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 Ginkgo Biloba



Ginkgo biloba for cerebral insufficiency.

Kleijnen J; Knipschild P

Br J Clin Pharmacol, 1992 Oct, 34:4, 352-8

1. By means of a critical review we tried to establish whether there is evidence from
controlled trials in humans on the efficacy of Ginkgo biloba extracts in cerebral
insufficiency. 2. The methodological quality of 40 trials on Ginkgo and cerebral
insufficiency was assessed using a list of predefined criteria of good methodology, and the
outcome of the trials was interpreted in relation to their quality. A comparison of the quality
was made with trials of co-dergocrine, which is registered for the same indication. 3. There
were eight well performed trials out of a total of 40. Shortcomings were limited numbers of
patients included, and incomplete description of randomization procedures, patient
characteristics, effect measurement and data presentation. In no trial was double-blindness
checked. Virtually all trials reported positive results, in most trials the dosage was 120 mg
Ginkgo extract a day, given for at least 4-6 weeks. For the best trials, there were no marked
differences in the quality of the evidence of the efficacy of Ginkgo in cerebral insufficiency
compared with co-dergocrine. The results of the review may be complicated by a
combination of publication bias and other biases, because there were no negative results
reported in many trials of low methodological quality. 4. Positive results have been reported
for Ginkgo biloba extracts in the treatment of cerebral insufficiency. The clinical evidence is
similar to that of a registered product which is prescribed for the same indication. However,
further studies should be conducted for a more detailed assessment of the efficacy.

A double-blind, placebo controlled study of Ginkgo biloba extract ('tanakan') in elderly
outpatients with mild to moderate memory impairment.

Rai GS; Shovlin C; Wesnes KA

Curr Med Res Opin, 1991, 12:6, 350-5

Thirty-one patients over the age of 50 years and showing a mild to moderate degree of
memory impairment entered a 6-month double-blind, placebo controlled, parallel group
design study to assess the effects of a standardized Ginkgo biloba extract (containing 24%
flavonoid glycosides and 6% terpenes) on cognitive function. Patients were allocated at
random to receive oral doses of 40 mg Ginkgo biloba extract or identical placebo 3-times
daily. Assessments were made at baseline and after 12 and 24 weeks of treatment using a
range of psychometric tests. Efficacy data were available for 27 patients (15 in the placebo
group and 12 in the active treatment group). Statistical analysis of the data as compared to
baseline suggests that Ginkgo biloba extract had a beneficial effect on cognitive function in
this group of patients. Performance on the Digit Copying sub-test of the Kendrick battery
was significantly improved at both 12 and 24 weeks, while the median speed of response on
a computerized version of a classification task also showed a significant superiority over
placebo at 24 weeks.

Effect of Ginkgo biloba on fluidity of blood and peripheral microcirculation in volunteers.

Jung F; Mrowietz C; Kiesewetter H; Wenzel E

Department of Clinical Haemostasiology and Transfusion Medicine, University of Saarland,
Homburg/Saar, Fed. Rep. of Germany.

Arzneimittelforschung, 1990 May, 40:5, 589-93

In a randomized placebo controlled single-blind cross-over study of n = 10 apparently
healthy subjects the influence of Ginkgo biloba (Kaveri) on blood fluidity and cutaneous
microcirculation was studied. Microcirculation was measured before and every 30 min for 4
h after administration of Ginkgo biloba; fluidity of blood was determined before and after 1,
2 and 4 h. Significant changes in blood pressure or heart rate were found neither during
Ginkgo phase nor placebo phase. Haematocrit, plasma viscosity, erythrocyte rigidity,
thrombocyte and leukocyte count as well as thrombocyte aggregation and the number of
circulating thrombocyte aggregates were also not influenced by the Ginkgo nor the placebo
solution. In contrast a remarkable influence on the erythrocyte aggregation was observed:
comparing two samples a significant decrease by 15.6% (p less than 0.001) with regard to
the initial value was observed after 2 h. The blood flow in the nail fold capillaries also
increased significantly by about 57% (p less than 0.004) 1 h after administration.

Water-soluble polysaccharides from Ginkgo biloba leaves.

