Design, synthesis and evaluation the bioactivities of novel 1,3-dimethyl-6-amino-1H-indazole derivatives as anticancer agents.

Indoleamine 2,3-dioxygenase (IDO1) is a heme-containing enzyme mainly responsible for the metabolism of tryptophan to kynurenine. To date, the IDO1 inhibitors have been developed intensively for the re-activation of the anticancer immune response. In this report, we designed, and synthesized novel 1,3-dimethyl-6-amino indazole derivatives as IDO1 inhibitors based on the structure of IDO1 active site. We further examined their anticancer activity on hypopharyngeal carcinoma cells (FaDu), squamous cell carcinoma of the oral tongue (YD-15), breast cancer cells (MCF7), and human dental pulp stem cells (HDPSC). Of them, compound N-(4-bromobenzyl)-1,3-dimethyl-1H-indazol-6-amine (7) remarkably suppressed IDO1 expression in a concentration - dependent manner. In addition, 7 was the most potential anticancer compound with inducing apoptosis activity as well as selectively activated extracellular signal-regulated kinases (ERK) in mitogen-activated protein kinase (MAPK) pathways on FaDu cells. Finally, compound 7 suppressed cell mobility in wound healing assay with the reduced expression of matrix metalloproteinase MMP9. Taken together, we believe that 7 is the most promising compound, which may be applied to treatment of hypopharyngeal carcinoma.