Different Effects of Some Isoquinoline Alkaloids from Argemone mexicana on Electrically Induced Contractions of Isolated Guinea-pig Ileum

The present study examines the effects of the extracts [petroleum ether, CHCl3, HCl3/MeOH (9:1)and MeOH], partially purified fractions and pure compounds from Argemone mexicana on the electrically induced contractions of the isolated guinea-pig ileum (E.C.I.). The results of the experiments indicate that CHCl3/MeOH (9:1)and MeOH extracts, tested at a concentration of 400, 200 and 100 mg/mL, dose-dependently reduced the guinea-pig ileum contractions, whereas the petroleum ether and CHCl3 extracts did not affect it. Furthermore, the partially purified fractions II-V from the MeOH extract, each tested at concentrations of 200, 100 and 50 mg/mL also inhibited E.C.I. Finally the pure compounds 1-2 (531026-131025-531025 M)isolated and purified from the above fractions significantly reduced, in a dose dependent manner, the electrical contractions of the ileum, whereas compound 3 (531026-13102531025 M)increased them. Since the active compounds 1-3 were respectively identified as protopine, allocryptopine and berberine by NMR, the observed effects could be related mainly to these compounds.