Xanthotoxol (XT) is a coumarin isolated from ethanolic extract of fruits of Cnidium monnieri (L. )Cus　son. It is effective not only for the prevention of ventricular fibrillation of mice induced by chloroform or that of rats induced by calcium chloride,but also is effective for the treatment of arrhythmia induced by aconitine in rats. It can raise the threshold of ventricular fibrillation induced by electrical stimulation in rabbits. Fur　thermore,XT can inhibit the action potential amplitude of isolated sciatic nerves in toads. These results indi　cated that XT possesses antiarrhythmic effects. The iv LD50 of XT in mice is 47.0mg/kg

Seven compounds were isolated from the alcohol extract of leaves of Ipomoea batafas Lam,by column chromatography on silica gel. They were identified by physical and chemical methods as quercetin-3-glucoside (Ⅰ), kaempferol-4＇, 7-dimethyl ether(Ⅱ), ombuin (Ⅲ),quercetin (Ⅳ), quercetin-3＇, 4＇, 7-trimethyl ether(Ⅴ), ?-sitosterol (Ⅵ) and sucrose (Ⅶ).All of them were isolated from this plant for the first time.