Monographs


Ginkgo biloba

Phytotherapy

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Synonyms

Ginkgo tree; Maiden hair tree; Japanese temple tree

Description

Introduction
In the Netherlands, the Ginkgo biloba is known as the ginkgo tree or temple tree. The name “temple tree” refers to these trees growing around the temples in the olden days. The Chinese considered the temple tree to be a holy tree and they worshipped and protected it. The fact that the tree has been able to survive for millions of years is partially on account of the good care given to the tree in the past. In addition, the ginkgo tree was found to be exceptionally strong because it was able to protect itself with its own antioxidants.
There are many names for the tree, all of which are illustrative in nature: elephant ear tree, duck foot tree, fan leaf tree, maiden hair tree and Venus hair tree. All of these names refer to the striking fan-shaped leaf with veins which run in parallel and which are similar to fine hair. The ginkgo tree is an impressively large tree which can grow to around 30 to 40 metres in height and which can achieve a trunk diameter of a metre. It can take approximately 20 to 30 years for the ginkgo tree to mature, but then the tree will continue to reproduce for around 1,000 years.

Origin
The ginkgo tree originated from the mountain forests of China, especially below the Jangste River in South-East China and belongs to the Ginkgoaceae family. The ginkgo tree is the last remaining species of this family. The tree is sometimes called a “living fossil” because the tree has such a strong ability to survive. The tree even survived the nuclear explosion in Hiroshima. It is suspected that the tree appeared on earth approximately 200 million years ago.
In China, the oldest standing ginkgo tree is probably 4000 years’ old. For a long period of time, the ginkgo tree only appeared in China and Japan; only in the middle of the 18th century was the tree planted in Europe. The oldest trees in Europe are located in the Netherlands.
The tree is winter hardy with good resistance to insects, fungi, parasites, bacteria and viruses. In the past, the Chinese already made grateful use of the insecticidal properties of this tree by placing the leaves in books to protect them against damage by insects.

Traditional Medicine
In the old Chinese herbal books, the inhalation of the vapours from a hot tincture of ginkgo leaves was already recommended for numerous complaints, including asthma, bronchitis, cough, stomach complaints, skin diseases, hypertension, agitation, tinnitus, tuberculosis, bladder complaints and vaginal discharge. The Chinese used the seeds (“bai gou”) as well as the leaves. In a cooked form, they were said to aid digestion, particularly if taken before meals. When taken in between meals, the seeds worked as laxatives. The cooked seeds were also recommended to reduce the effects of alcohol and, in a roasted form, they were sold by traders on Chinese markets as a true delicacy.
The spelling of Ginkgo biloba is actually incorrect and officially should be Ginkyô biloba. “Gin” means “silver” and “ Kyô” means “apricot”, so together “silver apricot”, referring to the white nut which is as big as an apricot kernel. However, in 1771, Linnés made a writing error in his book “Mantissa plantarum altera” and changed Ginkyô to Ginkgo. In 1942, in his “Paläobiologie der Pflanzen” Karl Mägdefrau attempted to restore the original spelling Ginkyô, however received strong criticism for his–as he called it - “Nomenklatur-Päpsten” and came off worst: it was and remained Ginkgo biloba. In 1985, Rudolf Weiss wrote the following about Ginkgo biloba “a significant improvement has been reported in the mental state, emotional imbalance, the memory and the tendency to become tired quickly”.

Action

Active ingredients:
Ginkgo flavonglycosides, terpene lactones, catechins, oligomeric proanthocyanidins, bioflavonoids, steroids and organic acids

Active ingredients
The initial research into the active ingredients of Ginkgo biloba took place in 1925. This was followed by pharmacological experiments a few years later involving purified compounds. In 1965, the first standardised extracts were published in Germany. Through specific reprocessing of the raw extract, it was possible to significantly increase the level of organic active ingredients. An increase to a factor 50-100 in comparison to the raw ingredient was possible (50:1). Using this extract as a basis, experts were able to perform the first clinical studies into the action of Ginkgo biloba on central and disturbed peripheral blood flow.
The aforementioned dry extract of the ginkgo leaves (50:1) was standardised at 24% ginkgo flavonglycosides and 6% terpene lactones. The flavonglycosides contain, amongst others, 0.5 to 1.8% monoglycosides, diglycosides and triglycosides including kaempferol, quercetin and isorhamnetin. The terpene lactones contain 0.23% ginkgolides A, B and C and 0.2% bilobalide. In addition, the extract contains catechins (0.04%), oligomeric proanthocyanidins (8% to 12%), bioflavonoids (0.4 to 1.9%), steroids and organic acids.

