Zijian Guo

DNA binding properties of novel cytotoxic gold(III) complexes of terpyridine ligands: the impact of steric and electrostatic effects

Four gold(III) complexes of terpyridine derivatives 1–4 have been synthesized and characterized by spectroscopic methods. In vitro data demonstrated that all of them showed higher cytotoxicity than cisplatin against the human non-small-cell lung cancer cell line (A-549), the human stomach carcinoma cell line (SGC-7901), the human cervix carcinoma cell line (HELA), the human colon carcinoma cell line (HCT-116), the human liver carcinoma cell line (BEL-7402), the murine leukemia cell line (P-388) and the human acute promyelocytic leukemia cell line (HL-60). Complex 3 exhibits the highest activity, with growth inhibition rates of over 80% at 10−8xa0molxa0L−1 against the A-549, HCT-116 and HELA tumor cell lines. Interestingly, ligands L1–L4 are also very cytotoxic against the cell lines tested. Complexes 1–4 are stable in aqueous solution for 2xa0days in the presence of the biological reducing agent glutathione. The inductively coupled plasma mass spectrometry data showed that DNA isolated from cells treated with complexes 1 and 3 contained gold with gold-to-nucleotide ratios of approximately 1:6,400 and 1:4,900, respectively. Fluorescence titration, UV and circular dichroism analyses proved that the steric and electrostatic effects of the ligand remarkably influence the interactions of their gold(III) complexes with DNA. The DNA binding ability of the complexes has been correlated with their cytotoxicity, which could potentially provide a new rationale for the future design of terpyridine-based metal complexes with antitumor potential.

5-Fluorouracil–cisplatin adducts with potential antitumor activity

Using 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum(II) (cisplatin, CDDP) as starting compounds, 5-FU-cisplatin adducts cis-[Pt(NH(3))(2)(HFU)Cl] (1) and cis-[Pt(NH(3))(2)(HFU)(2)] (2) were prepared. The obtained complexes were characterized by IR, ES-MS and 1H NMR spectroscopy. Complex 1 reacted with guanosine-5-monophosphate (5-GMP) and gave rise to a stable mixed-ligand complex cis-[Pt(NH(3))(2)(HFU)(GMP)] (3), whereas 2 did not undergo a similar reaction. In vitro cell growth inhibition tests of complexes 1 and 2 exhibited moderate antitumor activities against the melanoma B16-BL6 cell line. This work provides the basis for a potential alternative for the combinational use of 5-FU and CDDP in cancer therapy.

Crystal structure and superoxide dismutase activity of a six-coordinate manganese(III) complex

Abstract A six-coordinate manganese(III) complex [Mn(bpb)(H2O)Cl], where H2bpb is N,N′-(1,2-phenylene)bis(pyridine-2-carboxaminde), was prepared and characterized by X-ray crystallography. It crystallizes in the monoclinic system, space group P 2(1)/c with a=6.735(1) A, b=22.910(4) A, c=11.647(2) A, β=102.20(1)°, Z=4 and V =1756.5(5) A 3 . Mn (III) in the complex adopts an octahedral coordination geometry. The cyclic voltammetry of the complex recorded in DMF indicates a reversible one-electron redox reaction. The complex has been shown to catalyze effectively the dismutation of superoxide (O2−) in the riboflavin–methionine–nitro blue tetrazolium assay with an IC50 value of 2.93 μM.

Novel Cu(II)-quinoline carboxamide complexes: Structural characterization, cytotoxicity and reactivity towards 5′-GMP

Three new ligands, N-(8-quinolyl)pyridine-2-carboxamide (HL1), N-(8-quinolyl)glycine-N′-Boc-carboxamide (HL2), N-(8-quinolyl)-L-alanine-N′-Boc-carboxamide (HL3), and their Cu(II) complexes have been synthesized. Crystallographic data reveal that complexxa0I, [Cu(L1)(Ac)(H2O)], is penta-coordinated with a square-pyramidal geometry while complexesxa0V [Cu(L2′)(H2O)] and VI [Cu(L3′)(H2O)] are tetra-coordinated to give square planar geometry. In vitro tests showed that the Cu(II) complexes with L1 (I-IV) exhibited cytotoxicity at a concentration of 10−8xa0M against murine leukemia P-388 and human leukemia HL-60 cell lines, which is more potent than cisplatin. However, ligands HL2 and HL3 and their corresponding copper complexes demonstrated very weak in vitro activities towards the cell lines examined. ESMS data shows that complex I binds rapidly with 5′-GMP to form 1:1 and 2:2 adduct.

