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701.
Sonia Piacente Anna Capasso Nunziatina De Tommasi Cumanda Jativa Cosimo Pizza Ludovico Sorrentino 《Phytotherapy research : PTR》1997,11(2):155-157
The present study examines the effects of the extracts [petroleum ether, CHCl3, CHCl3/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 μg/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 μg/mL also inhibited E.C.I. Finally the pure compounds 1–2 (5×10−6–1×10−5–5×10−5 M ) isolated and purified from the above fractions significantly reduced, in a dose dependent manner, the electrical contractions of the ileum, whereas compound 3 (5×10−6–1×10−5×10−5 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. © 1997 by John Wiley & Sons, Ltd. 相似文献
702.
703.
Bert P. C. Melchers Anton L. Van der Laaken Herman P. M. Van Helden 《European journal of pharmacology》1991,200(2-3):331-337
Experiments were performed to elucidate the mechanism of action by which the oxime HI-6 causes a recovery of neuromuscular function after oxime-resistant inhibition of acetylcholinesterase by the organophosphate S27 (see 2.4). In the presence of HI-6 (1–3 mM), the ability of isolated rat diaphragm muscle strips to sustain tetanic contractions after inhibition by S27 was markedly improved, as was the electrophysiological response to indirect tetanic stimulation. At lower concentrations (0–1 mM), HI-6 reduced the amplitude of the miniature endplate potentials and their decay time constant in a dose-dependent manner without having any effect on the resting membrane potential. In addition, HI-6 dose dependently increased the quantal content. It is likely that these post- and presynaptic effects of HI-6 are responsible for the improvement of muscle contractions after inhibition of acetylcholinesterase and they could well be of value in the therapy of organophosphate poisoning. 相似文献