银杏叶黄酮提取方法比较

比较不同溶剂提取银杏（ＧｉｎｋｇｏｂｉｌｏｂａＬ．）叶黄酮类化合物的提取效率,从成本效益角度考虑,以７０％乙醇作为提取溶剂更为有利。在分级沉淀中,黄酮含量与蛋白质含量呈正相关,在乙醇提取液中黄酮和蛋白质含量最高;蛋白质的存在有助于提高黄酮的溶解度。乙醇提取液用饱和（ＮＨ４）２ＳＯ４浓缩两次,可使醇相中的黄酮沉淀析出。根据试验结果,提出了银杏叶黄酮的优化提取方法。     

HPLC法测定银杏叶征剂中决黄酮甙的含量

银杏 (ＧｉｎｋｇｏｂｉｌｏｂａＬｉｎｎ .)叶提取物 (ＧＢＥ)是银杏叶经提取、分离而得的干浸膏 ,是银杏叶制剂的主要原料。药理及临床表明 ,它能增加冠状动脉血流量 ,可用于动脉硬化及高血压所致的冠状动脉供血不全、心绞痛、心肌梗塞、脑血栓、脑血管痉挛等症[1] 。其活性成分主要是黄酮类和萜内酯[2 ] 。银杏叶黄酮类成分的测定方法 ,有紫外分光光度法和高效液相色谱法 ,因前者专属性较差 ,现多数厂家均采用后者。高效液相色谱法测定总黄酮甙的含量时 ,在对照品的使用上 ,既有单用槲皮素 (ｑｕｅｒｃｅｔｉｎ)为对照品的测定方法[3 ] ,…     

Protective effects of Ginkgo biloba leaf extract on aluminum-induced brain dysfunction in rats

This study examined the protective effects of Ginkgo biloba extract (GbE) on the learning and memory function in aluminum-treated rats and potential mechanisms. Wistar rats were given daily aluminum chloride 500 mg/kg, i.g, for one month, followed by continuous exposure via the drinking water containing 1600 ppm aluminum chloride for up to 5 months. The ability of spatial learning and memory was tested by Morris water maze. Aluminum administration significantly increased escape latency and searching distance, indicative of brain dysfunction. GbE treatment (50-200 mg/kg, i.g) significantly protected against aluminum-induced brain dysfunction, as evidenced by decreased escape latency and searching distance compared with the Al alone group. To examine the mechanisms of the protection, the expressions of amyloid precursor protein (APP) and caspase-3 in brain regions were examined by immunohistochemistry. GbE treatment reduced the contents of APP and caspase-3 in hippocampus of aluminum-treated rats in a dose-dependent manner. At the highest dose of GbE (200 mg/kg), the immunostain for APP and caspase-3 was returned to normal levels. In summary, this study demonstrates that GbE is effective in improving the ability of spatial learning and memory of aluminum-intoxicated rats. This protection appears to be due to a decreased expression of APP and caspase-3 in rat brain, resulting in a decrease in the production of insoluble fragments of Abeta-amyloid.     

A flavonoid sulphate and other compounds from the roots of Centaurea bracteata.

The roots of Centaurea bracteata Scop. (Asteraceae) have been studied for the first time. Twenty-three compounds were isolated and identified, namely a sterol glucoside, two quinic acid derivatives, one sugar, and 19 flavonoids (five sulphates), one of which, centaradixin, resulted in a new natural product. Structural elucidation was performed mainly by means of FABMS, 1D and 2D NMR spectroscopy. NMR data of some sulphate flavonoids are reported for the first time.     

Ginkgo biloba extract: from molecular mechanisms to the treatment of Alzhelmer's disease.

Ginkgo biloba is registered for the treatment of several diseases and disorders in Europe. In the United States, it is marketed as a dietary supplement; the French and the German agencies consider it to be effective for the treatment of several diseases, and the immense amount of clinical studies concerning Ginkgo biloba makes it worth revising the existing literature about this notable plant. A brief history of the common use of this drug will be followed by a short botanic characterization. The biochemical composition of the original drug, the leaf itself, will be described in detail together with a brief discussion of commercial extracts and the problem of studying Ginkgo biloba clinically to verify the safety and efficacy of its extracts in the treatment of disorders like Alzheimer's diseases. Aspects of molecular mechanisms modifying the efficacy of this drug will be outlined. Several agents like antioxidants, anti-inflammatory drugs, cholinergic agents, estrogens, or neurotrophic factors are in use for the treatment of this neurodegenerative disease, but none can prove fully convincing benefit. In this field, Ginkgo biloba appears as a useful and sensible supplementary medication to treat Alzheimer's disease, as it seems to be a synthesis of all the different profiles of action of the various, commonly used drugs but with less side effects.     

