Javier Hernández-Gil

DNA binding, nuclease activity, DNA photocleavage and cytotoxic properties of Cu(II) complexes of N-substituted sulfonamides.

Ternary copper(II) complexes [Cu(NST)2(phen)] (1) and [Cu(NST)2(NH3)2]·H2O (2) [HNST=N-(4,5-dimethylthiazol-2-yl)naphthalene-1-sulfonamide] were prepared and characterized by physico-chemical techniques. Both 1 and 2 were structurally characterized by X-ray crystallography. The crystal structures show the presence of a distorted square planar CuN4 geometry in which the deprotonated sulfonamide, acting as monodentate ligand, binds to the metal ion through the thiazole N atom. Both complexes present intermolecular π-π stacking interactions between phenanthroline rings (compound 1) and between naphthalene rings (compound 2). The interaction of the complexes with CT DNA was studied by means of thermal denaturation, viscosity measurements and fluorescence spectroscopy. The complexes display good binding propensity to the calf thymus DNA giving the order: 1>2. Complex 1, which has a higher capability for binding to DNA, showed better nuclease activity than 2 in the presence of ascorbate/H2O2. Both the kinetics and the mechanism of the DNA cleavage reaction were investigated. Furthermore, complex 1 showed efficient photo-induced DNA cleavage activity on irradiation with UV light in the absence of any external reagent. The UV light induced DNA cleavage follows a photo-redox pathway with generation of hydroxyl radicals as reactive species. In addition, the cytotoxic properties of both complexes (1 and 2) were evaluated in human cancer cells (HeLa, Caco-2 and MDA-468). The low IC50 values, in particular those against Caco-2, have indicated that the compounds can be considered as promising chemotherapeutic agents.

Novel hexanuclear copper(II) complex built from a simple tetrachelating triazole ligand: synthesis, structure, and magnetism.

A new easy symmetric 3,5-disubstituted 1,2,4-triazole ligand (H3diV) by reaction with an excess of copper(II) salt has afforded a novel hexanuclear compound (Cu/HdiV ratio of 6:2) through a bis(trans-cis-cis-trans) binding mode, exhibiting two types of Cu(II) centers and two clearly distinguishable antiferromagnetic J1 (-234 cm(-1)) and J2 (-35 cm(-1)) coupling constants.

An Iron Oxide Nanocarrier Loaded with a Pt(IV) Prodrug and Immunostimulatory dsRNA for Combining Complementary Cancer Killing Effects

There is major current interest in harnessing the immune system against cancer and in developing drugs that provide complementary cancer killing mechanisms. Although the recent advent of nanoparticle-based drug delivery systems has improved the efficacy of platinum drugs for chemotherapy, one of the fundamental paradigms in their design and use is evading surveillance by the immune system to enhance anticancer efficacy. However, new studies are showing that chemotherapy can profit from actively targeting stimulation of the immune system and that suitably functionalized nanomaterials might be ideal for overcoming some key challenges in immunotherapy. Pt(IV) prodrug-modified PEGylated phospholipid micelles that encapsulate biocompatible iron oxide nanoparticles (IONPs) as a new delivery system for cisplatin are reported. The Pt(IV)-IONPs are functionalized with polyinosinic-polycytidylic acid (poly (I:C))--a double stranded RNA (dsRNA) analog widely used as an adjuvant in clinical trials of cancer immunotherapy. The Pt(IV)-IONPs and poly (I:C)--Pt(IV)-IONPs enhance by more than an order of magnitude the prodrug cytotoxicity in different tumor cells, while greatly increasing the ability of cisplatin and poly (I:C) to activate dendritic cells--the key cellular players in immunotherapy. The results suggest that these constructs hold promise for targeted chemoimmunotherapy.

Mn(II) complexes with sulfonamides as ligands.: DNA interaction studies and nuclease activity

Sulfonamides derived from 8-aminoquinoline react with Mn(II) and Mn(III) salts to form Mn(II) complexes; the Mn(III) species are reduced to the divalent state in the presence of 1,10 phenanthroline and bipyridine. Their molecular structure, determined by single crystal X-ray diffraction, show that all the complexes present a distorted octahedral geometry, in which the deprotonated sulfonamide acts as a bidentate ligand. UV-visible spectroscopy and changes in the melting temperature (Tm) of calf thymus DNA show a strong interaction of these complexes with DNA. The significant hypochromicity of the charge transfer transition at 370 nm without an appreciable change in wavelength and the minor changes in the relative viscosity of calf thymus DNA have been attributed to an interaction between the surface of DNA and the complexes. [Mn(qbsa)(2)(MeOH)(2)], [Mn(qbsa)(2)(phen)], [Mn(qtsa)(2)(H(2)O)(2)] and [Mn(qtsa)(2)(phen)] (where qbsa=N-quinolin-8-yl-bencenesulfonamide, qtsa=N-quinolin-8-yl-p-toluenesulfonamide and qnsa=N-quinolin-8-yl-naftalenesulfonamide) exhibit a prominent nuclease activity and the mechanism of DNA cleavage is investigated.

N-(5-Amino-1H-1,2,4-triazol-3-yl)pyridine-2-carboxamide.

The title compound, C8H8N6O, was obtained by the reaction of 3,5-diamino-1,2,4-triazole with ethyl 2-picolinate in a glass oven. The dihedral angles formed between the plane of the amide group and the pyridine and triazole rings are 11.8 (3) and 5.8 (3)°, respectively. In the crystal, an extensive system of classical N—H⋯N and N—H⋯O hydrogen bonds generate an infinite three-dimensional network.