银杏叶提取物药理与心血管和神经系统实验研究进展

银杏叶提取物(extract ginkgo biloba,EGb)主要药用成分为黄酮(FGb)、萜类内酯、聚异戊烯醇3类化合物,具有抗氧化,清除自由基(FR),抗血小板激活因子(PAF)作用。在心血管方面,动物和临床实验证实, EGb通过调节血脂防治动脉粥样硬化,抗缺血、缺血再灌注损伤(I/R),抗心律失常,达到保护心脏功能的作用;在神经系统方面,Egb具有防治缺血缺氧性脑病(HIE),脑缺血和缺血再灌注(I/R)损伤,帕金森(PD)、血管性痴呆(VD)作用,对神经细胞具有保护作用,对神经损伤具有修复作用。     

培养神经细胞的氧自由基损伤及银杏叶提取物的治疗作用

目的 探讨氧自由基在Alzheimer病(AD)发病中的作用和评价银杏叶提取物(Ginkgo biloba extract，EGb)的临床应用价值。方法 以产生超氧阴离子系统黄嘌呤／黄嘌呤氧化酶(X／XO)作用于PC12细胞，并以EGb拮抗其作用，电镜观察细胞形态变化，MTF法检测细胞存活率，流式细胞术分析细胞凋亡情况，RT-PCR技术分析凋亡相关基因Bcl-2、Bax表达变化。结果 经X／XO损伤后，细胞存活率降低，凋亡率增加，促凋亡基因Bax表达上调。EGb(20mg／L)能改善凋亡情况。结论氧 自由基可诱导神经细胞凋亡而促进AD发生，EGb对神经细胞有保护作用，提示可用于AD的临床治疗与预防．     

银杏叶提取物对中枢神经系统影响的研究现状

<正> 银杏叶含有多种黄酮甙和4个萜类成分(包括银杏内酯A、B、C和白果内酯),具有重要药用价值,在中国已应用数千年。近年来随着药物提取工艺的标准化,以及药理效应和临床研究的深入,发现银杏叶提取物(ginkgo biloba extract,EGb)对中枢神经系统有独特的保护作用,在世界各地,尤其在德国等欧洲国家的应用日益广泛。研究表明EGb具有抗氧化和清除自由基,抑制由缺血而引起的神经细胞的凋     

银杏叶提取物对中枢神经系统作用机制研究的进展

银杏叶提取物（extract of Ginkgobiloba，EGb）具有多种生理活性，除对心血管系统具有明显的保护作用外，在神经系统疾病治疗中也有明显疗效，如改善脑和外周神经系统的血液供应、保护神经细胞免受损伤、改善神经退行性病变和衰老引起的认知能力下降等。本文就EGb对中枢神经系统作用的研究进展作一综述。     

银杏叶提取物对糖尿病大鼠心肌内皮素和一氧化氮水平的影响

内皮素（ET）和一氧化氮（NO）与糖尿病慢性并发症的发生、发展密切相关。我们以往的研究表明银杏叶提取物（extract of Ginsko biloba，EGb）可通过抗脂质过氧化作用和降低NO水平而对糖尿病心肌产生保护作用。为进一步探讨其作用机制，本文观察了EGb对链脲佐菌素诱导的糖尿病大鼠血浆、心肌组织NO和ET水平的影响。     

银杏叶提取物保护胰腺缺血再灌注损伤作用的机制探讨

目的探讨银杏叶提取物(EGb)对大鼠胰腺缺血/再灌注(IR)损伤的保护作用及其机制。方法制备大鼠胰腺IR损伤模型。取SD大鼠24只,随机分为3组(n=8)假手术组(Sham组)、IR组、缺血/再灌注银杏叶提取物保护组(EGb IR组)。光镜、电镜观察胰腺腺泡细胞结构改变;采用TUNEL方法检测细胞凋亡;流式细胞仪定量检测细胞凋亡;应用免疫组化染色检测Bcl-2、Bax蛋白表达。结果IR组凋亡指数明显大于Sham组(P<0.01),EGb IR组凋亡指数明显小于IR组(P<0.01);EGb IR组Bcl-2蛋白表达明显高于IR组(P<0.01);EGb IR组Bax蛋白表达明显低于IR组(P<0.01)。结论银杏叶提取物可能通过上调Bcl-2蛋白表达,下调Bax蛋白表达,对大鼠胰腺IR损伤起保护作用。     

