Ancient Remedy Mitigates the Harmful Effects of Stress and Aging
What is Ginkgo biloba?
The ginkgo (biloba) is a member of an ancient family of trees, very possibly the oldest living tree species on earth. The first fossil records of ginkgos date back to over 270 million years ago. In evolutionary terms, the ginkgo is more closely related to pine trees (gymnosperms), than to flowering trees (angiosperms), a fact that makes evolutionary sense, given that gymnosperms are phylogenetically much older than angiosperms. The reason that the ginkgo has thus far escaped extinction up to now is its high resistant to disease, pest and environmental insult, a genetic resilience that is also reflected in its potential to live to over 4,000 years.
Also known as the Maidenhair tree, ginkgos were once indigenous to many parts of the world. Today, however, the ginkgo only grows naturally in China. Nevertheless, due to its ability to survive harsh environments, man has once again transplanted the ginkgo to cover many parts of the globe. In fact, the ginkgo is one of the few trees that can survive ‘big city’ environments and hence, is often found lining the streets in some of the world’s busiest metropolitan areas. However, despite the fact that the fruit and the leaves of the Ginkgo have been used in traditional Chinese medicine for over six centuries, its re-appearance in the North American continent only took place a little over two centuries ago.
The ginkgo’s species name, biloba, is derived from the fact that its leaves possess two lobes (see image). Scientific nomenclature is generally straightforward.
Uses of Ginkgo biloba
Extracts of dried ginkgo leaves are among the best selling herbal medications in Europe, especially in France and Germany where it ranks among the top five of all prescriptions written. Achieving nearly a 300 million dollar a year industry at the commencement of the 21st century, ginkgo sales will continue to increase in the upcoming years as research reveals more about its healthful properties. Let there be no doubt, the increasing use of ginkgo for medical purposes stems from its success in the clinical arena.
Ginkgo biloba derivatives are currently being used to remedy asthma, coughs, age-related macular degeneration (reduced vision in the elderly) and bladder inflammation. Ginkgo also improves peripheral and cerebral circulation and, in this capacity, has been shown to be effective in mitigating cases of erectile dysfunction, intermittent claudication (pain caused by inadequate blood flow to the legs) and cerebral insufficiency (reduced blood flow to the brain in the elderly causing symptoms of cognitive decline). In fact, one of the more promising uses of ginkgo is as a neuroprotectant and cognitive enhancer; ginkgo is proving to be an effective anti-Alzheimer’s treatment (see below). Finally, ginkgo also reduces signs of stress, both mentally and physically (see Stress Inhibition).
Components of a standardized extract of Ginkgo biloba: EGb 761
One particularly well-defined extraction, EGb 761 (Extract Ginkgo biloba 761), is recently providing very promising results in scientific studies.
EGb 761 consists of 24% ginkgo-flavonol glycosides and 6% ginkgo terpenoid lactones, which can be further subdivided into the following classes of ingredients:
Ginkgo-flavonol glycosides: A mixture of biflavoness and flavonol glycosides that are found in their highest concentrations in the leaves of the Ginkgo.
Ginkgo terpenoids: Trilactones consisting of a mixture of ginkgolides and bilobalides. Ginkgolides are further separated into several subfractions A, B, C, J and M, with distinct pharmacological activities. These components only constitute about 0.1% of dry Ginkgo biloba leaves and are much more prevalent in the tree itself.
IMPORTANT: When purchasing ginkgo products look for this percentage composition of ginkgo-flavonol glycosides and ginkgo terpenoid lactones.
Unwanted contaminants: Ginkgolic acid should constitute less than 10 ppm (parts per million) to a final extraction, since it might cause skin irritation.
Biological activities of the components of Ginkgo biloba
Extracts of Ginkgo biloba have been found to increase circulation, enhance mood, accentuate cognitive capacity and improve memory. These effects are more often, than not, the result of the combined actions of the individual components of Ginkgo biloba working in concert, the so-called polyvalent effects (see below). Next is a description of the biological activities that each separate fraction of Ginkgo biloba (EGb 761) has at the cellular level.
Ginkgo-flavonol glycosides: Flavonoids (such as quercetin, kaempferol and isorhamnetin) are potent antioxidants. Acting as such, ginkgo’s falvonoids scavenger and neutralize free radicals that might cause the breakdown of integral cell membranes via a deleterious process of lipid peroxidation as well as damage DNA, leading to mutations of the cell’s genetic information. The ginkgo flavonoids thus extend cell survival under conditions (oxidative and free radical stress) that might otherwise lead to cell death or the development of cancer.
