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Flavonoids from Thymus vulgaris L. have been studied in vitro for spasmolytic activity on the smooth muscles of the guinea-pig ileum and trachea and of the rat vas deferens. The flavones and thyme extracts inhibit responses to agonists which stimulate specific receptors (acetylcholine, histamine, L-noradrenaline) as well as to agents whose actions are not mediated via specific receptors (BaCl2). Cumulative dose-response curves point to a non-competitive antagonism. Inhibition of Ca2+ contractions on K+ depolarized smooth muscles suggest inhibition of availability of Ca2+ for muscle contraction. pD'2 values were determined to compare the potency of these components to each other and to standard drugs. Flavones induce relaxation of the carbachol contracted tracheal strip without stimulation of the beta 2-receptors, which were blocked by propranolol.

Thymks vulgaris L. and Thymus ser-py1lun L. are used as antitussive remedies. Liquid thyme extracts have been studied in vitro for spasmolytic activity on the smooth muscles of the guinea-pig trachea and ileum. Treatment of the carbachol induced tracheal strip with thyme extracts resulted in relaxation of this preparation. Ileum contractions due to acetyicholine, were reduced in the same proportion. Thymol and carvacro! content was determined with HPLC. Phenol concentration of examined extracts was very low ( 0.001 %) and could not be responsible for antispasmodic activity. However, thymol and carvacrol in sufficient dose were found to have tracheal relaxant properties. pD2, intrinsic activity and relative potency to DL-isoprenaline of both of isomers were determined. Laboratorium voor Farmacognosie, Jnstituut voor Farmaceutische Wetenschappen, Katholieke Llnzverszteit te Leuven, Van Evenstraat 4, B-3000 Leuven, Belgium Downloaded by: NYU. Copyrighted material.

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Medlc~nal medica ~b n t Research r ,I , ' L J , r % , li 1 I ] , \ r- AbstractOriganum compactum has been studied for antispasmodic activity, using different smooth muscle preparations of the alimentary canal in vitro: the guineapig ileum and duodenum, the rat fundus strip and duodenum. Aqueous extract of Origanum powder inhibits responses to acetylcholine, histamine, serotonine, BaCI,, I ,I-dimethyl-4-phenylpiperazinium iodide and nicotine in the guineapig ileum. The extract also blocks contractions elicited by electrical coaxial stimulation. Responses to cumulative increased Ca2+ concentrations in depolarizing bathing medium were also blocked. Thymol and. carvacrol were found to be the active components. The results indicate that antispasmodic activity is caused by a direct and indirect action on the smooth muscle. It is suggested that muscle relaxant effect results from a decrease of the Ca2+ availability for muscle contraction by I) blocking the release of intracellular bound Ca2+ and 2) prevention of the extracellular Ca" influx in the smooth muscle cell. Inhibition of the nerve action potential in the postganglionic nerve fibre is proposed to be the indirect action of spasmolytic activity. Downloaded by: University of Arizona Library. Copyrighted material. Address: C . 0. Van Den Broucke and /.A. Lemli Laboratorium voor Farmacognosie Instituut voor Fannaceutiscbe Wetenschappen Katholieke Universiteit te Leuven Van Evenstraat 4, B 3000 Leuven, Belgium Downloaded by: University of Arizona Library. Copyrighted material.