X-Ray crystal structures of Mg2+ and Ca2+ dimers of the antibacterial drug norfloxacin

The hydrothermal reactions of norfloxacin (H-Norf) with MgCl2·6H2O and CaCl2·6H2O yield two unprecedented dimers containing a direct coordinate bond between H-Norf and a metal [Mg2(H2O)6(H-Norf)2]Cl4·4H2O 1 and [Ca2(Cl)(H-Norf)6]Cl3·10H2O 2.

Crystal structure of zinc(II) 2-sulfanilamidopyrimidine: a widely used topical burn drug

The reaction of H-SD (sulfadiazine) with Zn(OAc)2·2H2O in water–ethanol under solvothermal reaction conditions yields crystals of Zn(SD)2 (1) suitable for X-ray analysis and its 1-D polymeric nature is biologically relevant to the slow release of Zn2+ when applied in topical burn therapy.

Dimeric water embedded within a hydrophobic cavity of tetra-(p-tert-butyl)thiacalix[4] arene

Abstract X-ray crystallographic analysis and density functional B3LYP/6-31G(d) calculation confirm that dimeric water is embedded within a hydrophobic cavity of tetra-(p-tert-butyl)thiacalix[4]arene and stabilized by hydrogen bondings of aromatic π⋯H2O(1) and methyl⋯H2O(2) in the dimeric water inclusion complex with binding energies of 1.4 and 0.9xa0kcalxa0mol−1 respectively, and by hydrogen bonding formed between H2O(2) and four phenolic OH groups from an adjacent tetra-(p-tert-butyl)thiacalix[4]arene, with binding energy of 3.8–4.2xa0kcalxa0mol−1.

Compositions and conformations of several transition metal complexes with a nonapeptide hormone oxytocin

Similar co-ordination characteristics of oxytocin (OT) towards CuII, NiII, MnII and ZnII at different pH values have been demonstrated by electrospray mass spectrometry (ESMS) and rationalized by molecular mechanics simulation. At ca. pH 2 oxytocin does not interact with the metal ions; at pH 5 species with metal bound oxytocin were detected, including [OTxa0+xa0H+]+, [Mxa0+xa0OT]2+, [Mxa0+xa0OTxa0−xa0H+]+, [Mxa0+xa0OTxa0+xa0ClO4−xa0+xa0H+]2+ and [Mxa0+xa0OTxa0+xa0ClO4−]+ and only stable 4N complexes were found at pHxa0≈xa09. Molecular modelling studies using the Universal force field (UFF) showed that the four N-donor centers of oxytocin prefer the square planar geometry in complexes of NiII and MnII. For PdII, the Sγ(1) co-ordinated conformer was found to be more stable than the Sγ(6) co-ordinated one. Dramatic conformational changes occur upon oxytocin co-ordinating to NiII, MnII or PdII.

Cation-induced assembly of the first mixed molybdenum–vanadium hexadecametal host shell cluster anions

Two novel hexadecametal–oxygen cluster compounds, {Ni[(NH2)2(C2H4)2NH]2}3[PMoVI5MoV3VIV8O44]·[(NH2)2(C2H4)2NH]·H2O 1 and {Co[(NH2)2(C2H4)2NH]2}2Na[PMoVI6MoV2VIV8O44]·8H2O 2 are synthesized by a hydrothermal method, and characterized by X-ray crystallography, showing that the anion of 1 has a novel tetra-capping mode, and that the first hexadecametal–oxygen host shell is observed in 2.

4,5‐Diazafluoren‐9‐ol

The title compound, C(11)H(8)N(2)O, has two crystallographically independent molecules in the crystal. Each molecule is basically planar except for the O atom. The two N atoms in the molecule show different behaviour as hydrogen-bonding acceptors. One of them is involved in intermolecular O-H.N hydrogen bonds which stabilize the crystal packing.