DNA structural changes (photo)induced by tricarbonyl (pterin)rhenium(I) complex.

We report on interactions of different types of DNA molecules including double-stranded and plasmid DNA as well as polynucleotides (poly[dGdC]2 and poly[dAdT]2) with fac-[ReI(CO)3(pterin)(H2O)] (or Reptr) complex. The interaction was characterized spectroscopically and changes in the plasmid structure were verified by both electrophoresis and AFM microscopy. For comparative reasons, two others related tricarbonyl rhenium(I) complexes, fac-[(4,4'-bpy)ReI(CO)3(dppz)]+ (or Redppz) and fac-[(CF3SO3)ReI(CO)3(2,2'-bpy)] (or Rebpy) were also studied to further explore the influence of the different co-ligands on the interaction and DNA (photo)damage. Data reported herein suggests that DNA molecules can be structurally modified either by direct interaction with Re(I) complexes in their ground states inducing DNA relaxation, and/or through photoinduced cross-linking processes. The chemical nature of the co-ligands modulates the extent of the damage observed.

Resonance energy transfer in the solution phase photophysics of -Re(CO)3 L+ pendants bonded to poly(4-vinylpyridine).

Polymers with general formula ([(vpy) 2vpyRe(CO) 3(tmphen) (+)]) n ([(vpy) 2vpyRe(CO) 3(NO 2-phen) (+)]) m (NO 2-phen = 5-nitro-1,10-phenanthroline; tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline); vpy = 4-vinylpyridine) were prepared and their morphologies were studied by transmission electron microscopy (TEM). Multiple morphologies of aggregates from these Re I polymers were obtained by using different solvents. Energy transfer between MLCT Re-->tmphen and MLCT Re-->NO 2 -phen excited states inside the polymers was evidenced by steady state and time-resolved spectroscopy. Current Forster resonance energy transfer theory was successfully applied to energy transfer processes in these polymers.

Intercalation of fac-[(4,4'-bpy)ReI(CO)3(dppz)]+, dppz = dipyridyl[3,2-a:2'3'-c]phenazine, in polynucleotides. On the UV-vis photophysics of the Re(I) intercalator and the redox reactions with pulse radiolysis-generated radicals.

The intercalation of fac-[(4,4'-bpy)Re(I)(CO)3(dppz)]+ (dppz = dipyridyl[3,2-a:2'3'-c]phenazine) in polynucleotides, poly[dAdT]2 and poly[dGdC]2, where A = adenine, G = guanine, C = cytosine and T = thymine, is a major cause of changes in the absorption and emission spectra of the complex. A strong complex-poly[dAdT]2 interaction drives the intercalation process, which has a binding constant, Kb approximately 1.8 x 10(5) M(-1). Pulse radiolysis was used for a study of the redox reactions of e(-)(aq), C*H(2)OH and N3* radicals with the intercalated complex. These radicals exhibited more affinity for the intercalated complex than for the bases. Ligand-radical complexes, fac-[(4,4'-bpy*)Re(I)(CO)3(dppz)] and fac-[(4,4'-bpy)Re(I)(CO)3(dppz *)], were produced by e(-)(aq) and C*H(2)OH, respectively. A Re(II) species, fac-[(4,4'-bpy)Re(II)(CO)3(dppz)](2+), was produced by N3* radicals. The rate of annihilation of the ligand-radical species was second order on the concentration of ligand-radical while the disappearance of the Re(II) complex induced the oxidative cleavage of the polynucleotide strand.

On the association and structure of radicals derived from dipyridil[3,2-a:2'3'-c]phenazine. Contrast between the electrochemical, radiolytic, and photochemical reduction processes.

The reduction of dipyridil[3,2-a:2'3'-c]phenazine, dppz, by pulse radiolytically generated e(-)(sol) or by the reaction of the dppz excited states with electron donors produces the radical dppzH(.). The dimer radical, (dppz)(2)H(.), exists in equilibrium with dppz with an association constant, K = 10(3) M(-1). The rate constant for the reaction of dppzH(.) with dppz is k = 4.3 x 10(6) M(-1) s(-1). DFT calculations on the structures of dppzH(.) and the doubly reduced and doubly protonated dppzH(2) rendered a planar structure for the former species and a bent one for the latter.

Increased levels of amino acid neurotransmitters in the inferior colliculus of the genetically epilepsy-prone rat.

Previous studies have shown an increase in the number of GABAergic and total neurons in the inferior colliculus (IC) of the genetically epilepsy-prone rat (GEPR). Amino acid analysis of the central nucleus of the IC, as well as cerebellum, sensorimotor, temporal, and occipital cerebral cortices of GEPRs with high pressure liquid chromatography showed significant increases in the levels of GABA, taurine and glutamate. The IC of GEPR displayed a 2.3-fold increase in GABA as compared to that of non-epileptic rats, a 2.4-fold increase of taurine, and a 1.9-fold increase of glutamate. In addition, taurine and glutamate were increased in the sensorimotor and temporal cortex, respectively. These results are consistent with previous anatomical data on the GABAergic system in the IC and provide additional information. The increase in taurine and glutamate in the IC indicates that other neurotransmitters could be involved in the mechanism of seizure activity.