Phytochemical and pharmacological studies on medicinal herb Acicarpha tribuloides

In the present study we report the isolation of five iridoids and bis-iridoids identified as secologanin (I), swerosidic acid (II), secoxyloganin (III), sylvestroside I (IV) and sylvestroside III (V) from Acicarpha tribuloides Juss. (Calyceraceae). Also, the pharmacological profile of the extracts (Petroleum ether, CHCl3, CHCl3/MeOH (9:1), MeOH and n-(BuOH) from A. tribulodies was studied both in vivo and in vitro experiments. The in vivo experiments indicate that CHCl3/MeOH, MeOH and n-BuOH (100,50 and 10 mg/kg/po) induce a significative analgesic effect in mice whereas CHCl3 and petroleum ether extracts were inactive. In the in vitro experiments the extracts showed a similar activity because CHCl3/MeOH, MeOH and n-BuOH (500, 250 and 125 mu g/ml) were able to reduce the electrically induced contractions of guinea-pig ileum whereas CHCl3 and petroleum ether extracts did not. As the active extracts contain iridoids, the pharmacological effects observed appear to depend on these structures.