Anticancer Activity of New Organotin Complexes with Heterocyclic Thioamides
New complexes I–IV of di-tert-butyltin with ligands based on heterocyclic thioamides (2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole) and 2,6-di-tert-butyl-4-mercaptophenol are synthesized and studied by X-ray diffraction (XRD). The XRD results for single crystals of I, II, and IV are presented (CIF files CCDC nos. 2251495, 2251493, and 2251494, respectively). Specific features of the synthesized crystal structures are discussed. Complexes I and II contain the expected Sn–C and Sn–S bonds and an additional coordination with the nitrogen atom in the heterocycles, which indicates the octahedral environment of the Sn(IV) atom (coordination number 6). The coordination polyhedron in complex IV can be described as a distorted tetrahedron (coordination number 4). The proposed compounds are studied as antiproliferative agents. Their antiproliferative activity is determined using the human cancer cell lines (PC3, MCF-7, НСT116, A549, and normal cells WI38). A dependence of the activity on the ligand structure is found. A comparative evaluation of the activity shows that the introduction of the antioxidant 2,6-di-tert-butyl-4-mercaptophenol fragment into complex IV substantially decreases the cytotoxicity.