Ginkgo

GINKGO

Biological Source

The leaves of Ginkgo are obtained from the dioeceous tree Ginkgo biloba, belonging to family Ginkgoaceae.

Geographical Source

It is a native to China and Japan and cultivated ornamentally in many temperate regions.

Characteristics

The leaves are bilobed, each lobe being triangular in outline with a fine radiating, fan-like venation. The leaf is glabrous, petiolate and has an entire margin.

                                              Ginkgo biloba

Chemical Constituents

The diterpene lactones and flavonoids possess therapeutic activity. Five diterpene lactones (ginkgolides A, B, C, J, M ) have been characterized; these have a cage structure involving a tertiary butyl group and six 5-membered rings including a spirononane system; a tetrahydrofuran moiety and three lactonic groups. These compounds are platelet-activating factor (PAF) antagonists and as they do not react with any other known receptor, their effect is very specific. A tertiary butyl group is present in the sesquiterpene bilo-balide; no PAF-antagonist activity has been demonstrated for this compound.

About 40 flavonoids have now been isolated from the leaves including glycosides of kaempferol, quercetin and isorhamnetin derivatives. The tree also synthesizes a number of biflavonoids based on amentoflavone.

Uses

Ginkgo is used as an antiasthmatic and bronchodilator. Extracts of the leaf containing selected constituents are used for improving peripheral and cerebral circulation in those elderly with symptoms of loss of short-term memory, hearing and concentration; it is also claimed that vertigo, headaches, anxiety and apathy are cured.