Inhibition of intestinal motility by methanol extracts of Hibiscus sabdariffa L. (Malvaceae) in rats

The methanol extracts of Hibiscus sabdariffa (p < 0.01) showed a significant dose dependent relaxant effect (IC50 = 350 muM) on rat ileal strip comparable to the effect shown by nifedipin and papaverine as reference compounds. Similarly, the extract when administered intraperitoneally significantly (p < 0.05-0.01) reduced the intestinal transit (13%-35%) in rats (IC50 = 250 muM). The extracts (40% +/- 04%) and nifedipin (51 % +/- 05 %) also potentiated the diarrhoea inducing effect of castor oil (IC50 = 350 muM). It is postulated that these effects are possibly generated by constituents such as quercetin and eugenol via a Ca2+ channel modulated mode of action. Copyright (C) 2002 John Wiley Sons, Ltd.