Antispasmodic Effect of Aqueous Extract of Rubia tinctorum L. Roots on Rodents

Article history Received 11 June 2011 Revised 24 July 2011 Accepted 8 December 2011 Available online 30 April 2012 Rubia tinctorum L. (Rubiaceae) root is traditionally used in Morocco for treating the gastro-intestinal diseases. The aim of the present study was to assess the antispasmodic effects of the aqueous extract of this root plant (AR) on rodents.The effect of the AR on spontaneous contraction was studied, in vitro, on jejunum isolated from rabbits in the presence and absence of adrenergic inhibitors (Prasosin, Propranolol, and Yohimbine). This effect was assessed on jejunum of rats pre-contracted by carbachol and a KCl rich KHB. Also cumulative concentration-response curves were obtained for Cch (10 -8 10 -6 M) and CaCl2 (0.1-10 mM), in the absence or presence of the AR.The AR caused a dose dependent reversible inhibition (0.1-5 mg/ml) on basic rabbit jejunum contractions, with a total relaxation at 5 mg/ml. Pretreatment with adrenergic inhibitors (Prasosin, Propranolol, and Yohimbine) did not exhibit any action on the effect of this extract. Also extract inhibited carbachol (CCh) and KCl (75 mM) induced contractions in rat jejunum at a dose-dependent manner with IC50 value of 1.60 ± 0.14 ng/ml and 1.06 ± 0.21 mg/ml respectively. This extract has exhibited an inhibitory effect on the dose-response curves induced by CCh and CaCl2 on rat jejunum and significantly reduced the maximal response in a concentration-dependent manner, similar to the effect of non competitive antagonist of muscarinic receptors and calcium channels respectively. The results showed an antispasmodic effect which might explain the traditional use of Rubia tinctorum L. in gastrointestinal disorders.