Myocardial Protective Effect of Honokiol: An Active Component inMagnolia ofpcinalis

Honokiol is an active component of Magnolia officinalis. It was reported to be 1000 times more potent than alpha-tocopherol in inhibiting lipid peroxidation in rat heart mitochondria. In this study, we investigated the in vivo antiarrhythmic and antiischemic effects of honokiol in coronary ligated rats. Male Sprague-Dawley rats were anesthetized with urethane. Honokiol, at dosages of 10(-7) g/kg, 10(-8) g/kg, and 10(-9) g/kg, was administered intravenously 15 min before ligation of the coronary artery. Incidence and duration of ventricular tachycardia and ventricular fibrillation during 30 min coronary ligation were significantly reduced by 10(-7) g/kg honokiol. Ventricular arrhythmia during 10 min reperfusion after the relief of coronary ligation was also reduced. In rats subjected to 4 hours coronary ligation, 10(-7) g/kg, 10(-8) g/kg, and 10(-9) g/kg honokiol significantly reduced the infarct zone. We concluded that honokiol may protect the myocardium against ischemic injury and suppress ventricular arrhythmia during ischemia and reperfusion.