Synthesis of new steroidal imidazo [1,2-a] pyridines: DNA binding studies, cleavage activity and in vitro cytotoxicity

A one-pot strategy for the catalytic synthesis of series of new 5 alpha-cholestan-6-spiro-5'-phenylamino-2H-imidazo [1',2'-a] pyridines (4-14) has been investigated. The synthesized products were obtained in good yields (85-90%) and the protocol uses Multi-component Reaction (MCR) involving steroidal ketones, 2-aminopyridines, isocyanides and propylphosphonic anhydride ((R) T3P) as a catalyst. After characterization by spectral and analytical data, the interaction studies of compounds (4-6) with DNA were studied by UV-vis, fluorescence spectroscopy, gel electrophoresis and molecular docking. The compounds bind to DNA preferentially through electrostatic and hydrophobic interactions with K-b; 2.35 x 10(4), 3.71 x 10(4) and 3.24 x 10(4) M-1, respectively, indicating the higher binding affinity of compound 5 towards DNA Gel electrophoresis showed the concentration dependent cleavage activity of compounds 4-6 with DNA. Molecular docking studies suggested that compounds bind through minor groove to DNA The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay depicted promising anti-proliferative activity of compound 4-9 against different given cancer cells. In Western blotting, the expressions of relevant apoptotic markers depicted an apoptosis by steroidal imidazopyridines in A549 cells. Annexin V-FITC/PI staining data indicated that compounds could effectively induce apoptosis in A549 cells in a dose-dependent manner. FACS analysis shows that the compound 6 bring about cell cycle arrest at 2.62 mu M concentration. (C) 2015 Published by Elsevier Inc.