Abstract
Since Achillea wilhelmsii is used as antispasmodic in traditional medicine, we conducted our current work to investigate its rationale on scientific grounds. Acute toxicity studies of crude methanol extract of Achillea wilhelmsii (Aw. CMeOH) is also performed. Effect of Aw. CMeOH and its fractions were tested on isolated sections of rabbits' jejunum at test concentrations 0.01, 0.03, 1.0, 3.0, 5.0 and 10mg/ml. The test extracts, in similar concentrations, were also tested on KCl-induced contractions. Calcium chloride curves were constructed for those fractions which relaxed KCl induced contractions in the absence and presence of the test samples to investigate its possible mode of action through calcium channels. Aw. CMeOH tested positive for flavonoids, saponins, tannins, glycosides, terpenoids, sterols, phenols, carbohydrates and proteins. LD50 for acute toxicity studies is 2707 +/- 12.6 mg/kg. Mean EC50 values for Aw. CMeOH on spontaneous and KCl-induced contractions are 3.41 +/- 0.18 (2.56-3.8, n=6) and 0.68 +/- 0.05 (0.6-0.85, n=6) mg/ml, respectively. Respective EC50 values for n-hexane fraction on spontaneous and KCl-induced contractions are 3.06 +/- 0.08 (2.8-3.3, n=6) and 1.68 +/- 0.8 (1.4-1.9, n=6) mg/ml, respectively. Corresponding EC50 (mg/ml) values for chlorofoimic, ethylacetate and aqueous fractions of Achillea wilhelmsii on spontaneous rabbits' jejunum preparations are 4.8 +/- 0.2 (4.41-5.63, n=6), 5.07 +/- 0.15 (4.7-5.58, n=6) and 5.2 +/- 0.13 (4.91-5.64, n=4), respectively. Constructing calcium chloride curves, in the presence of 0.1 mg/ml of Aw. CMeOH, mean EC50 value (log molar [Ca++]) is-1.98 +/- 0.03 (-1.89-2.05, n=6) vs. control EC50 (log molar [Ca++])-2.41 +/- 0.02 (-2.32-2.44, n=6). Mean EC50 value (log molar [Ca++]) for 0.3 mg/ml n-hexane fraction is-1.76 +/- 0.05 (-1.70 -1.93, n=6) vs. control EC50 (log molar [Ca++]) value-2.18 +/- 0.07 (-2.0-2.46, n=6). While in the presence of chloroformic fraction (3 mg/ml), mean EC50 (log molar [Ca++]) value is -2.4 +/- 0.1 (-2.78-2.9, n=6) vs. control EC50 (log molar [Ca++]) value-2.70 +/- 0.05 (-2.5-2.8, n=6). Mean EC50 value (log molar [Ca++]) for ethyl acetate fraction (1 mg/ml) is-1.94 +/- 0.07 (-1.75-2.05, n=6) vs. control EC50 (log molar [Ca++]) value-2.69 +/- 0.04 (-2.57-2.79, n=6). Mean EC50 (log molar [Ca++]) value for residual aqueous fraction (3 mg/ml) is-1.8 +/- 0.3 (-1.71-1.84, n=6) vs. control EC50 (log molar [Ca++]) -2.6 +/- 0.04 (-2.59-2.76, n=6). Whereas, the verapamil (0.1 mu M) EC50 value (log molar [Ca++]) is-1.7 +/- 0.1 (-1.6-1.8, n=6) vs. control EC50 value (log molar [Ca++])-2.4 +/- 0.09 (-2.3-2.47, n=6). The present research work confirms that the intestinal relaxation effect of Achillea wilhelmsii is supporting its traditional use as antispasmodic. The plant species can be a source for calcium antagonist(s), which can preferably be isolated from n-hexane fraction.