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At least 19 recordsLinked to original sources
PubMed1993

[Biological standardization of Ginkgo extracts].

The determination of the inhibition of PAF (platelet-activating factor)-induced platelet aggregation has been proposed as a biological standardization method for commercially available Ginkgo biloba extracts by measuring the characteristic pharmacological effect of ginkgolides in vitro. The determination is specific for ginkgolides A, B, C, and J and is not influenced by other constituents present in Ginkgo biloba extracts. IC50 values of ginkgolide B can be used to standardize various Ginkgo extracts produced by special extraction methods with respect to equi-effective ginkgolide B contents. In order to compare values obtained by a chemical-analytical procedure with those obtained by the biological assay, the equi-effective total ginkgolide content of each Ginkgo extract had to be calculated. Accordingly, the concentrations of the individual ginkgolides in the various Ginkgo extracts were determined chromatographically by assaying ginkgolides as trime-thylsilyl derivatives. Their individual contributions towards the measured in vitro effects were derived from their respective IC50 values. The calculated equi-effective total ginkgolide contents of the Ginkgo extracts were in good agreement with those obtained by gas chromatography. The results demonstrate that, in addition to a chemical standardization, the biological standardization of Ginkgo extract preparations is also feasible.

Lactones↗
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↗
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↗
PubMed1988

Influence of the specific antagonist of PAF-acether, BN 52021, and of Ginkgo extract on the rejection of murine tail skin allografts and the PAF-acether mortality in mice in particular consideration of the role of TXB2.

An oral application of 2 x 10 mg/kg daily of the PAF antagonist, BN 52021, significantly prolonged the distal allograft survival in the murine tail skin model of cell-mediated allograft rejection. BN 52021 diminished the TXB2 content in the skin at and near to the transplantation site by two thirds whereas PAF-acether significantly enhanced the TXB2 content in murine tail skin. Similar to the tail skin BN 52021 also reduced by more than 70% the TXB2 release from human granulocytes stimulated by calcium ionophore A 23187. The PAF-acether mortality (LD75) in NMRI mice was decreased to 20% by BN 52021 with a lower dose than by BN 52020. Comparing Ginkgo total extract in doses which significantly diminished the 75% mortality by PAF-acether in mice with BN 52021 and BN 52020 in doses that produced the same inhibitory effect, a potentiated effect of Ginkgo extract resulted with respect to the share of BN 52021 and BN 52020 in Ginkgo extract.

Animals↗
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↗
PubMed1994

[Ginkgo extract EGb 761 (tenobin)/HAES versus naftidrofuryl (Dusodril)/HAES. A randomized study of therapy of sudden deafness].

80 patients with idiopathic sudden hearing loss existing no longer than 10 days were included in a randomised reference-controlled study. The therapeutic value of Ginkgo EGb 761 (Tebonin) + HAES was compared to that of Naftidrofuryl (Dusodril)+HAES. The main mechanisms of action of EGb 761 are a vasoregulating activity (increased blood flow), the platelet activating factor antagonism and a prevention of membrane damage caused by free radicals. Naftidrofuryl has antiserotonergic and therefore vasodilatory properties. The statistical analysis of the audiometric data was performed in measuring the relative hearing gain as described by Eibach 1979. After one week of observation, 40% of the patients in each group showed a complete remission of hearing loss. This was also observed by other authors who had compared other drugs. Therefore, in these cases, it is most likely that spontaneous recovery is the most important factor. After two and three weeks of observation, measuring the relative hearing gain, there was a significant borderline benefit of EGb 761 (p = 0.06) without any side effects. Some patients of the reference group developed side effects such as orthostatic dysregulation or headache or sleep disturbances. Minimising side effects should be one of the most important goals in therapy of sudden hearing loss until the efficiency of infusion therapy is proved.

Adult↗
PubMed1992

[Superoxide dismutase activity of Ginkgo biloba extract].

The Ginkgo biloba extract is obtained from green leaves of the Ginkgo biloba tree. Preparations with this active substance are among others used for the treatment of disturbances of the cerebral function and arteriosclerotic diseases. In in-vitro and in-vivo studies antagonistic effects of radical scavenger and PAF (platelet activating factor) were described. In this study a concentration-depending superoxide dismutase activity of the Ginkgo biloba extract rökan liquid could be made evident.

Diterpenes↗
PubMedDate not supplied

Effect of two doses of ginkgo biloba extract (EGb 761) on the dual-coding test in elderly subjects.

