(Chalcogen)semicarbazones and their cobalt complexes differentiate HL-60 myeloid leukaemia cells and are cytotoxic towards tumor cell lines

Small molecule selenium-containing compounds: Recent development and therapeutic applications

Selenium (Se) is an essential micronutrient of organism and has important function. It participates in the functions of selenoprotein in several manners. In recent years, Se has attracted much attention because of its therapeutic potential against several diseases. Many natural and synthetic organic Se-containing compounds were studied and explored for the treatment of cancer and other diseases. Studies have showed that incorporation of Se atom into small molecules significantly enhanced their bioactivities. In this paper, according to different applications and structural characteristics, the research progress and therapeutic application of Se-containing compounds are reviewed, and more than 110 Se-containing compounds were selected as representatives which showed potent activities such as anticancer, antioxidant, antifibrolytic, antiparasitic, antibacterial, antiviral, antifungal and central nervous system related effects. This review is expected to provide a basis for further study of new promising Se-containing compounds.

Thiosemicarbazone Complexes of Transition Metals as Catalysts for Cross-Coupling Reactions

Catalysis of cross-coupling reactions under phosphane-free conditions represents an important ongoing challenge. Although transition metal complexes based on the thiosemicarbazone unit have been known for a very long time, their use in homogeneous catalysis has been studied only relatively recently. In particular, reports of cross-coupling catalytic reactions with such complexes have appeared only in the last 15 years. This review provides a survey of the research in this area and a discussion of the prospects for future developments.

Synthesis, characterization, DNA binding, topoisomerase inhibition, and apoptosis induction studies of a novel cobalt(III) complex with a thiosemicarbazone ligand

In this study, 9-anthraldehyde-N(4)-methylthiosemicarbazone (MeATSC) 1 and [Co(phen)2(O2CO)]Cl·6H2O 2 (where phen = 1,10-phenanthroline) were synthesized. [Co(phen)2(O2CO)]Cl·6H2O 2 was used to produce anhydrous [Co(phen)2(H2O)2](NO3)33. Subsequently, anhydrous [Co(phen)2(H2O)2](NO3)33 was reacted with MeATSC 1 to produce [Co(phen)2(MeATSC)](NO3)3·1.5H2O·C2H5OH 4. The ligand, MeATSC 1 and all complexes were characterized by elemental analysis, FT IR, UV-visible, and multinuclear NMR (1H, 13C, and 59Co) spectroscopy, along with HRMS, and conductivity measurements, where appropriate. Interactions of MeATSC 1 and complex 4 with calf thymus DNA (ctDNA) were investigated by carrying out UV-visible spectrophotometric studies. UV-visible spectrophotometric studies revealed weak interactions between ctDNA and the analytes, MeATSC 1 and complex 4 (Kb = 8.1 × 105 and 1.6 × 104 M-1, respectively). Topoisomerase inhibition assays and cleavage studies proved that complex 4 was an efficient catalytic inhibitor of human topoisomerases I and IIα. Based upon the results obtained from the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay on 4T1-luc metastatic mammary breast cancer cells (IC50 = 34.4 ± 5.2 μM when compared to IC50 = 13.75 ± 1.08 μM for the control, cisplatin), further investigations into the molecular events initiated by exposure to complex 4 were investigated. Studies have shown that complex 4 activated both the apoptotic and autophagic signaling pathways in addition to causing dissipation of the mitochondrial membrane potential (ΔΨm). Furthermore, activation of cysteine-aspartic proteases3 (caspase 3) in a time- and concentration-dependent manner coupled with the ΔΨm, studies implicated the intrinsic apoptotic pathway as the major regulator of cell death mechanism.

Thiosemicarbazone-metal complexes exhibiting cytotoxicity in colon cancer cell lines through oxidative stress

Colorectal cancer is the third most common type of cancer and has a high incidence in developed countries. At present, specific treatments are being required to allow individualized therapy depending on the molecular alteration on which the drug may act. The aim of this project is to evaluate whether HPTSC and HPTSC* thiosemicarbazones (HPTSC = pyridine-2-carbaldehyde thiosemicarbazone and HPTSC* = pyridine-2-carbaldehyde 4N-methylthiosemicarbazone), and their complexes with different transition metal ions as Cu(II), Fe(III) and Co(III), have antitumor activity in colon cancer cells (HT-29 and SW-480), that have different oncogenic characteristics. Cytotoxicity was evaluated and the involvement of oxidative stress in its mechanism of action was analyzed by quantifying the superoxide dismutase activity, redox state by quantification of the thioredoxin levels and reduced/oxidized glutathione rate and biomolecules damage. The apoptotic effect was evaluated by measurements of the levels of caspase 9 and 3 and the index of histones. All the metal-thiosemicarbazones have antitumor activity mediated by oxidative stress. The HPTSC*-Cu was the compound that showed the best antitumor and apoptotic characteristics for the cell line SW480, that is KRAS gene mutated.