Kraus J

Phytochemistry, 1991, 30:9, 3017-20

The water-soluble polysaccharides from dried Ginkgo biloba leaves were isolated after
exhaustive extraction with organic solvents. The polysaccharide mixture could be separated
into a neutral (GF1) and two acidic (GF2 and GF3) polysaccharide fractions by ion
exchange chromatography. According to the Mr distribution GF1 and GF3 seemed to be
homogenous, whereas GF2 could be further fractionated into two subfractions (GF2a and
GF2b) by gel permeation chromatography. GF1 (Mr 23,000) showed the structural features
of a branched arabinan. The main chain was composed of 1,5-linked arabinose residues and
three in 12 arabinose molecules were branched via C-2 or C-3. GF2a (Mr 500,000)
consisted mainly of 1,2,4-branched mannose (29%), 1,4-linked glucuronic (32%) and
galacturonic (8%) acid as well as terminal rhamnose (25%). After removal of ca 70% of the
terminal rhamnose the remaining polysaccharide showed a decrease in 1,2,4-branched
mannose and an increase in 1,2-linked mannose indicating that at least half of the rhamnose
residues were linked to mannose via C-4. GF3 (Mr 40,000) consisted of 1,4-linked
galacturonic (30%) and glucuronic (16) acid, 1,3,6-branched galactose (15%), 1,2-linked
(5%) and 1,2,4-branched (3.5%) rhamnose as well as 1,5-linked arabinose (11%).
Rhamnose (5%) and arabinose (10%) were present as terminal groups. Mild acid hydrolysis
selectively cleaved arabinose and the remaining polysaccharide showed an increased amount
of 1,6-linked and terminal galactose and a decreased quantity of 1,3,6-branched galactose.
These results indicated that the terminal as well as the 1,5-linked arabinose were mainly
connected to galactose via C-3. The GF3 polysaccharide appeared to be a
rhamnogalacturonan with arabinogalactan side chains.

Influences of Ginkgo biloba on cyclosporin A induced lipid peroxidation in human liver
microsomes in comparison to vitamin E, glutathione and N-acetylcysteine.

Barth SA; Inselmann G; Engemann R; Heidemann HT

Biochem Pharmacol, 1991 May, 41:10, 1521-6

The in vitro effect of cyclosporin A (CsA) on lipid peroxidation in human liver microsomes
was investigated, and efforts were made to prevent the resulting toxic effect of CsA.
Microsomes were prepared from human liver resection material and incubated with CsA (0,
10, 30, 100, 300, 1000 micrograms/mL) for one hour (pH 7.4, 37 degrees, 95% O2, 5%
CO2). Subsequently the resulting concentrations of malondialdehyde equivalents (MDA)
were determined, a breakdown product of lipid peroxidation. Furthermore the duration of
incubation was varied (0, 15, 30, 60, 90 min) using a CsA concentration of 300
micrograms/mL. CsA was shown to stimulate MDA-formation to up to 10-fold of the
control value in both a time and concentration dependent manner. The dosage dependent
experiment stated above was repeated, adding alpha-tocopherol (vitamin E, 1 mM), reduced
glutathione (GSH, 1 mM), N-acetylcysteine (0.1, 0.3, 1, 3 mM), and Ginkgo biloba extract
(Gbe, 15, 50, 150 micrograms/mL), respectively, to the medium of incubation. Vitamin E,
a potent radical scavenger, proved to inhibit lipid peroxidation almost totally. Both GSH and
N-acetylcysteine were also able to prevent lipid peroxidation, suggesting that the antioxidant
effect of GSH might be caused by its thiol group and does not depend on the integrity of the
whole molecule. Gbe inhibited CsA induced lipid peroxidation in a concentration dependent
manner. This effect of Gbe was diminished yet not totally abolished when FeCl3 was added
to the medium of incubation, whereas N-acetylcysteine even slightly enhanced CsA
stimulated lipid peroxidation in the presence of iron. These results suggest that Gbe might
be able to prevent radical mediated damage to human membranes caused by CsA.

The neuroprotective properties of the Ginkgo biloba leaf: a review of the possible
relationship to platelet-activating factor (PAF).

Smith PF; Maclennan K; Darlington CL

J Ethnopharmacol, 1996 Mar, 50:3, 131-9

Ginkgo biloba (Ginkgoaceae) is an ancient Chinese tree which has been cultivated and held
sacred for its health-promoting properties. There is substantial experimental evidence to
support the view that Ginkgo biloba extracts have neuroprotective properties under
conditions such as hypoxia/ischemia, seizure activity and peripheral nerve damage. Research
on the biochemical effects of Ginkgo biloba extracts is still at a very early stage. One of the
components of Ginkgo biloba, ginkgolide B, is a potent platelet-activating factor (PAF)
antagonist. Although the terpene fraction of Ginkgo biloba, which contains the ginkgolides,
may contribute to the neuroprotective properties of the Ginkgo biloba leaf, it is also likely
that the flavonoid fraction, containing free radical scavengers, is important in this respect.
Taken together, the evidence suggests that Ginkgo biloba extracts are worthy of further
investigation as potential neuroprotectant agents.

Effect of Gingko biloba extract (EGb 761) on chloroquine induced retinal alterations.

