Elder Ginkgo Tree ( Ginkgo biloba )
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The ginkgo or ginko ( Ginkgo biloba ) is a tree species native to China , which is now planted worldwide . It is the only living representative of the ginkgoales , an otherwise extinct group of seed plants . Natural populations are only known from Chongqing City and Guizhou Province in southwest China.
In East Asia , the tree is cultivated for its edible seeds or as a temple tree. It was brought to Europe by Dutch sailors from Japan and has been planted here as an ornamental tree since around 1730 .
At the turn of the millennium, the German “Kuratorium Tree of the Year ” declared Ginkgo biloba a memorial for environmental protection and peace and the tree of the millennium . The ginkgo is a " living fossil ".
The ginkgo is a deciduous tree , which means that it sheds its leaves in autumn. It can live to be 1000 years and older and reach heights of up to 40 meters and a breast height diameter (BHD) of 1 to 4 meters. A specimen from Korea has a height of 64 meters and a BHD of 4.45 meters. The young tree usually grows slender and noticeably straight up. The broad, upwardly tapering crown is rather sparsely branched. This is increasingly changing with older trees from the age of 25, the branches of which move more and more horizontally and can thus form an expansive, mighty treetop . The ginkgo usually has two main shoots, one of which is less developed. Trees that are under stress can form secondary trunks near the ground or below, which arise from shoots that grow like roots.
The resin-free, soft and light wood of the ginkgo has a fine texture and is similar to that of the younger conifers . The light brown heartwood is difficult to distinguish from the light yellow sapwood . Pressure wood is often produced on the bends of the trunk or branches, and this grows independently of the control of the main shoot . The cellulose content is between 40 and 42 percent and the lignin content is 30 to 34 percent. The density of 12 to 15 percent wood moisture is around 430 kg / m³. In contrast to conifers , this type of tracheids come in different sizes. In the radial walls of the tracheids one to two, sometimes three rows of pits can be found. In addition, many calcium oxalate crystals accumulate in the tracheids . The wood is well suited for carving and is used as a panel . Hardly any stocks are grown for pure wood production.
Bark and bark
The bark of full-grown trees is dark gray, rough, deeply furrowed and hardly inflammable; this makes the trees moderately fire resistant. In younger trunks, it is gray-brown with light brown cracks. The bark of annual twigs is light gray and turns light brown on two-year twigs.
While in the old trees lateral roots dominate young trees form an up to one meter long taproot from. Contrary to what has been shown in many literature reports, the ginkgo does not develop root spawn . The tree has relatively thick fine roots of over 0.5 millimeters, which are covered by a large number of root hairs.
Ginkgo has the ability to form "aereal chichi" above the ground and "basal chichi" below the ground in poor environmental conditions. “Aereal chichi” are stalactite- like, lignified swellings that are more than a meter long and resemble stalactites, which in very old ginkgo trees arise from overgrown buds on the branches or trunk at branch height. If these lignified swellings touch the ground, numerous vegetative shoots develop under favorable conditions, which can develop into an independent plant. "Basal chichi" are woody, rhizome-like swellings from which mostly secondary trunks and adventitious roots emerge. The development of the "basal chichi" is mostly due to root-like shoots (also called lignotuber) growing towards gravity (positive geotropic). Stimulated by traumatic stimuli, one of these buds sprouts in the armpits of the two cotyledons, and the corresponding shoots grow from the shoot in the direction of gravity. Here, too, an independent plant can develop, but it usually remains connected to the mother plant.
Buds, leaves and shoots
The terminal buds are very noticeable. They are tan-colored (light brown), have a diameter of 2 to 5 mm and are surrounded by small leaves without axillary buds, whereby the tegmental areas are arranged like scales.
The very characteristic fan-shaped, wide leaves are a specialty of the flora . They are more or less notched in the middle and the shape of the leaves varies depending on the position on the shoot and the vigor of the tree, which is why hardly any ginkgo leaves are the same . Leaves of young trees are shaped significantly differently than those of old trees ( age dimorphism ). On short shoots and at the base of long shoots, the leaves reach a width of four to eight centimeters and are either undivided or bilobed by incision. The leaves at the tips of long shoots have significantly deeper bulges, which divide the leaves into two or more lobes. On the long shoots, the leaves are between six and ten centimeters wide. The petiole is four to ten centimeters long. All leaves are fork-veined ( dichotomous ), a very original feature from an evolutionary point of view. They are light green at the beginning of their growth in spring and darken over summer, in autumn they turn strikingly light yellow to golden yellow and finally fall off around the beginning of November.
