Wykorzystanie reakcji 1,3-dipolarnej cykloaddycji Huisgena do modyfikacji nukleozydów i ligonukleotydów

The 1,3-dipolar cycloaddition reaction between azides and terminal alkynes, known as the Huisgen reaction, constitutes a powerful tool for the synthesis of versatile molecules containing carbon – heteroatom bond. The use of a copper(I) salt in this reaction allowed Sharpless to develop the concept of „click chemistry” [1]. This strategy is based on reactions between small units characterized by mild reaction conditions, versatility, high yields and stereospecificity. The chemistry of nucleic acids and nucleoside analogues is undergoing rapid developments and numerous compounds from these classes of compounds are used in medicinal treatment. Analogues of nucleoside constitute a class of drugs that possesses either anticancer or/and antiviral activity (against HIV, HSV, VZV or HCV viruses) [3]. Many modified oligonucleotides show biological activity. As potential drugs oligonucleotides are employed in antisense, antigen and aptamer strategies. An antisense therapeutic agent acts on the pathogenic mRNA causing inactivation of the target whereas an antigen agent acts on DNA and aptamer on unwanted protein. It is not surprising that number of research groups are trying to join the concept of click chemistry with nucleic acids chemistry. In this way, it is possible to obtain new molecules like base- or sugar-modified nucleosides, nucleosides, bioconjugates and olignucleotides. The copper-catalyzed 1,3-dipolar cycloaddition CuAAC allows to functionalize DNA, for example by labelling it through attaching small molecules to DNA. Two general strategies have been developed for this purpose: presynthetic and postsynthetic labelling. In the presynthetic method nucleotide monomers are labelled before DNA synthesis and purification. In the postsynthetic strategy DNA containing small reactive groups is synthesized first and then it is conjugated with the desired molecules. CuAAC is also a convenient method for the synthesis of modified oligonucleotides in which phosphodiester linkage is replaced by 1,2,3- -triazole or for a solid phase synthesis. Such molecules appear to be useful in medicine, molecular diagnostic (e.g. fluorescent dyes) or mechanistic molecular model in the future.