Heterotheca inuloides: anti-inflammatory and analgesic effect.

Heterotheca inuloides Cass. (Asteraceae) is used in the traditional medicine of Mexico. The aqueous extract obtained from the flowers of H. inuloides was assessed for anti-inflammatory activity by carrageenan-induced edema test. At 100 mg/kg, i.p, it produced 29% inhibition of inflammation. Ethyl ether (HI-1), butanol (HI-2) and aqueous fraction (HI-3) were obtained from the aqueous extract. The biological assay, by carrageenan-induced edema test, gave the following values (% inhibition): HI-1, 19.9; HI-2, 58.0 and HI-3, 30.0. HI-2 was significantly more effective than HI-1 and HI-3. The dose-effect curve of HI-2 was obtained and the calculated ED50 was 29.7 (22.5-39.2) mg/kg. The peritoneal examination after the treatment with HI-2 showed that the anti-inflammatory action of H. inuloides was not due to an irritating effect at the injection site. At 50-100 mg/kg, i.p., HI-2 inhibited inflammation induced by dextran (38.9-68.1% inhibition) and arachidonic acid (0-33.9%). No effect was observed at the same doses for zymosan or C16-paf-induced edema. In addition, HI-2 reduced abdominal constrictions in mice following injection of acetic acid: at 50-100 mg/kg, it gave 73.8-78.2% inhibition. The ulcerogenic assay showed that ulcer indices after HI-2 i.p. treatment were 0.5 +/- 0.5 at 50 mg/kg and 1.2 +/- 0.4 at 100 mg/kg. The results showed related anti-inflammatory activity and the analgesic effect of HI-2.