According to a widespread opinion, the fan leaves inherited their characteristic shape of fused needles during their development history. But that is unscientific and cannot be proven anatomically, developmentally or evolutionarily.
The branches form long and short shoots . The long shoots can grow between 20 and 100 centimeters per year, depending on the conditions. Staggered (alternate) leaves grow from the long shoots, and axillary buds grow from their petioles. Short shoots are very long-lived - they can live up to 60 years and often only grow a few millimeters a year, which is why they hardly reach a length of 20 centimeters. Short shoots can develop into long shoots quite unexpectedly.
Ingredients of the leaves
The leaves, which are the only parts of the plant that are used pharmaceutically, contain around 0.5 to 1.8 percent flavonoids : these are flavone and flavonol glycosides , acylated flavonol glycosides, biflavonoids, flavan-3-ols and proanthocyanidins . In the first two groups occur as aglycones especially kaempferol , quercetin and isorhamnetin to a lesser extent apigenin and luteolin .
Terpenes are present at 0.03 to 0.25 percent, mainly as terpene lactones . The ginkgolids A, B, C, J and M should be mentioned as diterpenes . The sesquiterpene bilobalide is a breakdown product of the ginkgolide. Other terpenes are polyprenols and steroids .
Long-chain hydrocarbons and their derivatives also occur: alcohols, aldehydes, ketones and acids.
Flowers and seeds
The ginkgo is a wind pollinator and blooms in March, it is dioecious, separate sexes ( diocesan ), so there are male and female plants. Occasionally, single sexed ( monoecious ) trees appear. The trees of different sexes can hardly be distinguished from one another externally until they reach sexual maturity, which only occurs between the ages of 20 and 35 years. Female and male flowers grow on the axils of deciduous and lower leaves from perennial short shoots.
Male flowers look like catkins 2 to 3 cm long. They consist of many stamens (microsporophylls) arranged helically on a straight axis. The microsporophylls consist of a thin stem (filament) with two (sometimes up to four) hanging microsporangia (pollen sacs) at the tip (a short round apical enlargement), in which the pollen is formed. The flowers sprout before the actual leaves and, depending on the temperature, fall off after pollination from the beginning of April to the end of May. The boat-shaped pollen has a size of 30 µm × 10 µm.
The 2 to 3 mm large ovules (female flowers) stand in pairs on an apically forked 1 to 1.5 cm long stalk. Occasionally there is only one, in some cases more than two additional ovules per stem, of which usually only one matures. They consist of an outer integument with an opening called a micropyle in the upper area. Inside the ovules is the megasporangium (nucellus) encased by the integument, inside of which in turn the functional megaspore is located.
The ginkgo seeds that emerge from the ovule after fertilization are externally similar to mirabelle plums and are 20 to 30 mm × 16 to 24 mm in size. It consists of an inner embryo, embedded in the nutrient tissue (primary endosperm) of the female gametophyte, which is surrounded by three layers: the thin-skinned inner layer ( endotesta ), a hard lignified middle layer ( sclerotesta ) and a thick seed coat ( sarcotesta ), which used to be once was the integument of the ovule. The developing seed coat is green in autumn until it is ripe; when the cold snap it turns yellow until the seed finally falls off. When fully ripe, the seed coat develops an unpleasant smell of rancid butter. The fatty acids butyric acid and caproic acid contained in the seed coat are responsible for this . The phenols also contained can lead to skin irritation and allergies if the juice escapes . The ginkgo seed without a seed shell (the core) has a size of 19 to 30 mm × 11 to 14 mm and a thousand grain weight of 1500 grams.
The diploid genome of the ginkgo comprises 2n = 24 chromosomes . Female and male trees show noticeable differences in the type of chromosomes they have. These differences can be demonstrated microscopically using root tip preparations. This can be very helpful in order to be able to assign very young plants, mostly new cultivars, to the female or male sex. Female specimens have a heteromorphic (Greek differently shaped ) pair of chromosomes with only one small satellite , while male trees only have automorphic chromosomes.
The time of fertilization is between the end of August and the end of September, depending on the time of pollination . In the generation change , the ginkgo tree corresponds to the sporophyte of the ferns and mosses . However, the spores of the female trees are no longer released into the air, they have rather settled in the sporangium and are relatively large (called megaspores; megaspores are also found in various algae).
