Ginkgo biloba 銀杏

POISONOUS PARTS

Seeds, especially the immature and uncooked seeds.^4,5

TOXICITY

• Toxic Constituents

  4-O-Methoxypyridoxine.^4,6

• Toxic Dose

  10 seeds can be toxic. Reported lethal dose: 15−574 seeds.^5,7

• Mechanism

  4-O-Methoxypyridoxine inhibits glutamic acid decarboxylase, resulting in decreased γ-aminobutyric acid level and increased glutamate level. This leads to convulsion.⁶

• Poisoning Features

  Nausea, vomiting, diarrhoea, abdominal pain, confusion and convulsion.^6,8

• Poisoning Events

  Multiple poisoning cases due to excessive consumption of the seeds of G. biloba have been reported in China and Japan. Most patients recovered uneventfully but fatal cases have also been reported.^6,9–11

CLINICAL MANAGEMENT

Supportive treatment. Pyridoxal phosphate, the active form of vitamin B6, has been used as an antidote for G. biloba poisoning.⁶

IDENTIFICATION FEATURES

Deciduous trees, up to 40 m high. Bark greyish brown, fissured and rough; branches nearly verticillate, ascending. Leaves pale green, turning yellow in autumn, fan-shaped, 5−8 cm wide at apex, notched or bilobed; veins dichotomous. Pollen cones pedunculate, catkinlike; microsporophylls with short stipe. Seeds 2.5−3.5 × 2 cm, yellow or orange when ripe, glaucous.¹²

MEDICINAL USES

Uses in TCM—seeds: constrain the lung to reduce wheezing, reduce vaginal discharge and urination; leaves: activate blood and nourish the heart, resolve turbidity and lower lipid, unblock the collaterals and relieve pain, constrain the lung and astringe the intestines. Recommended dose: seeds 5–10 g, leaves 9–12 g.^2,13–15

LABORATORY ANALYSIS

4-O-Methoxypyridoxine can be detected by HPLC-FD and LC-MS.¹⁶