| Ischemic disease such as acute myocardial infraction and focal cerebral infraction is a kind of severe cardiovascular and cerebrovascular disease, which mechanism is very complex and related to many systems of body. Drugs treatment is one of the most important therapeutic methods of ischemic heart and brain diseases. There are many active substances with anti-ischemia physiological activity in nature products. So looking for the active substances with anti-ischemia physiological activity from nature products is important for exploitation of new drugs.Breviscapine is a flavonoid extracted from Erigeron beiviscapus(vant), a popular Chinese herb medicine, which have many effects on brain ischemia, hemodynamics and microcirculation. It has been applied broadly in clinic. A high-performance capillary electrophoresis with electrochemical detection method was performed for the determination of the pharmacologically active ingredients in breviscapine and its extract phytopharmaceuticals. Scutellarin, a known flavone 7-O-glucuronide with a molecular weight of 462.21, is considered the primary active molecule in breviscapine. The present work was designed to study the anti-ischemic effects of scutellarin and its mixture with other substance, breviscapine, in rats. In male Sprague-Dawley (SD) rats, ligature of left anterior descending arteries was performed to induce acute myocardial infarction (MI) and the middle cerebral artery occlusion was created to induce focal cerebral ischemia. The MI size was significantly reduced by scutellarin (15 and 50 mg/kg) while not by breviscapine (5-50 mg/kg); the effect of scutellarin on the anti-MI was dose dependent. Compared with control group, scutellarin reduced the myocardium cell apoptosis in MI rats. The two drugs (5-50 mg/kg) significantly reduced infarction size in focal brain ischemic rats (P<0.05). There was no significant difference among the 3 dosages in breviscapine-treated rats while the effect of scutellarin on the anti-cerebral ischemia was dose dependent. The results demonstrated that the protective effects of scutellarin on cardiovascular and cerebrovascular ischemia were better than its mixture, breviscapine, in rats.METHODExperiment 1KM mouse was performed in the experiment. 20 animals in each group were fasted for 24hr before and 6hr after administration. Scu and breviscapine suspended in 5% glucose in water (PH=7.4 by sodium hydroxide ) was intraperitoneally administeraed. Toxic signs and mortality were monitored up to day 14 when the test was terminated. LD50 value was caculated .Experiment 2Male SD rats (n=42) at the age of 6weeks were administered Scu and breviscapine compound via abdominal cavity fifteen minutes before LAD ligated with 6-0 polypropylene suture between the pulmonary outflow tract and left atrium. Four hours later, the myocardial infarct (MI) size was measurement. The MI size was expressed as a fraction of the total left ventricular weight.Experiment 3hybrid dogs (n=18) were administered Scu and breviscapine compound via femoral vein after LAD ligation. Epicardial electrogram was recorded before and after LAD ligation to assess the changes in the ST segment. Three hours after LAD ligation, the heart were harvested to measure the infarct size. MI size was expressed as a fraction of the total left ventricular weight.Experiment 4According to thwe way in experilment 2, four hours after LAD ligationg in SD rats, the infraction myocardium was fixed in 10% buffered formalin and embedded in paraffin. TUNEL was used to evaluate myocyte apoptosis.Experiment 5Male SD rats (n=42) at the age of 9 weeks were performed. Middle cerebral artery (MCA) was occlusion to induce focal cerebral ischemia Brain samples were obtained 24 hours after MCA occlusion and immediately stained with 2% TTC. The infarct region compared to risk region was calculated with a digital image analysis system.RESULTObservation on acute toxicity testDrug was feebly toxic. The intraperitoneal LD50 values for KM mouse were 2,402mg/kg BW in Scu and 2,682mg/kg BW in breviscapine. Hypersensitivity, shivering, hemorrhage in multi-organs and abdominal position were observed. All deaths occurred in rats of either sex during 6 to 72 hrs after administration.Effects of Scu and breviscapine on myocardial infarction in rats The average MI size (expressed as a percentage of LV) in Scu (50mg/kg) group was 18.9±2.8% (P<0.01) and in breviscapine (50mg/kg) group was 29.3±6.9%. With increasing the dose of Scu (from 5 to 50mg/kg weight), the inhibition ratio in infract size is increased. But there is no evident change in breviscapine groups.Effects of Scu and breviscapine on myocardial infarction in dogsAfter occlusion of the LAD, the ST segment of epicardial electrogram was elevated. The elevation can be inhibited by drugs. In control group, the ST segment elevation in epieardial electrogram after occlusion of the LAD was no change, the same was in breviscapine group. But in Scu group, the ST segment after occlusion of the LAD in 180 min was significant degression (P<0.01) compare to after ligation. The size of the infarct area in LAD ligation dogs was reduced in the Scu group compared with the control group and breviscapine groups.Estimation of apoptosis in the area at risk.More apoptotic nuclei are clearly observed in the control group after coronary artery ligation. In the Scu group, only 34.7±4.25% nuclei were TUNEL positive compared with 41.8±2.77% in the control group (P < 0.05).Effects of Scu and breviscapine on on cerebral infarction in rats.In the breviscapine group(50mg/kg), a percentage of infarction area to the left cerebral cortex was 42.2±5.7%. Cerebral infarction area in the scutellarin group (50mg/kg) was 33.2±4.7%, which was significant decreased compared with control values that was 58.4±6.8%. With increased the dose of Scu, the inhibition ratio of infraction size is boosted much more. But in breviscapine group, the phenomenon is no such manifest.ConclusionIn conclusion, scutellarin and breviscapin can decrease infraction size in focal cerebral ischemia. But in myocardial ischemia, the effect of scutellarin is better than breviscapine. And scutellarin monomer is the active component in breviscapin compound.
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