The female flowers (ovules) develop inside the megaspore (= embryo sac mother cell) an extremely reduced megagametophyte (= embryo sac capable of fertilization), which generates a megagamete (egg cell) via its megagametangium (synergids). The megaspores are given so much food that they can later develop sex cells (egg cells) without feeding themselves. The female gametophyte is initially created by free nuclear divisions, followed by cell wall formation. In the end, the gametophyte consists of several hundred cells and usually forms two - rarely three - archegonia . The gametophyte is colored green by possessing chlorophyll.
The spores of the male trees (called microspores or pollen) experience their first mitotic divisions in the “microsporangium”. In the first cell division, two inequitable divisions of the pollen cell result in two prothallium cells and one antheridial cell . The pollen tube cell and the generative cell emerge from this through renewed division. At this stage the pollen grain is released from the sporangium and as such is blown as a strongly reduced microgametophyte (multicellular pollen grain) by the wind to the megagametophyte.
In the receptive stage, the integument at the tip ( micropyle ) secretes a slimy liquid (pollination droplets) that is necessary for the movement of the male sex cells. It arises from the dissolution of the cells under the micropyle, which also creates a pollen chamber. When the pollen grain reaches the pollination droplet, it absorbs water and other substances from the liquid; in this way it becomes heavier, so that at the end of the readiness to receive with the pollination fluid in the micropyle it dries up and retreats into the pollen chamber. The micropyle is also closed by drying.
The pollen grain germinates in the pollen chamber and forms a short pollen tube , which develops a strongly branched, intercellular growing structure at its tip , which penetrates the female tissue ( nucellus ) for several months, serves as a kind of adhesive organ ( haustorium ) and absorbs nutrients, whereby the nucellus tissue between the pollen chamber and the archegonia chamber dissolves. During this, the sperm are formed in the pollen tube: the generative cell divides into a stem cell and the spermatogenic cell. The male gametophyte is now five-celled, consisting of two prothallium cells, a pollen tube cell, a stem cell and a spermatogenic cell. The latter divides and forms two sperm cells (spermatozoids). The pollen tube is nothing more than the rudiment of a gametophyte that once grew independently. Four months after the pollen grain has germinated, the basal end of the pollen tube swells until it takes on the shape of a sac-like structure that bursts in the immediate vicinity of the archegonium in the archegonia chamber filled with liquid and two multi-tagged, buoyant, independently moving sex cells ( spermatozoids) ) releases. Besides cycads, ginkgo is the only recent seed plant with spermatozoids. The sperm have a size of about 70-90 micrometers and were first described in the year 1895 to 1898 by Sakugoro Hirase . Once released, the two spermatozoids swim towards the archegonia. A spermatozoid penetrates the archegonia and fuses with the egg cell. This is a very original development for plants. Usually, the actual fusion of the spermatozoids with the egg does not take place until weeks after the ovules have fallen off.
After fertilization, the nucleus of the zygote divides quickly and forms over 1000 free cell nuclei. Thereafter, the cell walls and form a root from the tissue, a small stem-like structure of cells and two cotyledons developed gradually ( cotyledons ), whose top surfaces close to each other are placed.
Distribution and location
The mesophytic mixed forests, which once covered the hill country along the Yangtze , are named as the original distribution area . In documents from the 11th century, a region south of the Yangtze River, which corresponds to today's Ningguo District in Anhui Province , is named as the region of origin . Natural populations are only known from southwest China. The populations on the southern slopes of the Jinfo Mountains in the city of Chongqing show pronounced genetic diversity compared to other populations in China and are therefore considered natural. There are numerous small populations in the adjacent areas of Guizhou Province , which are also considered to be natural occurrences of ginkgo. The population on the western summit of Tianmu Shan in the northwest of Zhejiang Province, which has long been considered a natural occurrence, is in all likelihood due to plantings by Buddhist monks .
Like most trees and the Ginkgo is a symbiosis with various mycorrhizae - fungi , among other things with Glomus epigaeum . It is very insensitive to air pollutants and is therefore very suitable as a street and park tree. Furthermore, it is largely resistant to insect damage and diseases caused by fungi, bacteria or viruses, can withstand temperatures of up to −30 ° C and grows on both acidic and alkaline soils, although the former usually show poorer growth. Very wet, but also excessively dry soils, on the other hand, are not tolerated.
In the United States, ginkgo trees planted showed good growth with abundant rainfall spread over the year. In contrast, poor growth could be seen in cold winds, subtropical and very high temperatures during the growing season.
