Synthesis, Characterization, and Molecular Docking of a Novel Azo Ligand and Its Metal Complexes: Anticancer Activity of the Silver(I) Complex against Colon Cancer

Herein, a novel azo ligand [5-((5-mercapto-1,3,4-thiadiazol-2yl) diazenyl)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione] was synthesized from 5-amino-1,3,4-thiadiazole-2-thiol and thiobarbituric acid (TBA). The Cu (II), Co (II), and Ag(I) transition metal complexes with azo ligand were prepared. These compounds were characterized using UV-Vis, FTIR, electrical molar conductivity, and 1 H NMR spectra. According to analytical results, the ligand behaves as a neutral bidentate chelating agent. The coordination sites are the nitrogen atom of the azo group nearest to a thiadiazole ring, and oxygen atom of the ketone (carbonyl) group in the heterocyclic thiobarbituric ring to give sixmembered chelate rings. The coordination solid complexes, including metal ions Cu (II), Co (II), and Ag(I), had a molar ratio of 1:2 [metal-ligand]. The Cu (II) and Co (II) complexes have octahedral geometry, while the Ag(I) complex is tetrahedral. Also, molecular docking to the ligand and Ag(I) complex yields excellent results for the compounds under investigation, specifically the ligand and silver complex with protein 3PA3; in general, a low energy value (S) indicates greater docking site stability and a stronger interaction between the docking site and the protein receptor. In addition, the Ag(I) complex demonstrated biological activity against human colon cancer (HCT116) and normal cell lines (HDF), as revealed by the IC50 and selective indices (SI). This study could help design pharmacological preparations that take advantage of the various biological activities of the Ag (I) complex.