By: Nutrition Expert- Vidula Kozarekar, Mumbai.
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Ginkgo biloba (Gb) has demonstrated antioxidant and vasoactive properties as well as clinical benefits in several conditions such as ischemia, epilepsy, and peripheral nerve damage. Additionally, Gb is supposed to act as potential cognitive enhancer in dementia. So far, several trials have been conducted to investigate the potential effectiveness of Gb in neuropsychiatric conditions.
Since ancient times, Ginkgo biloba has been used for medicinal purposes. In the oldest Chinese Materia Medica (2800 B.C.), Ginkgo biloba was recommended for asthma, swelling of the hands and feet, coughs, vascular disorders, aging and for the brain. Since 1965, Ginkgo biloba has been used in Europe for the treatment of cerebral insufficiency and peripheral vascular disease (1).
Mechanism of action:
The ginkgo leaf extract protects the neurons from oxidative damage potentially preventing the progression of tissue degeneration in patients with dementia. Additionally, Ginkgo biloba leaf extract improves blood flow throughout the body, and it restores the balance between prostacyclin and thromboxane A2 resulting in improved vasoregulation. Vascular contraction and improvement in the venous tone are thought to be the result of phosphodiesterase inhibition and release of catecholamine. The beneficial effects of Ginkgo biloba leaf extract in Alzheimer’s disease might also be due to the inhibition of toxicity and cell death induced by beta-amyloid peptides (1).
The mechanism of action of ginkgo is believed to be produced by its functions as a neuroprotective agent, an antioxidant, a free-radical scavenger, a membrane stabilizer, and an inhibitor of platelet-activating factor via the terpene ginkgolide B (2).
Flavonoids and terpenes, two major fractions of the standard Ginkgo biloba extract, are responsible for its exceptionally diverse pharmacological activities. The flavonoid fraction has an antioxidant effect by reducing reactive oxygen species (ROS), promoting the expression of antioxidant proteins and increasing the levels of antioxidant metabolites such as glutathione. The terpene lactones include bilobalide and ginkgolides A, B, C, J and M. It has been showed that reperfused hearts treated with terpene constituents recovered their function (3).
Efficacy of Ginkgo Biloba:
- Masayuki Hashiguchi et al found in a study that; taking a 240-mg daily dose of Ginkgo biloba extract is effective and safe in the treatment of dementia (4).
- In a literature review, Barry S. Oken et al found that; there is a small but significant effect of 3- to 6-month treatment with 120 to 240 mg of G biloba extract on objective measures of cognitive function in Alzheimer disease (5).
- Chun-Xiao Dai et al found that; Ginkgo Biloba, as an adjunctive treatment, can effectively improve depressive symptoms and reduce expression of serum S100B, which is a marker of brain injury, suggesting that Gb restores neurologic function during the treatment of depression in elderly patients and S100B participates in the therapeutic mechanism. Gb combined with depressive drugs plays synergistic role, and the time of onset of efficacy is faster than single antidepressants (6).
- In 2000, a study was designed by Kennedy et al to investigate the effects of acute doses of Ginkgo Biloba on cognitive performance. Eighteen female and two male healthy college students (age 19–24 years) received 120, 240, and 360 mg of Gb or placebo. Compared with the placebo, cognitive function was improved in a number of assessment substances. It was noteworthy that a number of tests were performed dose-dependently after acute administration of EGb (7).
- Ischemia, impaired blood circulation, is a common underlying condition of cardiovascular and cerebral vascular diseases. During an ischemic attack, there is an increased release of free radicals and lipid peroxidation causing tissue damage and resulting in chronic diseases. Cardio protective effects of Ginkgo leaf extract are through antioxidant, antiplatelet activity and increased blood flow through release of nitric oxide and prostaglandins (8).
The standardized Ginkgo leaf extract preparation has been found to exhibit multifaceted therapeutic effects that include effects on neurodegenerative diseases, cancer, cardiovascular diseases, tinnitus, geriatric complaints, and psychiatric disorders. The main underlying mechanism of action in all these cases has been the antioxidant properties of the extract. Thus, Ginkgo leaf extract has been shown to be a promising herbal dietary supplement with proven therapeutic benefits.