The subjects of this double-blind study were 18 elderly men and women (mean age, 69.3 years) with slight age-related memory impairment. In a crossover-study design, each subject received placebo or an extract of Ginkgo biloba (EGb 761) (320 mg or 600 mg) 1 hour before performing a dual-coding test that measures the speed of information processing; the test consists of several coding series of drawings and words presented at decreasing times of 1920, 960, 480, 240, and 120 ms. The dual-coding phenomenon (a break point between coding verbal material and images) was demonstrated in all the tests. After placebo, the break point was observed at 960 ms and dual coding beginning at 1920 ms. After each dose of the ginkgo extract, the break point (at 480 ms) and dual coding (at 960 ms) were significantly shifted toward a shorter presentation time, indicating an improvement in the speed of information processing.

Aged↗
PubMed1994

The nitric oxide-scavenging properties of Ginkgo biloba extract EGb 761.

Ginkgo biloba extract EGb 761 was found to be a scavenger of nitric oxide in in vitro acellular systems, under physiological conditions. EGb 761 competed with oxyhemoglobin for reaction with nitric oxide generated during the interaction of hydroxylamine with Complex I of catalase. An EGb 761 dose-dependent decrease in the amount of nitrite formed in the reaction of oxygen with nitric oxide produced from solution of 5 mM sodium nitroprusside was also observed. These data implicate it as a potential therapeutic agent in conditions of altered production of nitric oxide.

Animals↗
PubMed1989

[Efficacy of an extract of Ginkgo biloba in the treatment of chronic obliterating arteriopathies of the lower limbs in stage III of Fontaine's classification].

UNLABELLED: A controlled trial of Ginkgo biloba extract in injectable form (Tanakan 50 mg, a lyophilizate for parenteral use) was carried out versus a placebo as a preoperative medical treatment of stage III (Fontaine classification) chronic occlusive arterial disease of the lower limbs (with pain in decubitus). The 64 men and women patients in this multicenter study (32 in each group) were over 18 years of age and had a cultural and intellectual level as well as a physical condition allowing them to play an active role in the experiment (self-evaluation of pain). During 8 days they received two daily infusions of 500 cc of normal saline solution containing either 100 mg of Ginkgo biloba extract or a placebo of identical appearance. During this period, anticoagulants were authorized; hemodilution, vasoactive drugs and platelet anti-aggregates were forbidden; pentazocine (Fortal, 50-mg tablets) was allowed at the patient's request. Pain was rated according to a visual scale, with each patient marking a point between two extremes ("maximum imaginable pain" and "total absence of pain") 100 mm apart. A questionnaire based on that of Melzack (McGill Pain Questionnaire) completed this qualitative as well as quantitative self-evaluation of pain. The results of these questionnaires were assessed on the basis of 4 scores, each determined by the patient's choice among 3 evaluation figures. The chi square, Student and Wilcoxon tests were used for statistical analysis. RESULTS: The two randomly-composed groups with Ginkgo biloba extract and a placebo were comparable (Table I). Analysis was based on 55 observations (26 in the extract group and 29 in the placebo group).(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial Occlusive Diseases↗
PubMed1990

[Drug therapy of disorders of cerebral performance. Randomized comparative study of dihydroergotoxine and Ginkgo biloba extract].

In a randomized trial lasting six weeks and involving 80 elderly patients with cerebrovascular disorders, the effectiveness and tolerance of dihydroergotoxine was compared with an extract of Ginkgo biloba. On the basis of psychometric tests and assessment scales, it was shown that treatment with either substance improved the condition of the patients. While, for the most part, intergroup comparison revealed no major statistically significant differences, such changes, affecting various parameters, were found during follow-up--more frequently within the dihydroergotoxine group than within the group treated with Ginkgo biloba extract.

Aged↗
PubMed1995

Lipid peroxide, phospholipids, glutathione levels and superoxide dismutase activity in rat brain after ischaemia: effect of ginkgo biloba extract.

The influence of ginkgo biloba extract on the lipid peroxide product (malondialdehyde, MDA), glutathione (GSH) and phospholipids levels as well as superoxide dismutase (SOD, 1.15.1.1) and lactate dehydrogenase (LDH, 1.1.1.27) activities in rat brain after occlusion of common carotid arteries was investigated. Two experimental models were studied: 60 min ischaemia without reperfusion and 60 min ischaemia followed by 60 min reperfusion. Compared to sham-operated animals, ischaemia followed by reperfusion increased cytosolic LDH activity and mitochondrial lipid peroxide content and decreased the superoxide dismutase activity and mitochondrial total phospholipids level. Preischaemic administration of ginkgo biloba extract (150 mg kg-1, p.o.) could normalize the SOD activity of the rat brain. The extract was also able to reduce the lipid peroxide and phospholipids contents of the mitochondrial rat brain. These effects could be explained on the basis of the antioxidant property of ginkgo biloba extract and suggests its beneficial role in the protection against post-ischaemic injury.

