Searching for "Greener" Bioequivalents of CF3 to Lower its Environmental Impact

Considering the broad use of the trifluoromethyl functional group (-CF3) in medicinal chemistry and taking into account the recent concerns on the negative environmental effects of CF3 containing compounds, we are searching for "greener" alternatives. Thus, different chemical groups (i. e. iodide, fluoride, cyclopropyl, isopropyl, cyclobutyl, 3-oxetyl, 2-oxetyl, methylsulfide, pentafluorosulfide, methylsulfonyl and sulfonamide) have been considered as potential bioequivalents of -CF3 aiming to use them in compounds with therapeutic interest instead of the polyfluoride functionality. Different structural (molecular surface and volume) and physicochemical (electronic and lipophilic) aspects of the bioequivalent functionalities proposed have been theoretically calculated and compared to those of -CF3. Additionally, the corresponding phenyl derivatives carrying these functionalities have been purchased or prepared and their experimental lipophilicity (i. e. LogP) measured using shake-flask experiments and UV-vis spectroscopy.

Copper-Based Complexes with Adamantane Ring-Conjugated bis(3,5-Dimethyl-pyrazol-1-yl)acetate Ligand as Promising Agents for the Treatment of Glioblastoma

The new ligand L2Ad, obtained by conjugating the bifunctional species bis(3,5-dimethylpyrazol-1-yl)-acetate and the drug amantadine, was used as a chelator for the synthesis of new Cu complexes 1-5. Their structures were investigated by synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and by combining X-ray absorption fine structure (XAFS) spectroscopy techniques and DFT modeling. The structure of complex 3 was determined by single-crystal X-ray diffraction analysis. Tested on U87, T98, and U251 glioma cells, Cu(II) complex 3 and Cu(I) complex 5 decreased cell viability with IC50 values significantly lower than cisplatin, affecting cell growth, proliferation, and death. Their effects were prevented by treatment with the Cu chelator tetrathiomolybdate, suggesting the involvement of copper in their cytotoxic activity. Both complexes were able to increase ROS production, leading to DNA damage and death. Interestingly, nontoxic doses of 3 or 5 enhanced the chemosensitivity to Temozolomide.

Biological Activity of Triazolopyrimidine Copper(II) Complexes Modulated by an Auxiliary N-N-Chelating Heterocycle Ligands

Novel complexes of type [Cu(N-N)(dmtp)2(OH2)](ClO4)2·dmtp ((1) N-N: 2,2'-bipyridine; (2) L: 1,10-phenantroline and dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine) were designed in order to obtain biologically active compounds. Complexes were characterized as mononuclear species that crystallized in the space group P-1 of the triclinic system with a square pyramidal geometry around the copper (II). In addition to the antiproliferative effect on murine melanoma B16 cells, complex (1) exhibited low toxicity on normal BJ cells and did not affect membrane integrity. Complex (2) proved to be a more potent antimicrobial in comparison with (1), but both compounds were more active in comparison with dmtp-both against planktonic cells and biofilms. A stronger antimicrobial and antibiofilm effect was noticed against the Gram-positive strains, including methicillin-resistant Staphylococcus aureus (MRSA). Both electron paramagnetic resonance (EPR) and Saccharomyces cerevisiae studies indicated that the complexes were scavengers rather than reactive oxygen species promoters. Their DNA intercalating capacity was evidenced by modifications in both absorption and fluorescence spectra. Furthermore, both complexes exhibited nuclease-like activity, which increased in the presence of hydrogen peroxide.

Dual sensing of methionine and aspartic acid in aqueous medium by a quinoline-based fluorescent probe

A quinoline-based Schiff base sensor, 6-methyl-2-oxo-1,2-dihydro-quinoline-3-carboxaldehyde-4(N)-phenylsemicarbazone (6MPS), has been developed for selective sensing of methionine and aspartic acid in aqueous medium through "on-off-on" type selective detection of copper ion. Fluorescence imaging of 6MPS, 6MPSC, 6MPSCN, 6MPSC-met, 6MPSCN-met, 6MPSC-asp and 6MPSCN-asp has been successfully demonstrated, in which the sensing probes 6MPSC-met, 6MPSCN-met, 6MPSC-asp and 6MPSCN-asp displayed bright green fluorescence in both in vitro and in vivo live cells.

