INHIBITING ACTIVITY OF SOME GLUCOINDOLALKALOIDS AND IRIDOIDS FROM SICKINGIA-WILLIAMSII ON ELECTRICALLY-INDUCED CONTRACTIONS OF ISOLATED GUINEA-PIG ILEUM

The present study examined the effects of the extracts (petroleum ethe r, CHCl3, CHCl3/MeOH (9:1) and MeOH), partially purified fractions and pure compounds (mainly alkaloids and iridoids) from Sickingia william sii on the electrically induced contractions of the Isolated guinea-pi g ileum, The results of our experiments indicate that CHCl3/MeOH (9:1) and CHCl3 extracts, tested at concentrations of 300, 150 and 30 mu g/ mL, dose-dependently reduced the guinea-pig ileum electrical contracti ons, whereas MeOH and petroleum ether extracts did not affect it. Furt hermore, both the partially purified fractions I-IV each tested at con centrations of 500, 250 and 100 mu g/mL from the CHCl3/MeOH (9:1) extr act and some pure compounds (10(-4) M, 5 x 10(-5) M and 2.5 x 10(-5) M ) isolated and purified from the above fractions significantly reduced , in a dose dependent manner, the electrical contractions of the ileum . As the active pure compounds possess an indole nucleus or/and an iri doid nucleus in their structures, the inhibitory effects appear to dep end on these structures.