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PubMed1986

[Protective effects of Ginkgo biloba extract on the early rupture of the hemato-encephalic barrier in the rat].

During the hours immediately following an hypertensive burst or a cerebral ischemia induced by the intracarotid administration of microspheres, damage to the blood brain barrier can be observed with molecules of low molecular weight, such as angiotensin, whereas albumin or large proteins will not yet have been able to cross over and there is virtually no edema. Gingko biloba extract causes the brain uptake index of angiotensin hypertensive animals. This effect is proportional to the dose of extract used (500-100 mg/kg). A similar effect can be observed in animals showing embolism in one hemisphere. The process can therefore doubtlessly be explained by the stabilizing effect of Ginkgo biloba on membranes.

Angiotensin II↗
PubMed2001

The in vivo neuromodulatory effects of the herbal medicine ginkgo biloba.

Extracts of Ginkgo biloba leaves are consumed as dietary supplements to counteract chronic, age-related neurological disorders. We have applied high-density oligonucleotide microarrays to define the transcriptional effects in the cortex and hippocampus of mice whose diets were supplemented with the herbal extract. Gene expression analysis focused on the mRNAs that showed a more than 3-fold change in their expression. In the cortex, mRNAs for neuronal tyrosine/threonine phosphatase 1, and microtubule-associated tau were significantly enhanced. Hyperphosphorylated tau is the major constituent of the neurofibrillary tangles in the brains of Alzheimer's disease patients. The expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-2, calcium and chloride channels, prolactin, and growth hormone (GH), all of which are associated with brain function, were also up-regulated. In the hippocampus, only transthyretin mRNA was upregulated. Transthyretin plays a role in hormone transport in the brain and possibly a neuroprotective role by amyloid-beta sequestration. This study reveals that diets supplemented with Ginkgo biloba extract have notable neuromodulatory effects in vivo and illustrates the utility of genome-wide expression monitoring to investigate the biological actions of complex extracts.

Animals↗
PubMed1975

[The influence on sound damages by an extract of ginkgo biloba (author's transl)].

A fraction of Ginkgo biloba, used in experiments with animals ensured significantly the diminution of sound damages caused by white noise or by a pure tone of 4.5 kHz. Higher amplitudes of the acoustic nerve potentials show the protective effect of this fraction of Ginkgo biloba at acute sound damages. It is moreover possible to hold physiologically the adaptation of excitation of the hair cells of the organ of Corti by the fraction of Ginkgo biloba before and after sound damage caused by white noise or during a pure tone of 4.5 kHz. The influence of the fraction of Ginkgo biloba can be seen by a significantly slower recovery of the noise damaged evoked potentials of the acoustic cortex. An efferent protective influence on the neurons of the acoustic cortex is discussed. The fraction of Ginkgo biloba in this form of solution has not been tested for clinical use but it seems to be rich in meaning.

Animals↗
PubMed1999

[Experimental studies of the protective effect of ginkgo biloba extract (GBE) on cisplatin-induced toxicity in rats].

Cisplatin (CDDP) is an effective antineoplastic agent in the treatment of solid malignant tumors. Its clinical use, however, is limited because of various side effects including sensorineural hearing loss. Several agents have been proposed to reduce these side effects. GBE has recently been reported to scavenge superoxide and hydroxyl radicals, resulting in a reduction of lipid peroxidation. GBE is expected to protect against CDDP-induced toxicity because its generative mechanism is thought to be associated with free-radical formation. The purpose of the present study was to evaluate GBE's efficacy as a protective agent against cisplatin-induced ototoxicity. Fisher rats were used in this study and were divided into three treatment groups: 1) animals administered 1.0 mg of CDDP per kg for 10 days (Group I), 2) animals receiving 100 mg of GBE per kg 90 min before administration 1.0 mg of CDDP per kg (Group II) and 3) a vehicle control (Group III). First, the protective effect of GBE on CDDP-induced ototoxicity was investigated. The auditory threshold was evaluated by means of the compound action potential (CAP) recording. After CAP recordings, cochlear sensory epithelia were observed throughout the cochlea by scanning electron microscopy. In Group II, the elevation of CAP thresholds at 12 kHz, 16 kHz, 20 kHz and the missing rate for the outer hair cells were significantly reduced as compared to those in Group I. These data suggest that GBE is effective for otoprotection against CDDP. Second, the protective effect of GBE on CDDP-induced nephrotoxicity was evaluated. Nephrotoxicity was evaluated by means of measurement of serum BUN and creatinine and histopathological examination of the kidney. These were significant differences in serum BUN and creatinine levels between Group I and Group II. Third, the influence of GBE against the antitumor effect of CDDP was researched in the rats inoculated subcutaneously with SCC-158 squamous cell carcinoma cells. There was no difference in tumor growth rate (TGR) between Group I and Group II. The result suggested that the combined administration had no influence on the antitumor activity of CDDP. In conclusion, the co-administration of CDDP with GBE is beneficial to ameliorate CDDP-induced toxicity without attenuation of CDDP antitumor activity.

Animals↗
PubMed2002

Sensitization of human neutrophil defense activities through activation of platelet-activating factor receptors by ginkgolide B, a bioactive component of the Ginkgo biloba extract EGB 761.

