GINKGO BILOBA Medecine

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GINKGO BILOBA in Medicine

The first mentioned use of Ginkgo biloba appears in China. Ginkgo leaf is first mentioned in Lan Mao's Dian Nan Ben Cao, published in 1436 during the Ming dynasty. Lan Mao notes external use to treat skin and head sores as well as freckles. Internal use of the leaves is first noted in Liu Wen-Tai's Ben Cao Pin Hui Jing Yao , an imperial commissioned work recorded in 1505. Liu Wen Tai notes use of the leaves in the treatment of diarrhea. The leaves of ginkgo are known in Chinese medicine as bai-guo-ye. Recent clinical reports in modern China suggest that the leaves lower serum cholesterol levels and have some clinical value in angina pectoris.

In Traditional Chinese pharmacopeia the seeds (with fleshy rind removed) are considered more important than the leaves. The nut, called Pak Ko, is recommended to expel phlegm, stop wheezing and coughing, urinary incontinence and spermatorrhea. The raw seed is said to help bladder ailments, menorrhea, uterine fluxes, and cardiovascular ailments. The powdered leaf is inhaled for ear, nose, and throat disorders like bronchitis and chronic rhinitis. Locally applied boiled leaves are used for chilblains.. The seeds are used as an astringent for the lung, to stop asthma and enuresis.

Ginkgo leaves are a Chinese herb that has been used much more in the West than in its homeland. Over five hundred scientific studies on the chemistry, pharmacology and clinical effects of gingko leaves have been conducted by European researchers over the last 20 to 30 years. The majority of studies on ginkgo leaf extract have involved a product produced by a German/French consortium, referred to in the scientific literature as EGb761.

More informations on Ginkgo biloba Extract Page

The extract utilized in medicine is standardized in a multi-step procedure designed to concentrate the desired active principles from the plant. These extracts contain approximately 24% flavone glycosides (primarily composed of quercetin, kaempferol, and isorhamnetin) and 6% terpene lactones (2.8-3.4% ginkgolides A, B, and C, and 2.6-3.2% bilobalide). Other constituents include proanthocyanadins, glucose, rhamnose, organic acids, D-glucaric acid and ginkgolic acid (at most 5 ppm ginkgolic acids). Biochemical studies have concentrated on the flavonoids: much of the curative properties of the ginkgo tree are due to the activities of these flavonoids. The complex extract itself, rather than a single isolated component, is believed to be responsible for Ginkgo's biological activity.

Ginkgo leaf extracts have been shown to have a wide range of biological activities. The most well-known use is the ability to improve short term memory. Other important effects include a protective effect on the blood-brain barrier and an anti-radical (antioxidant) effect. The leaf extracts has also been shown to increase vasodilation and peripheral blood flow rate in capillary vessels and end-arteries in various circulatory disorders. Ginkgo leaf helps to maintain integrity and permeability of cell walls by inhibiting lipid peroxidation of membranes. Other studies have shown vascular-tone regulating effects, and help in modulating cerebral energy metabolism.

Ginkgo standardized extracts have been widely used in Europe for a wide variety of clinical conditions

associated with age-related physical and mental deterioration. These include:

1) Alzheimer's Disease / age-related dementia: Ginkgo extracts appear to be capable of stabilizing and, in some cases, improving the cognitive performance of patients with schizophrenia. Based on a quantitative analysis of the literature there is a small but significant effect of 3 to 6 month treatment with 120 to 240 mg of Gbe on objective measures of cognitive function in Alzheimer's Disease ( Oken, Oregon Health Sciences University, 1998 ). The last publication ( Le Bars, Memory Centers of America, New York, Jan 2002 ) indicated that " a treatment effect favorable to EGb could be observed with respect to cognitive performance and social functioning regardless of the stage of dementia, whether mild or moderately severe. However, the relative changes from baseline measured at endpoint depended heavily on the severity at baseline. Improvement was observed in the group of patients with very mild to mild cognitive impairment, while in more severe dementia, the mean EGb effect should be considered more in terms of stabilization or slowing down of worsening, as compared to the greater deterioration observed with placebo". Further research in the area will need to determine if there are functional improvements and to determine the best dosage. Additional research will be needed to define which ingredients in the ginkgo extract are producing its effect in individuals with AD. A recent study makes clear that EGb treatment may enhance the effectiveness of antipsychotic drugs and reduce their extrapyramidal side effects ( Zhang, Yale University School of Medicine, 2001 ).

