Synthesis of C 5 -tethered indolyl-3-glyoxylamide derivatives as tubulin polymerization inhibitors.

A series of C5 -tethered Indolyl-3-glyoxylamide derivatives were synthesized and evaluated for their in vitro cytotoxic activity against DU145 (prostate), PC-3 (prostate), A549 (lung) and HCT-15 (colon) cancer cell lines by employing the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among all the synthesized compounds, compound 7f displayed cytotoxicity of IC50  = 140 nM towards DU145 cancer cell line. The treatment of DU145 cells with 7f led to inhibition of cell migration ability. Futher, the detailed studies such as acridine orange/ethidium Bromide (AO/EB), DAPI, annexin V-FITC/propidium iodide staining assay suggested that the compound 7f induced apoptosis in DU145 cells. The influence of the cytotoxic compound 7f on the cell cycle distribution was assessed on the DU145 cell line, exhibiting a cell cycle arrest at the G2/M phase (hallmark of tubulin polymerization) and next inhibited tubulin polymerization with IC50 0.40 μM. Furthermore, the treatment with compound 7f caused collapse of mitochondrial membrane potential and elevated intracellular superoxide ROS levels in DU145 cells. Western blotting was performed to examine the levels of apoptotic proteins (Bcl-2 and Bax); the study confirmed that compound 7f induced apoptosis through apoptosis-related protein expression. Thus, these studies provided a new molecular scaffold for the further development of anticancer agents that target tubulin.