)

Leaves of Piper ovatum are known in folk medicine as “joão burandi” or “anestésica” and in traditional Brazilian medicine are used to treat inflammatory disease. The hydroalcoholic extract, fractions, and a mixture of piperovatine (1) and piperlonguminine (2) in a proportion of 2:3 obtained from Piper ovatum were assayed for anti-inflammatory activity by means of carrageenan-induced pleurisy in rats and croton oil-induced ear edema in mice. The hydroalcoholic extract was analyzed by high-performance liquid chromatography. Fraction constituents were evaluated by phytochemical screening, and the mixture of amides (1 and 2) was identified by analyses of spectral data of 1H and 13C nuclear magnetic resonance. Acute toxicity of the extract also was evaluated. At 500 mg/kg, the hydroalcoholic extract of Piper ovatum leaves did not reduce the volume of inflammatory pleural exudates compared with control animals. However, the hydroalcoholic extract and fractions F1–F3 at doses of 5.0 mg/ear and a mixture of piperovatine (1) and piperlonguminine (2) at doses of 2.5, 1.25, and 0.625 mg/ear significantly reduced the degree of ear edema. Taken together, the results indicate that the amide fractions piperovatine and piperlonguminine showed the greatest inhibitory activity of topical inflammation induced by croton oil.