Table 1.

Main components of EGb761 and their possible functions

Component	Proportion	Function
Flavonoids: approximately 38 species, mainly Monoflavones, Flavonols and their glycosides, Biflavones and Latechines, which usually combine with glycosides.	24%	Excellent natural antioxidants that can scavenge free radicals.
Terpenoids lactone: mainly including diterpenoids such as Ginkgolide A, B, C, M and J, and sesquiterpenoids such as Bilobalide.	6% (Ginkgolides 3.1% and Bilobalide 2.9%, Bilobalide may be the metabolic intermediates of Ginkgolides)	The content of Ginkgolides is the key to evaluate EGb761 quality. Ginkgolides have a strong specific inhibitory effect on platelet activating factor (PAF) receptor, of which Ginkgolide B has the highest anti-PAF activity.
Others: polyisoenenol, fatty acids, hydroxy acids, shikimic acids, amino acids, 6-HKA, ginkgo acids (mainly Ginkgolic Acid, Hydroginkgolic Acid, Bilobo1 and Ginkgol).	Non flavonoid glycosides 20%, carboxylic acids 13%, proanthocyanidins 7%, catechin 2%, macromolecule compounds 4%, inorganic matter 5%, water 3%, other 3%.	Polyisopenyl alcohol is a type of polygene (or dolichol). It is a lipid compound in Ginkgo biloba leaves that has cis and trans forms, and plays an important role in maintaining liver function and promoting hematopoiesis. 6-HKA is a broad-spectrum central nervous amino acid antagonist. It acts on N-methyl-D-aspartate to reduce brain hypoxia. Ginkgo acids may be associated with allergy and mutagenesis, therefore are toxic and side effect components of Ginkgo biloba extract. Its content should be controlled below 5 μg/g.