Toxicity of 4′-O-methylpyridoxine-5′-glucoside in Ginkgo biloba seeds

A vitamin B6 derivative, 4′-O-methylpyridoxine (MPN) is responsible for food poisoning by Ginkgo biloba seeds. MPN-5′-glucoside is also contained in Ginkgo biloba seeds. In this study, we examined the toxicity of MPN-5′-glucoside in mice and MPN-5′-glucoside content in Ginkgo biloba seeds in order to estimate its contribution to poisoning by Ginkgo biloba seeds. The MPN-5′-glucoside content was comparable to that of MPN in row seeds but was much higher than that of MPN in heated Ginkgo biloba seeds. However, the total MPN content showed no significant differences in heated seeds compared with the content in non-treated seeds. The MPN-5′-glucoside (0.8 mmol/kg b.w.) had a lethal effect in mice, as well as MPN. Additionally, the onset time of convulsions after administration of MPN-5′-glucoside was longer than that after administration of MPN. Ginkgo biloba seeds are generally eaten after heating in Asia. Therefore, the intake of MPN-5′-glucoside, rather than MPN, might cause food poisoning by Ginkgo biloba seeds.