Biologically Active Acylthioureas and Their Ni(II) and Cu(II) Complexes: Structural, Spectroscopic, Anti-Proliferative, Nucleolytic and Antimicrobial Studies

Abstract

The study investigated the effects of morpholine substituent and metal complexation on in vitro anticancer and antimicrobial activities of acylthioureas using two acylthiourea molecules that differ only by the presence of morpholine oxygen; N,N-diethyl-N' -(4-chlorobenzoyl)thiourea (CBDEA) and N-morpholine-N' -(4-chlorobenzoyl) thiourea (CBMOR), and their Ni(II) and Cu(II) complexes (NiCBDEA, CuCBDEA, NiCBMOR, CuCBMOR). All compounds were synthesized and characterized by physicochemical and spectroscopic studies. CBDEA, CuCBDEA, NiCBDEA, CBMOR, and NiCBMOR were structurally elucidated by single-crystal X-ray diffraction. The metal complexes were isolated as neutral four coordinate complexes of the form, ML2 (M: Ni(II), Cu(II), H.L.: CBDEA/CBMOR) in square-planar geometry. The compounds were screened for DNA binding/cleavage, antimicrobial activity, and anti-proliferative effects on human prostate cancer PC-3 and breast cancer MCF-7 cells. DNA binding interaction studies suggest that the metal complexes bind more strongly to the DNA compared to the ligands. The morpholine derivative CBMOR shows similar activity to CBDEA against PC-3 cell lines but twice as effective against MCF-3 cells at cell death and apoptotic levels. Anticancer activities were enhanced by complexation with Cu(II), as evident in CuCBMOR, which showed the optimal anticancer activity (IC50: 1.76 mu M for MCF-7 and 1.97 mu M for PC-3), comparable to known anticancer drug paclitaxel. The CuCBMOR apoptosis results show that the cancer cells die by apoptotic mechanisms (Apoptosis rate: 91.53 % in MCF-7 and 85.95 % in PC-3). In vitro screening of the compounds against seventeen bacteria and four yeast strains confirmed antimicrobial potency against more susceptible Gram-positive bacteria strains. The results of the study suggest that some of the compounds could be developed into novel antimicrobial and anticancer agents.