银杏叶提取物对2型糖尿病大鼠动脉粥样硬化的抗氧化作用

目的探讨银杏叶提取物(Extract of Ginkgo biloba,EGb)在2型糖尿病大鼠模型中预防动脉粥样硬化的作用。方法 SD健康雄性大鼠30只,随机分为3组,分别为对照组,银杏叶提取物100 mg/kg剂量组(EGb100组),银杏叶提取物200 mg/kg剂量组(EGb200组),对照组给予等容积的生理盐水,实验组大鼠为胰岛素抵抗和Tokushima大鼠6周(颈动脉损伤前3周至损伤后3周),分别给予银杏叶提取物100 mg/kg,银杏叶提取物200 mg/kg。采用免疫组化染色方法观察损伤动脉的细胞增殖和凋亡情况。结果实验组较对照组内膜形成明显减少。EGb200组新生内膜形成少于EGb100组,两实验组IMR呈剂量依赖性降低。EGb处理组增殖指数明显低于对照组。EGb100组和EGb200组间增殖呈剂量依赖性下降。损伤后3周,EGb处理组细胞凋亡指数明显高于对照组。两组EGb细胞凋亡水平也呈剂量依赖性升高。结论 EGb在动脉粥样硬化的发生发展中具有保护作用,是一种潜在的预防动脉粥样硬化的治疗药物。     

银杏叶提取物对窒息后血清诱导人近曲肾小管上皮细胞损伤的影响

目的研究银杏叶提取物（EGb）对新生儿窒息后血清攻击人近曲肾小管上皮细胞（HK-2）损伤模型的影响。方法以人近曲肾小管上皮细胞（HK-2）为研究对象,200ml／L窒息血清作为攻击因素。实验共分为两阶段,均设对照组、模型组和EGb干预组（EGb预处理24h）。第一阶段EGb干预组设立5个质量浓度亚组。观察三组细胞形态学,乳酸脱氢酶（LDH）漏出率和细胞存活（MTT法）变化。第二阶段以第一阶段选出的EGb最适质量浓度预处理细胞,观察三组NF-κB p65蛋白（免疫组化）和抑制亚基I-κBα（western blot）的变化。结果与对照组相比,模型组细胞形态发生改变,LDH漏出率增加,细胞活力降低（P〈0．05）;与模型组比较,EGb预处理组细胞形态明显得到改善,LDH漏出率降低,细胞活力增加（P〈0．05）,在5—50mg／L保护效应逐渐增加,50mg／L时保护效果最强,而〉50mg／L时保护效应反而下降。与对照组相比,模型组细胞NF-κB p65蛋白表达明显增加,I-κBα量减少（P〈0．05）;与模型组比较,EGb干预组细胞NF-κB p65蛋白表达明显减少,I-κBα量增加（P〈0．05）。结论EGb具有减轻窒息血清所致HK-2细胞损伤的作用,其作用可能与抑制窒息血清所致NF—κB激活有关。     

Egb 761对NO供体SNP诱导的海马神经元凋亡的保护作用

目的　探讨银杏叶提取物 (EGb761 )对 NO供体硝普钠 (SNP)引起的大鼠海马神经元凋亡的影响。方法　采用 MTT比色分析测细胞存活率、 Hoechst 332 58荧光染色及 DNA琼脂糖凝胶电泳分析等方法检测凋亡。结果　不同剂量 EGb 761预处理海马神经元 6 h可剂量依赖地对抗 SNP引起的神经元凋亡 ,提高神经元的存活率 ;减少 SNP引起的核固缩、凝聚和碎裂现象 ;DNA凝胶电泳图谱未见典型的“梯子状”改变。结论　 EGb 761对 NO供体 SNP诱导的海马神经元凋亡具有明显的保护作用     

