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PubMed2004

Chemistry and biology of terpene trilactones from Ginkgo biloba.

Ginkgo biloba, the ginkgo tree, is the oldest living tree, with a long history of use in traditional Chinese medicine. In recent years, the leaf extracts have been widely sold as phytomedicine in Europe and as a dietary supplement worldwide. Effects of Ginkgo biloba extracts have been postulated to include improvement of memory, increased blood circulation, as well as beneficial effects to sufferers of Alzheimer's disease. The most unique components of the extracts are the terpene trilactones, that is, ginkgolides and bilobalide. These structurally complex molecules have been attractive targets for total synthesis. Terpene trilactones are believed to be partly responsible for the neuromodulatory properties of Ginkgo biloba extracts, and several biological effects of the terpene trilactones have been discovered in recent years, making them attractive pharmacological tools that could provide insight into the effects of Ginkgo biloba extracts.

Biology↗

PubMed2005

Liquid chromatography/electrospray tandem mass spectrometry of terpenoid lactones in Ginkgo biloba.

Ginkgo biloba (ginkgo) is one of most frequently used botanical dietary supplements. The bioactive constituents include the terpenoid lactones consisting of bilobalide and the ginkgolides A, B, C and J. A new assay based on high-performance liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) was developed for the measurement of the terpenoid lactones in ginkgo products such as leaf powder and extracts. Initially, the MS/MS fragmentation pathways of ginkgolides were investigated to identify abundant fragment ions that might be useful for the sensitive and selective detection of ginkgolides and bilobalide during LC/MS/MS. Then, sample preparation and clean-up procedures were streamlined to maximize throughput by taking advantage of the selectivity of LC/MS/MS detection. Analyte recoveries exceeded 90%, the intra-assay and inter-assay relative standard deviations were <5%, the relative error was <8% and the limits of detection and quantification were 3.6-120 and 11-350 fmol, depending on the analyte that was injected on to the LC column. Therefore, this LC/MS/MS assay facilitated the rapid quantitative analysis of ginkgolides A, B, C and J and bilobalide in ginkgo dietary supplements with excellent recovery, reproducibity, accuracy and sensitivity.

Chromatography, Liquid↗

PubMed2003

Ginkgo biloba.

Ginkgo biloba is commonly used in the treatment of early-stage Alzheimer's disease, vascular dementia, peripheral claudication, and tinnitus of vascular origin. Multiple trials investigating the efficacy of ginkgo for treating cerebrovascular disease and dementia have been performed, and systematic reviews suggest the herb can improve the symptoms of dementia. Ginkgo is generally well tolerated, but it can increase the risk of bleeding if used in combination with warfarin, antiplatelet agents, and certain other herbal medications. Clinical issues of safety, dosing, use in the perioperative period, and pharmacology are addressed in this review.

Clinical Trials as Topic↗

PubMed2006

Cloning and characterization of 2-C-methyl-D: -erythritol 2,4-cyclodiphosphate synthase (MECS) gene from Ginkgo biloba.

Ginkgo biloba contains secondary metabolites with interesting pharmacological properties, including highly modified diterpenoid ginkgolide, potent and selective antagonist of platelet-activating factor. 2-C-Methyl-D: -erythritol 2,4-cyclodiphosphate synthase gene (GbMECS) involved in ginkgolide biosynthesis pathway was cloned and characterized from G. biloba embryonic roots, and the full open reading frame was deduced as protein consisting of 238 amino acid residues. Putative mature protein with a 179 residue-long sequence, obtained by deleting N-terminal chloroplast transit peptide region composed of 59 amino acid residues, rescued Esherichia coli NMW26, an E. coli knock-out mutant of ygbB (EcMECS). Transcription levels of GbMECS were two-fold higher in embryo roots compared to leaves. When full-length GbMECS with chloroplast transit peptide sequence was fused to green fluorescent protein gene (GFP), and transiently expressed in Arabidopsis thaliana protoplast, green fluorescence was found in chloroplast, indication of protein transportation into plastid.

Amino Acid Sequence↗

PubMed2006

Inhibition of cGMP-phosphodiesterase-5 by biflavones of Ginkgo biloba.