Ginkgolide B (GKB, BN 52021) was described as a platelet-activating factor (Paf) receptor antagonist. However, it is not known whether all GKB biological effects are mediated through Paf receptor antagonism only. To gain insight into the drug mode of action, we investigated here the effects of GKB per se on functional and signaling activities in human polymorphonuclear leukocytes (PMN). Treatment of PMN with GKB (0.5-12 microM) stimulates a rapid and weak production of reactive oxygen species determined by chemiluminescence. ROS production required the activation of protein kinase C (PKC), tyrosine kinases and p38 mitogen-activated protein kinase as indicated by inhibitory effects of, respectively, GF 109203X (IC(50) of 0.5 microM), genistein (IC(50) of 0.5 microM) and SB 203580 (IC(50) of 0.2 microM) or SB 202190 (IC(50) of 1.1 microM). GKB stimulated a Pertussis toxin-sensitive PLD activity assessed by the formation of tritiated phosphatidic acid and choline. By contrast, GKB did prevent the Paf-mediated PLD activity and CL response (IC(50) of 2 microM). Interestingly, both GKB and Paf-induced CL response were prevented by selective Paf antagonists such as CV 6209 or WEB 2086 indicating that GKB may directly activate Paf receptors. Finally, GKB potentiated the CL response induced by fMet-Leu-Phe and zymosan. These results show that GKB is the first partial agonist of the Paf receptor described so far capable of priming the polymorphonuclear leukocyte function.

Azepines↗
PubMed1998

The pharmacological effects of ginkgo biloba, a plant extract, on the brain of dementia patients in comparison with tacrine.

In 1994, a standardized dry extract of Ginkgo biloba leaves (SeGb), has been approved by German health authorities for the treatment of primary degenerative dementia and vascular dementia. More than 24 different brands of Ginkgo biloba extract are sold in the United States. Tacrine, also known as tetrahydroaminoacrine (THA), and donepezil are currently the only drugs approved in the United States for the treatment of Alzheimer's disease. Previous studies demonstrated that SeGb and tacrine induce significant pharmacological effects on the brains of young, healthy human males, as determined by bioelectrical activity measurements obtained using the quantitative pharmaco-electroencephalogram (QPEEG) method. The type of central nervous system (CNS) effects we have seen on computer-analyzed EEGs (CEEGs) after administration of tacrine or EGb suggests both are "cognitive activators" which are, as a class of products, characterized by a (prepost) relative increase of 7.5 to 13 Hz ("alpha") and decrease of 1.3 to 7.5 Hz ("delta" and "theta") activity. To determine whether EGb or tacrine had noticeable pharmacological effects on elderly subjects diagnosed with possible or probable Alzheimer's, the present open, uncontrolled trial was conducted. Data from 18 subjects (11 males, 7 females) at an average age of 67.4 years with light to moderate dementia (Mini Mental mean score = 23.7, ranges: 15-29 [Geriatric Depression Scale mean scores = 3.7; range: 3.2-5.4]) were analyzed for this presentation. Each subject was randomly administered a single oral "Test-Dose" of either 40 mg of tacrine or 240 mg of EGb2 in two separate sessions within 3- to 7-day intervals. Before drug administration and at 1- and 3-hour intervals after drug administration, CEEGs were recorded for a minimum of 10 minutes. The CEEGs were analyzed using Period Analysis programs we developed for QPEEG. The results indicated that both EGb and, to a lesser degree, tacrine induced pharmacological effects, as established by QPEEG measurements, in the CNS similar to those previously established in healthy, young subjects. The type of CNS effects produced by EGb (as established by HZI's CEEG psychotropic drug database) in elderly dementia patients were similar to those induced by tacrine responders as well as those seen after the administration of other "cognitive activators" (pramiracetam, vinpocetine, BMY-21502, suloctidil, and lisuride) and anti-dementia drugs approved in the United States or Europe (tacrine, donepezil, nimodipine, piracetam, and oxiracetam) from our database. The results also showed that 240 mg of EGb has typical cognitive activator CEEG profiles (responders) in more subjects (8 of 18) than 40 mg tacrine (3 of 18 subjects). Because of the small sample size, we could not test the hypothesis that subjects who showed cognitive activator-type pharmacological response to the first Test-Dose of EGb or tacrine also exhibit more therapeutic effects (compared to nonresponders) when drugs are administered chronically.

Aged↗
PubMed1999

Inhibitory effect of Ginkgo biloba extract on human platelet aggregation.

The effect of pure flavonoids and Gingko biloba extract (GBE) on human platelet aggregation was investigated. Most of the flavonoids and vitamin E did not affect platelet aggregation in platelet-rich plasma (PRP); however some of these flavonoids inhibited platelet aggregation in gel-filtered platelets (GFP). GBE inhibited both ADP- and collagen-induced platelet aggregation in PRP, GFP and in whole blood in a dose-dependent manner. GBE at very low concentrations inhibited whole blood aggregation induced by ADP compared with those used for PRP or GFP. Flavonoids and GBE decreased the production of TxA(2) induced by collagen and ADP in PRP. However, no correlation was observed between the inhibition of platelet aggregation and the decrease of TxA(2) synthesis. GBE and flavonoids did not affect platelet membrane fluidity. However, the incubation of PRP with GBE increased cAMP levels in platelets, which is known to inhibit platelet activation by lowering intracellular Ca2+ levels. GBE is a mixture of many compounds, including flavonoids and gingkoglides, which affect metabolism of cAMP, TxA(2) and Ca2+ in platelets. It is effective in the inhibition of platelet aggregation, both in PRP and whole blood, and thus may be potentially used as an effective oral anti-platelet therapeutic agent.

Journal Article↗