Maidenhair tree-Ginkgo biloba L.-Poisonous plant

Maidenhair tree

General poisoning notes:

Ginkgo (Ginkgo biloba) is an ornamental tree growing in the warmer parts of Canada. This plant is of botanical interest because it is the sole survivor of the order Ginkgoales, with fossil evidence tracing back over 200 million years. The tree now survives only in cultivation. The trees are planted for their beautifully shaped leaves, which turn an attractive yellow in autumn. Usually only male trees are planted because the fleshy pulp on the fruits develop an obnoxious smell resembling rancid butter when the pulp is deteriorating on the ground. The interior kernel of the fruit is considered a delicacy by people of Chinese, Japanese, and southeast Asian descent. Contact dermatitis occurs in sensitive individuals when they remove the fleshy pulp from the seeds in the autumn. Children who handle the attractive yellow fruits may develop dermatitis. The pulp is also used as a folk medicine in China and Japan. The crude extract contains a toxin that causes convulsions and death if used in excess. This type of poisoning is unlikely unless the extract (gin-nan) is available in Canada.

Nomenclature:

Scientific Name: Ginkgo biloba L.

Vernacular name(s): maidenhair tree

Scientific family name: Ginkgoaceae

Vernacular family name: ginkgo

Geographic Information

Plant or plant parts used in or around the home.

Notes on Poisonous plant parts:

The endosperm (the food storage tissues) of the seeds contains a chemical that can cause convulsions and death in humans if taken in excessive quantities. The Chinese and Japanese use a crude extract of ginkgo seed, called gin-nan, as an antitussive and expectorant in folk medicine. Excessive use of this extract has caused gin-nan food poisoning in China and Japan. Some deaths have occurred. Ginkgo seeds can be obtained in specialized food stores, and gingko trees grow and bear fruit at least in some areas of the country, such as Ottawa. The seeds are often picked by Chinese and Japanese for food consumption. The seed coat and the fruit pulp of ginkgo can cause allergic contact dermatitis. This most often happens when the fruit pulp is removed to get at the seed, which is considered a delicacy in Chinese and Japanese cooking (Nakamura 1985).

Toxic parts:

Mature fruit, seeds

Notes on Toxic plant chemicals:

4-O-Methylpyridoxine is a chemical that has an antivitamin B6 activity. This chemical is found in the endosperm (the food storage tissue) of the seeds. The chemical causes convulsions in guinea pigs at oral doses of 11 mg/kg. 4-O-Methylpyridoxine also inhibits the formation of 4-aminobutyric acid from glutamate, which might induce seizures (Wada et al. 1988). Ginkgolic acids 1 are aromatic compounds found in the pulpy exterior of the fruit of ginkgo. These chemicals cause allergic contact dermatitis. Lepoittevin et al. (1989) determined that despite the close structure between ginkgolic acids 1 and the components of urushiol 4 (the allergen of poison-ivy), the hypothesis that the acids transform into catechol 4 in vivo (as with poison-ivy) cannot be supported. Cross-reactivity between ginkgo and urushiol did not occur when tested on guinea pigs.

Toxic plant chemicals:

Ginkgolic acids 1
4-O-methylpyridoxine

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Humans

General symptoms of poisoning:

Convulsions, death, erythema, unconsciousness.

Notes on poisoning:

A crude extract of gingko seeds is used in folk medicine in China and Japan. Excessive use can cause convulsions, unconsciousness, and death. Infants are especially vulnerable (Wada et al. 1988).