Ginkgotoxin is a pyridoxine antimetabolite that has been found in G. biloba.1,2 It inhibits pyridoxal kinase (Ki = 3 µM), the enzyme that converts pyridoxine into its active form, pyridoxal 5'-phosphate .3 Ginkgotoxin (200-1,000 µM) induces seizure-like behavior in zebrafish larvae, an effect that can be reversed by PLP or GABA.4
1.Wada, K., Ishigaki, S., Ueda, K., et al.An antivitamin B6, 4'-methoxypyridoxine, from the seed of Ginkgo biloba L.Chem. Pharm. Bull.33(8)3555-3557(1985) 2.Arenz, A., Klein, M.K., Fiehe, K., et al.Occurrence of neurotoxic 4'-O-methylpyridoxine in Ginkgo biloba leaves, Ginkgo medications and Japanese Ginkgo foodPlanta Med.62(6)548-551(1996) 3.Gandhi, A.K., Desai, J.V., Ghatge, M.S., et al.Crystal structures of human pyridoxal kinase in complex with the neurotoxins, ginkgotoxin and theophylline: Insights into pyridoxal kinase inhibitionPLoS One7(7)e40954(2012) 4.Lee, G.-H., Sung, S.-Y., Chang, W.-N., et al.Zebrafish larvae exposed to ginkgotoxin exhibit seizure-like behavior that is relieved by pyridoxal-5'-phosphate, GABA and anti-epileptic drugsDis. Model. Mech.5(6)785-795(2012)