Animals↗
PubMed1995

Protection of polyunsaturated fatty acids against iron-dependent lipid peroxidation by a Ginkgo biloba extract (EGb 761).

Iron can induce a peroxidative degradation of the membrane polyunsaturated fatty acids by the well-known Fenton reaction. Chelated iron can also form a complex with oxygen, called perferryl ion, which is able to induce lipoperoxidation without a detectable production of hydroxyl radicals. The antioxidant properties of a titrated and standardized extract of Ginkgo biloba leaves (EGb 761) against iron-dependent peroxidative degradation of the membrane polyunsaturated fatty acids were studied. Rat liver microsomes were exposed to a mixture of NADPH, ADP and FeCl3 hypothesized to produce iron-oxygen complexes. The results of the analysis of the microsomal polyunsaturated fatty acids by gas chromatography show that the susceptibility to peroxidation of the different polyunsaturated fatty acids increases with their unsaturation level, and that EGb 761 protects these membrane polyunsaturated fatty acids regardless of their susceptibility to peroxidation. This protective effect is correlated with the decrease in the thiobarbituric acid-reactive substances concentration, but the calculation of the antioxidant potency of EGb 761 as an IC50 value using results of the thiobarbituric acid reaction leads to an underestimated evaluation when the reaction is carried out in the presence of iron ions.

Animals↗
PubMed1995

Efficiency of Ginkgo biloba extract (EGb 761) in antioxidant protection against myocardial ischemia and reperfusion injury.

The cardio-protective mechanisms of EGb 761, an extract of Ginkgo biloba leaves, on myocardial ischemia-reperfusion injury were investigated using rabbits subjected to 30 minutes of regional cardiac ischemia and 120 min of reperfusion under anesthesia. Compared to the saline perfused group, EGb 761 treatment (10 mg/kg, injected into the coronary artery) significantly inhibited the increase in lipid peroxidation and maintained total and CuZn-SOD levels in both plasma and tissue during and at the end of reperfusion. Both the decrease in tissue type plasminogen activator (t-PA) and the increase in plasminogen activator inhibitor-1 (PAI-1) caused by ischemia-reperfusion were also significantly suppressed by EGb 761 treatment. Furthermore, the ultrastructure of the myocytes of the EGb 761 treated heart was slightly damaged after ischemia-reperfusion, while the control ischemic-reperfused hearts demonstrated severe histological damages such as swelling and vacuolization of the mitochondria. These results suggest that EGb 761 protects hearts by its antioxidant properties and by its ability to adjust fibrinolytic activity.

Animals↗
PubMed1995

Peroxyl radical scavenging activity of Ginkgo biloba extract EGb 761.

Antioxidant mechanisms have been proposed to underlie the beneficial pharmacological effects of EGb 761, an extract from Ginkgo biloba leaves used for treating peripheral vascular diseases and cerebrovascular insufficiency in the elderly. In vitro evidence has been reported that EGb 761 scavenges various reactive oxygen species, i.e. nitric oxide, and the superoxide, hydroxyl, and oxoferryl radicals. However, the ability of EGb 761 to scavenge peroxyl radicals (reactive species mainly involved in the propagation step of lipid peroxidation) has not been investigated. To characterize further the antioxidant action of EGb 761, we measured the protective effects of EGb 761 during: (1) the oxidation of B-phycoerythrin by peroxyl radicals generated in aqueous solution by 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH); and (2) the reaction of luminol or cis-parinaric acid with peroxyl radicals generated from 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN) in liposomes or in human low density lipoprotein (LDL), respectively. To evaluate the peroxyl radical scavenging activity of EGb 761 in a more physiologically relevant model of damage to lipid-containing systems, we also analyzed the effect of the extract on the oxidation of human LDL exposed to the azo-initiators in terms of: (1) accumulation of cholesterol linoleate ester hydroperoxides, (2) depletion of alpha-tocopherol and beta-carotene, and (3) changes in intrinsic tryptophan fluorescence. EGb 761 afforded protection against oxidative damage in all the systems we analyzed; thus, it is an efficient scavenger of peroxyl radicals. This result extends the oxygen radical scavenging properties of the extract and supports the hypothesis of an antioxidant therapeutic action of EGb 761.

