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PubMedDate not supplied

Quantitative analysis of ginkgolic acids from Ginkgo leaves and products using 1H-NMR.

The determination of ginkgolic acids in Ginkgo products is one of the principal components of quality control. However, a number of ginkgolic acids with different side chains may be present and this makes their analysis by conventional chromatographic methods more complex. In this study, 1H-NMR spectrometry was applied to the analysis of the total content of ginkgolic acids in leaves of Ginkgo biloba and in six types of commercial Ginkgo products in the absence of chromatographic purification. For this analysis, protons H-3, H-4, and H-5, which are well separated in the range 8 (ppm) 6.5-7.5 in the 1H-NMR spectrum, were utilised. For further confirmation, the correlations of H-3, H-4 and H-5 were examined by 1H-1H COSY spectra in all extracts. The quantity of the compounds was calculated from the relative ratio of the integral of each peak to the integral of the peaks of a known amount (100 microg) of anthracene used as an internal standard. The quantitative results obtained by 1H-NMR analysis were compared with those obtained by GC, which showed that the 1H-NMR method allows a simple quantification of total ginkgolic acids in Ginkgo extracts without any pre-purification steps.

Chromatography, Gas↗
PubMed1997

Experimental electroretinographic exploration of retinal ischemia: preventive use of free radical scavengers and anti-PAF agents.

Electroretinographic exploration is an effective approach to evaluate retinal function. In order to investigate physiopathological mechanisms and evaluate potentially protective therapies for retinal ischemia, we developed three experimental models: the first two on isolated retina, with ischemia induced by either stopping perfusion or clamping the ophthalmic artery, and the third, in vivo, with ischemia induced by ocular hypertonia. Since free radicals are implicated in the formation of post-ischemic lesions, we evaluated the protective effects of drugs known to be free radical scavengers and of an immunomediator antagonist, an anti-PAF (platelet activating factor) agent.

Analysis of Variance↗
PubMed1996

[Exploratory study of amitriptyline resistance in depressed patients: results of WHO French collaborating center on depressions resistant to treatments].

A multicountry, multicentre double-blind study in a group of depressives, coordinated by the Mental Health Division of the World Health Association (WHO) has been done. The goal of the study is to determine whether the therapeutic effects of amitriptyline can be enhanced and potentiated by combining it with an antioxydant (gingko biloba). An exploratory study has preceded the main study which had the objective to estimate the proportion of non-response patient to amitriptyline. We report the results concerning the French center. 23 inpatients meet the ICD-10 criteria for depression (F32 and F33) and were treated during 6 weeks by amitriptyline with the initial daily dose of 50 mg until the maximum dose of 200 mg. The proportion of non-responsive patient to amitriptyline was 34.78 (95% confidence interval : 15.32 to 54.24%), all clinically deteriorated.

Adult↗
PubMed1998

Optimization of placebos for double-blind clinical trials. Experience with a phytopharmaceutical.

The maintenance of double-blind conditions in placebo-controlled trials depends on the quality of the placebo preparation. The placebo should match the active substance-containing preparation as closely as possible, but it must not contain any substances that might themselves be pharmacologically active. Active substances characterized by a particular colour, taste, smell or other easily perceptible properties constitute a challenge to researchers. The way of developing a placebo that matches a phytopharmaceutical to a satisfactory extent is described and discussed.

Aged↗
PubMed1989

Allergic contact dermatitis to Ginkgo biloba L.: relationship with urushiol.

A Ginkgo biloba L. fruit extract was prepared and purified. Three groups of guinea pigs were sensitized to the crude extract, anacardic acids 1, and cardanols 2 respectively, using the FCAT method, and the fourth group to urushiol using the epicutaneous route. Each group was tested for reaction to the primary sensitizer and to the different main aromatic compounds isolated from Ginkgo fruits. Anacardic acids were found to be good sensitizers, while cardanols failed to induce allergic contact dermatitis (ACD). No cross-reactions were observed among the compounds tested. Ginkgolic acids 1 seem to be the main allergens of Ginkgo biloba L. and the hypothesis of a biotransformation of 1 into catechol 4 is not supported by experiment.

Animals↗
PubMed2003

Effects of Ginkgo biloba on corticosterone stress responses after inescapable shock exposure in the rat.