Changes in flavonoid content and tyrosinase inhibitory activity in kenaf leaf extract after far-infrared treatment

The tyrosinase inhibitory activity of ethanolic extract of kenaf (Hibiscus cannabinus L.) leaf was evaluated before and after subjecting it to far-infrared (FIR) irradiation. The main component of the extract was analyzed as kaempferitrin (kaempferol-3,7-O-α-dirhamnoside). Prior to FIR irradiation, no inhibitory activity of the extract was detected in a tyrosinase assay. However, after FIR irradiation for 1h at 60°C, significant tyrosinase inhibitory activity (IC(50)=3500 ppm) was observed in it. In HPLC analysis, derhamnosylation products (kaempferol, afzelin, and α-rhamnoisorobin) were detected. The inhibitory activity may be due to the existence of derhamnosylation products. This study demonstrated that FIR irradiation can be used as a convenient tool for deglycosylation of flavonoid glycoside.     

Tirucallane triterpenes from the leaf extract of Entandrophragma angolense

From the leaves of Entandrophragma angolense, three triterpenoidal compounds were isolated and structurally elucidated by mass and NMR spectroscopy. They belong to the tirucallane group but two of them possess the rare seco-ring-A feature. The phytochemical data are discussed from a chemotaxonomic and biogenetic points of view.     

Changes in citrus leaf flavonoid concentrations resulting from blight-induced zinc-deficiency

Increased flavonoid concentrations were found to correlate with the elevated levels of leaf phenolic compounds occurring in blight-induced zinc-deficient citrus. In orange (Citrus sinensis L.) leaves, the increases occurred primarily in hesperidin and diosmin, whereas in grapefruit (C. paradisi Macf.) the largest increases occurred in naringin and rhoifolin. Zinc-deficiency occurring in the blighted citrus leaves appeared to be the important contributing factor to the increased flavonoid content. Although the leaves from trees with blight were typically smaller than leaves from unaffected trees, the increased flavonoid content was not significantly due to a concentration effect. Large differences occurred in the percent increases in concentrations of certain citrus leaf flavonoids. While large increases occurred for a number of flavanone and flavone glycosides, much smaller percent increases occurred for other minor flavone glycosides, and the polymethoxyflavone aglycones. The parallel increases occurring in the concentrations of certain flavone glycosides and their flavanone analogs provide a further indication that flavanone glycosides are precursors in the biosynthesis of flavone glycosides in citrus.     

银杏叶中银杏内酯B及白果内酯的分离鉴定

前文中作者已报道从我国特有植物银杏(Ginkgo biloba L.)的叶子中分到银杏内酯A及C(ginkgolide A,C),本文报道从银杏叶中分到的另外二个结晶,经理化性质、薄层层析、红外光谱及质谱分析,鉴定结晶Ⅲ为银杏内酯B(ginkgolide B),结晶Ⅳ为白果内酯(bilobalide),后者为国内首次分离。     

Changes of dipole potential of phospholipid membranes resulted from flavonoid adsorption

The effects of flavonoids, phloridzin, quercetin, myricetin and biochanin A on the dipole potential of planar lipid bilayers formed from dioleylphosphoethanolamine, dioleylphosphoserine, dioleoylphosphocholine, and diphytanoylphosphocholine are investigated. The characteristic parameters of the Langmuir adsorption isotherm, the maximum changes in the membrane dipole potential at an infinitely large concentration of flavonoid and its dissociation constant, which reflects the affinity of flavonoid to the membrane lipids, are determined. Modifying effects of chalcones, flavonols and isoflavones are compared. The influence of the surface charge of the lipid bilayer and the spontaneous curvature of the membrane-forming phospholipids on the adsorption of flavonoids on the model membranes is discussed.     

桑叶提取物抑菌作用的研究

研究了桑叶水煎剂对常见微生物的抑菌作用,以及在不同pH值条件下的抑菌效果.结果表明:提取液对霉菌的生长没有明显的抑制作用;对供试细菌有效,其中对微球菌的抑制最强,其次为沙门氏菌和大肠杆菌,对枯草芽孢杆菌的作用较弱.抑菌效果随着桑叶水煎剂浓度的增加而加强.在酸性条件下,桑叶水煎剂的抑菌作用都有不同程度的增加,但效果均不如0.05%苯甲酸钠.     

Ginkgo biloba extract ameliorates gentamicin-induced nephrotoxicity in rats.