Amidines↗
PubMed1997

Interactions of Ginkgo biloba extract (EGb 761), diazepam and ethyl beta-carboline-3-carboxylate on social behavior of the rat.

The social interaction test was used to examine the effects of an extract of Ginkgo biloba (EGb 761) and its possible interactions with diazepam and ethyl beta-carboline-3-carboxylate (beta-CCE). Pairs of naive (unfamiliar) male Wistar AF rats subjected to the same treatment were placed in a novel test arena that was brightly illuminated, and the duration (in s) of social contact was observed over a 10 min period. Single injections of EGb 761 (8-16 mg/kg, i.p.), given 30 min prior to testing, or repeated oral administration of the extract (48 or 96 mg/kg/day) for 8 days, significantly decreased social contact under conditions that did not influence locomotor activity. Injection of diazepam (1 mg/kg, i.p.), 30 min before testing, significantly increased social contact. Injection of diazepam to animals that had received repeated oral treatment with EGb 761 (96 mg/kg/ day) increased social interaction to an extent greater than observed with diazepam alone. Injection of beta-CCE (2-16 mg/kg, i.p.), 15 min before testing, significantly decreased social contact. When the animals were treated with EGb 761 (48 or 96 mg/kg/day, p.o. for 8 days) and beta-CCE (4 mg/kg), both of which decreased social interaction when administered alone, the resulting level of social contact was similar to that of control animals. Interactions with certain sites of central GABAA/ benzodiazepine/Cl- channel receptor complexes could be involved in mediating these effects of EGb 761, diazepam and beta-CCE.

Animals↗
PubMedDate not supplied

Effects of Ginkgo biloba extract (EGb 761) on arteriolar spasm in a rat cremaster muscle preparation.

The effects of an extract of Ginkgo biloba (EGb 761) on arteriolar spasm were confirmed using a preparation of rat cremaster muscle. When vasospasm was induced by rat serum, arteriolar constriction reached 25-30% of the initial diameter after 10 min. Intravenous injection of EGb 761 (30 mg/kg) 5 min after inducing spasm inhibited about 80% of this serum-induced vasoconstriction. As previous studies have shown that EGb 761 has an antiaggregatory effect on platelets, thrombin, serotonin (platelet-derived compounds that are present in the serum) and a thromboxane analogue (U46619) were also used to induce vasospasm. Administration of EGb 761 (30 mg/kg) 5 min after exposure of the preparation to serotonin (10(-3) M) or 10 min after exposure to thrombin (20 units) did not affect vasospasm induced by these agents. In contrast, treatment with this same dose of EGb 761 5 min after exposure of the preparation to U46619 (10(-4) M) abolished the arteriolar constriction induced by this agent in 15 min. The thromboxane/prostaglandin H2 receptor antagonist SQ29548 antagonized serum-induced vasospasm, indicating an involvement of thromboxane. Other experiments indicated that the effects of EGb 761 of counteracting vasospasm may be mediated in part by ginkgolide B, a triterpene constituent of the extract that is an antagonist of platelet-activating factor and in part by an 'NO-like' action of its proanthocyanidin constituents. Taken together, these results have revealed that EGb 761 treatment can antagonize the vasoconstrictor effect of thromboxane on arterioles. As thromboxane is implicated in many cardiovascular disorders, this property of EGb 761 may explain some of its beneficial clinical effects in such pathologies.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1986

[From the body to the cell membrane: the different levels of pharmacological action of Ginkgo biloba extract].

The pharmacological study of Ginkgo biloba extract has required numerous experiments over several years: different pathological models of cerebral ischaemia to evaluate its effects, and experiments at both cellular and molecular levels to determine its mechanisms of action. In experimental models of ischaemia, oedema and hypoxia, Ginkgo biloba extract reduced vascular, tissular and metabolic disturbances as well as their neurological and behavioural consequences. The pharmacological effects of Ginkgo biloba extract concern vascular, rheological and metabolic processes. Several membrane mechanisms seem to be involved: protection of the membrane ultrastructure against free radicals, modulation of some enzymatic systems and ionic pumps. The originality of the pharmacological properties of Ginkgo biloba extract lies in preferential focusing of its effects on ischaemic areas.

Aging↗