Extracts from the leaves of the Ginkgo biloba tree (GBE) are found to be clinically effective in neuroprotection, cerebral and cardiovascular function and cognitive processing. Recent animal findings suggest that GBE also may improve stress adaptation and prevent learned helplessness, as evidenced by its reduction of behavioral acquisition deficits of active avoidance after inescapable shock exposure. In the present report, the effects of two doses of GBE were studied on corticosterone stress responses and acquisition of active avoidance after inescapable shock exposure. Forty-eight rats were divided into three groups: either receiving a daily dose of 50 mg/kg or 150 mg/kg of GBE (containing 24% flavonoid and 6% terpenoid) or vehicle for 2 weeks. After 2 weeks of administration, animals were trained for active-avoidance acquisition following inescapable shock exposure (stress induction) or nonshock exposure (nonstress). Administration of 150 mg/kg but not of 50 mg/kg of GBE significantly prevented a corticosterone stress response after inescapable shock exposure (P<.0001) without any beneficial behavioral effect on active avoidance. Repeated administration of GBE particularly improves biological adaptation to noxious stimuli without beneficial behavioral consequences. Present findings do not support previous claims about the benefits of G. biloba on improving behavioral stress adaptation and acquisition of active avoidance and on reducing behavioral deficits indicative of "learned helplessness."

Animals↗
PubMedDate not supplied

EGb 761 and the recovery of ion imbalance in ischemic reperfused diabetic rat retina.

We studied the effects of a free-radical scavenger, EGb 761, on electrolyte shifts (Na+, Ca2+, and K+) induced by ischemia and reperfusion in the retinas obtained from streptozotocin-induced diabetic rats. Eyes were subjected to 90 min ischemia followed by 24 h of reperfusion by clamping and releasing the central retinal artery. Ten days before the induction of ischemia and reperfusion, diabetic rats received a daily dose of 25, 50, and 100 mg/kg p.o. of EGb 761, respectively (n = 12 in each group). In the drug-free diabetic control group, 90 min ischemia followed by 24 h of reperfusion resulted in an increase in retinal Na+ and Ca2+ (measured by atomic absorption spectrophotometry) compared to nonischemic control values of 73 +/- 4 and 2.6 +/- 0.3 mumol/g dry weight to 113 +/- 5 (p < 0.05) and 5.3 +/- 0.3 mumol/g dry weight (p < 0.05), respectively. Tissue K+ content was significantly reduced compared to its nonischemic diabetic control value of 268 +/- 7 to 213 +/- 6 mumol/g dry weight (p < 0.05). EGb 761 dose-dependently reduced reperfusion-induced ion imbalance, improving the recovery of ion content in diabetic rat retina. EGb 761 did not reduce blood glucose in streptozotocin-induced diabetic rats. Therefore we may conclude that these protective effects of EGb 761 are independent of blood glucose content or of the severity of diabetes and protect against electrolyte shifts directly in retinal cells.

Animals↗
PubMed1989

Modulation of resynthesis of 1-alkyl-2-arachidonyl-glycero-3-phosphocholine and phosphatidylinositols for interception in vivo of free arachidonic acid, lyso-PAF, diacyl-glycerols, and phosphoinositides.

Thermal injury causes directly a liberation of inositolphosphates, diacylglycerols, free arachidonic acid, and lyso PAF from eukaryotic cells. From lyso PAF derivates PAF, from free arachidonic acid are derivating PG, LT, and TX. These "soluble mediators" are stimulating inflammatory cell populations in a feedback mechanism: the stimulus activates the inflammatory cells to produce the same soluble mediators (Fig.1). The arising soluble mediators are the take off for the inflammation cascade causing as later step the activation of kinin, clotting, and complement systems. The pure biochemical lesions at the onset results in the clinical manifestation of oedema, increased dermal temperature, and pains. The possibilities for prevention and allevation of early pain, due to the acute burn, lie in the inhibition of the spreading out of inflammatory mediators (Bauer 1987a) (Fig.2).

Animals↗
PubMed2006

Ferritin oxidation and proteasomal degradation: protection by antioxidants.

The accumulation of oxidatively damaged proteins is a well-known hallmark of aging and several neurodegenerative diseases including Alzheimer's, Parkinson's and Huntigton's diseases. These highly oxidized protein aggregates are in general not degradable by the main intracellular proteolytic machinery, the proteasomal system. One possible strategy to reduce the accumulation of such oxidized protein aggregates is the prevention of the formation of oxidized protein derivatives or to reduce the protein oxidation to a degree that can be handled by the proteasome. To do so an antioxidative strategy might be successful. Therefore, we undertook the present study to test whether antioxidants are able to prevent the protein oxidation and to influence the proteasomal degradation of moderate oxidized proteins. As a model protein we choose ferritin. H2O2 induced a concentration dependent increase of protein oxidation accompanied by an increased proteolytic susceptibility. This increase of proteolytic susceptibility is limited to moderate hydrogen peroxide concentrations, whereas higher concentrations are accompanied by protein aggregate formation. Protective effects of the vitamin E derivative Trolox, the pyridoindole derivative Stobadine and of the standardized extracts of flavonoids from bark of Pinus Pinaster Pycnogenol and from leaves of Ginkgo biloba (EGb 761) were studied on moderate damaged ferritin.

