Efeitos anti-inflamatório tópico e antinociceptivo do extrato etanólico de Lychnophora pinaster (Arnica Brasileira)

Abstract

Species of the genus Lychnophora, known in Brazil as arnica, are used in Brazilian popular medicine to treat inflammation, rheumatism, bruises and insect bites. Previous studies showed the anti-bacterial and antinociceptive effects of Lychnophora pinaster ethanolic extract. In the present work, the ethanolic extract of L. pinaster aereal parts was subjected to a chromatographic fractionation in a gel filtration column to obtain hexane, dichloromethane, ethyl acetate and methanolic fractions. The topical effect of the ethanolic extract and its fractions, into emulgel at 5%, was evaluated on Swiss mice paw oedema induced by carragenin. All treatments with ethanolic extract and its fractions were able to do reduce significantly the oedema, suggesting the presence of substances of low, medium and high polarity acting synergistically to the anti-inflammatory effect of the extract. Evaluation of the antinociceptive activity of ethanolic extract and its fractions were performed in mice, using hot plate and acetic acid induced contortion methods. The extract and its fractions were administered by oral route at 100 mg/kg. Indomethacin was used as reference drug for the contortions induced by acetic acid and morphine for the hot plate test. The ethanolic extract and its fractions presented antinociceptive activity observed by the contortion induced by acetic acid reduction, which suggests the peripheral effect, probably by the release modulation of the substances that induce nociception. The ethanolic extract and fractions of ethyl acetate and methanol showed effect at hot plate method, similarly to morphine. This result indicated the presence of substances of medium to high polarity, acting centrally. The results demonstrated the effects of arnica ethanolic extract to reduce inflammation and pain, as well as their potential to treat these conditions. The terpenes, flavonoids and phenolic acids of L. pinaster are maybe responsible for anti-inflammatory and antinociceptive effects of the ethanolic extract.