In particular, a specific flavonoid fraction of EGb 761 (CP 205) has been recently shown to prevent the death of neurons in an area of the brain known as the hippocampus in response to NO (nitrix oxide) over production (see reference below). As the hippocampus is the part of the brain that consolidates and stores memories, any damage to this part of the brain will severly interfere with normal cognitive capacity.
Selected Scientific Reference
EGb 761 protects brain cells from free radical damage
Bastianetto, S. et al. (2000) The Ginkgo biloba extract (EGb761) protects and rescues hippocampal cells against nitric oxide-induced toxicity: Involvement of its flavonoid constituents and protein kinase C. Journal of Neurochemistry, Volume 74, pages 2268-2277.
By acting as free radical scavengers the flavonoids also relax blood vessels by preventing a rise in intracellular calcium concentration that would otherwise cause vascular smooth muscle contraction (vasoconstirction).
Ginkgo terpenoids: Ginkgolides improve blood flow by reducing the stickiness of platelets, supporting cellular energy metabolism and by acting as antioxidants.
- Ginkgolides: These agents are highly selective antagonists of platelet aggregation mediated by platelet-activating factor (PAF) receptor. PAF, synthesized locally, mediate pain perception, blood coagulation, and smooth muscle contraction. When overexpressed, PAF contributes to various inflammatory, cardiovascular, and respiratory disorders.Ginkgolide B is most active of the ginkgolides in this capacity, followed by ginkgolides A, C, M in order of reducing potency.
- Bilobalide: Bilobalide is a sesquiterpene. Recent evidence indicates that bilobalide improves cellular energy metabolism, especially in response to cerebral ischemia, or greatly reduced blood flow. Specifically, bilobalide allows mitochondria to maintain respiratory activity when oxygen levels drop precipitously and by doing so maintains cellular energy (ATP) content from dropping dangerously.Bilobalide derivatives are currently used for treating neuropathy, edema, encephalopathy, spinal cord disease and senile dementia. There is also convincing evidence supporting an antioxidant role for bilobalide.
Selected Scientific Reference
Bilobalide is a potent antioxidant, preventing programmed cell death (apoptosis) in response to reactive oxygen species
Zhou, L. and Zhu, X. (2000) Reactive oxygen species-induced apoptosis in PC12 cells and protective effect of bilobalide. The Journal of Pharmacology and Experimental Therapeutics, Volume 293 (3), pages 982-988.
Bilobalide might also prove useful as an anticonvulsant. Over excitation by neurotransmitters, namely glutamate, can give rise to seizures.
Polyvalent effects: Ginkgo’s broad systemic effects are the consequence of interactions between the individual biological activities (increased circulation, antioxidant effects and metabolic effects) of its separate components (flavonoids, ginkgolides and bilobalide). Such multifaceted actions of ginkgo are most evident in the area of dementia and the decline in mental capacity observed with aging. This needs to be contrasted with synthetic medications that instead target a single cellular pathyway and are more limited in scope. For instance, ginkgo biloba is demonstrating to be effective in retarding the development of Alzheimer’s disease.
Selected Scientific Reference
EGb 761 slows the progression of senile dementias such as Alzheimer’s disease.
Luo, Y. (2006) Alzheimer’s disease, the nematode Caenorhabditis elegans, and ginkgo biloba leaf extract. Life Sciences, Volume 78, pages 2066-2072.
Interestingly, a significant proportion of patients suffering from dementia and depression exhibit elevated cortisol levels (see Stress Inhibition). Stress kills brain cells…
Precautions and counterindications of mixing Ginkgo biloba with certain prescribed medications
Ginkgo is widely considered safe and side effects are rare. In a few cases, gastrointestinal upset, headaches, skin reactions, sleeeplessness and dizziness have been reported.
- Because Ginkgo biloba decreases clot formation (platelet aggregation) there is some concern that it may increase the risk of intracranial (brain) hemorrhage. Therefore, until more is known, one should not mix ginkgo with other blood-thinning medications, including aspirin.
- Ginkgo biloba should not be taken within 36 hours of surgery to the possibility of bleeding complications.
- Ginkgo biloba should not be taken in combination with anticonvulsant medication.