Antioxidants↗
PubMedDate not supplied

Herbal medicine in the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is characterized by profound memory loss sufficient to interfere with social and occupational functioning. It is the most common form of dementia, affecting more than 20 million people worldwide. AD is characterized by an insidious loss of memory, associated functional decline, and behavioral disturbances. Patients may live for more than a decade after they are diagnosed with AD, making it the leading cause of disability in the elderly. The incidence of AD ranges from 1 to 4 percent of the population per year, rising from its lowest level at ages 65 to 70 years to rates that may approach 6 percent for those over the age of 85 years. The first neurotransmitter defect discovered in AD involved acetylcholine (ACh). As cholinergic function is required for short-term memory, the cholinergic deficit in AD was also believed to be responsible for much of the short-term memory deficit. Clinical drug trials in patients with AD have focused on drugs that augment levels of ACh in the brain to compensate for the loss of cholinergic function. These drugs have included ACh precursors, muscarinic agonists, nicotinic agonists, and acetylcholinesterase inhibitors. The most highly developed and successful approaches to date have employed acetylcholinestrase inhibition. Although some Food and Drug Administration-approved drugs are available for the treatment of Alzheimer's disease, the outcomes are often unsatisfactory, and there is a place for alternative medicine, in particular, herbal medicine. This paper reviews the clinical effects of a number of commonly used types of herbal medicines for the treatment of AD.

Alkaloids↗
PubMed2000

Gingko biloba (Rökan) therapy in tinnitus patients and measurable interactions between tinnitus and vestibular disturbances.

Tinnitus is one of the most important symptoms in neurootology after vertigo, nausea, and hearing loss. In most cases, the origin of the tinnitus remains inexplicable. Well-known, however, is that tinnitus may arise in any part of the hearing pathway (i.e., both within the cochlea receptor and in the temporal lobe and projections). Tinnitus also is associated frequently with vertigo, nausea and hearing loss. An age predominance exists, with tinnitus more common among those older than 40 years. From this starting point, a great demand exists today for new ideas and developments in the diagnosis and treatment of tinnitus.

Audiometry↗
PubMed2002

Bioflavonoid-rich botanical extracts show antioxidant and gene regulatory activity.

Reactive oxygen and nitrogen metabolites are obligatory and essential products of metabolism. Unregulated increase in their production is associated with a number of chronic illnesses. Diets rich in fruits, vegetables, and wines are implicated in the prevention of chronic diseases. Molecular mechanisms by which fruits and vegetables confer their disease-preventive actions are poorly defined. However, recent developments in the fields of genomics and bioinformatics provide powerful tools to investigate the mechanisms by which botanicals affect cellular functions. This monograph illustrates the potential of large-scale messenger RNA analysis to unravel the role of transcription in mediating the effects of botanical extracts with antioxidant properties. The application of microarrays and oligonucleotide arrays shows multiple effects of antioxidant extracts on the expression of a broad spectrum of genes.

Animals↗
PubMed2000

Effect of EGb-761 on vasospasm in experimental subarachnoid hemorrhage.

Based on the previously suggested hypothesis that the generation of free radicals leading to lipid peroxidation is involved in the genesis of vasospasm and vasculopathy following subarachnoid hemorrhage, the therapeutic effect of EGb 761 as an antioxidant on experimental vasospasm and vasculopathy was evaluated in a double hemorrhage dog model of chronic cerebral vasospasm. For this study 14 dogs were randomly assigned to two groups, a control and a Ginkgo biloba group. The control group was only administered saline in a volume equivalent to a dose of 100 mgEGb 761/kg while the treatment group was given 100 mg EGb 761/kg. The diameter of the basilar artery decreased from 1.95 +/- 0.16 mm at day 0 to 1.11 +/- 0.07 mm at day 8 in the control group, while in the treatment group the vessel diameter decreased from 2.01 +/- 0.17 mm at day 0 to 1.72 +/- 0.16 mm at day 8. These results correspond a decrease in vessel diameter of 15.1% in the treatment group and of 43.1% in the control group (P < 0.05). Histopathological studies of the specimens obtained from basilar arteries showed that pathological signs of proliferative vasculopathy, including narrowing of the vessel lumen, corrugation of the lamina elastica and subendothelial thickening, were present in all the animals in the control group, while they could not be demonstrated in the Ginkgo biloba group. These results suggest that Ginkgo biloba may have a protective effect against subarachnoid hemorrhage-induced vasospasm and vasculopathy as a result of antioxidants.

Animals↗