Ginkgo biloba dimeric flavonoids (GBDF) were shown to inhibit cAMP phosphodiesterase activity and to promote vasorelaxation. In particular, amentoflavone exhibited endothelium-dependent relaxation of rat aorta rings via enhanced generation and/or increased biological activity of nitric oxide, leading to elevated cGMP levels. The aim of this study was to investigate whether GBDF were able to inhibit cGMP-specific phosphodiesterase-5 (PDE5) as well. Human recombinant PDE5A1 was prepared by expression of the full-length cDNA of PDE5A1 in COS-7 cells. The PDE activity was determined in the presence of biflavones at 0.1-100 microM. All biflavones inhibited PDE5A1 in a concentration-dependent fashion, ginkgetin being the most potent (IC50 = 0.59 microM). The ability to inhibit the enzyme followed this order: ginkgetin > bilobetin > sciadopitysin > amentoflavone > sequoiaflavone. These data suggest that GBDF could exert a vasodilating effect through a mechanism independent of NO release.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2006

A new capillary zone electrophoresis method for the analysis of Ginkgo biloba extracts and Ginkgo biloba pharmaceutical products.

Ginkgo biloba, traditional Chinese medicine is now generally accepted. Separation and determination of active components in G. biloba is important for the product quality control. Therefore, the development of an effective and reliable separation method is important. In this work, a new capillary electrophoretic (CZE) method for separation of the G. biloba leaf extracts components was developed and optimized by the use of experimental design and artificial neural network (ANN). Under best separation conditions, in gamma-CD-modified buffer, the separation was reached within 10 min (36 mM borate BGE, pH 9.2, 1 mM gamma-CD), while the hydrodynamic mode for sample injection (2 s) and UV detection at 270 nm were applied. The method developed was validated and applied for analysis of various extracts and G. biloba products.

Cyclodextrins↗

PubMed2001

Evaluation of the allergenic potential of Ginkgo biloba extracts.

Ginkgo biloba extracts are used for the treatment of central and peripheral malperfusion, cerebral insufficiency and dementia. Between 1996 and 1998, several patients in Austria who had received parenteral Ginkgo extracts were reported to have developed allergy-like symptoms. The aim of the present study was to determine whether Ginkgo biloba extracts contain type I allergens. The protein content of Ginkgo biloba extracts was determined by BCA protein determination and SDS-PAGE. We used sera from 95 polysensitized plant-allergic patients (the sera contained IgE antibodies against most plant allergens), and rabbit antisera raised against defined recombinant plant allergens. The presence of allergens in Ginkgo extracts was determined by dot-blotting and Wester blot. Neither rabbit antisera nor IgE antibodies of patients reacted to the Ginkgo extracts. In addition, it was shown that prick testing of the skin could be conveniently used to study Gingko extracts for allergenic activity. In conclusion, no evidence for the presence of type I allergens in Ginkgo extracts was found. We recommend serological and/or skin testing to exclude sensitisation to components of Ginkgo biloba extracts.

Adult↗

PubMed2003

Quantitative analysis of bilobalide and ginkgolides from Ginkgo biloba leaves and Ginkgo products using (1)H-NMR.

1H-NMR spectrometry was applied to the quantitative analysis of the bilobalide, ginkgolides A, B, and C in Ginkgo biloba leaves and six kinds of commercial Ginkgo products without any chromatographic purification. The experiment was performed by the analysis of each singlet H-12, which were well separated in the range of delta 6.0-7.0 in the (1)H-NMR spectrum. However, the H-12 protons of bilobalide and ginkgolides may have overlapped with H-6 or H-8 protons of the Ginkgo flavonoids. Therefore, the optimum (1)H-NMR solvent for the analysis of the compound was selected through the evaluation of solvent effects on the resolution of these signals from the compounds. Acetone-d(6)-benzene-d(6) (50 : 50) was found to be the best one among the solvents evaluated. The quantity of the compounds was calculated by the relative ratio of the intensity of each compound to the known amount of internal standard (25 microgram), phloroglucinol. This method allows rapid and simple quantitation of underivatized bilobalide and ginkgolides in 5 min without any pre-purification steps.

Cyclopentanes↗

PubMed1986

[Preparation and definition of Ginkgo biloba extract].

Ginkgo biloba extract is a well-defined and complex product prepared from green leaves of Ginkgo biloba. The leaves are harvested from trees growing in plantations in South Corea, Japan and France. The mode of culture, harvesting and extraction are perfectly standardized and controlled. Analysis of Ginkgo biloba extract makes it possible to confirm that undesirable substances have been eliminated and to measure the amount of active principles. The extract contains flavonoid substances, such as the Ginkgo-flavone glycosides and terponoids which are characteristic of Ginkgo and have a unique structure (ginkgolides, bilobalide).

Chemical Phenomena↗

PubMedDate not supplied

Induction of superoxide dismutase and catalase activity in different rat tissues and protection from UVB irradiation after topical application of Ginkgo biloba extracts.

