Ginkgo biloba extract Chemische Eigenschaften,Einsatz,Produktion Methoden
Verwenden
ginkgo biloba extract (ginkgo extract) is credited with anti-oxidant properties, it also appears to aid fibroblast cells in the production of collagen and elastin. This ability is attributed to a number of flavonoid fractions, including quercetin, kaempferol, and ginkgetin. Additionally, ginkgo is an anti-inflammatory and may help improve a couperose condition because of a protective effect on vascular walls. ginkgo was used in folkloric medicine as a blood vessel dilator because of its ability to increase blood flow and stimulate tissue oxygen consumption. It is considered a beneficial anti-aging ingredient. ginkgo’s key constituents include ginkgolide and bilobalide, catechin, tannin, quercetin, and luteolin.
Indications
Ginkgo, or maidenhair tree (Ginkgo biloba), is thought
to be the most ancient of living tree species, and it is
now also one of the top selling herbs in Europe and the
United States because of its reputed ability to improve
cognitive function. Ginkgo leaf extract is prepared from
ginkgo leaf by a complex process that removes toxic
ginkgolic acid. This reduces the risk of allergic reactions
to the leaves if they are consumed directly. Ginkgo leaf
extract contains 24% flavone glycosides (including the
antioxidant rutin, which improves capillary fragility)
and 6% terpene lactones.
Allgemeine Beschreibung
Ginkgo is extracted by an extremely complex multistep process that concentrates the active constituents and removes the toxic ginkgolic acid. The ginkgo extract is a complex mixture of both polar and nonpolar components . The more polar fractions contain flavonol and flavone glycosides. The more nonpolar fractions contain some diterpene lactones, known as ginkgetin, ginkgolic acid, and isoginkgetin, and some interesting caged diterpenes known as ginkgolide A, B, C, J, and M. There is also a 15-carbon sesquiterpene (bilobalide) and other minor components.
G. biloba extract is prepared by picking the leaves, drying them, and constituting them into an acetone-water extract that is standardized to contain 24% flavone glycosides and 6% terpenes. G. biloba produces vasodilating effects on both the arterial and venous circulation. The result is increased tissue perfusion (i.e., in the peripheral circulation) and cerebral blood flow. The extract produces arterial vasodilatation (rodent models), dampens arterial spasticity, and decreases capillary permeability, capillary fragility, erythrocyte aggregation, and blood viscosity. There are several possible explanations for these effects. One possibility is that the compounds in G. biloba extract inhibit prostaglandin and thromboxane biosynthesis. It has also been speculated that G. biloba extract has an indirect regulatory effect on catecholamines. Ginkgolide B is reportedly a potent inhibitor of PAF.
Hazard
Lowtoxicity by ingestion. Human systemic
effects.
Mechanism of action
Ginkgo leaf extract appears to act primarily as a mild
cerebral vasodilator that increases cerebral blood flow
and reduces blood viscosity. Ginkgolides inhibit platelet
activating factor, and this may improve microcirculatory
blood flow in atherosclerotic disease with slightly
increased risk of bleeding. There appears to be an antioxidant
effect that may be neuroprotective.Although
some studies suggested a monoamine oxidase inhibitor
(MAOI) effect, this is considered to have questionable
clinical relevance.
Clinical Use
Ginkgo leaf extract is most popular for cognitive disorders,
including memory loss, dementia, and cerebrovascular
insufficiency. A number of well-designed clinical
trials have shown modest benefit in Alzheimer’s disease,
with ginkgo extract appearing as effective as second-
generation cholinesterase inhibitors. At least one
large (214 patient) study, however, failed to show a
memory improvement in dementia patients. Studies are
now under way to see whether ginkgo use will protect
against development of Alzheimer’s disease.
Intermittent claudication appears to benefit from
ginkgo therapy: many studies demonstrate improved
walking distance and decreased pain. One meta-analysis
of eight studies documented statistically significant improvement
but questioned its clinical relevance. In some
studies, the high doses (240 mg) appeared more effective.
Vertigo and tinnitus are difficult to treat conditions
for which ginkgo is frequently recommended. At least
two trials support the use of gingko extract for vertigo,
but the evidence for tinnitus remains inconclusive.
Other suggested uses include sexual dysfunction
secondary to selective serotonin reuptake inhibitors
(SSRIs), macular degeneration, premenstrual syndrome,
and the prevention of acute mountain sickness
at high altitude. Some of these uses are supported only
by a single study.
Nebenwirkungen
Allergic reactions are a significant concern with unprocessed
ginkgo leaf (ginkgolic acid) but are much less
likely to occur with the leaf extract. The malodorous
ginkgo fruit cross-reacts with poison ivy (urushiol) and
may cause an identical contact dermatitis.
Children eating large numbers (>50) of the uncooked
ginkgo kernels have had seizures, and consequently
there is some concern about using high doses of
ginkgo in seizure patients. However, most patients tolerate
gingko extract very well, with only occasional GI
upset or headache being reported, and the product is
considered safe for healthy nonpregnant adults.
Bleeding complications are an infrequent but serious
concern, with subdural hematomas, subarachnoid
hemorrhages, hyphema (bleeding of the iris), and surgical
bleeding occasionally reported. Stopping ginkgo administration
prior to surgery and the avoidance of its
use with anticoagulant drugs and perhaps with aspirin is
recommended. Use of ginkgo extract should be avoided
in pregnant women and children, since at least one study
showed in a ginkgo preparation small amounts of
colchicine, a compound that can block cellular division
and cause abortion; however, it is unclear whether this
is a problem in all ginkgo preparations.
Ginkgo may reduce the effectiveness of thiazide diuretics
for blood pressure control and at least theoretically
should be avoided with MAOIs. There is also a
suggestion that ginkgo may decrease male and female
fertility, and it should be avoided in those trying to conceive.
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