Isolation and inhibitory effects of eupatilin, a flavone isolated from Artemisia monosperma Del, on rat isolated smooth muscle

The isolation for the first time from Artemisia monosperma (Compositae) of the known flavone eupatilin and its effects on rat isolated smooth muscle preparations are described. In concentrations from 10(-7)M to 3x10(-4)M, eupatilin (5, 7-dihydroxy-6, 3',4'-trimethoxyflavone) inhibited in a reversible manner the phasic contractions and the tone of rat isolated ileum, uterus, and urinary bladder. It relaxed the tonic contractions of the phenylephrine-precontracted pulmonary artery and acetylcholine-precontracted trachea. Eupatilin also shifted the concentration-effect curves of acetylcholine and calcium chloride on rat isolated ileum, oxytocin concentration-effect curve on uterine smooth muscle and phenylephrine concentration-effect curve on pulmonary artery smooth muscle. These observations indicate that eupatilin possesses a nonspecific antispasmodic effect on rat isolated smooth muscle. They also suggest that the inhibitory effect of eupatilin may be mediated by changes in Ca2+ metabolism in these preparations.