One-step to get 5-azidomethyl-2′-deoxyuridine from 5-hydroxymethyl-2′-deoxyuridine and detection of it through click reaction

Gram-scale enzymatic synthesis of 2'-deoxyribonucleoside analogues using nucleoside transglycosylase-2

Nucleosides are pervasive building blocks that are found throughout nature and used extensively in medicinal chemistry and biotechnology. However, the preparation of base-modified analogues using conventional synthetic methodology poses challenges in scale-up and purification. In this work, an integrated approach involving structural analysis, screening and reaction optimization, is established to prepare 2'-deoxyribonucleoside analogues catalysed by the type II nucleoside 2'-deoxyribosyltransferase from Lactobacillus leichmannii (LlNDT-2). Structural analysis in combination with substrate profiling, identified the constraints on pyrimidine and purine acceptor bases by LlNDT2. A solvent screen identifies pure water as a suitable solvent for the preparation of high value purine and pyrimidine 2'-deoxyribonucleoside analogues on a gram scale under optimized reaction conditions. This approach provides the basis to establish a convergent, step-efficient chemoenzymatic platform for the preparation of high value 2'-deoxyribonucleosides.

Synthesis and 18F-radiolabeling of thymidine AMBF3 conjugates

In pursuit of 18F-labeled nucleosides for positron emission tomography (PET) imaging, we report on the chemical and radiochemical synthesis of two thymidine (dT) analogs, dT-C5-AMBF3 and dT-N3-AMBF3, that are radiofluorinated by isotope exchange (IEX) and studied as PET imaging agents in mice with tumor xenografts. dT-C5-AMBF3 shows preferential, and tumor-specific, uptake over dT-N3-AMBF3. This work provides a new synthetic method in order to access new nucleoside tracers for PET imaging.

An oligonucleotide probe incorporating the chromophore of green fluorescent protein is useful for the detection of HER-2 mRNA breast cancer marker

Diagnosis and treatment of breast cancer can be greatly enhanced and personalized based on the quantitative detection of mRNA markers. Here, we targeted the development of a fluorescent oligonucleotide probe to detect specifically the HER-2 mRNA breast cancer marker. We have selected the chromophore of the Green Fluorescent Protein (GFP), 4-hydroxybenzylidene imidazolinone (HBI), as a fluorophore covalently bound to an oligonucleotide probe and potentially capable of intercalating within a probe-mRNA duplex. We first synthesized the two-ring scaffold of the HBI chromophore 5 and coupled it to 2'-deoxyuridine at C5-position via a 7-atom-spacer, to give 4. Indeed, in the highly viscous glycerol used to mimic the reduced conformational flexibility of the intercalated HBI, chromophore 4 displayed a quantum yield of 0.29 and brightness of 20600 M^-1cm^-1, while no fluorescent signal was observed in methanol. Next, we synthesized a 20-mer oligonucleotide probe incorporating 4 at position 6 (5'-CCCGTUTCAACAGGAGTTTC-3'), ON^HBI, targeting nucleotides 1233-1253 of HER-2 mRNA. A 16-fold enhancement of ON^HBI emission intensity upon hybridization with the complementary RNA vs that of the oligonucleotide probe alone indicated the presence of target oligonucleotide and proved the intercalation of the chromophore (quantum yield 0.52; brightness 23500 M^-1cm^-1). Even more, an 11-fold enhancement of ON^HBI emission (quantum yield 0.50; brightness 23200 M^-1cm^-1) was observed when the probe was mixed with total RNA extract from a human cell line that has high levels of HER2 mRNA expression. Thus, we propose ON^HBI as a promising probe potentially useful for the sensitive and specific detection of HER2 mRNA breast cancer marker.

CuSO4/KI As Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-Triazolo-Nucleosides

A simple and inexpensive procedure has been developed for the selective formation of 1,4-disubstituted-1,2,3-triazolo-nucleosides starting from organic azides and terminal alkynes, mediated by in situ generated copper(I) catalyst from readily available CuSO4 and KI.