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Ginkgo biloba extract EGb 761 protects against mitochondrial aging in the brain and in the liver.

According to the free radical theory of aging, oxygen-derived free radicals causes the age-associated impairment at the cellular and tissue levels. The mitochondrial theory of aging points to mitochondria, and specially mitochondrial DNA, as the major targets of free radical attack upon aging. Thus, oxidative damage to mtDNA accumulate with age in human and rodent tissues and also is inversely related to maximum life span of mammals. Mitochondrial deficits, such as a decrease in mitochondrial membrane potential, occur upon aging due to oxidative damage. The age-related mitochondrial oxidative stress may be prevented by late onset administration of certain antioxidants, such as Ginkgo biloba extract EGb 761. These antioxidants may also delay the physiological impairment associated with aging.

Aging↗

Ginkgo biloba extract (EGb 761): inhibitory effect on nitric oxide production in the macrophage cell line RAW 264.7.

The present study was conducted to evaluate the effect of Ginkgo biloba extract (EGb 761) on the synthesis of nitric oxide (NO) induced by lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma) in the mouse macrophage cell line RAW 264.7. EGb 761 inhibited nitrite and nitrate production, taken as an index for NO, in a concentration-dependent fashion. The IC50 for inhibition of nitrite production by activated macrophages was about 100 micrograms/mL EGb 761. The inducible NO synthase (iNOS) enzyme activity of cytosolic preparations from activated RAW 264.7 cells was inhibited by treatment with EGb 761. In addition, reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the expression of iNOS mRNA in activated macrophages was suppressed by high concentrations of EGb 761. However, NF-kappa B DNA binding activity induced by activation with LPS/IFN-gamma was not inhibited by EGb 761. These findings indicate that not only does EGb 761 directly act as an NO scavenger but also that it inhibits NO production in LPS/IFN-gamma-activated macrophages by concomitant inhibition of induction of iNOS mRNA and the enzyme activity of iNOS. Thus, EGb 761 may act as a potent inhibitor of NO production under tissue-damaging inflammatory conditions.

Animals↗

Progress in researches on the pharmaceutical mechanism and clinical application of Ginkgo Biloba extract on various kinds of diseases.

Progress made over the pharmaceutical mechanism and clinical application of Ginkgo Biloba extract (GBE) on various kinds of diseases were reviewed in this paper. The effective elements contained in GBE are mainly kinds of Ginkgo flavonoid and Ginkgolide, which have marked protective effects on cardio-cerebral vascular and central nerve systems. In clinical practice, it is applied mostly in treatment of cardio-cerebral vascular diseases. Also it shows apparent effects in the treatment processes of some other diseases as an adjuvant, and therefore, has been gradually accepted by the medical circle in the world, proving to be a medicine of wide prospect in development and application.

Cardiovascular Diseases↗

The effect of the ingestion of Ginkgo biloba extract (EGb 761) on the pharmacokinetics of metformin in non-diabetic and type 2 diabetic subjects--a double blind placebo-controlled, crossover study.

BACKGROUND & AIMS: Ginkgo biloba extract (EGb 761) has been shown to ameliorate some defects associated with the insulin resistance syndrome and so patients with Type 2 diabetes mellitus (T2DM) may be inclined to co-ingest the herb with their medications, such as metformin. This study was designed to determine if the co-ingestion of EGb 761 and metformin would alter the pharmacokinetic properties of metformin in T2DM patients and persons without diabetes, who may ingest it for other purposes. METHOD: Normal glucose tolerance (NGT) subjects (n=10; age, 39.2+/-14.0 years; fasting plasma glucose (FPG), 90+/-7 mg/dl; body mass index (BMI), 24.1+/-3.7 kg/m(2)) and 10 T2DM patients (n=10; age, 51.7+/-8.9 years; FPG, 150+/-7 mg/dl; BMI, 33.7+/-5.7 kg/m(2)) completed a randomized, double-blind, placebo-controlled crossover study. They ingested either EGb 761 (12 0mg/day as a single dose) or a vegetable-based placebo during each arm for 3 months. At the end of each arm, the NGT subject ingested a single 500 mg dose of metformin (non-diabetics) and the T2DM subject took his/her prescribed metformin dose (250-850 mg) with 120 mg EGb 761. Blood and urine samples were collected over an 8-h period, and in the case of T2DM subjects, additionally over the first 2h of the subsequent 3 days. RESULTS: Ingestion of EGb 761 produced no significant changes in diagnostic laboratory tests in either group, except reducing glycosylated hemoglobin A(1c) levels (from 7.7+/-1.2 to 7.2+/-0.9%, P<0.05) in T2DM the subjects. The pharmacokinetic parameters of metformin were all significantly different (P<0.05) between the NGT (500 mg) and 8 out of 10 of the T2DM subjects who were prescribed 500 mg of metformin during the placebo cycles. During the EGb 761 cycles, only the elimination half-life in the T2DM subjects was significantly increased (0.117+/-0.085 to 0.141+/-0.100, P<0.05). CONCLUSION: The co-ingestion of 120 mg of EGb 761 and 500 mg of metformin did not significantly affect the pharmacokinetic properties of metformin. Further studies are required to verify this observation for smaller and larger dose of metformin with other doses of EGb 761, since T2DM patients on medication constitute a very heterogeneous group.

