[N-methyl-11C]MeAIB, a Tracer for System A Amino Acid Transport: Preparation from [11C]Methyl Triflate and HPLC Metabolite Analysis of Plasma Samples After Intravenous Administration in Man

Article abstract of DOI:10.1002/1099-1344(200009)43:10<1013::AID-JLCR387>3.0.CO;2-H

MeAIB, α-methylamino-isobutyric acid, is an achiral synthetic ammo acid which is a highly selective substrate for the A-type, or alanine-preferring, amino acid transport system. [N-methyl-11C]MeAIB ([11C]MeAIB) was prepared by reaction of [11C]methyl triflate with AIB methyl ester, generated in situ from its corresponding hydrochloride, followed by hydrolysis of the ester function with aqueous NaOH. After HPLC-purification, the product was obtained in a 60-70 percent decay corrected yield counted from [11C]methyl triflate. The total synthesis time was 32-37 min and the radiochemical purity of the product higher than 98 percent. HPLC analysis of plasma samples taken 5-30 min after the administration of [11C]MeAlB to man showed that more than 95 percent of the total radioactivity in the plasma consisted of unchanged [11C]MeAIB. The simple preparation and the high metabolic stability of [11C]MeAlB makes this novel tracer a potential candidate for positron emission tomography investigations for the system A amino acid transport system in vivo.