Herbivores and Diseases
The ginkgo shows a high resistance to diseases and herbivores, no single species is considered a threat on its own. Pathogens such as fungi , bacteria or viruses can only be observed in the seedling stage or in very weakened plants. In terms of insects , the ginkgo is one of the least vulnerable trees around . Neither in the original habitat (East Asia) nor in North America or Europe could a natural predator fauna be discovered.
The resistance of the ginkgo to fungi can partly be explained by a waxy substance in the cuticle of the leaves, which reduces the spore germination and the growth of the germ tube of some fungi and thus prevents the fungi from penetrating the cuticle. The leaves also contain 2-hexenal , which has fungicidal properties. 2-Hexenal is present in low concentration and is separated from the steam distillate of the leaves. In rare cases, Fusarium sp. and Macrophomina phaseoli , which causes root and stem rot.
The high immunity to bacterial and virus attacks is explained on the one hand by the acidity of the leaves, which makes it resistant to bacteria such as Pseudomonas phaseolicola , Escherichia coli , Bacillus pumilus and Xanthomonas phaseoli . On the other hand, studies have shown that the growth of the tobacco mosaic and bean mosaic virus is significantly inhibited by active ingredients from the roots.
Leaves, wood and roots are more or less toxic to almost all insects . In Japan and China, for example, leaves of the ginkgo tree are used as bookmarks to protect books from silverfish and insect larvae. For example, Japanese beetles are more likely to die of malnutrition than to eat fresh ginkgo leaves. When damaged, the acidic leaves increasingly form 2-hexenals, which together with substances such as ginkgolide A, bilobalide and ginkgolic acid have been found to be the most active components of the leaves against insects. A few pests could be identified in young, old and severely damaged plants. Rarely occurring insects are Cacoecimorpha pronubana and the larva of the European corn borer ( Ostrinia nubilalis ), which feed on the leaves, as well as Brachytrupes portentosus , Agrotis ypsilon and Gulcula panterinaria , which in isolated cases feed on the seedlings.
Animals such as snails , slugs , mice , rabbits , hares and deer are in young plants of the most important predators . They eat the leaves, roots or bark in the lower part of the tree, which often leads to the death of the plant. Seedlings are also at risk of being destroyed by birds.
Etymology and Nomenclature
The name Ginkgo is derived from the Chinese Yínxìng ( 銀杏 / 银杏 ), whose Sino-Japanese pronunciation is Ginkyō ( Japanese phonographic ギ ン キ ョ ウ ). It is a combination of the characters "gin = silver" and "kyō = apricot", a reference to the silvery shimmering ovules. The name is first attested to in 1578. He came to Europe through the German doctor and Japan researcher Engelbert Kaempfer, who, encouraged by Andreas Cleyer and other scholars, carried out extensive research on the flora of the archipelago in Batavia during his two-year stay in Japan (1690 to 1691). He published a large part of his research results under the title "Flora Japonica" in his work Amoenitatum Exoticarum (Lemgo, 1712). He had drawn almost all plants in Japan. Since he attached importance to the reproduction of the native names, he had them displayed by the Japanese in the illustrated dictionary Kinmōzui ( 訓 蒙 図 彙 ). The Chinese characters were copied from this book for printing, but Kaempfer made a typo when rendering the Ginkyō reading in Latin. He usually noted the syllable, which is now transliterated as “kyo”, in the form “kjo”, but here, for unexplained reasons, he wrote “kgo” in a completely atypical way. This form was adopted by Carl von Linné when the genus was first published in 1771 and is therefore an unchangeable part of the nomenclature. The specific epithet biloba chosen by him for the species indicates the bilobed nature of the leaf. Since the spelling reform , the spelling “Ginko” has also been permitted as a trivial name in addition to “Ginkgo”.
A synonym of Ginkgo biloba L. is Salisburia adiantifolia Sm. The English botanist James Edward Smith proposed the generic name Salisburia in 1797 and wanted to honor the botanist Richard A. Salisbury . In 1824 the name Salisburia biloba Hoffmanns was added. But the name could not prevail against the internationally recognized name Ginkgo biloba , so that Salisburia remained a synonym. Other synonyms are: Pterophyllus ginkgo K. Koch and Pterophyllus salisburiensis (L.) J. Nelson.