The point of departure for dry extracts of Ginkgo biloba is the dried leaf which is extracted in a water/acetone mixture. Once the initial extract has been acquired, the undesirable substances are removed. Subsequently, through special reprocessing of the raw extract, there is a significant increase in the level of organic active ingredients, until the correct standardised final product is obtained (50:1). With this standardised product as a basis, hundreds of scientific studies have been performed, which mainly focussed on the effectiveness of this ginkgo extract in cerebral and disturbed peripheral blood flow.

Disrupted cerebral blood flow
More than 40 correctly performed and controlled studies have been published which demonstrate the positive effect of the standardised ginkgo leaf extract in the treatment of disturbed cerebral blood flow. When there is a poor blood flow to the brain, symptoms occur which, in the first instance, are similar to the initial signs of dementia. There is a wide symptom complex which is denoted as “cerebral insufficiency”. The most common symptoms of this complex are:
  • loss of concentration
  • forgetfulness
  • confusion
  • fatigue (both physical and psychological)
  • anxiety
  • depression
  • dizziness
  • tinnitus
  • hearing disorders
  • headache

Often these symptoms are not recognised as being signs of cerebral insufficiency. These symptoms –certainly if they only involve loss of concentration or forgetfulness – are grouped under the heading “symptoms of old age” and it is said that patients have to learn to live with the symptoms because there is no effective medication for these (?). Extensive scientific clinical research has, however, demonstrated the positive effect of ginkgo leaf extracts on disturbed cerebral blood flow.

German Commission E
The monography of “Commission E” about the dry extract of the ginkgo leaf names the following pharmacological properties:
  • stimulates the blood flow, particularly within the microcirculation
  • lowers blood viscosity and improves the flow rate of the blood
  • an increase in hypoxia tolerance, in particular of the brain tissue
  • inhibition of the development of a traumatic or toxic brain oedema
  • a decrease in oedema of the retina and damage to the retina
  • an increase in learning ability and intellectual performance
  • an effect on the cerebral metabolism
  • recovery in the event of balance disorders
  • inactivation of oxygen radicals
  • antagonist against PAF (Platelet Activating Factor)
  • PAF antagonist and the associated reactions
  • neuronal metabolic effect
  • an effect on the metabolism and/or the function of neurotransmitters
  • an effect on various transmitter systems.

PAF antagonist
Numerous scientific publications show that the flavonglycosides and the terpene lactones are the main active ingredients in ginkgo leaf extracts. The flavonglycosides are especially important free radical scavengers and the terpene lactones - particularly ginkgolide B - are powerful PAF antagonists.

An endogenous activator of platelet aggregation is PAF, which is formed by the activation of phospholipase A2 in ischaemia. PAF is then attached by the PAF receptors to target cells – for example, endothelial cells of the blood vessels, leukocytes, mast cells and thrombocytes – which can result in the release of various mediators (histamine and eicosanoids). In addition, PAF can result in physiological actions such as vasodilatation and thrombocyte aggregation. Tissue damage, inflammatory responses, asthma and allergic reactions can result from this.
PAF antagonists block the PAF receptors of the target cells. For the use of ginkgo leaf extracts, mainly the thrombocyte aggregation inhibition comes to the fore. PAF receptors are also demonstrated in the brain. It is the combination of the PAF antagonist (ginkgolide B) and radical scavengers (flavonglycosides) that convert the ginkgo extract into a particularly interesting phytotherapeutic agent in disturbed central and peripheral blood flow.

Disturbed peripheral blood flow
Disturbed arterial blood flow of the extremities are often the first signs of arteriosclerosis, characterised by hardening of the vascular walls, loss of elasticity and narrowing of the blood vessels. It is a polyethiologic clinical picture that can be advanced by smoking, hypertension, hyperlipidemia, lack of movement, diabetes mellitus and other factors. The seriousness of disturbed arterial blood blow is grouped by Fontaine into four stages:
  1. Nondescript symptoms: itchiness, a cold feeling and feeling of heaviness
  2. Intermittent claudication: substantial pain in the legs when walking caused by oxygen deficiency and, in the muscles, as a result of disturbed blood flow. The pain disappears after a few minutes of rest but when exercise is continued, reoccurs, which forces the patient to keep on resting (peripheral artery disease)
  3. Pain in the muscles and skin while at rest, particularly during the night in the calves
  4. Necrosis, gangrene and well-defined and poorly healing tissue damage.

