3′-Aminothiocyclohexanespiro-5′-hydantoin and Its Pt(II) Complex—Synthesis, Cytotoxicity and Xanthine Oxidase Inhibitory Activity

Herein, we report the synthesis of platinum(II) complex bearing 3′-aminothiocyclohexanespiro-5′-hydantoin as ligand. The complex was characterized by IR, NMR spectral analyses, elemental analyses and density functional theory (DFT) calculations. Cytotoxicity and inhibitory potential on xanthine oxidase (XO) were evaluated by performed docking calculations. The cytotoxic activities of the 3′-aminothiocyclohexanespiro-5′-hydantoin (1), its Pt(II) complex (2), thiocyclohexanespiro-5′-hydantoin (3), and its platinum complex (4) were assessed against HL-60 and MDA-MB-231 cells in comparison with the antiproliferative activity of cisplatin as a referent. The ligands (1 and 3) did not exhibit in vitro antitumor efficacy on either of the human tumor cell lines. Complex 2 showed higher antitumor activity (IC50 = 42.1 ± 2.8 µM on HL-60 and 97.8 ± 7.5 µM against MDA-MB-231 cells) than complex 4 (IC50 = 89.6 ± 2.8 µM on HL-60 and 112.5 ± 4.2 µM in MDA-MB-231 cells). IC50 values of cisplatin as referent were 8.7 ± 2.4 µM on HL-60 and 31.6 ± 5.4 µM on MDA-MB-231 cell lines. The inhibitory activity of ligands and complexes against XO, evaluated in vitro, were compared with allopurinol (IC50 = 1.70 ± 0.51 μM) as standard inhibitor. The platinum(II) complexes (2 and 4) inhibited the activity of XO, with IC50 values 110.33 ± 26.38 μM and 115.45 ± 42.43 μM, respectively, while the ligands 1 and 3 did not show higher degrees of inhibition at concentrations lower than 150 µM. The inhibitory potential against XO might be a possible precedent resulting in improved profile and anticancer properties.