Glutamine Probe Images Tumors

Doctors may soon have a new tool for spying on growing tumors, thanks to chemists at the University of Pennsylvania. Researchers led by Wenchao Qu and Hank F. Kung, have developed a simple synthesis for ¹⁸F-glutamine derivatives, which could serve as positron emission tomography probes for following tumors that use glutamine as an alternative source of energy (J. Am. Chem. Soc., DOI: 10.1021/ja109203d). Because of ¹⁸F’s 110-minute half-life, the researchers needed a synthesis that incorporated the halide in the final stages. They also wanted a stereospecific route. To that end, they first used a Passerini three-component reaction to assemble the amino acid’s basic skeleton and then incorporated the radioactive fluorine using nucleophilic fluoride under neutralizing conditions. In vitro studies with certain tumor cells suggest uptake is highly specific for both fluorinated isomers of the natural amino acid. The (2S,4R) isomer (shown) is being further evaluated as a biological probe.