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 which 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 preparation of Ginkgo medications. Consequently the toxin ws also present in Ginkgo medications and is even detectable in homoeopathic preparations. 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.