Cobalt(II) Diphenylazodioxide Complexes Induce Apoptosis in SK-HEP-1 Cells

The cobalt(II) complex salts [Co(bpy)(az)₂](PF₆)₂ and [Co(az)₄](PF₆), each bearing the unusual cis-N,N'-diphenylazodioxide ligand, were both screened as possible anticancer agents against SK-HEP-1 liver cancer cells. Both compounds were found to induce substantial apoptosis as an increasing function of concentration and time. Measurement of apoptosis-related proteins indicated that both the extrinsic and intrinsic pathways of apoptosis were activated. The apoptotic activity induced by these salts is not displayed either by simple cobalt(II) salts or complexes or by the free nitrosobenzene ligand. Additionally, these compounds did not induce apoptosis, as assessed by poly(adenosine diphosphate-ribose) polymerase cleavage, in several other cell lines.

Copper(ii) complexes based on quinoline-derived Schiff-base ligands: synthesis, characterization, HSA/DNA binding ability, and anticancer activity

Three copper(ii) complexes, [Cu(L1)(NO₃)₂] (C1), [Cu(L2)Cl₂] (C2) and [Cu(L2)SO₄]₂·H₂O (C3), were designed and synthesized by the reaction of Cu(NO₃)₂·3H₂O, CuCl₂·2H₂O and CuSO₄·5H₂O with a quinoline-derived Schiff base ligand, L1 or L2, prepared by the condensation of quinoline-8-carbaldehyde with 4-aminobenzoic acid methyl ester or 4-aminobenzoic acid ethyl ester (benzocaine). The efficient bindings of the C1-C3 complexes with human serum albumin (HSA) and calf thymus DNA (CT-DNA) were analyzed by spectroscopy and molecular docking. These complexes could significantly quench the fluorescence of HSA through the static quenching process, and hydrophobic interactions with HSA through the sub-domain IIA and IIIA cavities. The complexes bind to DNA via the intercalative mode and they fit well into the curved contour of the DNA target in the minor groove region. Furthermore, the interaction abilities of the Cu(ii) complexes with HSA/DNA were greater as compared to their corresponding ligands. Interestingly, C1-C3, particularly C3, exhibited more cytotoxicity toward HeLa cells compared to normal HL-7702 cells and three other tumor cell lines (Hep-G2, NCI-H460, and MGC80-3). Their cytotoxicity toward the HeLa cell lines was 1.9-3.5-fold more potent than cisplatin. Further studies indicated that these complexes arrested the cell cycle in the G0/G1 phase and promoted tumor cell apoptosis via a reactive oxygen species (ROS)-mediated mitochondrial pathway.

Bis(thiosemicarbazone) Complexes of Cobalt(III). Synthesis, Characterization, and Anticancer Potential

Nine bis(thiosemicarbazone) (BTSC) cobalt(III) complexes of the general formula [Co(BTSC)(L)2]NO3 were synthesized, where BTSC = diacetyl bis(thiosemicarbazone) (ATS), pyruvaldehyde bis(thiosemicarbazone) (PTS), or glyoxal bis(thiosemicarbazone) (GTS) and L = ammonia, imidazole (Im), or benzylamine (BnA). These compounds were characterized by multinuclear NMR spectroscopy, mass spectrometry, cyclic voltammetry, and X-ray crystallography. Their stability in phosphate-buffered saline was investigated and found to be highly dependent on the nature of the axial ligand, L. These studies revealed that complex stability is primarily dictated by the axial ligand following the sequence NH3 > Im > BnA. The cellular uptake and cytotoxicity in cancer cells were also determined. Both the cellular uptake and cytotoxicity were significantly affected by the nature of the equatorial BTSC. Complexes of ATS were taken up much more effectively than those of PTS and GTS. The cytotoxicity of the complexes was correlated to that of the free ligand. Cell uptake and cytotoxicity were also determined under hypoxic conditions. Only minor differences in the hypoxia activity and uptake were observed. Treatment of the cancer cells with the copper-depleting agent tetrathiomolybdate decreased the cytotoxic potency of the complexes, indicating that they may operate via a copper-dependent mechanism. These results provide a structure-activity relationship for this class of compounds, which may be applied for the rational design of new cobalt(III) anticancer agents.