In today's Japanese language the tree is usually called Ichō , the seeds Ginnan , also written 銀杏 . Because of the chaos when Chinese names were adopted before and during the Edo period, botanical texts in Japan usually only write the name phonographically イ チ ョ ウ . Here and there you can also find the reading for the characters 銀杏 . This is actually wrong linguistically, because Ichō comes from the alternative Chinese name Yājiǎoshù ( 鴨 腳 樹 / 鸭 脚 树 - "duck-foot tree"), which alludes to the shape of the leaves. In Chinese texts you can also find the terms Báiguǒ ( 白果 - "white fruit") and "grandfather-grandchildren tree" ( Gōngsūnshù , 公孫 樹 / 公孙 树 ). The latter refers to the long time that elapses before a newly planted tree bears the first seeds. Other names translated into German were elephant ear tree, duck foot tree, girl's hair tree, fan leaf tree (an allusion to the leaves), Chinese temple tree (because of the frequent plantings in Buddhist temples) and ensouled egg, almond fruit, white nut, nut-apricot, whatever the appearance or the Shape of the seeds is decreasing.
Use as an ornamental tree
The first ginkgo plants reached Europe from Japan around 1730 and were raised in the botanical garden of the University of Utrecht in the Netherlands. In 1754 specimens came from Utrecht to Kew Gardens in England. The first specimens were brought to the United States ( Philadelphia ) in 1784. Today the ginkgo is an important and good alternative to other street and park trees in most of the temperate zones and is also very popular.
Possibly the oldest ginkgo tree in Germany, the ginkgo in Rödelheim , was allegedly planted around 1750 and is located in the Rödelheim district of Frankfurt . The Harbke Castle Park (Saxony-Anhalt) also has one of the oldest German ginkgos in its extensive tree population, which was planted around 1758. In the Bergpark Wilhelmshöhe in Kassel there are other old ginkgos that are said to have been planted around 1780. In Mannheim and Dresden there are also very old ginkgos without further annual data. In the Jena Botanical Garden , on the Fürstengraben next to the old inspector's house, there is a ginkgo that is said to have been planted at the end of the 18th century and which is said to have been planted by Johann Wolfgang von Goethe . Inside the garden, next to a male ginkgo, there is a female specimen on the so-called “Mittelberg”. In Leipzig there is a female tree planted by Willmar Schwabe without any further annual data . In Weimar , behind the Princely House of Weimar, on Puschkinstrasse is the "Goethe Ginkgo", which Goethe had the court gardener Sckell planted around 1815 .
Due to its resistance to pest infestation and its undemanding nature, the ginkgo is now being planted as a city tree around the world. Long-standing cultivation as a street tree in Berlin has shown that it is resistant to car exhaust fumes and road salt, but also sensitive to frost at a young age.
The unpleasant smell of the seeds of butyric acid means that mainly male ginkgo trees are planted from cuttings in Europe , while in China and Japan - exactly the other way around - predominantly female trees (see use as food ) are planted as avenues and street trees and, at the same time, around to facilitate fertilization, place male and female trees side by side.
The propagation of the ginkgo requires a lot of patience from a gardener: Ginkgo seeds germinate without problems even on a windowsill, but it can take more than two years for them to germinate , and only about 30 percent of all cuttings are also after a very long time , whereby they are also usually slower growing than seedling plants. In addition, the ginkgo is sensitive to transplantation.
Seeds intended for sowing are collected in late autumn under female trees, which are less than 100 meters away from a male tree in order to ensure that the seeds are fertilized. Then the outer, fleshy seed coat ( sarcotesta ) must first be carefully removed, whereby the juice of the sarcotesta can lead to skin irritation and allergies . The seeds cleaned in this way are then optionally prepared again by stratification for the subsequent sowing.
Use of cultivars
More and more cultivars are being selected so that the ginkgo can meet the requirements as a seed supplier, its use in medicine and the ever increasing requirements as a street and ornamental tree. In China, 28 varieties were selected for their superior seed size, seed shape and superior seed yield. A widespread method of propagation of the cultivars is grafting, in which the plants already bear seeds at the age of five (fructification). A frequently used cultivar is 'Dafushon', which already achieves annual yields of 5 to 10 kg at the age of 15 and between 50 and 100 kg at the age of 50. Another cultivar that is often used is 'King of Dongling' with a thousand grain weight of around 2800 g.
After the fruit cultivars grown almost exclusively in Asia, cultivars for purely leaf production have been grown on a large scale in the USA and France since 1980. Ingredients such as ginkgolide and bilobalide are used, which are obtained from the leaves and are used in human medicine (see medical use ). The trees in question are cut back just above the ground immediately after the leaves have been harvested in order to avoid a height of over three meters. Normally the trees reach a height of one meter again by the next year, which can be kept constant from year to year.
