Synthesis and antituberculosis activity of new 5-alkynyl derivatives of 2-thiouridine: application of new scaffold

We herein describe new potent inhibitors of mycobacteria based on 5-substituted 2-thiouridine derivatives. A series of new 5-alkynyl-substituted 2-thiouridine derivatives were synthesized via palladium-catalysed Sonogashira cross-coupling reaction of 5-iodo-2-thiopyrimidine base with terminal acetylenes with good yields in DMF at room temperature. It was found that sulfur atom in C2 position of pyrimidine ring had no impact on yields of target compounds. All obtained compounds were evaluated for their antimycobacterial activity against Mycobacetrium bovis and Mycobacterium tuberculosis at concentrations of 0.1-100 µg/ml using MABA test. Synthesized nucleosides showed high antimycobacterial activity against Mycobacterium bovis and Mycobacteri um tuberculosis. The obtained MIC50 values of 2-thionucleosides 14, 15 and 16 (0.28-0.75 µg/ml) significantly exceed characteristics of reference drug rifampicin, D-cycloserine and isoniazid, which gives prerequisites for further more detailed studies.