银杏叶提取物EGb761对局灶性脑缺血再灌注大鼠XIAP和Smac表达的影响

目的 探讨银杏叶提取物EGb761对局灶性脑缺血大鼠脑组织X-连锁凋亡蛋白抑制剂(X-linked inhibitor of apoptosis protein,XIAP)和Smac蛋白表达的影响.方法 40只雄性Wistar大鼠随机分为假手术组、脑缺血再灌注组、EGb761小剂量组和EGb761大剂量组,每组10只.制作大鼠大脑中动脉闭塞1.5 h再灌注24 h模型.EGb761小剂量组和EGb761大剂量绀于模型制作前1 h分别腹腔注射ECY0761 50 mg/kg和100 mg/kg.大鼠脑组织XIAP和Smac表达用免疫组化方法 检测.结果 EGb761小剂量绀和EGb761大剂量组脑组织XIAP表达分别为18.33±4.01和26.7±3.27,显著高于脑缺血再灌注绀的12.13±3.44(P均<0.01),且EGb761大剂量组高于EGb761小剂量组(P<0.01);EGb761小剂量组和EGb761大剂量组脑组织Smac表达分别为21.33±3.15和11.33±2.10,显著低于脑缺血再灌注组的28.93±4.96(P均<0.05),EGb761大剂最组显著低于EGb761小剂量组(P<0.01).结论 脑缺血再灌注可诱导XIAP和Smae表达,EGn761干预在上调XIAP表达的同时能抑制Smac蛋白表达,提高XIAP/Smac比值,可能是EGb761干预的保护机制之一.     

银杏叶提取物对大鼠应激性溃疡的保护作用

目的　探讨银杏叶提取物（ＥＧｂ） 对大鼠应激性胃溃疡发生的保护作用．方法　♂ Ｗｉｓｔａｒ 大鼠,随机分成对照组、模型组和ＥＧｂ 处理组;通过胃窦部埋置电极记录束缚水浸应激过程胃平滑肌电活动变化,同时测定血浆和胃粘膜组织中丙二醛（ ＭＤＡ） 水平及观察胃粘膜的病理改变情况．结果　应激模型组大鼠胃电活动节律明显紊乱、慢波振幅和峰电位发放率较对照组显著增加,ＭＤＡ 显著升高（ Ｐ＜ ０－０５） ,并伴有胃粘膜广泛充血、溃疡;ＥＧｂ １５ ｍ ｇ／ ｋｇ 腹腔注射预处理可显著压抑（ Ｐ＜ ０－０１） 应激过程的胃电紊乱、降低 ＭＤＡ 水平和胃粘膜溃疡指数．结论　ＥＧｂ 对束缚水浸应激引起的胃运动功能障碍和胃粘膜溃疡有明显地保护作用,其机制可能是通过调整平滑肌电活动和对自由基的清除．     

Ginkgo biloba extract EGb 761 attenuates myocardial stunning in the pig heart

Myocardial stunning, a transient contractile dysfunction that appears following a brief period of ischemia, is at least partly due to the production of oxygen-derived free radicals. The objective of the present study was to determine whether the Ginkgo biloba extract EGb761, which has antioxidant properties in vitro, can attenuate myocardial stunning in vivo. Forty-seven anesthetized open-chest farm pigs underwent 10 min of occlusion of the left anterior descending coronary artery (LAD), followed by 3 hours of reperfusion. They were pretreated with either physiological saline, 100 mg or 300 mg of EGb 761 (Protocol I) or 3 mg or 9 mg of ginkgolide B (GkB) (Protocol II). Contractile function was assessed by sonomicrometry. Both doses of EGb 761 significantly improved recovery of contractile function in the reperfused myocardium with segment shortening averaging 23 +/- 5 % of baseline values at 3 hours post-reflow in controls versus 81 +/- 10 % and 57 +/- 12 % in the EGb100 and EGb300 groups, respectively (p < 0.05 vs control in both cases). In contrast, neither dose of GkB improved functional recovery during reperfusion. ESR experiments revealed that EGb761 resulted in a 59 % decrease in myocardial spin-adduct release during reperfusion (p < 0.05 versus control and GkB groups). A significant 28 % decrease (p < 0.05 vs control group) was also obtained in GkB-treated animals. These results indicate that EGb 761 can attenuate myocardial stunning following a brief ischemic insult in the in situ pig heart by an effect that involves a decrease in the formation of free radicals. As the effect of EGb 761 on functional recovery cannot be explained by the presence of GkB, the beneficial action of the extract on myocardial stunning likely involves complementary effects of both its non-ginkgolide and ginkgolide constituents.     

