OCCURRENCE OF NEUROTOXIC 4'-O-METHYLPYRIDOXINE IN GINKGO-BILOBA LEAVES, GINKGO MEDICATIONS AND JAPANESE GINKGO FOOD

4'-O-Methylpyridoxine (ginkgotoxin) is a neurotoxic antivitamin B-6 wh ich occurs in Ginkgo biloba L. seeds. Contrary to a previous report by Wada et al. (15), the toxin was also detected in Ginkgo biloba leaves . The leaves are a source of extracts (e.g. EGb761) employed in the pr eparation of Ginkgo medications. Consequently the toxin ws also presen t in Ginkgo medications and is even detectable in homoeopathic prepara tions. The toxin occurs also in boiled Japanese Ginkgo food. However, the amount of the toxin is likely to-be too low to exert a detrimental effect after administration of the medication or ingestion of food.