傅里叶红外标准加入法测定银杏叶提取物(EGb)中的总内酯

银杏叶提取物（ＥＧｂ）经ＫＢｒ压片后,在１８４０～１７２６ｃｍ－１区间,用傅里叶变换红外光谱仪测量峰面积,以美国Ｓｉｇｍａ的银杏内酯Ｂ为标准品,用ＦＴＩＲ标准加入法测定ＥＧｂ中的总内酯含量,其结果与ＲＰＨＰＬＣ、ＲＩ法接近,平均回收率９６．８％,ＳＤ０．４,ＲＳＤ５．５％,方法简便,结果可靠,适于ＥＧｂ及其制剂在生产过程中作质量控制的测定方法用。     

银杏内酯对活性氧自由基和过氧化氢清除作用的研究

研究了银杏叶中内酯类提取物对超氧阴离子自由基、羟自由基和过氧化氢的清除作用。为了进一步分析内酯类在细胞内的清除作用,在反应体系中加入了大肠杆菌提取物以部分模拟细胞环境,结果表明,内酯类提取物对自由基和过氧化氢的清除作用不显著。在清除过程中,内酯类对黄酮类自由基清除的协同作用比较复杂。但可以肯定的是大肠杆菌提取物对自由基和过氧化氢的清除没有影响或影响较小。     

银杏萜内酯调控研究进展

银杏叶萜内酯具有重要的药用价值。综述了银杏萜内酯的合成途径和影响银杏叶萜内酯合成的各种因素,及各种调控银杏萜内酯含量变化的措施。喷施矮壮素、乙烯利能够通过反馈抑制内源激素的合成来增加银杏内酯合成前体GGPP含量。赤霉素具有与前者相同的抑制机理,通过反馈抑制GA20-氧化酶、3β-羟化酶mRNA的积累,增加GGPP的含量。还介绍了通过2,3-环氧角鲨烯抑制2,3-环氧角鲨烯环化酶来阻断甾醇生成途径,使MVA途径的IPP进入质体参加内酯的合成     

银杏内酯A对LPS诱导的小鼠急性肺损伤的保护作用

为了研究银杏内酯A对非特异性肺损伤小鼠的保护作用,采用脂多糖（LPS）滴鼻法建立了小鼠急性肺损伤（ALI）模型。于造模前1h给予银杏内酯A（50,100mg/kg）,在LPS滴入后18h检测支气管肺泡灌洗液（BALF）中的细胞因子TNF-α、IL-6、IL-1β水平,观察肺部组织学的病理变化。结果表明：银杏内酯A可以显著抑制肺组织中炎性细胞的浸润,抑制肿瘤坏死因子α（TNF-α）、白细胞介素6（IL-6）和白细胞介素1β（IL-1β）炎性细胞因子的产生。由此得出结论,银杏内酯A对LPS诱导的小鼠ALI具有一定的保护作用。     

RP-HPLC法测定银杏外种皮中银杏内酯C含量

[目的]采用反相高效液相色谱法（RP-HPLC）法测定银杏外种皮中银杏内酯C含量。[方法]采用Waters ODSC18柱（250.0 mm×4.6 mm）;以乙腈∶水=40∶60为流动相;流速1.0 ml/min;柱温30℃;检测波长为210 nm。以银杏内酯C标准品为对照,采用外标法定量测定。[结果]银杏外种皮中银杏内酯C含量为0.043%;该方法平均回收率为101.06%,RSD为2.25%。[结论]该方法结果准确、可靠,便于操作,为银杏外种皮中银杏内酯C含量的测定以及进一步开发银杏外种皮资源提供了理论依据。     

Protective mechanisms of ginkgolide B on rat retinal cell apoptosis induced by N-methyl-N-nitrosourea