Research
In studies, following six months use of 120 mg of ginkgo leaf extract each day in patients at stage 2 – pain when walking – a doubling of the pain-free walking distance is shown. A different study revealed that patients at stage 3 –  pain at rest – noticed a reduction in pain by 50% already after taking 200 mg of ginkgo leaf extract a day for eight days, measured on a visual scale.
Different studies with standardised ginkgo leaf extracts (24% flavonglycosides and 6% terpene lactones) show a positive result in disturbed peripheral blood flow. In starting disturbed peripheral blood flow - stage 1- the extract was found to especially have a prophylactic effect; in advanced disturbed blood flow – stage 2- the pain-free walking distance increased. In significantly advanced disturbed blood flow - stage 3 –the severity of pain reduces.

Use
The monography of “Commission E” concerns dry extracts (50:1) from ginkgo leaves and lists the following as indications:
  1. Disorders which can be traced back to symptoms of cerebral insufficiency such as concentration disorders, loss of memory, forgetfulness, inattention, irritability, rapid fatigue, depression, anxiety, agitation, tinnitus, balance disorders, dizziness and headache;
  2. Disorders resulting from disturbed peripheral arterial blood flow in Fontaine stages 2 and 3;
  3. Dizziness and tinnitus of vascular and involutive genesis (worsening as a result of aging).
  4. Most research lasted for a period of 1 to 12 months, on average three months. Patients took 120, 160 or 240 mg of standardised leaf extract each day.

Subsequent research
In the German pharmacological studies, Ginkgo biloba emerged (amongst others) as “nootropic”, in other words, a drug that activates mental performance, the alertness and the cognitive functions. Many studies into the ginkgo tree are still underway. For example, research is being performed into the effectiveness of ginkgo leaf extracts in bronchial hyperactivity, allergic skin reactions, allergies in general, PMS, disorders as a result of changes in the immune system, a decrease in visual acuity of vascular origin, psoriasis and MS.

Indications

Described in the monography of the German Commission E and the WHO are the following indications for standardised leaf extracts of the Ginkgo biloba:
  • Disorders which can be traced back to symptoms of a cerebral insufficiency: such as concentration disorders, loss of memory, rapid fatigue, forgetfulness, inattention, irritability, anxiety, agitation, depression, balance disorders, dizziness and headache.
  • Disorders resulting from disturbed peripheral arterial blood flow: at stages II and III of Fontaine.  A prophylactic action applies to stage I.
  • Dizziness and tinnitus of vascular origin or as a result of ageing.

Contra-indications

Little is known about interactions of ginkgo leaf extracts with mainstream medication. There are equally few publications about the safety of the use during pregnancy and the lactation period. For safety’s sake, it is inadvisable to use the extracts in the aforementioned periods.

Side effects

Symptoms of intoxication with ginkgo leaf extracts have not been reported to date. Through the specific recycling of the organic active substances almost all undesirable substances are removed from the extract. Slight gastrointestinal symptoms, headache or allergic reactions have very rarely been reported when standardised leaf extracts have been taken. The patients also used mainstream medication for the aforementioned adverse effects, meaning that the reactions that were reported could not solely be attributed to the use of the ginkgo extract.

Dosage

The “Commission E” recommends 120 to 240 mg of standardised leaf extract per day, preferably given in 2 to 3 doses. This recommendation guarantees the effectiveness and safety. Although primitive tinctures of the ginkgo leaf are available –these are prepared in accordance with the H.A.B. (Homeopathisch Arznei Buch) from water/ alcohol extracts – manufacturers of these primitive tinctures are unable to claim the same action as that claimed for standardised products. Primitive tinctures contain a minimum of 10 to 15% less biologically active substances, which undoubtedly has an effect on the action. Separate studies would need to prove the effectiveness of these primitive tinctures.
Treatment lasting for a minimum of 8 to 12 weeks is recommended in order for the results to be properly assessed. In moderate to serious disturbed blood flow, a long-term treatment period (minimum six months) is often required.

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