Adult↗

[Comparison of the inhibitory activities of salvianolic acid B and Ginkgo biloba extract EGb 761 on neurotoxicity of beta-amyloid peptide].

AIM: To compare the effects of salvianolic acid B (Sal B) and Ginkgo biloba extract EGb 761 on beta-amyloid peptide (beta-AP) fibril formation and cytotoxicity to PC12 cells. METHODS: The inhibitory effects of Sal B and EGb 761 on beta-AP1-40 fibril formation were determined by using fluorescence analysis with Thioflavin T (ThT) and electron microscopic image. beta-AP25-35 was aged by incubating at 37 degrees C for 7 d, then the protein was incubated with PC12 cells. The protective effects of Sal B and EGb 761 against cytotoxicity induced by aged beta-AP25-35 in PC12 cells were evaluated by MTT reduction assay and flow cytometric analysis. beta-AP25-35-induced accumulation of intracellular reactive oxygen species (ROS) was determined by fluorescence analysis. RESULTS: Both Sal B and EGb 761 inhibited the formation of amyloid fibrils, protected PC12 cells from beta-AP25-35-induced cytotoxicity, and decreased ROS accumulation caused by beta-AP25-35. The effective doses of Sal B were far lower than those of EGb 761. CONCLUSION: Sal B was much more efficient than EGb 761 in inhibiting beta-AP aggregation and in protecting PC12 cells from beta-AP-induced cytotoxicity.

Amyloid beta-Peptides↗

Evidence that the ginkgo biloba extract, EGb 761, neither accelerates nor enhances the rapid compensation of the static symptoms of unilateral vestibular deafferentation in guinea pig.

The concentrated Ginkgo biloba extract, EGb 761, has previously been reported to enhance and accelerate vestibular compensation following unilateral vestibular deafferentation (UVD), in particular, compensation of the dynamic postural symptoms such as locomotor dysequilibrium. However, many of these studies have not included a complete analysis of the static symptoms of UVD, such as spontaneous nystagmus (SN), yaw head tilt (YHT), and roll head tilt (RHT), nor have they included a dose-response analysis or vehicle controls for EGb 761. The aim of the present study was to examine the effects of the EGb 761 extract on static vestibular compensation in guinea pig, using a dose-response analysis and both vehicle and saline controls. Analysis of variance showed that there was a significant decrease in SN frequency (P < 0.05) and a significant change in the rate of SN compensation (P < 0.05), using 3 i.p. injections of EGb 761 (25, 50, or 100 mg/kg), or vehicle, or saline, at 0, 25, and 40 h post-UVD. However, post-hoc testing revealed that this was due entirely to significant differences between the saline and vehicle groups at 35, 40, and 50 h post-UVD (P < 0.05 in all cases) and between the saline and the 100 mg/kg and 25 mg/kg EGb 761 groups at 35 and 50 h post-UVD, respectively (P < 0.05 for both comparisons); there were no significant differences between the vehicle and drug groups at any time. YHT and RHT were not significantly different between the drug, saline, and vehicle groups. In a second set of experiments, the 50 and 100 mg/kg EGb 761 i.p. injection frequencies were doubled. However, once again, neither SN nor YHT were significantly different between the EGb 761 groups and the vehicle controls. These results suggest that 1) EGb 761 does not significantly enhance or accelerate compensation of the static symptoms of UVD in guinea pig and 2) the EGb 761 vehicle may exert some effects on its own. Therefore, EGb 761 may be of limited use in the treatment of acute vestibular dysfunction in humans.