AIM: To investigate the protective mechanisms of ginkgolide B (GB) on rat retinal degeneration induced by N-methyl-N-nitrosourea (MNU). METHODS: The rat retinal degeneration model was made. Photoreceptor cell apoptosis was measured by TUNEL assay. The expression of Bcl-2 and Bax in the different time points in the rat retina after treated with MNU was measured by RT-PCR and immunohistochemical methods. RESULTS: The outer nuclear layer cell apoptotic index in GB treatment group was significantly lower than that in model group (P<0.01). The bcl-2/bax mRNA ratios at scheduled time points of 12 h, 1 d, 2 d, 3 d and 5 d after MNU injection in model control were 0.36, 0.15, 0.29, 0.42 and 0.64, respectively, while the ratios in GB group were 0.98, 0.92, 0.53, 0.45 and 0.68, respectively, larger than those in model control group (P<0.01). No Bcl-2 positive expression was detected at any scheduled time points after MNU injection in model control group. Strong positive Bcl-2 expression was detected in GB group 1 d after MNU injection, decreased at the 2nd day and disappeared at the 3rd day. Compared with model control group, the Bax expression in GB group was significantly decreased (P<0.01).CONCLUSION: Ginkgolide B effectively inhibits the apoptosis of photoreceptor cells. The mechanism of GB action may be related to the increase in the expression of Bcl-2 and the increase in the ratio of Bcl-2/Bax.     

银杏萜内酯调控研究进展

银杏叶萜内酯具有重要的药用价值。综述了银杏萜内酯的合成途径和影响银杏叶萜内酯合成的各种因素,及各种调控银杏萜内酯含量变化的措施。喷施矮壮素、乙烯利能够通过反馈抑制内源激素的合成来增加银杏内酯合成前体GGPP含量。赤霉素具有与前者相同的抑制机理,通过反馈抑制GA20-氧化酶、3β-羟化酶mRNA的积累,增加GGPP的含量。还介绍了通过2,3-环氧角鲨烯抑制2,3-环氧角鲨烯环化酶来阻断甾醇生成途径,使MVA途径的IPP进入质体参加内酯的合成。     

Ginkgolide B produced endophytic fungus (Fusarium oxysporum) isolated from Ginkgo biloba

To screen the presence of ginkgolide B-producing endophytic fungi from the root bark of Ginkgo biloba, a total of 27 fungal isolates, belonging to 6 different genus, were isolated from the internal root bark of the plant Ginkgo biloba. The fungal isolates were fermented on solid media and their metabolites were analyzed by TLC. The obtained potential ginkgolides-producing fungus, the isolate SYP0056 which was identified as Fusarium oxysporum, was successively cultured in the liquid fermentation media, and its metabolite was analyzed by HPLC. The ginkgolide B was successfully isolated from the metabolite and identified by HPLC/ESI-MS and (13)C-NMR. The current research provides a new method to produce ginkgolide B by fungal fermentation, which could overcome the natural resource limitation of isolating from the leaves and barks of the plant Ginkgo biloba.     

Effect of ginkgolide B on cholesterol content in PC12 cells under high cholesterol culture

AIM: To explore the effect of ginkgolide B (GB) on high cholesterol-induced dysfunction in PC12 cells. METHODS: The rat brain microvascular endothelial cells and astrocytes were used to establish the blood-brain barrier (BBB) model by in vitro co-culture in the Transwell device with PC12 cells. Cholesterol at the concentration of 40 μmol/L was added into the side of brain microvascular endothelial cells of the Transwell. Various concentrations of GB were applied to deal with the culture system. The morphological changes of the cells were observed under microscope. The safe doses of GB were screened by MTT assay. The level of cholesterol in the PC12 cells was determined by the high-performance liquid chromatography. RESULTS: The morphology of PC12 cells in control group was normal,with round,short spindle or triangle shape,cytoplasm extension,two-pole short processes,good refraction and obvious nucleus.The doses of GB determined by MTT assay were 1 μmol/L for low dose,5 μmol/L for middle dose and 25 μmol/L for high dose. Compared with control group, the cholesterol obviously increased in model group with statistical difference (P<0.05). GB at dose of 25 μmol/L for 16 h exposure had the optimum results to decrease the cholesterol level in PC12 cells. However, no significant difference between GB high dose group and simvastatin group was observed (P>0.05). CONCLUSION: The active monomer of ginkgo leaf, GB, may effectively reduce the cholesterol content in PC12 cells with the condition of BBB in vitro.     

Ginkgolide production in relation to organogenesis inGinkgo biloba

The contents of diterpenoids, ginkgolides A, B, and C, in seeds, embryos, and plantlets ofGinkgo biloba were analyzed to clarify the relations between organogenesis and terpene contents inG. biloba. There is so far no published report on the contents and changes in such terpenes in seeds and very young plantlets ofG. biloba. Ginkgolides were present in seeds and embryos. Plantlets cultured in both the dark and under illumination contained substantial amounts of ginkgolides, more abundant than in seeds and embryos. It is concluded that ginkgo yields ginkgolides in its early stage of development regardless of light.