Leonurine Synthesis And Its Cardiovascular Protective Effects

In recent years, the incidence of cardiovascular disease mortality and disability all over the world has shown the obviously upward trend. Ischemic heart disease is one of the most common clinical cardiovascular diseases. Ischemic heart disease is myocardial damage for the reason of the imbalance between coronary blood flow and myocardial demand, causing by change of coronary circulation. Acute coronary artery stenosis and occlusion may lead to acute myocardial ischemia or myocardial infarction. There are a lot of treatments of myocardial ischemia, in which drug therapy may be one important means. Although some traditional anti-myocardial ischemia drugs, such as nitrates, calcium channel blockers andβ-receptor blockers, has good therapeutic effects, but there still are some deficiencies. Therefore, the exploration of anti-myocardial ischemia drugs and their mechanism remains an important research topic.Traditional Chinese medicine causes more and more attention because of its small toxic side effects. Leonurus, which belongs to lips Section Motherwort Leonurus genus, has lots of effects, such as promoting blood flow, removing blood stasis, diuresis and clearing away heat and toxic. It's used for the treatment of irregular menstruation, postpartum abdominal pain, etc. In recent years, with the increase in its research, its medicinal value, particularly in the treatment of cardiovascular diseases has been more in-depth understood. Our studies have found that an effective active ingredient from Leonurus, Leonurine, can be used for the protection of cardiac function, and clarified its antioxidant mechanism. It has been reported that Leonurine can inhibit ectocellular calcium influx and intracellular calcium release and play a role in relaxation of vascular smooth muscle. Our study was to further discover the protective effect of Leonurine in myocardial ischemia.As the minor amount of leonurine in Herb leonuri and the poor purity of its extracts, we explored synthesis of leonurine starting from syringic acid: the protecting of syringic acid's hydroxyl group by benzyl was followed by the condensation reaction between the resulting intermediate and amino-butanol. This is an economic and environment friendly route with 99.8% purity of final product identified by HPLC.We took method of chemical total synthesis to get leonurine, and use model of hypoxic neonatal rat cardiomyocytes, oxidative stressed H9c2 cells, and rats with acute myocardial infracted and heart failure in vivo and vitro. We tested DNA breakage fragment using DNA gel electrophoresis, and the apoptosis proteins and signaling molecules using RT-PCR and Western blot, for further investigating the role of myocardial protection of Leonurine.The results showed that Leonurine can enhance the viability of myocytes injuried by hypoxia or H₂O₂, reduce the leakage of LDH, increase the vitality of antioxidant enzymes and eliminate the effect of ROS, inhibit myocyte apoptosis, to reduce intracellular calcium overload. At the same time, it limited mitochondrial apoptosis due to ROS activation induced by H₂O₂, including increase of membrane potential, cytochrome c release and Bax protein from cytoplasm to mitochondrial translocation, and also inhibiting the activation of caspase-3 and broken of PARP. Leonurine in vivo study showed that it can reduce heart infarct size of acute myocardial ischemic rats, lower plasma CK, LDH levels, enhance the vitality of antioxidant enzymes and inhibit myocyte apoptosis, while Leonurine can increase the maximum changing rate of left ventricular, improve systolic performance, diastolic coronary artery, so that lower left ventricular end diastolic pressure, improve cardiac function and reduce pulmonary congestion in rats with heart failure.As above, we found Leonurine has direct cardio-protective effect via antioxidant, lowering intracellular calcium overload, up-regulating Bcl-2 gene expression and inhibiting mitochondrial apoptosis by blocking Bax protein translocation from cytoplasm to mitochondrial, through which, it showed its protection to myocyte injury causing by hypoxia and ischemic induced by ROS.