Since the need for ginkgo wood is relatively low and ginkgos are only rarely grown for pure wood production, no cultivars for pure wood production have yet been selected.
In addition to the selection of new Ginkgo varieties for medical purposes and for pure seed production, most of the cultivars were selected for use as ornamental and street trees.
Use as food
In Asia, several breeding lines of the ginkgo tree with different qualities were grown as a food plant. The core of the seed is used, but it has to be cooked. In Japan , the peeled (therefore freed from sarcotesta and sclerotesta ) ginkgo seeds (in small quantities) are used as an accompaniment to various dishes. Some of them are cooked with rice, used as a filler in an egg dish or roasted and salted as a snack. To do this, the seeds are freed from their hard shell, only the yellow inner core is used. In Europe, ginkgo seeds are mostly only available as canned food. Roasted and chopped kernels are used as a spice in Asian cuisine. The seeds contain 37.8% carbohydrates , 4.3% protein and 1.7% fat . An excess of ginkgo seeds can lead to symptoms of poisoning because they contain the vitamin B6 antagonist 4-methoxypyridoxine . In the 11th century AD, these "nuts" are said to have been so valued that the Emperor of China demanded the seeds from the southeastern provinces as a tribute payment .
Special extracts from the ginkgo leaves are used. These are enriched in the desired active ingredients (ginkgolide, terpene lactones) and depleted in the undesirable substances (especially ginkgolic acid). The Commission E denotes the dry extract of Ginkgo leaves with a drug-extract ratio of from 35 1 to 67: 1; a content of 22 to 27% flavone glycosides and 5 to 7% terpene lactones; and below 5 ppm ginkgolic acid. The definition of dry ginkgo extract (Ginkgo extractum siccum raffinatum et quantificatum) according to the European Pharmacopoeia is very similar. Only such extracts are marketable for the treatment of dementia in Germany. Most of the pharmacological studies were carried out with the extracts EGb 761 and LI 1370. In the case of ginkgo-based food supplements, for example from supermarkets or drugstores, the desired effectiveness is unclear, as their quality is often questionable and scientific studies are lacking.
Ginkgo extracts are special to the ATC Classification of the WHO to the anti-dementia drugs counted. Earlier monographs by Commission E (1994) and the European Scientific Cooperative on Phytotherapy (2003) assessed the use of ginkgo special extracts as positive for the following indications:
- for the symptomatic treatment of organ-organically induced performance disorders. The most important symptoms are memory disorders, difficulty concentrating, dizziness, ringing in the ears and headaches. The target group is particularly people with primary degenerative dementia , with vascular dementia or mixed forms of both;
- for the symptomatic treatment of arterial circulatory disorders;
- for dizziness ( vertigo ) and ringing in the ears ( tinnitus ).
- Improvement of age-related cognitive limitations, improvement of quality of life ("well-established use")
- for heavy legs, cold hands and feet in connection with slight circulatory disorders ("traditional use")
The focus today is on the treatment of dementia. Similar to acetylcholinesterase inhibitors or cholinesterase inhibitors , which cause an increase in the concentration of acetylcholine , ginkgo drugs can improve cognitive parameters for a certain period of time, i.e. increase mental performance and make it easier to cope with everyday life, which also reduces the stress on relatives. CHE inhibitors are defined by the drug commission of the German medical profession as the first choice. In the latest international guideline of the World Federation of Societas of Biological Diseases , ginkgo medicinal products are assessed as being equally effective to CHE inhibitors and memantine and more tolerable.
German-language guidelines contain recommendations for the use of special extracts for:
- Dementia (German S3 guideline 2016)
- vascular dementia (German S1 guideline 2016)
- mild to moderate Alzheimer's dementias (Austrian consensus statement 2014)
- behavioral and psychological symptoms of dementia (BPSD) (Switzerland 2014)
According to a French study published in 2014, patients suffering from Alzheimer's disease also seem to benefit from taking ginkgo drugs in addition to the classic cholinesterase inhibitors. Overall, drug therapy for dementia patients is still considered very modest today .
Another indication is mild cognitive impairment (MCI, mild cognitive impairment ), which are mainly based on normal aging processes and which progress to dementia in some of the patients (10 to 20 percent).
In total, there are over 40 clinical studies on ginkgo preparations (including the prescription Rezirkane , Symfona , Tebokan and the pharmacy- only Tebonin ), with only a few meeting the strict guidelines for high-quality clinical trials. Some of these studies found significant benefits from ginkgo therapy, others none. A meta-analysis from 2010 showed that a ginkgo drug is more effective than a sham drug, but, like all other dementia drugs, the effect is moderate and the clinical significance of this effect is difficult to determine, as is generally the case with antidementia drugs.
