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       【摘要】 
       目的研究小叶黄杨叶不同提取物的降血脂作用。方法选用系统溶媒(石油醚、醋酸乙酯、氯仿、正丁醇、水)的方法对小叶黄杨叶进行提取，观察各提取物对腹腔注射75%蛋黄乳液致高血脂症模型小鼠血清总胆固醇及甘油三酯的影响。结果小叶黄杨叶醋酸乙酯提取物的高、低两个剂量组均有显著的降低血清总胆固醇和甘油三酯的作用，小叶黄杨叶的水提取物和石油醚提取物均有显著的降低血清中总胆固醇的作用，小叶黄杨叶氯仿提取物及正丁醇提取物均无降血脂的作用。结论小叶黄杨叶醋酸乙酯提取物对高血脂症小鼠有降血脂作用。
       【关键词】  小叶黄杨叶 提取物 降血脂
       Study on the Antihyperlipidemia Effect of Buxus microphylla Leaf Extract
       LI Yongwen，YANG  Chengfang， ZHANG  Huiqin， LI Li 
       （Department of Pharmacology，Guilin Medical University，Guilin ，Guangxi 541004，China）
       Abstract：ObjectiveTo study the antihyperlipidemia effects of diferent Buxus microphylla leaf extracts．MethodsDifferent extracts were extracted from Buxus microphylla leaf by systematic solvents (petroleum benzin，ethyl acetate，chloroform，n-butyl alcohol and water respectively) and the antihyperlipidemia effects of different extracts were observed on serum levels of total cholesterol and triglyceride in hyperlipidemia models，which were established through celiac injection of 75% egg-yolk emulsion. ResultsThe Buxus microphylla leaf ethyl acetate extract (high dose and low dose )had obvious effect on the levels of serum total cholesterol and triglyceride. Moreover，the effect of high-dose ethyl acetate extract was better than the other extracts. In addition, the water extract and n-butyl alcohol extract could significantly reduce serum total cholesterol, and the chloroform extract and n-butyl alcohol extract had no remarkable effect on blood lipid. ConclusionBuxus microphylla leaf ethyl -acetate extract is the active part of Buxus microphylla leaf in reducing blood lipid.
       Key words：Buxus microphylla leaf Extracts Antihyperlipidemia effect
       Buxus Microphylla leaf is the dry leaf from Buxus microphylla. (Family Genus). According to the “Compendium of Materia Medica”, Buxus microphylla can promote flow of “qi” and blood circulation ,eliminate pathogenic wetness ,dredge and activate the meridian.Cyclovirobuxine D is one kind of alkaloid extracted from  the rhizome of Buxus Microphylla and other plants belonged to the same Genus［1］. In recent years, clinically and experimentally Cyclovirobuxine D plays a good role in anti-arrythmia, anti-myocardial Ischemia and strengthening heart, and it has protective function  to the acute brain ischemia because it can pass through the blood brain barrier, suppress the formation of thrombus, improve microcycle［2-3］, however, until now no  pharmacological research reports on the Buxus Microphylla leaf has been seen in the literature.In this experiment  we observed the effects of system solvent extract from buxus microphylla leaf on the serum total cholesterol and triglyceride in hyperlipidemia model mice.
       1  Materials and Methods
       1.1  Drugs, Reagents, Animals and Instruments
       1.1.1  Preparation of drugsDry Buxus microphylla leaves,from Yongfu, Guangxi Guilin, were extracted with 70 percent ethanol. The process was as follows：Firstly, 500g Buxus microphylla leaves were taken into round flask,at the same time added 3 000 ml 70% ethyl alcohol, then heated backflow, totally three times, three hours each time. After extracting the filtration, merged the filtrate. Finnally the gross extracts were concentrated to non- alcohol flavor. The gross extracts were extracted with benzine, ethyl acetate, chloroform, normal butyl alcohol respectively according to resolver polarity order from small to big ,then every extracted liquid was evaporated on the water bath to get each various part of extractions (after multiple withdraws, obtains stable fingerprint atlas). When experiment being carried on, each extraction was dissolved with 2% Twain - 80 distilled water.
       1.1.2  Reagents Xue Zhi Kang capsule (Beijing University, WBL Biotech Co,LTD. Batch number: 20040513);
        Total cholesterol reagent kit (Zhe Jiang Dong Ou Biological Engineering Co, LTD. Batch number:2006120060);
        Triglyceride determination reagent kit (Zhe Jiang Dong Ou Biological Engineering Co, LTD. Batch number:2006120173);other reagents, analytical reagent available on market.
       1.1.3  AnimalsOne hundred and thirty SPF-Kunming mice, 8-10 weeks,weighing（25.0±2.0）g,male and female, supplied by experimental animal center of Guangxi medical college（Certificate No：Gui Dong acceptance  proposal 2003-0003st）; All animal experiments were carried out according to the guidelines for the care and use of the laboratory animals and were approved by the Experimental Animal Ethical Committee of Guilin Medical University.All possible efforts were taken during these experiments to avoid unnecessary suffering and to minimize the number of animals used.
