New Indole-6-Carboxylic Acid Derivatives as Multi-Target Antiproliferative Agents: Synthesis, in Silico Studies, and Cytotoxicity Evaluation.

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) are commonly overexpressed in cancers making them appealing targets for cancer therapeutics. Two groups of indole-6-carboxylic acid derivatives, hydrazone derivatives targeting EGFR and oxadiazole derivatives targeting VEGFR-2, were synthesized and characterized using FT-IR, 1 H-NMR, 13 CNMR, and HR-MS techniques. Binding patterns to potential molecular targets were studied using molecular docking and compared to standard EGFR and VEGFR-2 inhibitors. The newly synthesized compounds were cytotoxic to the three cancer cell lines tested (HCT-116, HeLa, and HT-29 cell lines) as evaluated by the MTT assay. Compound 3 b (EGFR-targeting) and compound 6 e (VEGFR-2-targeting) possessed the highest antiproliferation activity, were cancer-selective, arrested cancer cells in the G2/M phase, induced the extrinsic apoptosis pathway, and had the highest EGFR/VEGFR-2 enzyme inhibitory activity, respectively. The structure-activity relationships of the new compounds showed that the presence of an aryl or heteroaryl fragment attached to a linker is required for the anti-tumor activity. In conclusion, the findings of the current study suggest that compounds 3 b and 6 e are promising cytotoxic agents that act by inhibiting EGFR and VEGFR-2 tyrosine kinases, respectively.