The Institute for Quality and Efficiency in Health investigated in 2008 as part of a drug evaluation studies and documents 761 for preparation EGb Based on the seven evaluated studies led to the conclusion that it in the treatment of Alzheimer's disease a proof of benefit when therapeutic goal "Activities of daily living" give, provided 240 mg of extract are taken daily. For the therapy goals “cognitive abilities” and “general psychopathological symptoms” as well as for the relatives-relevant therapy goal “quality of life of the (caring) relatives” (measured by the emotional stress of the relatives) there is only one indication of a benefit with the same dosage . However, the neutrality of the studies examined is controversial.
The 2015 S3 guideline for chronic tinnitus of the Working Group of the Scientific Medical Societies in Germany comes to the conclusion that there is no evidence for the effectiveness of ginkgo preparations in tinnitus, and therefore does not make a recommendation.
The following main effects are said to apply to special ginkgo extracts:
- Improvement of memory performance and the ability to learn.
- Promotion of cerebral neurotransmission and reduction of age-related neurotransmission defects.
- Promote blood circulation and improve the flow properties of the blood.
New work mainly examines the effect of ginkgo extracts on the central nervous system. Older studies rather examined the effect on blood circulation.
Mechanisms of Action
On the one hand, the ginkgo extracts have free radical scavenging properties. This effect against reactive oxygen species is mainly mediated by the flavonoids; on the other hand, they inhibit platelet-activating factor (PAF) in the blood, which plays a role in inflammation, for example. However, these two mechanisms fail to explain many of the effects observed. In addition, the pure substance with the strongest neuroprotective effect, bilobalide, has neither of these two properties.
The effects of the ingredients on gene expression should therefore also play an important role . The extract EGb 761 changes the expression of at least 155 genes in microarray studies. These include transcription factors, genes for antioxidant enzymes, mitochondrial proteins and proteins used in DNA synthesis and repair. An influence of terpene lactones on various receptors is discussed as a further mechanism .
The interaction of ginkgo extracts with platelet activating factor (PAF) has been linked to a number of effects on diseases of the cardiovascular system, kidneys, and central nervous system. The ingredient ginkgolide B seems to be most responsible for this effect.
In experiments, extracts from Ginko biloba are characterized by estrogenic and anti-estrogenic effects via an interaction with the estrogen receptor.
Adverse effects, health risks
Gastrointestinal complaints, headaches and allergic skin reactions are described as very rare undesirable effects. Individual bleeding during long-term treatment could not be causally related to ginkgo extracts. Ginkgo extract itself does not affect blood clotting.
However, according to the Drugs Commission of the German Medical Association, based on several case reports in their database, there is an increased risk of bleeding when combined with anticoagulants (such as oral anticoagulants or platelet function inhibitors ), as well as with an inherited or acquired coagulation disorder. However, the individual reports of bleeding do not prove beyond any doubt that there was a causal relationship, since mostly other anticoagulant drugs were taken.
Many medicines and teas containing ginkgo contain the disruptive substance ginkgolic acid in appreciable amounts . As the concentration of ginkgolic acid in tea products, unlike in medicinal products, has not yet been controlled, teas containing ginkgo are discussed as potentially hazardous to health. Ginkgolic acid can cause severe allergies and inflammation of the stomach lining. Cytotoxic, neurotoxic and mutagenic effects have also been demonstrated.
In a 2013 study by the National Toxicology Program of the National Institutes of Health , an increased rate of liver and thyroid cancer was observed in animal experiments, these experiments being carried out at very high doses of up to 2000 mg / kg body weight, which are usually far in humans cannot be achieved.
Traditional medical usage
In contrast to the scientific-pharmacological use, not only the leaves, but also the seeds and roots of the tree are used in traditional Chinese medicine .
Applications of the seeds
The seeds are used for cough, bladder infections, asthma, tuberculosis, alcohol poisoning, flatulence, gonorrhea, and frequent and painful urination.
Here, a decoction of the ginkgo seeds freed from sarcotesta and sclerotesta is taken, which is taken without seeds after cooking. The seeds can also be used pure in roasted or cooked form against severe asthmoid dyspnoea , phlegm formation and coughing , whereby with regular consumption, due to the small amount of the vitamin B6 antagonist 4-methoxypyridoxine, 6-10 g / day should not be exceeded.