Ginkgo biloba extract (GBE) prepared from the leaves of Ginkgo biloba with 50% diluted alcohol was found to locally induce superoxide dismutase (SOD) and catalase (CAT) enzyme activity in epidermis after topical application, and also to systemically increase the activity of both enzymes in the liver, heart and kidney of Sprague Dawley rats. Skin pretreated with 50% diluted alcohol-extracted liquid formulation was protected from exacerbation of UVB damage. Changes in the lipid structure of the skin of rats determined by ATR/FT-IR spectroscopy demonstrated penetration of active components from GBE dosage formulations.

Administration, Topical↗

PubMed2004

Estrogenic activities of Ginkgo biloba extracts.

Ginkgo biloba extracts (GBE) are extracted from the leaves of Ginkgo biloba tree. GBE contains 24% of phytoestrogens, which is kaempferol, quercetin, and isorhamnetin. It has been reported that phytoestrogens could be a part of SERMs (Selective estrogen receptor modulators) and possibly the alternative HRT (Hormone replacement therapy) for postmenopausal women. The goal of this study was to investigate the potencies of GBE and its major components (quercetin, kaempferol, isorhamnetin) for estrogenic effect, which confirms the capacity as an alternative HRP. It was found that GBE and its major components exerted a dual action on ER-alpha and ER-beta in competitive binding assay. The binding affinity of these chemicals to ER-beta was higher than to ER-alpha. In the E-screen assay, these chemicals induced cell proliferation in ER-positive MCF-7 cell, but not in ER-negative MDA-MB-231 cells. The cell proliferation induced by these chemicals was blocked by tamoxifen. Also, GBE and its major components induced pS2 and PR (progesterone receptor) transcription in MCF-7 cells. Therefore these results indicated that GBE and its major components had the weak estrogenic activities through the estrogen response pathway by an interaction with the ER. In conclusion, we provided the evidence of potential estrogenic activities of GBE, which could be useful as an alternative HRP. However, further studies are required to assess the physiological significance of GBE in animals and humans.

Binding, Competitive↗

PubMed2002

Ginkgo biloba: a smart drug? A systematic review of controlled trials of the cognitive effects of ginkgo biloba extracts in healthy people.

Extracts of Ginkgo biloba are widely used to alleviate or delay the progress of age-related cognitive impairment. Its use as a "smart" drug by healthy individuals has also been commercially promoted. The aim of this study was to systematically review and critically evaluate the trial data to test whether Ginkgo biloba enhances cognitive function in healthy subjects. Literatures searches of 6 computerised databases were made for placebo-controlled, double-blind trials of the effect of standardized Ginkgo biloba extracts on cognitive function in healthy subjects. Trials published in any language were included and data were extracted independently by the authors following a standardized protocol. Nine trials were identified, and these were mainly short term. The longest had a treatment period of 30 days. Trials were mostly of good intrinsic methodological quality, but certain aspects of methodology were inadequately reported by all trials. Taken together, these studies indicate no marked or consistent positive effects of Ginkgo biloba on any particular objective measure of cognitive function. A positive subjective effect was reported only in the longest trial. It is concluded that a positive effect of Ginkgo biloba on cognitive function is not proven by data from rigorous clinical trials. The use of Ginkgo biloba as a "smart" drug cannot be recommended on the basis of the evidence available to date, and there is a particular need for further long-term trials with healthy subjects.

Cognition↗

PubMed2003

Neuroprotective effects of Ginkgo biloba extract.

Ginkgo biloba extract has been therapeutically used for several decades to increase peripheral and cerebral blood flow as well as for the treatment of dementia. The extract contains multiple compounds such as flavonoids and terpenoids that are thought to contribute to its neuroprotective and vasotropic effects. In this review, we summarize the experimental results on the mechanism of neuroprotection induced by standardized extract of Ginkgo biloba leaves (EGb 761) and its constituents. The effects described mostly in animals include those on cerebral blood flow, neurotransmitter systems, cellular redox state and nitric oxide level. Furthermore, we discuss the current status of clinical trials as well as undesired side effects of EGb 761.

Animals↗

PubMed1989

Superoxide anion scavenging effect and superoxide dismutase activity of Ginkgo biloba extract.

Ginkgo biloba extract is known to be efficient in diseases associated with free radical generation. The purpose of this work was to study, under in vitro conditions, the action of Ginkgo biloba extract (Gbe) against superoxide anion (O2-.), which is directly or indirectly implicated in cell damage. Gbe appears to have both an O2-. scavenging effect and also a superoxide dismutase activity. Its antiradical effect was demonstrated by low temperature electron spin resonance and in a non-enzymatic system (phenazine methosulfate-NADH), and its enzymatic activity was shown by polarographic determination.