2) Cardiovascular Disease: Treatment with Ginkgo biloba extract lowers fibrinogen levels and decreases plasma viscosity ( EGb can limit oxidative stress )

3) Cerebral vascular insufficiency and impaired cerebral performance: Administration of EGb has been shown to improve a variety of conditions associated with cognitive functions, particularly for memory loss, attention, alertness, vigilance, reaction times and depressive mood. A recent australian study indicates significant improvements in speed of information processing working memory and executive processing attributable to the EGb ( Stough C, Swinburne University of Technology, Melbourne, 2001 ).

Other therapeutic applications include:

1) Congestive symptoms of premenstrual syndrome: Ginkgo extract was effective for the treatment of the congestive (particularly breast symptoms) and neuropsychological symptoms of PMS.

2) Intermittent Claudication: A recent meta-analysis ( Pittler, University of Exeter, 2000 ) found a significant difference in the increase in pain-free walking distance in favor of Ginkgo biloba (weighted mean difference: 34 meters ). In studies using similar methodological features (ergometer speed: 3 km/h, inclination: 12%) this difference was 33 meters in favor of Ginkgo biloba.

3) Vertigo / Equilibrium Disorder / Prevention of altitude sickness.

4) Tinnitus (ringing in the ear). An overview ( Holstein, Karlsruhe, 2001 ) of results of 19 clinical trials shows a statistically significant superiority of treatment with the Gbe 761 as compared with placebo or reference drugs applied of periods of 1 to 3 months. " Therapeutic success was not directly correlated with either the genesis or the duration of tinnitus. However, investigations of prognostic factors revealed that short-standing disorders have a better prognosis, so that better results can be expected from early-onset treatment."

5) Liver Fibrosis: Ginkgo biloba was shown to be effective in arresting the development of liver fibrosis associated with chronic hepatitis B.

6) Macular degeneration: In spite of the small population sample, a statistically significant improvement in long distance visual acuity was observed in patients with macular degeneration.

Clostre F	Ginkgo biloba extract. State of knowledge in the dawn of the year 2000 Ann Pharm Fr 1999 Jul;57 Suppl 1:1S8-88 [Article in French]
Drew S	Effectiveness of Ginkgo biloba in treating tinnitus: double blind, placebo controlled trial. BMJ 2001 Jan 13;322(7278):73 FREE full text article at bmj.com
Holstein N.	Ginkgo special extract EGb 761 in tinnitus therapy. An overview of results of completed clinical trials Fortschr Med 2001 Jan 11;118(4):157-64
Le Bars PL	Influence of the Severity of Cognitive Impairment on the Effect of the Ginkgo biloba Extract EGb 761((R)) in Alzheimer's Disease. Neuropsychobiology 2002 Jan;45(1):19-26
McKenna DJ	Efficacy, safety, and use of ginkgo biloba in clinical and preclinical applications. Altern Ther Health Med. 2001 Sep-Oct;7(5):70-86.
Moulton PL	The effect of Ginkgo biloba on memory in healthy male volunteers. Physiol Behav. 2001 Jul;73(4):659-65.
Oken BS	The efficacy of Ginkgo biloba on cognitive function in Alzheimer disease. Arch Neurol 1998 Nov;55(11):1409-15
Pittler MH	Ginkgo biloba extract for the treatment of intermittent claudication: a meta-analysis of randomized trials. Am J Med 2000 Mar;108(4):276-81
Stough C	Neuropsychological changes after 30-day Ginkgo biloba administration in healthy participants. Int J Neuropsychopharmacol. 2001 Jun;4(2):131-4.
Yoshikawa T	Ginkgo biloba leaf extract: review of biological actions and clinical applications. Antioxid Redox Signal. 1999 Winter;1(4):469-80. Review.
Zhang XY	A double-blind, placebo-controlled trial of extract of Ginkgo biloba added to haloperidol in treatment-resistant patients with schizophrenia. J Clin Psychiatry. 2001 Nov;62(11):878-83.

Current interest in Ginkgo biloba relates to potential medical applications of the plant extracts. The major active component of GBE was considered, until 1993, to be a flavonoid complex that removed free radicals in the peripheral and/or cerebral vascular systems, and also as a inhibitor of lipid peroxidation. More recent evidence suggests that the ginkgolides may be more important bioactive ingredients in the leaf extract, as they are platelet activating factor (PAF) antagonists. An increase in PAF occurs in asthma, graft rejection and in immune disorders that induce toxic shock. Ginkgolide B and related diterpenes inhibit the binding of PAF to receptors on the cell surface of some human leukocytes.

There is no doubt that ginkgo leaf extracts are of clinical benefit for a number of clinical conditions. More research will be published in the next few years that will further confirm ginkgo's utility.

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