Abstract
ABSTRACTChemoenzymatic techniques have been applied extensively to pharmaceutical development, most effectively when routine synthetic methods fail. The regioselective and stereoselective construction of structurally complex glycans is an elegant application of this approach, that is seldom applied to positron emission tomography (PET) tracers. We sought a method to dimerize 2-deoxy-[18F]-fluoro-D-glucose ([18F]FDG), the most common tracer used in clinical imaging, to form [18F]-labeled disaccharides for detecting microorganismsin vivobased on their bacteria-specific glycan incorporation. When [18F]FDG was reacted with β-D-glucose-1-phosphate in the presence of maltose phosphorylase, both the α-1,4 and α-1,3-linked products 2-deoxy-[18F]-fluoro-maltose ([18F]FDM) and 2-deoxy-2-[18F]-fluoro-sakebiose ([18F]FSK) were obtained. This method was further extended with the use of trehalose (α,α-1,1), laminaribiose (β-1,3), and cellobiose (β-1,4) phosphorylases to synthesize 2-deoxy-2-[18F]fluoro-trehalose ([18F]FDT), 2-deoxy-2-[18F]fluoro-laminaribiose ([18F]FDL), and 2-deoxy-2-[18F]fluoro-cellobiose ([18F]FDC). We subsequently tested [18F]FDM and [18F]FSKin vitro,showing accumulation by several clinically relevant pathogens includingStaphylococcus aureusandAcinetobacter baumannii,and demonstrated their specific uptakein vivo.The lead sakebiose-derived tracer [18F]FSK was stable in human serum and showed high uptake in preclinical models of myositis and vertebral discitis-osteomyelitis. Both the synthetic ease, and high sensitivity of [18F]FSK toS. aureusincluding methicillin-resistant (MRSA) strains strongly justify clinical translation of this tracer to infected patients. Furthermore, this work suggests that chemoenzymatic radiosyntheses of complex [18F]FDG-derived oligomers will afford a wide array of PET radiotracers for infectious and oncologic applications.
Publisher
Cold Spring Harbor Laboratory