Copper(II) Complexes with Mixed Heterocycle Ligands as Promising Antibacterial and Antitumor Species

Complexes with mixed ligands [Cu(N-N)₂(pmtp)](ClO₄)₂ ((1) N-N: 2,2′-bipyridine; (2) L: 1,10-phenanthroline and pmpt: 5-phenyl-7-methyl-1,2,4-triazolo[1,5-a]pyrimidine) were synthesized and structurally and biologically characterized. Compound (1) crystallizes into space group Pa and (2) in P-1. Both complexes display an intermediate stereochemistry between the two five-coordinated ones. The biological tests indicated that the two compounds exhibited superoxide scavenging capacity, intercalative DNA properties, and metallonuclease activity. Tests on various cell systems indicated that the two complexes neither interfere with the proliferation of Saccharomyces cerevisiae or BJ healthy skin cells, nor cause hemolysis in the active concentration range. Nevertheless, the compounds showed antibacterial potential, with complex (2) being significantly more active than complex (1) against all tested bacterial strains, both in planktonic and biofilm growth state. Both complexes exhibited a very good activity against B16 melanoma cells, with a higher specificity being displayed by compound (1). Taken together, the results indicate that complexes (1) and (2) have specific biological relevance, with potential for the development of antitumor or antimicrobial drugs.

Molecular docking, DFT and antimicrobial studies of Cu(II) complex as topoisomerase I inhibitor

Herein, we report the synthesis and single crystal X-ray structure of Cu(II)-picolinic acid complex, 1 as a potent topoisomerase I inhibitor. The complex 1 crystallized in the triclinic crystal system with space group P-1. Comparative in vitro binding studies of complex 1 with CT DNA and tRNA were carried out revealing an electrostatic binding mode with higher binding propensity towards tRNA. The intrinsic bonding constant value, K_b was calculated to be 4.36 × 10⁴ and 8.78 × 10⁴ M^-1 with CT DNA and tRNA respectively. DNA cleavage activity was carried out with a pBR322 plasmid DNA substrate to ascertain the cleaving ability. Furthermore, Topo-I inhibition assay of complex 1, performed via gel electrophoresis revealed a significant inhibitory effect on the enzyme catalytic activity at a minimum concentration of 15 µM. The DFT studies were carried out to provide better insight in the electronic transitions observed in the absorption spectrum of the complex 1. Molecular docking studies were carried out with DNA, RNA and Topo-I to determine the specific binding preferences at the target site and complement the spectroscopic studies. The antimicrobial potential of complex 1 was screened against E. coli, S. aureus, P. aeruginosa, B. subtilis and C. albicans; and compared with doxycycline, exhibiting an excellent maximum zone of inhibition of 28 mm against E. coli.Communicated by Ramaswamy H. Sarma.

A fluorescent Cu(ii) complex as a dual functional sensor for selective and sensitive detection of acetone and Cd(ii) pollutants

