Studies on synthesis, characterization, and G-quadruplex binding of Ru(II) complexes containing two dppz ligands

In this work, the interaction between the guanine-rich single-strand oligomer AG(3)(T(2)AG(3))(3) quadruplex and two Ru(II) complexes, [Ru(L(1))(dppz)(2)](PF(6))(4) (1) and [Ru(L(2))(dppz)(2)](PF(6))(4) (2) (L(1) = 5,5'-di(1-(trimethylammonio)methyl)-2,2'-dipyridyl cation, L(2) = 5,5'-di(1-(triethylammonio)methyl)-2,2'-dipyridyl cation, dppz = dipyrido[3,2-a:2',3'-c] phenazine), has been studied by UV-Visible, fluorescence, DNA melting, and circular dichroism in K(+) buffer. The two complexes after binding to G-quadruplex have shown different DNA stability and fluorescence enhancement. The results show that both complexes can induce the stabilization of quadruplex DNA. ΔT(m) values of complexes 1 and 2 at [Ru]/[DNA] ratio of 1:1 were 9.4 and 7.0, respectively. Binding stoichiometry along with the quadruplex was investigated through a luminescence-based Job plot. The major inflection points for complexes 1 and 2 were 0.49 and 0.46, respectively. The data were consistent with the binding mode at a [quadruplex]/[complex] ratio of 1:1. In addition, the conformation of G-quadruplex was not changed by the complexes at the high ionic strength of K(+) buffer.

DNA binding and photocleavage specificities of a group of tricationic metalloporphyrins

The interactions of 5,10,15-tris(1-methylpyridinium-4-yl)-20-(4-hydroxyphenyl)porphyrinatozinc(II) Zn[TMPyHP](3+) (2) along with Cu[TMPyHP](3+) (3), Co[TMPyHP](4+) (4), Mn[TMPyHP](4+) (5) and the free base porphyrin H(2)[TMPyHP](3+) (1) with duplex DNA have been studied by using a combination of absorption, fluorescence titration, surface-enhanced Raman spectroscopy (SERS), induced circular dichroism (ICD) spectroscopy, thermal DNA denaturation, viscosity measurements as well as gel electrophoresis experiment. Their binding modes and intrinsic binding constants (K(b)) to calf DNA (CT DNA) were comparatively studied and were found significantly influenced by different metals coordinated with the porphyrin plane. Except 3, which has four-coordination structure at the metal, all the metal derivatives showed non-intercalative DNA-binding mode and lower K(b) than the free base porphyrin 1, most probably due to the steric hindrance results from the axial ligands of the inserted metals which are five or six-coordination structures. Meanwhile, the insertion of metals into cationic porphyrin greatly removed the self-aggregation of the metal-free porphyrins, and thus fully enhanced the singlet oxygen ((1)O(2)) productivities in the DNA photocleavage experiments. Therefore, these metalloporphyrins have comparable DNA cleavage ability with the free base porphyrin.

Synthesis, Characterization, and Acid - Base Properties of Ruthenium(II) Complexes Containing N-ethyl-4-([1,10]-phenanthroline[5,6 - f]imidazol-2-yl)carbazole

Three new ruthenium(ii) polypyridyl complexes, [Ru(phen)2(Hecip)]2+ (1), [Ru(phen)(Hecip)2]2+ (2), and [Ru(Hecip)3]2+ (3) complexes (phen = 1,10-phenanthroline, Hecip = N-ethyl-4-([1,10]-phenanthroline[5,6–f]imidazol-2-yl)carbazole) were synthesized and characterized by ES-MS, 1H NMR spectroscopy, elemental analysis, and cyclic voltammetry. The emission spectra of complexes were measured both at room temperature and at 77 K in a 4/1 (v/v) EtOH/MeOH matrix. All three complexes display luminescence properties which are close to that featured by the parent [Ru(phen)3]2+ species. The pH effects on the UV-vis and emission spectra of RuII complexes were also studied, and complexes 1, 2, and 3 were found to act as ‘on–off’ luminescent pH switches with maximum on–off ratios of 17, 230, and 90, respectively.

Performance of HbA(1c) for detecting newly diagnosed diabetes and pre-diabetes in Chinese communities living in Beijing

AIM

To determine the performance of glycated haemoglobin (HbA(1c)) as a screening tool for detecting newly diagnosed diabetes (NDM) and pre-diabetes.

METHODS

A diabetes survey was conducted in Beijing among community dwellers who were willing to participate in the survey. Included in the survey were 903 individuals aged 21-79 years without previously diagnosed diabetes and in whom HbA(1c) and other required covariates had been measured. NDM and pre-diabetes (impaired glucose tolerance + impaired fasting glucose) were defined according to the World Health Organization 1999 criteria based on 75-g oral glucose tolerance test. Receiver operating characteristic curve (ROC) was plotted to determine the performance of HbA(1c).

RESULTS

The prevalence of NDM and pre-diabetes was 11.1% and 22.4%, respectively. At an optimal HbA(1c) cut-off point of > or = 6.0%, the test gave a sensitivity of 80.0% and a specificity of 89.8% for diagnosing NDM; at an optimal cut-off point of > or = 5.7%, the sensitivity was 59.4% and specificity 73.9% for diagnosing pre-diabetes. Individuals with HbA(1c)> or = 6.0% tended to be more obese than those with HbA(1c) < 6.0%, but blood pressure and lipid profiles did not differ between the two groups.

CONCLUSIONS

HbA(1c) as a single screening test is adequate to detect newly diagnosed diabetes but is not able to identify pre-diabetes in this obese Chinese population.

Synthesis, characterization and DNA-binding studies of ruthenium(II) mixed-ligand complexes containing dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline

A novel ligand dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline (dpoq) and its complexes [Ru(bpy)(2)(dpoq)](2+) and [Ru(phen)(2)(dpoq)](2+) (bpy=2,2'-bipyridine; phen=1,10-phenanthroline) have been synthesized and characterized by elemental analysis, electrospray mass spectra and (1)H NMR. The interaction of Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by absorption spectroscopy, fluorescence spectroscopy, thermal denaturation and viscosity measurements. Results suggest that two Ru(II) complexes bind to DNA via an intercalative mode.