Animals↗

Effect of Ginkgo biloba extract, EGb 761, on the cellular immune response in a hypothalamic-pituitary-adrenal axis activation model in the rat.

We evaluated the effects of Ginkgo biloba extract (EGb 761) on the cellular immune response of rats with immunosuppression induced by activation of the hypothalamic-pituitary-adrenal (HPA) axis. Groups of five rats were subjected to chronic stress by the application of daily electric shocks (ES) over 7 days. This stress produced a significant decrement in the delayed-type hypersensitivity response (DTH) to dinitrofluorobenzene (DNFB), and a decrease in the proliferation index of splenocytes. Treatment with oral doses of the phytopharmaceutical EGb 761 (100 mg/kg per day over 7 days) restored both the DTH response to DNFB and the proliferation index. EGb 761 has stress-alleviating properties through its moderation of corticosterone levels. It also possesses antioxidant activity that may contribute to its effects on the immune response. Our observations indicate that the phytopharmaceutical EGb 761 possesses immunostimulatory properties.

Animals↗

Induction of glutathione synthesis in human keratinocytes by Ginkgo biloba extract (EGb761).

The objective of the present study was to characterize the action of Ginkgo biloba extract (EGb761) and its sub-fractions on glutathione homeostasis in a human keratinocyte cell culture model. Cells were incubated with EGb761, its purified flavonoid (quercetin, kaempferol, rutin) or terpenoids (gingkolides A, B, C, J, bilobalide) constituents or the vehicle for up to 72 hours. Incubation of keratinocytes with the purified flavonoids or terpenoids did not affect cellular GSH levels. However, EGb761 treatment (up to 200 microg/ml) resulted in a dose-dependent increase of cellular GSH. Western blot analysis of extracts from cells treated with EGb761 revealed increased levels of the catalytic subunit of gamma-glutamylcysteinyl synthetase (gamma-GCS), the rate-limiting enzyme in GSH synthesis. The abundance of mRNA for the catalytic subunit (assayed by RT-PCR) was also increased by the treatment with EGb761. Increased levels of cellular GSH by EGb761 were also observed in other cell lines including those from human bladder and liver as well as in murine macrophages indicating that the induction of gamma-GCS mRNA, protein and GSH may be an ubiquitous effect of EGb761 in mammalian cells.

Cell Death↗

Nitric oxide synthase isoforms I, III and protein kinase-Ctheta in skeletal muscle fibres of normal and streptozotocin-induced diabetic rats with and without Ginkgo biloba extract treatment.

The expression of nitric oxide synthase (NOS) isoforms I, III and protein kinase-Ctheta (PKCtheta) in rat vastus lateralis muscle was demonstrated immunohistochemically and then correlated to the physiological metabolic fibre types: SO (slow-oxidative), FOGI, FOGII (fast-oxidative glycolytic; I more glycolytic, II more oxidative), and FG (fast-glycolytic). NOS expression in muscles from different experimental groups (normal and diabetic rats, with and without Ginkgo biloba extract treatment) was assayed by Western blotting. Generally, NOS I and PKCtheta were co-expressed in fibres with predominantly oxidative metabolism (SO, FOGII). This suggests an interplay of PKCtheta and NOS I in nitric oxide production by oxidative fibres. NOS III was more highly expressed in fibres with predominantly glycolytic metabolism (FOGI, FG). A somewhat lower NOS I immunoreactivity was also found in NOS III positive fibres suggesting that NOS III and NOS I are co-expressed in these fibres. Western blotting revealed that NOS I as well as NOS III expression in the vastus lateralis muscle was down-regulated in diabetes and increased after Ginkgo biloba extract treatment. These effects may be associated with a diminished glucose uptake by myocytes of diabetic musclesand with an improved muscle function after Ginkgo biloba treatment.

Animals↗

Effects of an extract of Ginkgo biloba and diverse substances on the phasic and tonic components of the contraction of an isolated rabbit aorta.