In this study, Cu²⁺ perchlorate complexes of 3,5-dimetylpyrazole(dmpy), namely [Cu(dmpy)₃(H₂O)₂](H₂O)(ClO₄)₂ (1), were prepared and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared (IR) spectroscopy, elemental analysis, mass spectrometry, and ultraviolet visible (UV-Vis) spectroscopy. It was determined that Cu²⁺ coordinated to the nitrogen atoms of three dmpy molecules as well as to the oxygen atoms of two H₂O molecules in a square pyramidal geometry. To balance the charge, two uncoordinated perchlorate anions and one H₂O molecule were also present in the lattice. The resulting Cu²⁺ complex was involved in extensive hydrogen bonding, which stabilized the structure. The fluorescence properties of complex 1 were studied in acetonitrile at room temperature upon the addition of different organic solvents. It was confirmed that the complex exhibited remarkable acetone selectivity via a fluorescence quenching mechanism. At low concentrations, the fluorescence intensities were nearly completely quenched via a turn-off mode. Moreover, complex 1 displayed exceptional selectivity, fast detection time, and high sensitivity for Cd²⁺ in aqueous solutions via a fluorescence enhancement mechanism (turn-on mode). Hence, the prepared complex showed potential for application in Cd²⁺ detection. Notably, in an aqueous solution, complex 1 exhibited highly selective fluorescence enhancement effects (turn-on mode) with respect to Cd²⁺ and was not affected by the interference of other metal ions.

The prepared complex 1 exhibited highly sensitive and selective fluorescence quenching (turn-off) effect in the presence of acetone as well as fluorescence enhancement (turn-on) effect toward Cd²⁺ ions in aqueous solutions.

Multiple coordination modes of a new ditopic bis(pyrazolyl)methane-based ligand

A new ditopic ligand, N-(2,2-bis(pyrazolyl)ethyl)-2,2-bis(pyrazolyl)acetamide ((pz)₂CH-C(O)-NH-CH₂-CH(pz)₂, L4Pz, pz = pyrazolyl ring), comprising two bis(pyrazolyl)methane donor groups linked via an amide bridge, has been prepared from the reaction of HOOCCH(pz)₂ and H₂NCH₂CH(pz)₂. The ligand coordinates to various metallic salts (i.e. AgO₃SCF₃, PdCl₂, Re(CO)₅Br, and Fe(BF₄)₂), in either a κ²-μ-κ² or a κ³-μ-κ² fashion, depending on the coordination preferences of the metallic center. These compounds were characterized by NMR, UV-Vis and IR spectroscopy, and in solid state by single crystal X-ray diffraction. In the case of silver(i), a mono-dimensional coordination polymer was obtained, while the others were found to be discrete complexes. The synthesis and characterization of a heterobimetallic complex is also described. In solid state, all compounds are associated into supramolecular architectures via hydrogen bonding and pyrazolyl embrace interactions.

Single X-ray crystal structure, DFT studies and topoisomerase I inhibition activity of a tailored ionic Ag(i) nalidixic acid–piperazinium drug entity specific for pancreatic cancer cells

DFT studies, Topo I inhibition assay and cytotoxic activity of novel ionic Ag(i) nalidixic acid–piperazinium molecular entity.

Spectroscopic Definition of the CuZ° Intermediate in Turnover of Nitrous Oxide Reductase and Molecular Insight into the Catalytic Mechanism

Spectroscopic methods and density functional theory (DFT) calculations are used to determine the geometric and electronic structure of Cu_Z°, an intermediate form of the Cu₄S active site of nitrous oxide reductase (N₂OR) that is observed in single turnover of fully reduced N₂OR with N₂O. Electron paramagnetic resonance (EPR), absorption, and magnetic circular dichroism (MCD) spectroscopies show that Cu_Z° is a 1-hole (i.e., 3Cu^ICu^II) state with spin density delocalized evenly over Cu_I and Cu_IV. Resonance Raman spectroscopy shows two Cu-S vibrations at 425 and 413 cm^-1, the latter with a -3 cm^-1 O¹⁸ solvent isotope shift. DFT calculations correlated to these spectral features show that Cu_Z° has a terminal hydroxide ligand coordinated to Cu_IV, stabilized by a hydrogen bond to a nearby lysine residue. Cu_Z° can be reduced via electron transfer from Cu_A using a physiologically relevant reductant. We obtain a lower limit on the rate of this intramolecular electron transfer (IET) that is >10⁴ faster than the unobserved IET in the resting state, showing that Cu_Z° is the catalytically relevant oxidized form of N₂OR. Terminal hydroxide coordination to Cu_IV in the Cu_Z° intermediate yields insight into the nature of N₂O binding and reduction, specifying a molecular mechanism in which N₂O coordinates in a μ-1,3 fashion to the fully reduced state, with hydrogen bonding from Lys397, and two electrons are transferred from the fully reduced μ₄S^2- bridged tetranuclear copper cluster to N₂O via a single Cu atom to accomplish N-O bond cleavage.

