Inhibition of amyloid-ß aggregation and apoptosis by Ginkgo biloba extract EGb 761® in vitro.
PNAS, 2002, Vol 99, No. 19, 12197-12202

Ginkgo special extract EGb 761® demonstrates two interesting effects which are of potential significance in the prevention of Alzheimer's disease. These new and possibly pioneering findings were presented by American scientists at the 8th International Conference on Alzheimer's Disease in Stockholm. According to these findings, Ginkgo special extract EGb 761® inhibits the aggregation of amyloid-beta peptide to form beta-amyloid, the key process in the formation of "Alzheimer plaques". Furthermore, the proportion of apoptotic cells is decreased - i.e. fewer cells die. Both mechanisms of action commence at an early stage in the development of Alzheimer's disease and make Ginkgo special extract EGb 761® (trade name: Tebonin®) even more interesting as a medication for Alzheimer prophylaxis.

Despite intensive research, there is still no effective therapy for Alzheimer's disease. Consequently, potential means of disease prophylaxis are becoming increasingly more important. Experimental findings which suggest that a medication has a preventive action are therefore of great value. Ginkgo drugs have been used to treat Alzheimer's disease and other forms of age-related dementia over a considerable period. The leaves of this tree contain active substances which act in a neuroprotective manner, i.e. effectively protect nerve cells against damage, due to their anti-oxidative or radical capturing properties, amongst others.

Prof. Peter Butko's research team from the University of Southern Mississippi have now found a further, new mechanism of action of Ginkgo extract, which acts in an earlier stage of development of Morbus Alzheimer, and which may possibly be important in the prevention of this disease.

Ginkgo special extract inhibits the formation of Alzheimer plaques

As reported by the US researchers at the 8th International Conference on Alzheimer's Disease in Stockholm, EGb 761® inhibits the aggregation of amyloid-ß protein in cell cultures, i.e. an important step in the formation of the so-called plaques. These plaques, insoluble deposits of amyloid-beta protein, are microscopically the most noticeable and typical sign of Alzheimer's disease in the brain. Apart from other factors, these protein clumps lead to irreparable damage to the nerve cells in the brain.

World-wide, the search for medication which could prevent the formation and deposition of amyloid plaques is being pursued with feverish activity. Specific enzyme inhibitors to inhibit the aggregation of amyloid-beta protein are under discussion, for example. In contrast to such substances, EGb 761® has been shown to be well tolerated during long-term applications.
 

Ginkgo special extract reduces nerve cell death

As shown in the same paper, EGb 761® also significantly reduces the proportion of dying cells. Inhibition of caspase-3, a key enzyme in "programmed cell death" (apoptosis), is responsible for this action. This effect should also contribute to the neuroprotective action of Ginkgo extract in Alzheimer's disease.

The results indicate that the neuroprotective effect of Ginkgo special extract EGb 761® (Tebonin®) is mediated by several cellular and molecular mechanisms. Ginkgo preparations, with their well-known good tolerability, are therefore plainly predestined for the prevention of Alzheimer's disease - in which long-term medical treatment is unavoidable.
 

Authors of the Original Paper:
Yuan Luo, Julie Smith, Kenneth Curry, Justin Buford, Huaxi Xu, Peter Butko (University of Southern Mississippi, Hattiesburg, Mississippi and Rockefeller University, New York)

Presented at the
8th International Conference on Alzheimer's Disease and Related Disorders, 20-25th July 2002, Stockholm