1. The effects of phentolamine, propranolol, D 600, theophylline, papaverine and an extract of Ginkgo biloba were studied with respect to the two phases of the contractile response induced by norepinephrine in an isolated rabbit aorta. 2. Phentolamine (3 x 10(-6) M) inhibits the rapid phase of the contraction of the rabbit aorta brought on by norepinephrine (NE) 10(-5) M more strongly than the tonic phase. Propranolol (10(-6) M) potentiates this rapid phase. 3. D 600 inhibits the slow phase with an EC50 = to 3.8 x 10(-8) M. 4. Papaverine and theophylline increase the relaxation that follows the rapid phase of contraction. The slow phase is inhibited only by papaverine. 5. The extract of Ginkgo biloba (Gb) at a concentration of 3 mg/ml has the same type of effect as papaverine 3 X 10(-5) M.

Animals↗

The effect of ginkgo biloba extract on free radical production in hypoxic rats.

In the present study, we assayed the antioxidant properties of Ginkgo biloba (Gb) extract on rats submitted to 21 d of chronic hypoxia. Doses of 25 and 50 mg/kg were examined. Oxygenated free radical production measured by the chemiluminescence technique was significantly decreased in treated rats compared to control rats placed in similar experimental conditions, and this effect was more significant at the 50 mg/kg dose. On the other hand, no antioxidant enzyme activities of the drug were observed towards red blood cells. These results suggest that ginkgo biloba extract has a free radical scavenging action. These antioxidant properties could explain the beneficial hematological properties of Gb extract.

Animals↗

Comparative study of two Ginkgo biloba extracts on the phagocytic activity and DTH response of healthy mice.

The phagocytic activity and delayed-type Hypersensitivity (DTH) response to dinitrofluorobenzene (DNFB) of healthy BALB/c mice treated orally (100 mg/kg/day for 7 days) using two Ginkgo biloba extracts were studied. The phytopharmaceuticals Gb 30 (Alban Muller International, France) and EGb 761 (Schwabe, Germany) administered orally stimulated the phagocytic activity of peritoneal and alveolar macrophages. Likewise, the DTH response was found to be increased only with Gb 30 treatment. These results suggest that Ginkgo biloba possesses immunological activity in addition to the biological activity reported. The different chemical concentration of the components of the Ginkgo biloba extracts mentioned above may be responsible for the differences in the observed findings.

Animals↗

Cancer-related overexpression of the peripheral-type benzodiazepine receptor and cytostatic anticancer effects of Ginkgo biloba extract (EGb 761).

The peripheral-type benzodiazepine receptor (PBR) is an 18-kDa high affinity drug- and cholesterol-binding protein that is involved in various cell functions, including cell proliferation and apoptosis. PBR was shown to be overexpressed in certain types of malignant human tumors and cancer cell lines, correlating with enhanced tumorigenicity and cell proliferation rates. The present study was conducted in order to further define the role of PBR in cancer and to extend our recent findings regarding the possible anticancer effects of the standardized Ginkgo biloba extract EGb 761. Treatment with EGb 761 decreased PBR mRNA levels and inhibited the proliferation of breast, glioma and hepatocarcinoma cell lines, further corroborating our previous contention that its mechanism of action is through the modification of PBR expression. In vivo treatment with Ginkgo biloba extract led to dose-dependent decreases in xenograft growth of both MDA-MB-231 breast cancer and U-87 glioma cell lines in nude mice, although the effects were not maintained after 50 days of treatment in the latter. The results obtained in MDA-MB-231 xenografts indicated pronounced inhibition of tumor growth, verified by MRI imaging. These results were obtained using a modified experimental protocol where the animals were treated with the extract before cell inoculation. Although an exact role for PBR in relation to the initiation and progression of various types of cancer remains to be defined, our results indicate that PBR overexpression in certain cancer cells is related to an aggressive phenotype. Since EGb 761 treatment opposes this aggressive phenotype by decreasing PBR overexpression, it could be useful in preventing or treating cancer invasiveness and metastasis.

Animals↗

[Treatment of senile macular degeneration with Ginkgo biloba extract. A preliminary double-blind drug vs. placebo study].

Senile macular degeneration is a frequent cause of blindness for which there is no satisfactory medical treatment. A double-blind trial comparing Ginkgo biloba extract with a placebo was conducted in 10 out-patients at the Hôpital Foch. Drug effectiveness was assessed on the results of fundoscopy and of measurements of visual acuity and visual field. In spite of the small population sample, a statistically significant improvement in long distance visual acuity was observed after treatment with Ginkgo biloba extract. The assumed pathogenesis of senile macular degeneration is discussed with emphasis on free oxygenated radicals.

