Synthesis, characterization and biological studies of new antimony(III) halide complexes with ω-thiocaprolactam

Abstract

Three new antimony(III) halide complexes (SbX3, X=Cl, Br and I) with the heterocyclic thione ω-thiocaprolactam (1-azacycloheptane-2-thione, (Hthcl)) of formulae {[SbCl2(μ2-Cl)(Hthcl)2]n} (1), {[(SbBr2(μ2-Br)(Hthcl)2)2]} (2) and {[(SbI2(μ2-I)(Hthcl)2)2]} (3) were synthesized from the reaction of antimony(III) halides with ω-thiocaprolactam in 1:2 stoichiometry. The complexes were characterized by elemental analysis, FT-IR spectroscopy, 1H, 13C NMR spectroscopy and Thermal Gravimetry–Differential Thermal Analysis (TG–DTA). Crystal structures of the ligand ω-thiocaprolactam and its complexes 1–3 were determined with single crystal X-ray diffraction analysis. Complexes 1–3 and ω-thiocaprolactam were evaluated for their in vitro cytotoxic activity against leiomyosarcoma (LMS) and human breast adenocarcinoma (MCF-7) tumor cell lines. Antimony complexes 1–3 exhibit strong antiproliferative activity against both cell lines tested. The higher such activity was found for 3 with IC50 values of 0.12±0.04μM (LMS) and 0.76±0.16μM (MCF-7) which are 60 and 10 times respectively, stronger than that of cisplatin. The influence of these complexes 1–3 and ω-thiocaprolactam upon the catalytic peroxidation of linoleic acid to hyperoxolinoleic acid by the enzyme lipoxygenase (LOX) was kinetically and theoretically studied. The results were shown negligible inhibitory activity of 1–3 against LOX.