Occurrence of Neurotoxic 4′-O-Methylpyridoxine inGinkgo bilobaLeaves,GinkgoMedications and JapaneseGinkgoFood

Abstract

4'-O-methylpyridoxine (ginkgotoxin) is a neurotoxic antivitamin B6 which occurs in Ginkgo biloba L. seeds. Contrary to a previous report by Wada et al., 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 is 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.

Tissue Culture Studies on Ginkgo biloba

“…A recent report on the occurrence of the neurotoxic chemical 4' -O-methyl pyridoxine in the leaves and in the medicines derived from the leaves of Ginkgo [77] suggests that efforts will be made to select and propagate specific chemotype tissues of Ginkgo and then regenerate plants from those cells. Either through the selection of the source of cuttings or by the propagation of somatic embryos from such a source, it seems that clonal forests low in 4'-methyl pyridoxine will be developed at some point in the future.…”

Review of the use of botanicals for epilepsy in complementary medical systems — Traditional Chinese Medicine

“…Ginkgo biloba comprises a variety of biologically active chemical constituents, including components that induce [47,48] and inhibit [49][50][51][52] seizure activity. The principal antiepileptic compounds in the ginkgo plant are ginkgolides and bilobalide.…”

“…Components of the ginkgo leaf, bilobalide in particular, may enhance the metabolism of the ginkgotoxin responsible for seizure induction [55]. Ginkgotoxin (4-O-methylpyridoxine or MPN) is present in ginkgo seeds and other plant parts [49]. The exact mechanism of action by which increased ginkgotoxin metabolism occurs is unknown; however, it is hypothesized to be the induction of a hepatic drug.…”

Ginkgo biloba L. 银杏 (Yinxing, Baiguo, Ginkgo)

“…4′-O-methodypyridoxine (MPN) and MPN-5′-glucoside are both responsible for ginkgo seed poisoning, though the latter is more prevalent in heat-treated ginkgo nuts [28]. The neurotoxin 4′-O-methylpyridoxine (ginkgotoxin) was found as high as 360 ng/ml in serum from a toddler poisoned from eating ginkgo nuts [29], compared to 181 ppm in raw seeds, and 50 ppm in leaf extracts [30]. Ginkgotoxin and its glucoside can be reduced via heat treatment in nuts, confirmed by LC/MS analysis [31].…”