Animals↗

PubMed1986

[The doyen of trees: the Ginkgo biloba].

The Ginkgo biloba tree is the sole representative of a once flourishing botanical division, that of the so-called ginkgophytes. It is in fact a living fossil, the most ancient of all trees, and this claim to fame is accompanied by numerous peculiarities as diverse as its reproduction cycle (it scatters neither seeds nor spores but ovules), its extraordinary resistance to pollution, viruses and fungi, or again its extremely original biochemistry; in particular, Ginkgo biloba leaves countain specific terpens namely bilobalide and ginkgolides.

Environmental Pollution↗

PubMedDate not supplied

Ginkgo biloba--an appraisal.

Ginkgo biloba has been used in traditional Chinese medicine for about 5000 years. A standardized preparation, EGb 761 has been recently prepared. The pharmacologically active constituents, flavonol glycosides and the terpene lactones are standardized. The terpene lactones comprise of ginkgolides A, B, C and bilobalides. The extract scavenges excess free radicals and pretreatment with EGb 761 reduces damage by free radicals in patients undergoing coronary bypass surgery. The action of platelet activating factor is antagonized and platelet aggregation is reduced. Blood flow is increased. Release of prostacyclines and nitric oxide was shown to be stimulated. Ginkgo biloba has been found to be useful in the treatment of Alzheimers disease and cognitive impairment. EGB 761 has shown beneficial effect in aging and mild cognitive impairment. Bilobalide has been shown to be protective against glutamate-induced excitotoxic neuronal death. Early studies indicate a potential role in age-related macular degeneration and some types of glaucoma. Anticancer action is related to antioxidant, anti-angiogenic and gene regulatory actions. Ginkgo biloba has shown overall improvement in about 65% of patients with cerebral impairment and a similar percentage suffering from peripheral vascular diseases. A recent study suggested that phytoestrogens in Ginkgo biloba may have a role as alternative hormone replacement therapy. Recent trials have not shown a beneficial effect of Ginkgo biloba in tinnitus and acute mountain sickness. Ginkgo biloba increased the bioavailability of diltiazem. The extract has been shown to protect against doxorubicin-induced cardiotoxicity and gentamicin-induced nephrotoxicity in animals. Ginkgo biloba inhibits microsomal enzymes and has a potential for drug interactions. Further studies to establish the efficacy of Ginkgo biloba are required.

Ginkgo biloba↗

PubMed2002

Pharmaceutical quality of different Ginkgo biloba brands.

Ginkgo biloba-containing brands are one of the top sellers within the growing market for herbal remedies in many European countries as well as in the USA. In the consumers' interest, these brands should feature a certain quality and should be transparent in quality claims. In this investigation, a variety of products on the USA market was studied with respect to pharmaceutical quality, such as quantity of constituents and in-vitro dissolution. In terms of the content of active substances, flavone glycosides ranged from 24% to 36% and terpene lactones from 4% to 11%. With ginkgolic acids, there was a very large range, from < 500 ppm to about 90000 ppm. Comparing the dissolution rates of terpene lactones and flavone glycosides within the single products, most were approximately the same. Thus, terpene lactones and flavone glycosides were released from these products and dissolved at the same rate in most cases. Furthermore, most of the products investigated released more than the required 75% of the content of both components within 30 min. However, several products showed clear and relevant differences in dissolution rates to the rest (e.g. < 75% within 30 min or even less than 25% after 60 min in one case, indicating much poorer pharmaceutical quality). Beside the comparability respectively standardisation of the extracts used, the in-vitro dissolution of the relevant constituents should be similar to other drugs to guarantee comparable in-vivo performance of herbal products. An important step in standardising pharmaceutical quality is the pharmacopoeial monograph for Ginkgo biloba extract in Germany, standardising the content of pharmacologically relevant substances (flavone glycosides 22-27% and terpenlactones 5-7%, 2.8-3.4% ginkgolides A, B, C and 2.6-3.2% bilobalide thereof). Many of the investigated products, which refer to the German Commission E (of the Federal Institute for Drugs and Medicinal Devices) monograph, are not in accordance with this specification. Thus, they can not be considered to be pharmaceutically equivalent.

Chromatography, High Pressure Liquid↗

PubMed1986

[Neuromediator changes during cerebral aging. The effect of Ginkgo biloba extract].

Ginkgo biloba extract exerts a specific effect on the noradrenergic system and on beta-receptors. No variation was found in alpha 2-receptors and serotonin uptake. These findings provide the first evidence of central effects of a drug acting on cerebral ageing, connected specifically to reactivation of the noradrenergic system in the cerebral cortex.

Aging↗