Droy Lefaix MT; Vennat JC; Besse G; Doly M

Lens Eye Toxic Res, 1992, 9:3-4, 521-8

Electroretinography was used to investigate the preventive action of Ginkgo biloba extract
(EGb 761) in experimental chloroquine-induced retinopathy in rats. EGb 761 contains
flavones and anthocyanosides known for their oxygenated radical scavenging properties.
Chronic administration of chloroquine (20 days) caused an overall lengthening of the
duration of the ERG b-wave, together with delayed peaking. These anomalies became more
marked with increased duration of treatment. In rats treated simultaneously with chloroquine
and EGb 761 no such modification of the electroretinogram (ERG) was observed. These
results suggest that retinal toxicity may be related to a localized inflammation releasing
oxygenated free radicals and/or PAF. EGb 761 may thus afford a useful preventive
treatment for chloroquine-induced retinopathy, and generally for xenobiotic retinotoxicities.

The clinical applications of Ginkgo biloba, St. John's wort, saw palmetto, and soy.

Glisson J; Crawford R; Street S

Nurse Pract, 1999 Jun, 24:6, 28, 31, 35-6 passim; quiz 47-9

The use of herbal or alternative therapies continues to increase each year. This article
extensively reviews four of the more commonly used herbs and dietary supplements:
ginkgo biloba, St. John's wort, saw palmetto, and soy. The pharmacology, precautions,
therapeutic uses, and adverse effects for each of these therapies are discussed.

Ginkgo biloba extract increases ocular blood flow velocity.

Chung HS; Harris A; Kristinsson JK; Ciulla TA; Kagemann C; Ritch R

J Ocul Pharmacol Ther, 1999 Jun, 15:3, 233-40

We evaluated a possible therapeutic effect of Ginkgo biloba extract (GBE) on glaucoma
patients that may benefit from improvements in ocular blood flow. A Phase I cross-over
trial of GBE with placebo control in 11 healthy volunteers (8 women, 3 men: Age; 34 +/- 3
years, mean +/- SE) was performed. Patients were treated with either GBE 40 mg or
placebo three times daily orally, for 2 days. Color Doppler imaging (Siemens Quantum
2000) was used to measure ocular blood flow before and after treatment. There was a two
week washout period between GBE and placebo treatment. Ginkgo biloba extract
significantly increased end diastolic velocity (EDV) in the ophthalmic artery (OA) (baseline
vs GBE-treatment; 6.5 +/- 0.5 vs 7.7 +/- 0.5 cm/sec, 23% change, p=0.023), with no
change seen in placebo (baseline vs GBE-treatment; 7.2 +/- 0.6 vs 7.1 +/- 0.5 cm/sec, 3%
change, p=0.892). No side effects related to GBE were found. Ginkgo biloba extract did not
alter arterial blood pressure, heart rate, or IOP. Ginkgo biloba extract significantly increased
EDV in the OA and deserves further investigation in ocular blood flow and neuroprotection
for possible application to the treatment of glaucomatous optic neuropathy as well as other
ischemic ocular diseases.

Effects on skeletal muscle fibres of diabetes and Ginkgo biloba extract treatment.

Punkt K; Psinia I; Welt K; Barth W; Asmussen G

Acta Histochem, 1999 Feb, 101:1, 53-69

Combined cytophotometric and morphometric analysis of muscle fibre properties and
myosin heavy chain electrophoresis were performed on extensor digitorum longus and
soleus muscles from healthy rats and rats with streptozotocin-induced diabetes. Moreover,
the protective effect of Ginkgo biloba extract, a potent oxygen radical scavenger, on diabetic
muscles was investigated. Changes in fibre type-related enzyme activities, fibre type
distribution, fibre cross areas and myosin isoforms were found. In muscles of diabetic rats,
a metabolic shift was measured mainly in fibres with oxidative metabolism. Fast-oxidative
glycolytic fibres showed a shift to more glycolytic metabolism and about a third
transformed into fast-glycolytic fibres. Slow-oxidative fibres became more oxidative. Fibre
atrophy was measured in diabetic muscles dependent on fibre type and muscle. Different
fibre types atrophied to a different degree. Therefore, a decreased area percentage of slow
fibres and an increased area percentage of fast fibres of the whole muscle cross section in
both muscles were found. This is supported by reduced slow and increased fast myosin
heavy chain isoforms. These alterations of diabetic muscle fibres could be due to less
motion of diabetic rats and diabetic neuropathy. After treatment with Ginkgo biloba extract,
enzyme activities were increased mainly in oxidative fibres of diabetic muscles, which was
interpreted as protective effect. Generally, the soleus muscle with predominant oxidative
metabolism was more vulnerable to diabetic alterations and Ginkgo biloba extract treatment
than the extensor digitorum longus muscle with predominant glycolytic metabolism.


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