In vitro DNA binding profile of enantiomeric dinuclear Cu(II)/Ni(II) complexes derived from l-/d-histidine-terepthaldehyde reduced Schiff base as potential chemotherapeutic agents

New chiral reduced Schiff base ligands, L1 and L2 derived from l-/d-histidine and terepthaldehyde, and their Cu(II) and Ni(II) dinuclear complexes 1 &2 (a and b) were synthesized and thoroughly characterized by various spectroscopic techniques. Comparative binding profile of both l-/d-enantiomeric Cu(II) and Ni(II) complexes with ct-DNA was studied by employing optical and spectroscopic techniques to evaluate their enantiopreferential selectivity towards molecular target DNA and thereby explore their relative chemotherapeutic potential. Quantitative assessment of DNA binding propensity was ascertained by calculating K_b, K and K_sv values of 1 &2 (a and b) which demonstrated higher binding affinity of l-enantiomeric Cu(II) complex, 1a and followed the order as 1a>1b>2a>2b. Scanning electron microscopy (SEM) was used to analyze the morphological changes of the DNA condensate in presence of complexes 1 (a and b). The SEM micrographs condensates revealed morphological transitions and formation of different structural features implicating the condensation process between the complexes and biomolecule occurred to form compact massive structures. The gel electrophoretic assay of complex 1a was carried out with pBR322 plasmid DNA which revealed an efficient cleaving ability of the complex via oxidative pathway with the involvement of singlet oxygen (¹O₂) and the superoxide anion (O₂^•-) radicals as the ROS responsible the cleavage reactions. Molecular docking studies of 1 (a and b) with DNA revealed selective recognition of G-C residues of the narrow minor groove of the DNA duplex and complex 1a demonstrated binding affinity towards DNA ascertained from its higher binding energy values. Furthermore, the cytotoxic assessment of 1a was examined on a panel of cancer cell lines of different histological origin employing SRB assay which revealed remarkably good cytotoxic activity towards HL60, HeLa and MCF7 cancer cell lines.

Mechanistic insights into a novel chromone-appended Cu(II) anticancer drug entity: in vitro binding profile with DNA/RNA substrates and cytotoxic activity against MCF-7 and HepG2 cancer cells

A new chromone-appended Cu(ii) drug entity () was designed and synthesized as a potential anticancer chemotherapeutic agent. The structural elucidation was carried out thoroughly by elemental analysis, FT-IR, EPR, ESI-MS and single crystal X-ray crystallography. Complex resulted from the in situ methoxylation reaction of the 3-formylchromone ligand and its subsequent complexation with the copper nitrate salt in a 2 : 1 ratio, respectively. crystallized in the monoclinic P21/c space group possessing the lattice parameters, a = 8.75 Å, b = 5.07 Å, c = 26.22 Å, α = γ = 90°, β = 96.3° per unit cell. Furthermore, in vitro interaction studies of with ct-DNA and tRNA were carried out which suggested more avid binding propensity towards the RNA target via intercalative mode, which was reflected from its Kb, K and Ksv values. The gel electrophoretic mobility assay was carried out on the pBR322 plasmid DNA substrate, to ascertain the cleaving ability and the mechanistic pathway in the presence of additives, and the results revealed the efficient cleaving ability of via the oxidative pathway. In vitro cell growth inhibition via the MTT assay was carried out to evaluate the cytotoxicity of complex and IC50 values were found to be in the range of 5-10 μg mL(-1) in HepG2 and MCF-7 cancer cell lines, which were found to be much lower than the IC50 values of previously reported similar Cu(ii) complexes. Additionally, in the presence of , reactive oxygen species (ROS) and thiobarbituric acid reactive substance (TBARS) levels in the tested cancer cell lines increased significantly, coupled with reduced glutathione (GSH) levels. Thus, our results suggested that ROS plays an important role in cell apoptosis induced by the Cu(ii) complex and validates its potential to act as a robust anticancer drug entity.

