Carbohydrate-conjugate heterobimetallic complexes: synthesis, DNA binding studies, artificial nuclease activity and in vitro cytotoxicity

Carbohydrate-based heteronuclear complexes as topoisomerase Iα inhibitor: approach toward anticancer chemotherapeutics

Due to the critical role of cellular enzymes necessary for cell proliferation by deciphering topological hurdles in the process of DNA replication, topoisomerases have been one of the major targets in the anticancer drug development area. A need, therefore, arises for new metallodrugs that specifically recognizes DNA and inhibits the activity of topoisomerase enzymes, herein, we report the synthesis and characterization of new metal-based glycoconjugate entities containing heterobimetallic core Cu^II-Sn^IV (1) and Ni^II-Sn^IV (2) derived from N-glycoside ligand (L). The optimized structure of complex 1 and other significant vibrational modes have been explained using dispersion corrected B3LYP/DFT calculations. In vitro DNA binding profile of the L and both the complexes 1 and 2 were done by various biophysical studies. Complex 1 breaks pBR322 DNA via a hydrolytic means which was validated by T4 DNA enzymatic assay. To get a mechanistic insight of mode of action topoisomerase I (Topo I) inhibition assay was carried out. Also, we have taken the help of molecular modeling studies in accordance with experimental findings. In vitro cytotoxicity of the complex 1 was evaluated against a panel of cancer cells which exhibited remarkably good anticancer activity (GI₅₀ values <10 μg/ml). Moreover, intracellular localization of the complex 1 was visualized by confocal microscopy against HeLa cells.

Halogen and solvent effects on the conformational, vibrational and electronic properties of 1,4-diformylpiperazine: A combined experimental and DFT study

The molecular structure and properties of 1,4-diformylpiperazine (1,4-dfp, C6H[Formula: see text]N2O2) were investigated by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and density functional theory (DFT). The Becke-3-Lee–Yang–Parr (B3LYP) functional was used with the 6-31[Formula: see text]G(d,p) basis set. Total energy distribution (TED) analysis of normal modes was performed to identify characteristic frequencies by the scaled quantum mechanical (SQM) method. Halogeno-analogs of 1,4-dfp were studied to understand the halogen effect. Computations were focused on five conformational isomers of the compounds in the gas phase and in solutions. The computed and experimental frequencies of the C[Formula: see text]O stretching vibration of 1,4-dfp were correlated with the empirical solvent parameters such as the Kirkwood–Bauer–Magat (KBM) equation, the solvent acceptor number (AN), Swain parameters and linear solvation energy relationships (LSER). The electronic properties of the compounds were also examined. The findings from the present work may be useful to understand systems involving the halogens and conformational changes analogous to the compounds investigated.

DNA-interacting and biological properties of copper(ii) complexes from amidino-O-methylurea

Two copper(ii) complexes from the water-soluble amidino-O-methylureas exhibit interesting activities which are of paramount importance for biological applications.

Design, synthesis and mode of action of some benzothiazole derivatives bearing an amide moiety as antibacterial agents

Schematic outline of the most potent compound, benzothiazole bearing amide moiety A07, showing antibacterial activity and its mode of action.

Carbohydrate linked organotin(IV) complexes as human topoisomerase Iα inhibitor and their antiproliferative effects against the human carcinoma cell line

Dimethyltin(IV) complexes with ethanolamine (1) and biologically significant N-glycosides (2 and 3) were designed and synthesized. The structural elucidation of complexes 1-3 was done using elemental and spectroscopic methods; in addition, complex 1 was studied by single crystal X-ray diffraction studies. The in vitro DNA binding profile of complexes 2 and 3 was carried out by employing different biophysical methods to ascertain the feasibility of glycosylated complexes. Further, the cleaving ability of 2 and 3 was investigated by the agarose gel electrophoretic mobility assay with supercoiled pBR322 DNA, and demonstrated significantly good nuclease activity. Furthermore, both the complexes exhibited significant inhibitory effects on the catalytic activity of human Topo I at lower concentration than standard drugs. Computer-aided molecular docking techniques were used to ascertain the mode and mechanism of action towards the molecular target DNA and Topo I. The cytotoxicity of 2 and 3 against human hepatoma cancer cells (Huh7) was evaluated, which revealed significant regression in cancerous cells as compared with the standard drug. The antiproliferative activities of 2 and 3 were tested against human hepatoma cancer cells (Huh7), and results showed significantly good activity. Additionally, to validate the remarkable antiproliferative activity of complexes 2 and 3, specific regulatory gene expression (MMP-2 and TGF-β) was obtained by real time PCR.

Synthesis, characterization, and antibacterial and anticancer screening of {M(2+)-Co (3+)-M (2+)} and {Co (3+)-M (2+)} (M is Zn, Cd, Hg) heterometallic complexes

The cobalt(III) complexes Et(4)N[Co(L(1))(2)] and [Co(L(2))(3)] [H(2)L(1) is 2,6-bis(N-(2-pyridyl)carbamoyl)pyridine and HL(2) is 2-(N-(2-pyridyl)carbamoyl)pyridine] were used as the building blocks for preparing a series of {M(2+)-Co(3+)-M(2+)} (where M is Zn, Cd, or Hg) and {Co(3+)-M(2+)} (where M is Zn or Cd) heterometallic complexes. All heterometallic complexes were characterized using a host of spectroscopic methods (IR, NMR, and UV/vis spectroscopy and mass spectrometry), elemental analysis, and conductivity measurements. One of the representative compounds, {Hg(2+)-Co(3+)-Hg(2+)}, was characterized crystallographically, and it was revealed that two Hg(II) ions are coordinated within the clefts created by the building block Et(4)N[Co(L(1))(2)]. The results of screening for anticancer activity against the human brain tumor U87 cell line and antibacterial activity against a range of resistant (Pseudomonas aeruginosa and Proteus vulgaris) as well as standard (Staphylococcus aureus SA 96, P. aeruginosa MTCC 1688, Klebsiella planticola MTCC 2272, and Escherichia coli T7) bacterial strains indicate promising activities. Notably, the observed activity was found to vary with the type of building block and the secondary metal ion present in the heterometallic complex. Treatment-induced cell death [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT and macrocolony assay), growth inhibition, cytogenetic damage, cell cycle delay, and apoptosis were studied as the parameters for cellular response.

New modulated design and synthesis of chiral CuII/SnIV bimetallic potential anticancer drug entity: in vitro DNA binding and pBR322 DNA cleavage activity

A new chiral ligand scaffold L derived from (R)-2-amino-2-phenyl ethanol and diethyl oxalate was isolated and thoroughly characterized by various spectroscopic methods. The ligand L was allowed to react with CuCl(2)·2H(2)O and NiCl(2)·6H(2)O to achieve monometallic complexes 1 and 2, respectively. Subsequently modulation of 1 and 2 was carried out in the presence of SnCl(4)·5H(2)O to obtain heterobimetallic potential drug candidates 3 and 4 possessing (Cu(II)/Sn(IV) and Ni(II)/Sn(IV)) metallic cores, respectively and characterized by elemental analysis and spectroscopic data including (1)H, (13)C and (119)Sn NMR in case of 3 and 4. In vitro DNA binding studies revealed that complex 3 avidly binds to DNA as quantified by K(b) and K(sv) values. Complex 3 exhibits a remarkable DNA cleavage activity (concentration dependent) with pBR322 DNA and the cleavage activity of 3 was significantly enhanced in the presence of activators and follows the order H(2)O(2)>Asc>MPA>GSH. Complex 3 cleave pBR322 DNA via hydrolytic pathway and accessible to major groove of DNA.