Design, synthesis, and bioactivity assessment of highly potent isatin-based small-molecules bearing...

The present study reports the design, synthesis, and biological evaluation of 25 novel isatin-based small molecules bearing 3-hydrazineyl-6-aryl-1,2,4-triazine motifs, generated through anticancer-scaffold hybridization and structure-guided modification of a c-MET inhibitor hit compound 3a. The antiproliferative properties of the target compounds (E1-25) were assessed against three cancer cell lines comprising EBC-1 (c-MET-amplified NSCLC), SUIT-2 (pancreatic ductal adenocarcinoma), MDA-MB-231 (triple-negative breast adenocarcinoma) as well as non-malignant fibroblast cells NIH-3T3. Several derivatives exhibited pronounced antiproliferative activity, with IC₅₀ values ranging from the sub-micromolar level to as low as 11 nM, while showing reduced effects on non-cancerous cells. Further analysis of the effects of highly active compounds E20, E21, E23 and E24 on cell cycle and cancer cell growth in 3-dimensional spheroid cultures showed that these derivatives induce apoptosis and significantly inhibit the growth of cancer cells in the 3D environment. Molecular docking simulations revealed that the evaluated compounds adopt a linear binding mode within the c-MET active site, in contrast to the U-shaped binding pattern characteristic of class Ib c-MET inhibitors. Overall, the newly developed isatin-1,2,4-triazine hybrids exhibited potent anticancer activity, highlighting their potential as promising lead structures for future anticancer drug development.