The role of β-adrenergic receptors in the antispasmodic effect of flavonoid from Petroselinum crispum (parsley) leaf on adult male rat ileum

Petroselinum crispum (parsley) has received much attention in recent researches for its flavonoid content. Former studies have shown that flavonoids can suppress the contraction of the ileum induced by KCl and acetylcholine. This study aimed to examine the role of the beta-adrenergic receptors in the antispasmodic effect of parsley leaf extract on smooth muscle contraction of rat ileum. In this study, a 2-cm segment of terminal ileum from male Wistar rats was isolated and suspended in organ bath containing Tyrode's solution under a 1g tension and contractions were recorded by an isotonic transducer. Rats were divided into two groups of seven each. The spasmolytic effect of the cumulative concentration of the extract was investigated after tissue incubation with propranolol as a β-adrenergic antagonist. The extract of parsley leaves reduced the ileum contraction induced by KCl (60mM) in a dose dependent manner (P<0.001). Moreover, the antispasmodic effect of flavonoids in the extract at a concentration of 16 mg/ml was influenced and significantly decreased by propranolol. Parsley leaf extract at higher concentrations has a relaxing effect on rat ileum and this effect is mediated via β-adrenergic receptors.