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 microM) 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 microM). The extracts (40% +/- 04%) and nifedipin (51% +/- 05%) also potentiated the diarrhoea inducing effect of castor oil (IC50 = 350 microM). It is postulated that these effects are possibly generated by constituents such as quercetin and eugenol via a Ca2+ channel modulated mode of action.