Effect of the antioxidant action of Ginkgo biloba extract (EGb 761) on aging and oxidative stress

Aging is responsible for oxidative damage to DNA, protein, lipid, and other macromolecules linked to tissue alterations. The resultant damage contributes significantly to degenerative diseases, to include those of the brain, sensorial tissues, and cardiovascular system. To protect cellular components from oxyradical attack, especially lipoperoxidation, a substantial interest in the use of antioxidants has evolved. A free radical scavenger, Ginkgo biloba extract (EGb 761) may be effective in fighting the oxidative stress related to aging. Many data support the efficacy of EGb 761 in biological model systems. In aging processes, EGb 761 may ameliorate the mitochondria respiratory chain function by quenching the superoxide anion, and the hydroxyl and peroxyl radicals. It protects the brain by facilitating the uptake of neurotransmitters and by reducing ischemia-reperfusion episodes and level of apoptosis. Moreover, in sensorial tissues, EGb 761 reduces apoptosis in the olfactive bulb and in the retinal pigmented epithelium of the eye, and protects against the lipoperoxidation alteration of the retina that results in a decrease of the electroretinogram response. In the cardiovascular system, by a direct effect on oxidative low density lipoproteins, EGb 761 may decrease atherosclerosis evolution, and is shown to accelerate cardiac mechanical recovery after ischemia-reperfusion. In conclusion, the antioxidant effects of EGb 761 noted in many experimental data, may explain the therapeutic efficacy observed in clinical trials of the elderly. These beneficial properties seem in part to come from the activity of EGb 761 constituents, such as flavonoids and terpens.     

The effect of vitamin e on splenocytes apoptosis of gamma- irradiated BALB/c mice

Apoptosis, a physiologic mechanism to eliminate unwanted cells, is also induced by ionizing irradiation, through production of free radicals. It has been demonstrated that antioxidants such as vitamin E are able to protect cells from damage caused by free radicals. Taken together we found it reasonable to make an attempt to evaluate the protective effect of vitamin E against apoptosis. The irradiated mice received 1 Gy/day gamma radiation for one day (low dose) or for three successive days (high dose, 3Gy). The splenocytes were then isolated at 6, 14 and 24 h after exposure. DNA gel electrophoresis and DNA fragmentation assay were done in addition to the evaluation of splenocytes cytology.Our results showed that Vitamin E can reduce apoptosis against low dose irradiation. However it is not able to completely block programmed cell death in high dose irradiation.     

Protective factors against oxygen free radicals and hydrogen peroxide in rheumatoid arthritis synovial fluid

Oxygen free radicals are probably involved in the pathogenesis of rheumatoid arthritis (RA). The enzymes involved in protection against oxygen free radicals and H2O2 (superoxide dismutase, catalase, and glutathione peroxidase) were measured. Superoxide dismutase was not increased, glutathione peroxidase was slightly and catalase was strongly elevated in RA synovial fluid (SF) compared with control SF. Although these enzymes are present in SF, the activities are insufficient to protect against oxygen free radicals and H2O2. In contrast to transferrin, ferritin was increased in RA synovial fluid. Ceruloplasmin was also elevated. When rat liver microsomes were used as a target for oxygen free radicals, serum and SF were both protective. Gel filtration experiments showed that the fraction pattern in which there was maximal protective potential against lipid peroxidation corresponded closely to the level of ceruloplasmin. After removal of ceruloplasmin from serum or SF, about 70% of the protective capacity disappeared. It is concluded that ceruloplasmin is an important protector against oxygen free radicals.     

Study of antioxidant effect of apigenin, luteolin and quercetin by DNA protective method

A DNA protective capacity of three flavonoids, apigenin (AP), luteolin (LU) and quercetin (QU) against free radicals generated by H202, resp. Fe2+ is reported. This effect corresponding with scavenging of free radicals or with chelating of iron was assayed at two concentrations of flavonoids studied (1 microM and 10 microM). The quantitative analysis has shown that LU possesses the highest DNA protective effect of flavonoids investigated in the presence of H2O2. On the other hand, in the presence of 10 microM Fe2+, AP exhibited the highest DNA protective effect at the concentration of 1 microM and the following order was reached at the stoichiometric concentrations (10 microM) of Fe2+. It is believed that this discrepancy is caused by the ability of LU and QU iron-complex formation as it was separately investigated using UV-VIS spectrometry.     

