Chemical and pharmacological examination of antinociceptive constituents of Wedelia paludosa.

The present work describes the antinociceptive effects of some fractions and two pure compounds obtained from the Wedelia paludosa, a Brazilian medicinal plant employed in folk medicine against a variety of diseases, including dolorous pathologies. It was found that such fractions as well as kaurenoic acid and luteolin exhibit marked antinociceptive action in mice using acetic acid-induced writhing. They were more active than some well-known analgesic drugs, such as acetyl salicylic acid, acetaminophen, dipyrone and indomethacin. The results confirm our previous studies conducted with this plant, suggesting that different chemical constituents are responsible for the antinociceptive activity shown by the extracts and fractions prepared from W. paludosa.