Synthesis,in vitro screening and molecular docking of isoquinolinium-5-carbaldoximes as acetylcholinesterase and butyrylcholinesterase reactivators

Abstract

The series of symmetrical and unsymmetrical isoquinolinium-5-carbaldoximes was designed and prepared for cholinesterase reactivation purposes. The novel compounds were evaluated for intrinsic acetylcholinesterase (AChE) or butyrylcholinesterase (BChE) inhibition, when the majority of novel compounds resulted with high inhibition of both enzymes and only weak inhibitors were selected for reactivation experiments on human AChE or BChE inhibited by sarin, VX, or paraoxon. The AChE reactivation for all used organophosphates was found negligible if compared to the reactivation ability of obidoxime. Importantly, two compounds were found to reactivate BChE inhibited by sarin or VX better to obidoxime at human attainable concentration. One compound resulted as better reactivator of NEMP (VX surrogate)-inhibited BChE than obidoxime. The in vitro results were further rationalized by molecular docking studies showing future directions on designing potent BChE reactivators.     

Endothelial expression of endoglin in normocholesterolemic and hypercholesterolemic C57BL/6J mice before and after atorvastatin treatment

Endoglin (CD105) is a homodimeric transmembrane glycoprotein strongly related to transforming growth factor (TGF)-beta signaling and many pathological states. In this study, we wanted to evaluate whether endoglin is expressed in normocholesterolemic and hypercholesterolemic C57BL/6J mice as well as whether it is affected by atorvastatin treatment in these mice. C57BL/6J mice were fed with chow diet or an atherogenic diet for 12 weeks after weaning. In 2 atorvastatin-treated groups, mice were fed the same diets (chow or atherogenic) as described above except atorvastatin was added at the dosage of 10 mg x kg(-1) x day(-1) for the last 8 weeks before euthanasia. Biochemical analysis of blood samples revealed that administration of atherogenic diet significantly increased levels of total cholesterol, VLDL, LDL, and decreased levels of HDL. Atorvastatin treatment resulted in a significant decrease in total cholesterol and VLDL only in mice fed by atherogenic diet. Quantitative stereological analysis revealed that atorvastatin significantly decreased endothelial expression of endoglin in C57BL/6J mice fed the atherogenic diet. In conclusion, we demonstrated that endothelial expression of endoglin is upregulated by hypercholesterolemia and decreased by the hypolipidemic effect of atorvastatin in C57BL/6J mice, suggesting that endoglin expression could be involved in atherogenesis.     

Key role for mast cells in nonatopic asthma

The mechanisms involved in nonatopic asthma are poorly defined. In particular, the importance of mast cells in the development of nonatopic asthma is not clear. In the mouse, pulmonary hypersensitivity reactions induced by skin sensitization with the low-m.w. compound dinitrofluorobenzene (DNFB) followed by an intra-airway application of the hapten have been featured as a model for nonatopic asthma. In present study, we used this model to examine the role of mast cells in the pathogenesis of nonatopic asthma. First, the effect of DNFB sensitization and intra-airway challenge with dinitrobenzene sulfonic acid (DNS) on mast cell activation was monitored during the early phase of the response in BALB/c mice. Second, mast cell-deficient W/W(v) and Sl/Sl(d) mice and their respective normal (+/+) littermate mice and mast cell-reconstituted W/W(v) mice (bone marrow-derived mast cells-->W/W(v)) were used. Early phase mast cell activation was found, which was maximal 30 min after DNS challenge in DNFB-sensitized BALB/c, +/+ mice but not in mast cell-deficient mice. An acute bronchoconstriction and increase in vascular permeability accompanied the early phase mast cell activation. BALB/c, +/+ and bone marrow-derived mast cell-->W/W(v) mice sensitized with DNFB and DNS-challenged exhibited tracheal hyperreactivity 24 and 48 h after the challenge when compared with vehicle-treated mice. Mucosal exudation and infiltration of neutrophils in bronchoalveolar lavage fluid associated the late phase response. Both mast cell-deficient strains failed to show any features of this hypersensitivity response. Our findings show that mast cells play a key role in the regulation of pulmonary hypersensitivity responses in this murine model for nonatopic asthma.     

Human Rap1 modulates TRF2 attraction to telomeric DNA

More than two decades of genetic research have identified and assigned main biological functions of shelterin proteins that safeguard telomeres. However, a molecular mechanism of how each protein subunit contributes to the protecting function of the whole shelterin complex remains elusive. Human Repressor activator protein 1 (Rap1) forms a multifunctional complex with Telomeric Repeat binding Factor 2 (TRF2). Rap1–TRF2 complex is a critical part of shelterin as it suppresses homology-directed repair in Ku 70/80 heterodimer absence. To understand how Rap1 affects key functions of TRF2, we investigated full-length Rap1 binding to TRF2 and Rap1–TRF2 complex interactions with double-stranded DNA by quantitative biochemical approaches. We observed that Rap1 reduces the overall DNA duplex binding affinity of TRF2 but increases the selectivity of TRF2 to telomeric DNA. Additionally, we observed that Rap1 induces a partial release of TRF2 from DNA duplex. The improved TRF2 selectivity to telomeric DNA is caused by less pronounced electrostatic attractions between TRF2 and DNA in Rap1 presence. Thus, Rap1 prompts more accurate and selective TRF2 recognition of telomeric DNA and TRF2 localization on single/double-strand DNA junctions. These quantitative functional studies contribute to the understanding of the selective recognition of telomeric DNA by the whole shelterin complex.     

