Biological Activity of Amidino-Substituted Imidazo [4,5- b ]pyridines.

A series of cyano- and amidino-substituted imidazo[4,5- b ]pyridines were synthesized using standard methods of organic synthesis, and their biological activity was evaluated. Biological evaluation included in vitro assessment of antiproliferative effects on a diverse selection of human cancer cell lines, antibacterial activity against chosen Gram-positive and Gram-negative bacterial strains, and antiviral activity on a broad panel of DNA and RNA viruses. The most pronounced antiproliferative activity was observed for compound 10 , which contained an unsubstituted amidino group, and compound 14 , which contained a 2-imidazolinyl amidino group; both displayed selective and strong activity in sub-micromolar inhibitory concentration range against colon carcinoma (IC 50 0.4 and 0.7 μM, respectively). All tested compounds lacked antibacterial activity, with the exception of compound 14 , which showed moderate activity against E. coli (MIC 32 μM). Bromo-substituted derivative 7 , which contained an unsubstituted phenyl ring (EC 50 21 μM), and para -cyano-substituted derivative 17 (EC 50 58 μM) showed selective but moderate activity against respiratory syncytial virus (RSV).