The effect of Ginkgo biloba (EGb), a plant extract with an antioxidant effect, has been studied on gentamicin-induced nephrotoxicity in male wistar rats. Ginkgo biloba extract (300 mg/kg BW) was administered orally 2 days before and 8 days concurrently with gentamicin (80 mg/kg BW). Saline treated animals served as control. Estimations of urine creatinine, glucose, blood urea, serum creatinine, plasma and kidney tissue MDA were carried out after 8 days of gentamicin treatment. Kidneys were examined using histological techniques. Blood urea and serum creatinine were increased by 896% and 461% respectively, with gentamicin, compared to saline treated group. Creatinine clearance was significantly decreased with gentamicin. Ginkgo biloba extract protected rats from gentamicin-induced nephrotoxicity. Changes in blood urea, serum creatinine and creatinine clearance induced by gentamicin were significantly prevented by Ginkgo biloba extract. There was a 177% and 374% rise in plasma and kidney tissue MDA with gentamicin, which were significantly reduced to normal with Ginkgo biloba extract. Histomorphology showed necrosis and desquamation of tubular epithelial cells in renal cortex with gentamicin, while it was normal and comparable to control with Ginkgo biloba extract. These data suggest that supplementation of Ginkgo biloba extract may be helpful to reduce gentamicin nephrotoxicity.     

Ethanolic Ginkgo biloba leaf extract prevents renal fibrosis through Akt/mTOR signaling in diabetic nephropathy

BackgroundRecently, extract of Ginkgo biloba leaves (GbE) have become widely known phytomedicines and have shown various pharmacological activities, including improvement of blood circulation, protection of oxidative cell damage, prevention of Alzheimer's disease, treatment of cardiovascular disease and diabetes complications. This study was designed to investigate the effects of an ethanolic GbE on renal fibrosis in diabetic nephropathy (DN) and to clarify the possible mechanism by which GbE prevents renal fibrosis.Study designWe investigated the protective effects of GbE on renal fibrosis in STZ-induced diabetic rats. Rats were randomized into six groups termed normal control, diabetes mellitus, low dose of GbE (50 mg/kg/d), intermediate dose of GbE (100 mg/kg/d), high dose of GbE (200 mg/kg/d) and rapamycin (1 mg/kg/d).MethodsAfter 12 weeks, the rats were sacrificed and then fasting blood glucose (FBG), creatinine (Cr), blood urea nitrogen (BUN), urine protein, relative kidney weight, glycogen and collagen accumulation, and collagen IV and laminin expression were measured by different methods. The amounts of E-cadherin, α-SMA and snail, as well as the phosphorylation of Akt, mTOR and p70S6K in the renal cortex of rats, were examined by western blotting.ResultsCompared with diabetic rats, the levels of Cr, BUN, urine protein, relative kidney weight, accumulation of glycogen and collagen, and expression of collagen IV and laminin in the renal cortex were all decreased in GbE treated rats. In addition, GbE reduced the expression of E-cadherin, α-SMA, snail and the phosphorylation of Akt, mTOR and p70S6K in diabetic renal cortex.ConclusionGbE can prevent renal fibrosis in rats with diabetic nephropathy, which is most likely to be associated with its abilities to inhibit the Akt/mTOR signaling pathway.     

Hepatoprotective activity of Cassia fistula leaf extract.

Hepatoprotective activity of the n-heptane extract of Cassia fistula leaves was investigated by inducing hepatotoxicity with paracetamol in rats. The extract at a dose of 400 mg/kg body wt. exhibited orally, significant protective effect by lowering the serum levels of transaminases (SGOT and SGPT), bilirubin and alkaline phosphatase (ALP). The effects produced were comparable to that of a standard hepatoprotective agent.     

银杏叶提取物猴头菌转化前后降血糖作用的比较研究

以正常对照组、模型对照组和阳性(二甲双胍)对照组为参照,试验比较了银杏叶提取物(EGB)、猴头菌转化EGB的产物、猴头菌发酵液、猴头菌发酵液中添加EGB对链脲佐菌素诱导的2型糖尿病模型大鼠血糖和血脂代谢的调节作用以及对自由基清除作用。结果显示:相对于其他给药组,猴头菌转化EGB的转化产物能更加显著地降低糖尿病模型大鼠的血糖和果糖胺水平,但是对胰岛素水平无显著的调节作用,与模型对照组和其他给药组相比,EGB转化产物可以显著提高超氧化物岐化酶活性;与模型对照组相比亦可显著降低丙二醛水平,但与其他给药组相比其降丙二醛作用差异不明显。本项研究对采用微生物转化法提高植物提取物药用效果提供了参考资料。     

银杏叶提取物猴头菌转化前后降血糖作用的比较研究

The regulatory effects of blood glucose, lipid metabolism and free radical elimination were compared in streptozotocin-induced hyperglycemic rats among the following treatments: Ginkgo biloba leaf extract (EGB), the biotransformation of EGB by Hericium erinaceus, a cultural filtrate of H.erinaceus, and the cultural filtrate of H.erinaceus plus EGB, together with the normal control, the model control and the positive control (Metformin). The best results were obtained from the biotransformation treatment group, which could significantly reduce the levels of blood glucose and fructosamine. However, the treatment did not increase the blood insulin level. The EGB transformed products could obviously increase the serum superoxide dismutase activity and reduce the malondialdehyde level, but the reduction of malondialdehyde was not obvious as compared with that of the other treatment groups. This study provides a useful information on improving the medical properties of the herb extracts by biotransformation.