       1.1.4  Instruments 722-model UV-visible spectrophotometer (Shanghai Precision & Scientific Instrument Co.,LTD) ; TGL-168 high-speed desktop centrifuges (Shanghai Anting Scientific Instrument Factory);Digital two heated water bath pot (Zhengzhou Greatwall Scientific Industrial & Trade Co.,Ltd).
       1.2  Methods
       1.2.1  Division and administrationOne hundred and thirty mice, male and female, weight (25.0 ± 2.0) g, were  randomly divided into 13 groups, each with 10, namely: ⑴control group;⑵model group;⑶XueZhiKang group;⑷Water extract high-dose;⑸Water extract low-dose;⑹Petroleum ether extract high-dose;⑺Petroleum ether extract low -dose;⑻Ethyl acetate extract high-dose;⑼Ethyl acetate extract low-dose;⑽Chloroform extract high-dose;⑾Chloroform extract low-dose;⑿n-butyl alcohol extract high-dose;⒀n-butyl alcohol extract low-dose.Sixteen hours after fasting, the mice of group (1)and(2) were given solvent (distilled water including 2% Twain - 80, 0.2 ml/10 g) by gavage; the mice of Group(3) were given Xuezhikang (0.24 g/kg) by intragastric administration; Experimental high-dose treatment groups were gavage corresponding drug 0.90 g / kg; low-dose group were gavage corresponding drug 0.45 g/kg. All above groups delivery capacities were 0.2 ml/10 g. Two hours later, except blank group all the other mice were injected intraperitoneally with 75 percent egg yolk emulsion, dose  0.1 ml/10 g (75 percent egg yolk emulsion: egg yolk from 1-2 d fresh eggs matched with saline ). Six hours later, each group was administered by gastric perfusion  corresponding solvent or the medicine once more, the dosage detto, twenty hours after injection of egg-yolk emulsion, blood was extracted from the ophthalmic venous plexus, then blood serum was separated (3 000 RPM per minute, centrifugal 15 minutes). Finally, serum total cholesterol (TC) and triglyceride content (TG) were measured ［6,7,8］.
       1.2.2   DeterminationTotal cholesterol was determined by CHOD-PAP; triglycerides was determined by GPO-PAP law operated according to specification.
       1.2.3  Statistical treatmentThe measurement data were expressed as mean±standard deviation( ±s)and analyzed by ANOVA with SPSS 1 0.0 software.
       2  Result
        Serum total cholesterol and triglyceride levels of the model group were higher than those in the control group, the differences were statistically significant (P<0.01), hyperlipidemia model successed.In contrast with  the model group, the levels of serum total cholesterol in mice of water extracts of high-and low-dose groups and petroleum ether extracts of high-and low-dose groups and ethyl acetate extracts of high-and low-dose groups were lower,the differences were statistically significant (P<0.01).Compared with the model,the levels of triglyceride in mice of ethyl acetate extracts of high-and low-dose groups were lower than that of model groups, the differences were statistically significant(P<0.01), but the water extracts of high-and low-dose groups and petroleum ether extract high-and low-dose group had no statistically difference (P> 0.05).Compared with the model group, the contents of total cholesterol and triglycerides chloroform extracts of high-and low-dose groups and n-butyl alcohol extracts of high-and low-dose groups had no significant statistical difference (P>0.05). See table 1.Table 1  The effects of the different extracts from Buxus microphylla leaf on TC and TG in hyperlipidemia model mice. 　（略）
       
       3  Discussion
        Hyperlipidemia resulted from lipid metabolism disorder in the body is a common disease in the elderly, frequently-occurring disease,and it is a risk factor leading to arteriosclerotic cardiovascular disease, seriously does harm to human health. With the improvement of living standards, the population of hyperlipidemia is increasing, the demand of human to hypolipidemic drugs is on growing, hence, the development of hypolipidemic agents have good social and economic benefits ［9,10］.A considerable amount of research shows that alkaloids isolated from wood of Buxus microphylla(such as Cyclovirobuxine D) have a better clinical effect on cardiovascular disease .However, the study on the Buxus microphylla leaf is less, and the study on its hypolipidemic isn" t more reported in literatures. In this study the system solvent was used to get different extracts. At the same time their effects on mice hyperlipidemia were observed. The results show that ethyl acetate extracts from Buxus microphylla leaf (0.45-0.90g/kg) significantly reduce level of the serum total cholesterol and triglyceride in hyperlipidemia mice.It provides the experimental data for further study on hyperlipidemic active ingredients and explore  Guangxi"s rich plant resources.
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