Areas of application of the roots
A decoction is taken here , which is taken after cooking without roots before eating. An overdose of the root as with the seeds is not possible.
The ginkgo plants belong neither to the coniferous nor to the deciduous trees, but form a separate group. Although the ginkgo at first glance resembles deciduous trees (bedecktsamer), it is more closely related to the conifers and is therefore, like them, counted among the naked samers. The ginkgo is placed in a class of its own , the class Ginkgoopsida (or Ginkgophyta). It differs from the class Coniferopsida by the different structures of the generative organs, especially the flagellated spermatozoids . It differs from the class of cycads (Cycadopsida) mainly in the anatomy of the vegetative organs. The Ginkgoopsida in turn contain a single order, the ginkgo-like (Ginkgoales), whose only family is the Ginkgo family (Ginkgoaceae) with only one living genus 'Ginkgo'.
The genus Ginkgo itself has been present with fossil finds since the early Jurassic . The oldest species unequivocally assigned to the genus, Gingkgo yimaensis from China, has very similar ovules to the recent Gingko biloba , it differs mainly in the more heavily slashed leaves. Other similar species have been described in the Jurassic sediments of Inner Mongolia . The genus seems to have reached the maximum of its diversity in the Cretaceous, when it was circumpolar with numerous species in the northern hemisphere and in some regions of the southern hemisphere. The genus survived the mass extinction on the Cretaceous-Paleogene border on both hemispheres, but died out soon after in the southern hemisphere. The species Ginkgo adiantoides, which has been documented since the Lower Cretaceous and is widespread in the Palaeogene, is morphologically extremely similar to the modern species, so that most of today's researchers no longer distinguish it from it. Most of the other species described since the Paleogene, with the exception of a single one ( Ginkgo gardneri from Scotland), are neither convincingly morphologically distinguishable from Ginkgo adiantoides nor from Ginkgo biloba and are probably conspecific to this. Ginkgo biloba is probably the oldest living plant species on earth. According to the fossil record, the genus Ginkgo disappeared in the Oligocene from the northern latitudes near the Pole (where it was previously detected as far as Spitzbergen and Ellesmere Island , on the latter, among other things, in the Margaret Formation ). At the end of the Miocene, the North American deposits disappeared. In Europe it survived until the end of the Pliocene and in Japan until the Pleistocene.
In the literature
The poem entitled Gingo biloba , which the 66-year-old Goethe wrote in September 1815 and published in his West-Eastern Divan collection in 1819, made a significant contribution to the popularity and spread of the ginkgo in Germany . The poem is dedicated to Goethe's later love, Marianne von Willemer , and represents the ginkgo leaf due to its shape as a symbol of friendship. The letter with the poem, with which Goethe enclosed two ginkgo leaves, can be seen today in the Goethe Museum in Düsseldorf , in whose immediate surroundings are numerous ginkgo trees.
The reason for the great importance of ginkgo for art, culture and medicine to this day lies primarily in the Chinese philosophy and the appealing morphology of the tree and its leaves. The ginkgo has long been revered as giving strength and life-extending. The Chinese and Japanese have worshiped the ginkgo for centuries because of its vitality and promises of miracles and asked for their wishes under it. Under him women ask for milk to breastfeed their children and farmers implore rain for a plentiful harvest. Ginkgos can be found in this and other ways in myths, folk tales and stories. The ginkgo is under nature protection in Japan. Many a giant tree towers over entire villages and is a landmark for its residents. There is a widespread legend in the Tanzhe-si monastery from the 18th century . According to it, there was a gate of honor that led to a ginkgo tree. This tree was protected by an imperial label. The Chinese belief there said that with every change of throne within the Manchu dynasty, the main trunk planted a new rice in the tree, which would then develop into a splendid branch. Trees between 1000 and 2000 years old are not uncommon. You can find them at temples, in the neighborhood, on hills and also in cemeteries next to graves. In Japan , the peeled ( freed from sarkotesta and sclerotesta ) ginkgo seeds are consumed as a symbol of happiness at wedding feasts. A 3000-year-old and 26-meter-high ginkgo in Shandong Province delivered seeds totaling one tonne when the weather was favorable. In many stories and tales, the tree is described as the place where ghosts live and is therefore highly valued and equally feared.
In addition, the two-part leaf, which is unique in the plant world, and its two-part structure was closely associated with the symbol of Yin-Yang at an early stage . The history of the temple tree in Hiroshima, which went up in flames in the atomic bomb explosion in 1945, but sprouted again in the same year and lived on, also contributed significantly to the formation of modern myths.
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