Ginkgo (Ginkgo biloba) – Botany, Therapeutic Uses, Constituents, Pharmaco, Adverse Effects

One of the most popular herbal supplements, extracts of the ginkgo leaf are recommended for the treatment of a variety of conditions. In particular, they are thought to be of benefit for enhancing memory and cognition. The popularity of this product is demonstrated by the fact that annual sales of ginkgo exceed $1 billion worldwide, with more than $100 million of this spent in the United States alone.

Ginkgo has been widely available in the Western hemisphere for the past 40 years, first in Europe and then in the United States. The relatively recent interest in this leaf extract is notable because ginkgo, also known as maidenhair or kew, is one of the oldest living species of tree. Fossil evidence suggests that ginkgos were present throughout the world up to 200 million years ago, but were rendered nearly extinct during the last ice age, surviving only in Asia. Reintroduced to the West in the sixteenth century, modern ginkgo is the sole survivor of the Ginkgophyla division of the Ginkgoaceae family. A dioecious species, the female ginkgo produces a plum-like fruit that emits an offensive odor due to the presence of butanoic and hexanoic acids. The male ginkgo is preferred for ornamental planting in part because of the unpleasant odor of the rotting fruit.

Although the ginkgo was present throughout human evolution, the possible medicinal value of its fruit, seeds, and leaves was not recorded until some 800 years ago. One of the earliest extant publications on its therapeutic potential is Lan Mao’s Dian Nan Ben Cao where it is suggested that the leaves be used as a topical treatment for freckles, head sores, chilblains, and wounds. The first known mention of systemic use, for the treatment of diarrhea, appeared in the fourteenth century with the publication of Liu Wen-Tai’s Ben Cao Pin Hui Jing Yao. At about the same time, Li Shih-Chen in Pen Ts’ao Kang Mu proposed ginkgo seeds as a remedy for a host of conditions, including cough, asthma, and worm infections. It was not until the 1960s, however, that ginkgo leaf extract was introduced as an herbal remedy in Western Europe. Its popularity in the United States dates from the 1980s.

It is possible the delay in documenting the possible medicinal value of ginkgo was because of its limited geographical distribution and the unpleasant aroma of its fruit. The former seems unlikely as the Chinese were publishing descriptions of herbal remedies, such as in the Shen Nong Ben Cao Jing, as early as 2800 BC. As for the possibility that the foul odor lessened enthusiasm for consumption of the fruit, seeds, and leaves, there is written evidence suggesting ginkgo seeds were a food source in China from at least 200 BC. This indicates these plant products have been ingested for more than 2000 years. It seems more likely that the ancients were slow to appreciate the possible medical value of the ginkgo because responses to the application or consumption of its seeds, leaves, fruit, or their extracts, are subtle and unpredictable. This differentiates the ginkgo from other natural products, such as opium, which display a rapid, dramatic, and consistent effect on central nervous system function. Even with the most modern tools available for assessing cognition and memory, there is still debate about whether gingko extract improves brain function. A careful analysis of the literature on the chemical composition of gingko extract, and on what is known of its pharmacokinetics and pharmacodynamics, provides some insights into this ongoing controversy.