In vitro purgative effect of Ruellia praetermissa. Sceinf.ex.Lindau (Acanthaceae)

Methanol, ethylacetate and aqueous extracts of Ruellia praetermissa initiated spontaneous contractions in the quiescent and increased contraction on the electrically stimulated ileal strip at a concentration of 30 μg/ml. The extracts produced concentration-related contractions both in amplitude and tone up till 750 μg/ml with IC₅₀ of 360 μg/ml (methanol extract), 425 μg/ml (ethylacetate extract) and 540 μg/ml (aqueous extract). Acetylcholine also produced a concentration-related (IC₅₀ = 18 μg/ml) contractions of the isolated ileum. Atropine in concentrations of 3.4 x 10^-6 - 3 x 10^-3 μg/ml antagonized progressively the response of the isolated ileum to acetylcholine (32 x 10^-2 μg/ml) and the methanol extract (650 μg/ml) induced contractions suggesting a mode of action via cholinergic system. Luteolin and apigenin and iridoid glucosides (taxiphilin and 8-epi-deoyganic acid) might be responsible at least in part for the observed effect. (C) 2000 Elsevier Science Ireland Ltd.