Cardiovascular diseases: protective effects of melatonin

This brief review considers some of the cardiac diseases and conditions where free radicals and related reactants are believed to be causative. The report also describes the beneficial actions of melatonin against oxidative cardiovascular disorders. Based on the data available, melatonin seems to have cardioprotective properties via its direct free radical scavenger and its indirect antioxidant activity. Melatonin efficiently interacts with various reactive oxygen and reactive nitrogen species (receptor independent actions) and it also upregulates antioxidant enzymes and downregulates pro-oxidant enzymes (receptor-dependent actions). Moreover, melatonin enters all cells and subcellular compartments and crosses morphophysiologic barriers. These findings have implications for the protective effects of melatonin against cardiac diseases induced by oxidative stress. Melatonin attenuates molecular and cellular damages resulting from cardiac ischemia/reperfusion in which destructive free radicals are involved. Anti-inflammatory and antioxidative properties of melatonin are also involved in the protection against a chronic vascular disease, atherosclerosis. The administration of melatonin, as a result of its antioxidant features, has been reported to reduce hypertension and cardiotoxicity induced by clinically used drugs. The results described herein help to clarify the beneficial effects of melatonin against these conditions and define the potential clinical applicability of melatonin in cardiovascular diseases.     

ESR spin trapping studies on the OH* free radical reactions of idebenone

Experiments have been performed using oxidized (ID-O) and reduced (ID-H) idebenone in various spin trapping systems. The following results were obtained. (1) ID-O does not have any detectable scavenger effect on the OH* free radicals when they are generated by means of Fenton reaction and trapped using DMPO, PBN or 4-POBN. (2) ID-H represents a serious competition for all spin traps used in capturing OH* free radicals. The mechanism of this competition is, however, not a direct reaction, but it is based on the rather quick autoxidation of the dissolved ID-H generating O2(-*) radicals. They interact with the OH* radicals (or with the OH-spin adducts) by means of electron donation to them. This statement has been proven by showing (i) that O2* radicals generated during the autoxidation of ID-H can directly be trapped on DMPO; (ii) the effect of ID-H on the OH* free radicals is abolished if SOD is added to the system; (iii) the O2(-*) radicals generated by ID-H autoxidation reduce directly the OH-spin adducts on various kinds of nitroxide type spin traps (e.g. TEMPO, TMPN). (3) The rate of autoxidation of ID-H in solution is about an order of magnitude faster than that of ubiquinone. Similar differences could be observed in the rate of reduction of the oxidized forms of both compounds by Na-borohydride. The results fully explain the in vitro protective effect of ID-H against lipid peroxidation of artificial membranes.     

银杏叶提取物对肝硬化大鼠门静脉压及肝窦病理变化的影响

目的探讨银杏叶提取物（EGb）对肝硬化大鼠肝窦微循环及门静脉高压的影响。方法25只雄性Wistar大鼠分为3组：正常对照组（5只）,CCl_4组（10只）,EGb治疗组（10只）。肠系膜上静脉插管测定各组大鼠灌注EGb前后门静脉压力;肝组织匀浆中检测丙二醛（MDA）,血管内皮素（ET-1）,血小板活化因子（PAF）,一氧化氮（NO）,构生型一氧化氮合成酶（cNOS）和诱生型一氧化氮合成酶（iNOS）水平;电镜观察各组肝窦微循环特征。结果EGb灌注后CCl4组门静脉压由（8．7±0．8）mm Hg降至（7．4±0．6）mmHg,降低幅度15%,t 4．11,P＜0．01; EGb治疗组与CCl_4组比较,门静脉压、肝组织MDA、ET-1、PAF、NO和iNOS水平显著降低（P＜0．05或P＜0．01）,肝窦内胶原沉积、微血栓形成、肝窦毛细血管化程度减轻。结论银杏叶提取物能改善肝窦微循环障碍,降低门静脉压力,其可能机制是降低MDA、ET 1、PAF含量,下调iNOS的表达调节NO含量,对慢性肝病治疗具有重要意义。     

糖脂抗体和银杏制剂对体外培养雪旺细胞影响的研究

目的研究抗糖脂抗体对离体培养的雪旺细胞(schwanncell,SC)的影响和银杏制剂对其的保护作用。方法研究对象为1998年2月至1999年12月上海复旦大学附属华山医院神经内科自身免疫性周围神经病患者25例以及4名正常体检者。用饱和硫酸铵法提取血清球蛋白,加入离体培养的SC中,观察细胞形态改变,并通过单因素方差分析和配对t检验的方法分析细胞密度、周长和面积变化以及银杏制剂在其中是否具有保护细胞生长的作用。结果加入患者免疫球蛋白的SC形态发生显著改变,加入补体后细胞密度更显著下降。加入银杏制剂后细胞形态和密度无明显改变。结论自身免疫性周围神经病患者的免疫球蛋白在补体的参与下对体外培养的SC有明显的破坏作用,银杏制剂在这种情况下无显著的保护体外SC继续生长的作用。