Synthesis and Diels-Alder reactivity of ortho-carbazolequinones

Oxidation of 2- and 3-hydroxycarbazoles with Frémy's salt gave the corresponding ortho-carbazolequinones. These molecules react as carbodienophiles in Diels-Alder reaction with 1-acetoxy-1,3-butadiene and 1,3-cyclopentadiene to provide the novel benzocarbazolequinone structures 15, 16, 18 and 19.     

Equations différentielles invariantes sur les groupes et algèbres de Lie réductifs II

Dans un article précédent, nous avons démontré que si D est un opérateur différentiel bi-invariant sur un groupe réductif G vérifiant la condition de Benabdallah-Rouvière, alors on peut résoudre l’équation différentielle Du=v dans l'espace des distributions G-invariantes (par automorphismes intérieurs) d'ordre fini; nous allons montrer ici que, sous la même hypothèse, on peut résoudre cette équation dans l'espace de toutes les distributions G-invariantes. D'autre part, nous donnons un exemple dans qui montre que les équations différentielles invariantes dans les algèbres de Lie réductives ne sont pas toujours résolubles dans l'espace des fonctions indéfiniment différentiables invariantes.     

Dianions d'aldoximes: preparation et applications en synthese

Aldoximes are converted to their dilithium derivatives by lithium diisopropylamide at 0°C in THF solution. These dianions react with electrophiles to give α-substituted aldoximes.     

Synthesis of high added value compounds through catalytic oxidation of 2-phenylethanol: A Kinetic study

An effective procedure was developed to produce high-value added phenolic compounds through the conversion of 2-phenylethanol (2-PhEt) by using acid-activated clays KSF for the hydrogen peroxide. Owing to KSF's ability to catalyze a variety of complex oxidations, it was likely to convert 2-PhEt to hydroxytyrosol (HTY) and tyrosol (TY) derivatives. The analyses of catalytic solution revealed that the optimum conditions, giving a higher concentration of oxidation products such as HTY, were as follows: 2-PhEt concentration 10⁻² mol/L, the hydrogen peroxide concentration 5.05 × 10⁻² and 0.6 g L^–1 of KSF clays . The yield during the conversion reaction into HTY was around 25%. All compounds in the reaction mixture were identified by mass spectrophotometry using a LC-MS apparatus. HTY, TY, meta-tyrosol and ortho-tyrosol were the major compounds. The antioxidant activity was realized by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. In fact, it is revealed that the strongest inhibition percentage (PI = 96) was detected with the increase in the concentration of HTY. The approach proposed in the present work presents an environment friendly method.     

Quasi-stability and upper semicontinuity for coupled parabolic equations with memory

This current study deals with the long-time dynamics of a nonlinear system of coupled parabolic equations with memory. The system describes the thermodiffusion phenomenon where the fluxes of mass diffusion and heat depend on the past history of the chemical potential and the temperature gradients, respectively, according to Gurtin-Pipkin's law. Inspired by the works of Chueshov and Lasiecka on the property of quasi-stability of dynamic systems, we prove this property for the problem considered in this study. This property allows us to analyze certain properties of global and exponential attractors in a more efficient and practical way. This approach is applied for the first time for coupled parabolic equations. We analyze the continuity of global attractors with respect to a pair of parameters in a residual dense set and their upper semicontinuity in a complete metric space. Finally, we analyze the upper semicontinuity of global attractors with respect to small perturbations of the damping terms.     

Chemical composition and biological potential of seed oil and leaf extracts of Henophyton deserti Coss. & Durieu

Henophyton deserti was characterized in respect to its chemical composition, antioxidant potential and antimicrobial activity. Fourteen compounds were identified by LC/MS, GC/MS, and GC in leaf and seed extracts. Total flavonoids ranged between 45.66 and 181.2 mg QE g^?1 and 2.03 and 38.95 mg QE g^?1 dry weight (dw) in leaf and seed polar extracts, respectively. Rutin, Kaempferol 3-rutinoside, Diosmetin 7-O-Glucoside, and Acacetin 7-O-Glucoside flavonoids were tentatively identified in this plant. The profile of seed fatty acids revealed oleic acid (C18:1, 27%), linoleic acid (C18:2, 12%) and linolenic acid (C18:3, 17%). The highest antioxidant activities of 85.2% and 67.5% were obtained with methanol and ethyl acetate leaf extracts. All H. deserti extracts were active against at least one of the tested bacteria, leaf ethyl acetate extract showed the lowest MIC of 0.156 mg ml^?1. Only seed ethyl acetate extract showed antifungal activity with a MIC of 2.5 mg ml^?1.     

Application of molecular topology to the prediction of mosquito repellents of a group of terpenoid compounds

A topological-mathematical model based on multilinear regression analysis has been built to search new terpenoid actives as mosquito repellents. The structural depiction was performed using topological indices, and a four-variable model for the prediction of corrected repellent ratio (r ² = 0.9672, Q ² = 0.9435) was selected. The model was checked by cross-validation, internal validation, and randomization test. The results confirm its capability to predict the property analyzed. After carrying out a virtual screening upon such a model, new structures with potential repellent activity against mosquitoes are proposed.     

Stability constants determination of successive metal complexes by hyphenated CE‐ICPMS

The study of radionuclides speciation requires accurate evaluation of stability constants, which can be achieved by CE‐ICPMS. We have previously described a method for 1:1 metal complexes stability constants determination. In this paper, we present its extension to the case of successive complexations and its application to uranyl‐oxalate and lanthanum‐oxalate systems. Several significant steps are discussed: analytical conditions choice, mathematical treatment by non‐linear regression, ligand concentration and ionic strength corrections. The following values were obtained: at infinite dilution, log(β₁°(UO₂Oxa))=6.93±0.05, log(β₂°(UO₂(Oxa)₂^2?))=11.92±0.43 and log(β₃°(UO₂(Oxa)₃^4?))=15.11±0.12; log(β₁°(LaOxa⁺))=5.90±0.07, log(β₂°(La(Oxa)₂^?))=9.18±0.19 and log(β₃°(La(Oxa)₃^3?))=9.81±0.33. These values are in good agreement with the literature data, even though we suggest the existence of a new lanthanum‐oxalate complex: La(Oxa)₃^3?. This study confirms the suitability of CE‐ICPMS for complexation studies.     

Targeting the proangiogenic VEGF-VEGFR protein-protein interface with drug-like compounds by in silico and in vitro screening

Protein-protein interactions play a central role in medicine, and their modulation with small organic compounds remains an enormous challenge. Because it has been noted that the macromolecular complexes modulated to date have a relatively pronounced binding cavity at the interface, we decided to perform screening experiments over the vascular endothelial growth factor receptor (VEGFR), a validated target for antiangiogenic treatments with a very flat interface. We focused the study on the VEGFR-1 D2 domain, and 20 active compounds were identified. These small compounds contained a (3-carboxy-2-ureido)thiophen unit and had IC₅₀ values in the low micromolar range. The most potent compound inhibited the VEGF-induced VEGFR-1 transduction pathways. Our findings suggest that our best hit may be a promising scaffold to probe this macromolecular complex and for the development of treatments of VEGFR-1-dependent diseases.