Aged↗

The Ginkgo biloba extract (EGb 761) provides a neuroprotective effect on retinal ganglion cells in a rat model of chronic glaucoma.

PURPOSE: To investigate the effect of Ginkgo biloba extract (EGb 761) against neurotoxicity of retinal ganglion cells of rats with chronic moderately elevated intraocular pressure (IOP). METHODS: Unilateral chronic moderately elevated IOP was produced in rats by cautery of three episcleral vessels. Secondary degeneration was measured with and without EGb 761 for 5 months. At 5 months, retinal ganglion cells were labeled with a fast blue tracer applied to both superior colliculi. Densities of surviving retinal ganglion cells were estimated by counting fast blue labeled cells in whole mounted retinas. RESULTS: When compared with their contralateral control eyes with normal IOP, in the peripheral retina, retinal ganglion cell loss in eyes with chronic, moderately elevated IOP was 29.8 +/- 1.5% (n=5) at 5 months in untreated animals and 4.6 +/- 4.5% (n=5) at 5 months in treated animals with EGb 761. CONCLUSIONS: Pretreatment and early posttreatment with EGb 761 is an effective neuroprotectant in a rat model of chronic glaucoma.

Animals↗

[Delay in progression of dependency and need of care of dementia patients treated with Ginkgo special extract EGb 761].

In studies on the efficacy of antidementia drugs, a delay in symptom progression was often postulated based on a comparison of the change upon treatment and an assumed "natural" progression. Such comparisons were usually based on the cognitive subscore of the Alzheimer's Disease Assessment Scale (ADAS-cog), using either the drug-placebo differences after randomized treatment or the changes upon active drug treatment in open-label extension studies. Considering quality of life, competence, cost of care, and economics of therapeutic measures, a delay in the progression of dependency and need of care appears to be more relevant than a delay in cognitive abilities not directly related to activities of daily living. Therefore, for dementia patients treated with the Ginkgo special extract EGb 761, the delay in loss of capacities needed to cope with the demands of daily living was estimated, based on the Geriatric Evaluation of Relative's Rating Instrument (GERRI). The drug-placebo differences documented after 26 and 52 weeks of treatment corresponded to a delay in progression by 10 and 21 months, respectively. Regarding the subgroup with dementia of the Alzheimer type, the estimated delay was 16 and 25 months, respectively. It could thus be shown that by treatment with EGb 761 the progression of dependency and need of care can be slowed down, which may have an impact on costs for care, e.g. by delaying nursing home placement.

Activities of Daily Living↗

Protective effects of Ginkgo biloba extract on cultured rat cardiomyocytes damaged by H2O2.

AIM: To investigate the influence of Ginkgo biloba extract (GbE) on cardiomyocytes damaged by H2O2. METHODS: Cultured rat cardiomyocytes were divided into 3 groups randomly: control group; H2O2 (2.5 mmol.L-1) group; H2O2 2.5 mmol.L-1 + GbE 150 mg.L-1 group. The cardiomyocytes were cultured in MEM (Eagle's) at 37 degrees C in the presence of 5% CO2 for 4 h. Lactate dehydrogenase (LDH) was assayed by colorimetric method. Lipid peroxidation was determined by measuring thiobarbituric acid-reactive substances. Ultrastructure was viewed under transmission electron microscope. RESULTS: Compared with the control group, LDH leakage and malondialdehyde (MDA) content increased in H2O2 group, LDH increased from (2166 +/- 247) U.L-1 to (5180 +/- 648) U.L-1, MDA increased from (3.5 +/- 0.2) nmol/10(6) cells to (7.2 +/- 0.4) nmol/10(6) cells (P < 0.01). The ultrastructure was damaged seriously. GbE inhibited the increase of LDH leakage and MDA content induced by H2O2. In this group, LDH decreased from (5180 +/- 648) U.L-1 to (3496 +/- 386) U.L-1, MDA decreased from (7.2 +/- 0.4) nmol/10(6) cells to (4.8 +/- 0.9) nmol/10(6) cells (P < 0.01). Ultrastructure of cells was also protected by GbE. CONCLUSION: GbE protected the cardiomyocyte against H2O2 injury, the protective action was attributed to its antiperoxidative effect.

Animals↗