Effects Of Phenanthroline Research Articles

How the Intercalation of Phenanthroline Affects the Structure, Energetics, and Bond Properties of DNA Base Pairs: Theoretical Study Applied to Adenine–Thymine and Guanine–Cytosine Tetramers

The effects of phenanthroline (phen) intercalation on the structure, energetics, and bonding of adenine-thymine and guanine-cytosine tetramers (A-T/T-A and G-C/C-G) were studied through density functional theory (DFT) using functionals that were recently improved to consider the effect of dispersion forces. Our results given by energy decomposition analysis show that the dispersion contribution, ΔEdisp, is the most important contribution to the interaction energy, ΔEint. However, it is not enough to compensate the Pauli repulsion term, ΔEPauli, and the roles of the orbital contribution, ΔEorb, and, in particular, the electrostatic contribution, ΔEelstat, become crucial for the stabilization of the structures in the intercalation process. On the other hand, for G-C/C-G systems, hydrogen-bonding (HB) interactions are more important than stacking (S) interactions, whereas for A-T/T-A systems, HB and S become competitive. Moreover, intercalation produces important changes not only in the hydrogen bonds of base pairs, because S and HB are deeply connected, but also in other characteristic geometric parameters of the base pairs.

The Effect of 1,10-Phenanthroline on the Luminescent Properties of Eu (III) and Tb (III) Complexes with 2-Acetylnaphthol-Hydrazinehydrate

Four complexes have been prepared by reaction of rare earth nitrates with 2-acetylnaphthol-hydrazinehydrate (ANH) and phenanthroline. The complexes were characterized by IR spectra. The fluorescent properties of the europium and terbium complexes in solid and in DMSO solution were investigated and the effects of phenanthroline on the luminescent intensity of europium and terbium complexes also were studied. The results show that the europium and terbium ions formed stable complexes by coordinating to the nitrogen atoms and oxygen atoms of the ligands and the nitrates. And the complexes exhibited maximum fluorescence emissions in blue region.

Therapeutic effect of phenanthroline on trinitrobenzene sulfonic acid-induced colitis in rats

Therapeutic effect of phenanthroline on trinitrobenzene sulfonic acid-induced colitis in rats

Inhibition of matrix metalloproteinase MMP-2 activates chloride current in human airway epithelial cells

Matrix metalloproteinases (MMPs) are involved in the remodeling and degradation of the extracellular matrix. Recently, it has been found that MMPs also contribute to processes not directly related to tissue remodeling, such as platelet aggregation or degranulation of airway gland cells. Since mucus secretion is closely related to ion channel function, we investigated whether MMPs could also be involved in the regulation of ion channels. We used human airway submucosal cell line Calu-3 to study the effects of MMPs on whole-cell current and transepithelial short-circuit current (I(sc)). Phenanthroline, a specific inhibitor of MMPs, increased whole-cell current with the half-maximally effective dose of 5.2 microM, and reversibly activated I(sc) in transepithelial measurements. Current stimulated by phenanthroline displayed linear current-voltage relationships and had inhibitor pharmacology and ion selectivity consistent with cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel activity. Zymography and Western blot showed significant expression of MMP-2 in Calu-3 cells. Moreover, anti-MMP-2 antibodies (1 microg/mL) increased whole-cell current and I(sc), whereas human recombinant MMP-2 (10 ng/mL) reduced it. We also studied the expression of MMPs and the effects of phenanthroline on whole-cell current in A549 cells, which are derived from airway surface epithelium and do not express CFTR Cl- channels. While these cells also showed significant expression of MMP-2, inhibition of this enzyme with phenanthroline exerted no significant effect on whole-cell current. It is concluded that MMP-2 is involved in the regulation of CFTR Cl- channels in human airways.

The zinc chelator 1,10-phenanthroline enhances the stimulatory effects of protein kinase C activators and staurosporine, but not sphingosine and H2O2, on phospholipase D activity in NIH 3T3 fibroblasts

Protein kinase C (PKC), an enzyme which is believed to mediate the stimulatory effects of the PKC activator phorbol 12-myristate 13-acetate (PMA) on phospholipase D (PLD) activity, has a zinc-dependent structure required for phorbol ester binding. Accordingly, zinc or zinc chelators would be expected to promote or inhibit, respectively, the stimulatory effects of PMA on PLD-mediated phospholipid hydrolysis. Instead, treatment of [14C]choline- and [14C]ethanolamine-labelled NIH 3T3 fibroblasts with the high-affinity zinc chelator 1,10-phenanthroline (0.2-1 mM) for 20-30 min was found to enhance the stimulatory effects of PMA on PLD-mediated hydrolysis of phosphatidylcholine and phosphatidylethanolamine. In [14C]palmitic acid-labelled fibroblasts, in the presence of ethanol, phenanthroline also enhanced the stimulatory effect of PMA on the synthesis of phosphatidylethanol, a marker of PLD activity. Addition of zinc (250 microM) to phenanthroline-treated fibroblasts reversed the stimulatory effects of the chelator. The potentiating effects of phenanthroline were also partially reversed by cadmium, whereas iron, lead, copper, magnesium and calcium were without effects. Of the other activators of PLD tested, phenanthroline also enhanced the stimulatory effects of platelet-derived growth factor and staurosporine, but not that of sphingosine and H2O2, on the hydrolysis of both phospholipids. These results suggest that regulation of PLD by PKC activators and staurosporine involves a common intermediate step, which is inhibited by a chelatable cellular pool of zinc.

Role of Zn2+ and other divalent metal ions in human lymphokine production in vitro.

The effects of phenanthroline and of various metal ions on human leucocyte migration inhibitory factor (LIF) production were studied. Previously reported preliminary data showed that phenanthroline, a divalent metal ion chelator, reduced the elaboration o LIF in a dose-dependent manner by specifically but not by non-specifically stimulated lymphocytes. This paper shows that suppression of LIF production caused by phenanthroline could be entirely reversed by Zn2+, Ni2+ and, most effectively, by Co2+. When a battery of divalent cations were tested for direct inhibitory effects on LIF production, Cd2+ and, to a lesser extent, Cu2+ were found to be effective. Again, only specifically stimulated cells were susceptible. This profile of responses resembles greatly that seen in experiments with carboxypeptidases, indicating that a carboxypeptidase-like, probably Zn2+-dependent enzyme is active during antigen-induced lymphokine production. This metalloenzyme may be derived from activated monocytes/macrophages and, like the lymphocyte-activating factor, exerts its activity in the G1 phase of the cell cycle.