Design, synthesis and biological evaluation of some new 1,3,4-thiadiazine-thiourea derivatives as potential antitumor agents against non-small cell lung cancer cells.

New 1,3,4-thiadiazine-thiourea derivatives have been synthesized. All the synthesized compounds were examined for in vitro cytotoxic activity against Non-Small Cell Lung Cancer (NSCLC) cell line A549, using MTT bioassay. Compounds 5d, 5i, 5j showed the highest cytotoxic activity with IC50 values of 0.27 ± 0.01, 0.30 ± 0.02, and 0.32 ± 0.012 μM respectively with sorafenib as reference (IC50 3.85 ± 0.27 μM). These compounds were chosen for further investigations against various biological targets known to play roles in NSCLC specifically: vascular endothelial growth factor receptor 2 (VEGFR2), B-RAF and matrix metalloproteinase 9 (MMP9). Encouraging results were exhibited by the three compounds against the selected targets. Compound 5j was specially promising as it exhibited inhibitory activity of VEGFR2 close to sorafenib (IC50 0.11 ± 0.01 μM), most potent B-RAF activity inhibition (IC50 0.178 ± 0.004 μM) and MMP9 inhibition (IC50 0.08 ± 0.004 μM). Moreover, cell cycle analysis of A549 cells treated with 5j exhibited cell cycle arrest at G2-M phase and pro-apoptotic activity as indicated by Annexin V-FITC staining. Also, it reflected antinvasive and antimigration properties to A549 cells. Additionally, docking study of 5j on VEGFR2, B-RAF and MMP9 revealed that it binds to the target enzymes in a similar way as the co-crystallized ligand. The three compounds exhibited significantly high selectivity to A549 cancer cells against the normal human fetal lung fibroblast cell line WI-38 with higher selectivity index compared to sorafenib (5d IC50 136.76 ± 2.38 μM, SI = 506.52; 5i IC50 89.20 ± 2.11 μM, SI = 297.33; 5j IC50 79.60 ± 3.8 μM, SI = 248.75; sorafenib IC50 30.32 ± 2.41 μM, SI = 7.88). In conclusion, compounds 5d, 5i and 5j, specially 5j are promising anticancer agents targeting important pathways in NSCLC and warrant further preclinical and clinical trials.