4'-O-methylpyridoxine

4'-O-Methylpyridoxine (also known as ginkgotoxin or 4'-MPN) is a naturally occurring small-molecule antivitamin B6 found in the seeds and leaves of *Ginkgo biloba*. It acts as a competitive inhibitor of pyridoxal kinase (PDXK), the enzyme responsible for synthesizing the active cofactor pyridoxal-5'-phosphate (PLP) from vitamin B6. By lowering brain PLP levels, 4'-O-methylpyridoxine reduces the synthesis of gamma-aminobutyric acid (GABA), leading to an imbalance in the GABA/glutamate ratio that can trigger hyperactivity, convulsions, and seizures (ginkgo seed poisoning). In addition to its role as a neurotoxin, radiolabeled [11C]-4'-O-methylpyridoxine is being investigated as a first-in-class PET imaging radiotracer to monitor the PDXK:PDXP activity ratio in vivo, which serves as a biomarker for chemotherapy resistance (such as cisplatin resistance) in non-small cell lung cancer (NSCLC).

Other names

4'-MPN4'-methoxypyridoxine4-methoxymethylpyridoxineginkgotoxin