Search results for " Cyclic"
showing 10 items of 163 documents
Phosphasalen group IV metal complexes: synthesis, characterization and ring opening polymerization of lactide.
2020
International audience; We report the synthesis of a series of Zr and Ti complexes bearing phosphasalen which differs from salen by the incorporation of two P atoms in the ligand backbone. The reaction of phosphasalen proligands (1a-1c)H2 with Zr(CH2Ph)4 led to different products depending on the nature of the N,N-linker in the ligand. In case of ethylene-linked phosphasalen, octahedral Zr complex 2a formed as a single stereoisomer in trans geometry. With the phenylene linker, it was shown by dynamic NMR spectroscopy that complex 2b exists as a mixture of trans and cis-β isomers in solution, both enantiomers (Δ and Λ) of the cis-β isomer being in fast equilibrium with respect to the NMR tim…
Ionic Liquid Gels: Supramolecular Reaction Media for the Alcoholysis of Anhydrides.
2019
The search of new enantioselective catalysts, able to promote synthetically useful organic reactions with high levels of asymmetric induction, should be associated with the attention to the suitable reaction medium able to achieve the best efficiency in chemical processes. We have investigated the enantioselective desymmetrization of cyclic meso-anhydrides in nonconventional reaction media such as ionic liquids and supramolecular gels. With this aim, we examined several variables in the reacting system: the nature of ionic liquid used as the reaction medium, the gelation solvent, the structure of the anhydrides, the structure of alcohols, the chiral catalysts, and the reaction conditions, i…
Description of the sexual generation of Dryocosmus destefanii (Hymenoptera: Cynipidae: Cynipini) and disclosure of its life cycle
2020
The sexual generation of Dryocosmus destefanii Cerasa & Melika, 2018 that emerges from galls on Q. suber L. in Italy is described for the first time, establishing its heterogonic life cycle. We provide observations on its distribution, illustration of adults and galls and information on its biology as supported by morphological and molecular data. An illustrated identification key to Western Palaearctic Dryocosmus species is also given.
Best proximity point theorems for proximal cyclic contractions
2017
The purpose of this article is to compute a global minimizer of the function $$x\longrightarrow d(x, Tx)$$ , where T is a proximal cyclic contraction in the framework of a best proximally complete space, thereby ensuring the existence of an optimal approximate solution, called a best proximity point, to the equation $$Tx=x$$ when T is not necessarily a self-mapping.
Downregulation of thioredoxin-1-dependent CD95 S-nitrosation by Sorafenib reduces liver cancer
2020
Hepatocellular carcinoma (HCC) represents 80% of the primary hepatic neoplasms. It is the sixth most frequent neoplasm, the fourth cause of cancer-related death, and 7% of registered malignancies. Sorafenib is the first line molecular targeted therapy for patients in advanced stage of HCC. The present study shows that Sorafenib exerts free radical scavenging properties associated with the downregulation of nuclear factor E2-related factor 2 (Nrf2)-regulated thioredoxin 1 (Trx1) expression in liver cancer cells. The experimental downregulation and/or overexpression strategies showed that Trx1 induced activation of nitric oxide synthase (NOS) type 3 (NOS3) and S-nitrosation (SNO) of CD95 rece…
Cyclic pentapeptide cRGDfK enhances the inhibitory effect of sunitinib on TGF-β1-induced epithelial-to-mesenchymal transition in human non-small cell…
2020
AbstractIn human lung cancer progression, the EMT process is characterized by the transformation of cancer cells into invasive forms that migrate to other organs. Targeting to EMT-related molecules is emerging as a novel therapeutic approach for the prevention of lung cancer cell migration and invasion. Traf2- and Nck-interacting kinase (TNIK) has recently been considered as an anti-proliferative target molecule to regulate the Wnt signaling pathway in several types of cancer cells. In the present study, we evaluated the inhibitory effect of a tyrosine kinase inhibitor sunitinib and the integrin-αVβ3targeted cyclic peptide (cRGDfK) on EMT in human lung cancer cells. Sunitinib strongly inhib…
Role of secondary metabolites in the biocontrol activity of Pseudomonas corrugata and Pseudomonas mediterranea
2017
In this study, the Pseudomonas corrugata strain CFBP 5454 and the P. mediterranea strain CFBP 5447 were shown to produce diffusible compounds that inhibit the in vitro growth of plant pathogenic fungi and bacteria and antifungal volatile compounds. In addition, both bacterial strains were found to produce cyanide. Mutant derivatives in LuxR transcriptional regulators, i.e. P. corrugata GL2 (pcoR mutant) and GLRFIA (rfiA mutant), and P. mediterranea PSMER (pmeR mutant) and PSRFIA (rfiA mutant) impaired in cyclic lipopeptide (CLP) production, showed a diffusible compound-mediated reduced activity, depending on the biocontrol strain, challenge microorganism and culture medium. The volatile com…
Toxicological implications of enzymatic control of reactive metabolites.
1990
Many foreign compounds are transformed into reactive metabolites, which may produce genotoxic effects by chemically altering critical biomolecules. Reactive metabolites are under the control of activating, inactivating and precursor sequestering enzymes. Such enzymes are under the long-term control of induction and repression, as well as the short-term control of post-translational modification and low molecular weight activators or inhibitors. In addition, the efficiency of these enzyme systems in preventing reactive metabolite-mediated toxicity is directed by their subcellular compartmentalization and isoenzymic multiplicity. Extrapolation from toxicological test systems to the human req…
Cannabinoid Control of Learning and Memory through HCN Channels
2016
The mechanisms underlying the effects of cannabinoids on cognitive processes are not understood. Here we show that cannabinoid type-1 receptors (CB1Rs) control hippocampal synaptic plasticity and spatial memory through the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that underlie the h-current (Ih), a key regulator of dendritic excitability. The CB1R-HCN pathway, involving c-Jun-N-terminal kinases (JNKs), nitric oxide synthase, and intracellular cGMP, exerts a tonic enhancement of Ih selectively in pyramidal cells located in the superficial portion of the CA1 pyramidal cell layer, whereas it is absent from deep-layer cells. Activation of the CB1R-HCN pathway impairs d…
Ribosome-Targeting Antibiotics Impair T Cell Effector Function and Ameliorate Autoimmunity by Blocking Mitochondrial Protein Synthesis
2019
Summary While antibiotics are intended to specifically target bacteria, most are known to affect host cell physiology. In addition, some antibiotic classes are reported as immunosuppressive for reasons that remain unclear. Here, we show that Linezolid, a ribosomal-targeting antibiotic (RAbo), effectively blocked the course of a T cell-mediated autoimmune disease. Linezolid and other RAbos were strong inhibitors of T helper-17 cell effector function in vitro, showing that this effect was independent of their antibiotic activity. Perturbing mitochondrial translation in differentiating T cells, either with RAbos or through the inhibition of mitochondrial elongation factor G1 (mEF-G1) progressi…