Synthesis of pyrazolylbisindoles over mesoporous Lewis acidic ZrTUD-1: Potential application in selective Cu(2+) colorimetric detection

A series of pyrazolylbisindole (PBI) derivatives were prepared by simple condensation of indole and pyrazole aldehyde utilizing amorphous mesoporous ZrTUD-1 having predominant Lewis acid sites. The applicability of pyrazolylbisindolyl derivate as a colorimetric chemosensor with high selectivity toward Cu(2+) over other cations were tested. Among heavy and transition metal (HTM) ions in CH3CN solution, the probe only sensed Cu(2+) detectable by naked eye. The sensor exhibited a new absorption band at 488 nm (a red shift of 206 nm from 282 nm) with a large colorimetric response and affinity to Cu(2+) over other cations tested (Al(3+), Pb(2+), Cd(2+), Mg(2+), Mn(2+), Zn(2+), K(+), Fe(2+), Ca(2+), Cu(2+) and Hg(2+)).

Synthesis and antitumor mechanisms of a copper(ii) complex of anthracene-9-imidazoline hydrazone (9-AIH)

A copper(ii) complex of anthracene-9-imidazoline hydrazone induced cell apoptosis by suppressing mutant p53 expression and activating caspase cascade pathway.

Copper(ii) complexes of macrocyclic and open-chain pseudopeptidic ligands: synthesis, characterization and interaction with dicarboxylates

Cu(ii) complexes of pseudopeptides interact with very similar dicarboxylates of biological interest (malate and aspartate) affording strikingly different outcomes.

Effect of glucosamine conjugation to zinc(II) complexes of a bis-pyrazole ligand: syntheses, characterization and anticancer activity

The bis(3,5-dimethyl-1H- pyrazol-1yl)acetic acid (bdmpza) ligand was conjugated with tert-butyl-N-(2-aminoethyl) carbonate, methyl-2-amino-4-(methylthio)butanoate and 1,3,4,6-tetra-O-acetyl-β-d-glucosamine hydrochloride via amide coupling method to form three ligands L1-L3 which were then reacted with Zn(II) salts to form four zinc complexes (1-4). The complexes were characterized by (1)H NMR, (13)C NMR, electrospray ionization mass spectrometry (ESI-MS), FT-IR, CHN analyses. Complexes 1, 2 and 4 were also characterized by single crystal X-ray diffraction. It was found that Zn(II) salts could selectively remove the acetyl group from anomeric position leaving everything else intact. The cytotoxicity studies of the ligand and the complexes showed that the conjugation to acetylated glucosamine enhances cytotoxic ability although the complexes become more hydrophilic. Cytotoxicity studies in human breast adenocarcinoma (MCF-7), human cervical cancer (HeLa WT) and human lung adenocarcinoma (A549) showed that the acetylated glucosamine conjugation to the bis-pyrazole ligated Zn(II) complex led to 2-4 fold increase in cytotoxicity (IC50 values ca. 57-80μM) against HeLa WT and MCF-7 cell lines. The Zn(II) complex bearing the acetylated glucosamine inhibits the cell cycle in the G2/M phase of MCF-7 cell line. ICP-MS data shows more accumulation of Zn(II) inside the cell upon use of complex 4 as compared to Zn(II) salts or the other presented complexes. Further studies suggest that the mitochondrial transmembrane potential changes in the presence of complex 4 and caspase-7 is activated by Zn(II) salts but the activation is much more by complex 4 and hence there is apoptosis and dose dependent chromatin condensation/nuclear fragmentation as observed by microscopy.