Synthesis, Biological Evaluation and Ligand Based Pharmacophore Modeling of New Aromatic Thiosemicarbazones as Potential Anticancer Agents

Highly Efficient Spectrophotometric Determination of Cu2+ ion in Aqueous Medium Using a thiosemicarbazone–derivative Ligand

A new simple spectrophotometric method for the determination of Cu²⁺ ion was developed using an thiosemicarbazone compound, 2-{4-[Bis(2-chloroethyl)amino]benzylidene}-N-[(4-methylthio)phenyl]hydrazinecarbothioamide (TSC). A simultaneous color change was observed (from colorless to bright yellow) by the addition of Cu²⁺ ion to the TSC ligand solution. The maximum absorbance of the TSC ligand measured at 366 nm was decreased by the presence of Cu²⁺ ion. The graphs of absorbance obtained by means of the Job's method and the molar-ratio method proposed a complex formation with a 1:2 Cu²⁺-TSC ligand stoichiometry. The molar-ratio method with emission measurements also confirmed the stoichiometry. The complex stability constant of TSC-Cu²⁺ complex (K) was evaluated to be 1.76 × 10⁵. The proposed spectrophotometric method was associated with the change in absorbance at 366 nm owing to the interaction between the TSC ligand and Cu²⁺ ion. From the spectrophotometric titration data, it was pointed out that TSC ligand (1.5 × 10^- 5 mol L^-1) selectively reacted with Cu²⁺ ion in DMSO/water (1:1, v/v, citrate buffer at pH = 6.0). The calibration curve for Cu²⁺ ion was obtained with a good linearity in the range of 0.0191-0.3241 mg L^-1. The detection limit for Cu²⁺ ion was 0.0063 mg L^-1. The proposed method was achievemently implemented in real water samples (drink water, tap water and, distilled water). Satisfactory recoveries were confirmed at three different concentrations. The method presented a relative standard deviation (RSD%) of less than 3.08%.

Synthesis, Structure, and Biologic Activity of Some Copper, Nickel, Cobalt, and Zinc Complexes with 2-Formylpyridine N4-Allylthiosemicarbazone

A series of zinc(II) ([Zn(H₂O)(L)Cl] (1)), copper (II) ([Cu(L)Cl] (2), [Cu(L)Br] (3), [Cu₂(L)₂(CH₃COO)₂]·4H₂O (4)), nickel(II) ([Ni(HL)₂]Cl₂·H₂O (5)), and cobalt(III) ([Co(L)₂]Cl (6)) complexes were obtained with 2-formylpyridine N⁴-allylthiosemicarbazone (HL). In addition another two thiosemicarbazones (3-formylpyridine N⁴-allylthiosemicarbazone (HL^a) and 4-formylpyridine N⁴-allylthiosemicarbazone (HL^b)) have been obtained. The synthesized thiosemicarbazones have been studied using ¹H and ¹³C NMR spectroscopy, IR spectroscopy, and X-ray diffraction analysis. The composition and structure of complexes were studied using elemental analysis, IR and UV-Vis spectroscopies, molar conductivity, and magnetic susceptibility measurements. Single crystal X-ray diffraction analysis elucidated the structure of thiosemicarbazones HL, HL^a, and HL^b, as well as complexes 4 and 5. The antiproliferative properties of these compounds toward a series of cancer cell lines (HL-60, HeLa, BxPC-3, RD) and a normal cell line (MDCK) have been investigated. The nickel complex shows high selectivity (SI > 1000) toward HL-60 cell line and is the least toxic. The zinc complex shows the highest selectivity toward RD cell line (SI = 640). The copper complexes (2–4) are the most active molecular inhibitors of proliferation of cancer cells, but exhibit not such a high selectivity and are significantly more toxic. Zinc and copper complexes manifest high antibacterial activity. It was found that calculated at B3LYP level of theory different reactivity descriptors of studied compounds strongly correlate with their biological activity.