Evaluation of Antispasmodic Effect of Arcapillin on Smooth Muscles of Rats

Background: Arcapillin, 2',4',5-trihydroxy-5',6,7–trimethoxyflavone, is a flavone aglycone isolated from several Artemisia species, though, it was first identified from A. capillaris. The Artemisia species are used in folk medicine as a remedy for gastrointestinal and liver illnesses, hypertension, fever and inflammation. Studies indicated a potential role of arcapillin to relieve symptoms of liver disorders; however, there is no report yet in the literature of its effect on smooth muscles. Objective: Our study aims to evaluate the effect of arcapillin, isolated from A. monosperma, on the contractile activity of rat smooth muscles. Materials and Methods: Increased concentrations of arcapillin were tested on isolated rat ileum, pulmonary artery, trachea, and urinary bladder. The muscle contraction was recorded upon addition of arcapillin in eight cumulative concentrations of half log units in the range of [10^-7 M -3×10^-4 M]. Depending on the organ-containing muscles, the preparations were treated with arcapillin either at basal tonus or after pre-stimulated via a contractile agent; 10^-3 M O-acetylcholine on ileum and 10^-5 M L-phenylephrine on pulmonary artery rings. Control tissues were treated with sodium hydroxide in an equivalent concentration to that used to dissolve the flavone. Results: Arcapillin caused a dose-dependent relaxation on ileum preparation and pulmonary artery. The inhibition of the contractile activity of ileum was reversible within 60 seconds after washing off the flavone. The urinary bladder showed a slight increase in contraction at the highest concentrations starting at [10^-4 M] of arcapillin. There was no observed effect on the contraction of tracheal smooth muscles by all tested concentrations of arcapillin. Conclusion: The antispasmodic activity of arcapillin may contribute to the pharmaceutical importance of A. monosperma in particularly to treat gastrointestinal disorders.