- Syntheses of [18F]5-fluoro-3-nitro-L-tyrosine
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The detection of 3-nitro-L-tyrosine has been used as a biomarker of "reactive nitrogen species" in biological matrices and has been an ongoing challenge in analytical chemistry. In this work, fluorine-18 labelled 5-fluoro-3-nitro-L-tyrosine (FNT) was synthesized as a potential radiotracer to probe the biological fate of 3-nitro-L-tyrosine. The synthesis of [18F]FNT was carried out by reaction of [18F]3-fluoro-L-tyrosine with NaNO3 in TFA solvent for 5min at 4 °C. The radiochemical yield (RCY) of [18F]FNT was 96±2% and [18F]3-fluoro-l-tyrosine, was 29±1%, relative to [18F]3-fluoro-l-tyrosine and [18F]F2, respectively. The syntheses of [18F]FNT were also accomplished by direct fluorination of 3-nitro-L-tyrosine with [18F]F 2 and by nitration of L-tyrosine with NaNO3, followed by fluorination, in TFA (4 °C) or anhydrous HF (-65 °C) solvent. The latter two synthetic routes produced [18F]FNT in 13.5±1.5% RCY, within 1h. Products were characterized by use of 1H, 13C and 19F NMR spectroscopy and mass spectrometry.
- Vasdev, Neil,Chirakal, Raman,Ashique, Rezwan,Schrobilgen, Gary J.,Gulenchyn, Karen
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- Biocascade Synthesis of L-Tyrosine Derivatives by Coupling a Thermophilic Tyrosine Phenol-Lyase and L-Lactate Oxidase
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A one-pot biocascade of two enzymatic steps catalyzed by an l-lactate oxidase and a tyrosine phenol-lyase has been successfully developed in the present study. The reaction provides an efficient method for the synthesis of l-tyrosine derivatives, which exhibits readily available starting materials and excellent yields. In the first step, an in situ generation of pyruvate from readily available bio-based l-lactate catalyzed by a highly active l-lactate oxidase from Aerococcus viridans (AvLOX) was developed (using oxygen as oxidant and catalase as hydrogen peroxide removing reagent). Pyruvate thus produced underwent C–C coupling with phenol derivatives as acceptor substrate using specially designed thermophilic tyrosine phenol-lyase mutants from Symbiobacterium toebii (TTPL). Overall, this cascade avoids the high cost and easy decomposition of pyruvate and offered an efficient and environmentally friendly procedure for l-tyrosine derivatives synthesis.
- Jiang, Yiqi,Ju, Shuyun,Li, Guosi,Lian, Jiazhang,Lin, Jianping,Wu, Mianbin,Xue, Hailong,Yang, Lirong
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(2020/02/25)
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