Thermal stability and energetics of 15-mer DNA duplex interstrand crosslinked by trans-diamminedichloroplatinum(II)

The effect of the location of the interstrand cross-link formed by trans-diamminedichloroplatinum(II) (transplatin) on the thermal stability and energetics of 15-mer DNA duplex has been investigated. The duplex containing single, site-specific cross-link, thermodynamically equivalent model structures (hairpins) and nonmodified duplexes were characterized by differential scanning calorimetry, temperature-dependent uv absorption, and circular dichroism. The results demonstrate that the formation of the interstrand cross-link of transplatin does not affect pronouncedly thermodynamic stability of DNA: the cross-link induces no marked changes not only in enthalpy, but also in "reduced" (concentration independent) monomolecular transition entropy. These results are consistent with the previous observations that interstrand cross-links of transplatin structurally perturb DNA only to a relatively small extent. On the other hand, constraining the duplex with the interstrand cross-link of transplatin results in a significant increase in thermal stability that is primarily due to entropic effects: the cross-link reduces the molecularity of the oligomer system from bimolecular to monomolecular. Importantly, the position of the interstrand cross-link within the duplex modulates cooperativity of the melting transition of the duplex and consequently its thermal stability.     

Increase in the Figure of Merit by Cd‐Substitution in Sn1–xPbxTe and Effect of Pb/Sn Ratio on Thermoelectric Properties

The effects of Cd‐doping on the thermoelectric properties of Sn_1–xPb_xTe are investigated and compared to the properties of the corresponding Sn_1–xPb_xTe solid solutions. The addition of Cd results in a reduction in the carrier concentration and changes in the physical properties, as well as in the conduction type of Sn_1–xPb_xTe. A significant increase in the power factor accompanied by a reduction in the thermal conductivity result in a higher figure of merit (ZT) for (Sn_1–xPb_x)_0.97Cd_0.03Te than that of undoped Sn_1–xPb_xTe. The maximum ZT (～0.7) values are observed for p‐type material with x = 0.36 at 560 K. Much higher values (ZT ～ 1.2 at 560 K for x = 0.73) are obtained on n‐type samples.     

Apoptosis and inhibition of gap-junctional intercellular communication induced by LA-12, a novel hydrophobic platinum(IV) complex

A new hydrophobic platinum(IV) complex, LA-12, a very efficient anticancer drug lacking cross-resistance with cisplatin (CDDP), is now being tested in clinical trials. Here we investigated the apoptogenic activity of LA-12 and its effect on gap-junctional intercellular communication (GJIC) in the rat liver epithelial cell line WB-F344. LA-12 induced apoptosis much more efficiently than did CDDP due to a combination of rapid penetration into the cell and attack on DNA, leading to fast activation of p53 and caspase-3. Exposure of WB-F344 cells to LA-12 led to rapid induction of the time- and dose-dependent decrease in GJIC. On the molecular level, loss of GJIC induced by LA-12 was mediated by activation of extracellular signal-regulated kinase (ERK)-1 and ERK-2, as demonstrated by the use of inhibitors of ERK activation. Inhibition of GJIC was linked to rapid hyperphosphorylation of connexin-43 and disappearance of connexon clusters from membranes, which was not observed in the case of CDDP.     

An evaluation of three pesticides: Piritione,supercypermethrin and metolachlor in transformation bioassays of BHK21 and hamster embryo cells

In a study of potential carcinogenicity of pesticides, Piritione, metolachlor (in the form of Dual and VUCHT 524) and Supercypermethrin (in the form of Supercypermethrin EC and Supercypermethrin TP) were assayed for induction of anchorage independent growth of BHK21 cells and morphological transformation of Syrian hamster embryo cells. The activity of these substances in both transformation assays was compared to the activity of the direct-acting ultimate carcinogen N-methyl-N-nitrosourea. In comparison to the very strong transforming activity of N-methyl-N-nitrosourea all pesticides tested with or without S9 fraction manifested a very weak, weak, medium or strong effect. The ability to induce anchorage independent growth was graded as follows: Dual < Supercypermethrin EC < Supercypermethrin TP Piritione < VUCHT 524. Results of Syrian hamster embryo cell transformation assay were very similar to the BKH21 transformation assay. VUCHT 524 strongly induced transformation whereas Dual was inactive. Piritione and Supercypermethrin EC and Supercypermethrin TP elicited a slight but significant positive response.