Effect of Hydroalcoholic Extract Onion (Allium cepa L.) Peel of on the Male Rat Ileum Contractility

Onion (Allium cepa) bulb from Liliaceae has antioxidant, spasmolytic and antihypertensive activities. The goal of this study was to investigate the effect of onion peel extract on the rat ileum contractility. Onion peel powder was extracted by maceration in 70% alcohol for 72 h. A terminal portion of ileum from Wistar male rat was dissected and its contractions were recorded isotonically in an organ bath containing Tyrode solution (37 ºC) under 1 g tension. Cumulative concentrations of the extract (0.1, 0.2, 0.4 mg/ml) reduced the ileum contractions induced by KCl (60 mM) and by carbachol (10μM) dose-dependently (p<0.0001). The spasmolytic effect of extract was not reduced by tissue incubation with propranolol (1μM, 30 min), naloxone (1μM, 30 min), L-NAME (100μM, 20 min), glibenclamide (10μM, 5 min) and neither by tetraethylammonium (1mM, 5 min). In Ca2+-free with high K+ (60mM) Tyrode solution, the extract (0.0125-0.1mg/ml) reduced the ileum contractions induced by cumulative concentrations of CaCl2 (0.225-2.7 mM) dose-dependently (p<0.05-p<0.01). Onion peel extract reduced the ileum contraction, however, neither the β-adrenoceptors opioid receptors, nor the potassium channels activation were involved in this activity. It seems that the voltage dependent calcium channels are involved in the spasmolytic effect of the extract. Nevertheless, the quercetin extract might be responsible for this activity.