Organocatalytic synthesis of novel renewable non‐isocyanate polyhydroxyurethanes

Novel fully renewable AA‐BB type non‐isocyanate polyhydroxyurethanes were synthesized by the classical reaction between a diamine and a dicyclocarbonate. Sebacic acid was first reacted with an excess of glycerol carbonate, in presence of DCC and DMPA, leading to a renewable dicyclocarbonate monomer. Then, this monomer was reacted with several renewable diamines, in presence of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), as organocatalyst, to afford linear and branched polymers. The obtained materials exhibited T_g values varied from ?27 to ?8 °C, T_m values varying from 100 to 165 °C, and thermal stabilities above 200 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 758–764     

Mechanisms,Anti-Quorum-Sensing Actions,and Clinical Trials of Medicinal Plant Bioactive Compounds against Bacteria: A Comprehensive Review

Bacterial strains have developed an ability to resist antibiotics via numerous mechanisms. Recently, researchers conducted several studies to identify natural bioactive compounds, particularly secondary metabolites of medicinal plants, such as terpenoids, flavonoids, and phenolic acids, as antibacterial agents. These molecules exert several mechanisms of action at different structural, cellular, and molecular levels, which could make them candidates or lead compounds for developing natural antibiotics. Research findings revealed that these bioactive compounds can inhibit the synthesis of DNA and proteins, block oxidative respiration, increase membrane permeability, and decrease membrane integrity. Furthermore, recent investigations showed that some bacterial strains resist these different mechanisms of antibacterial agents. Researchers demonstrated that this resistance to antibiotics is linked to a microbial cell-to-cell communication system called quorum sensing (QS). Consequently, inhibition of QS or quorum quenching is a promising strategy to not only overcome the resistance problems but also to treat infections. In this respect, various bioactive molecules, including terpenoids, flavonoids, and phenolic acids, exhibit numerous anti-QS mechanisms via the inhibition of auto-inducer releases, sequestration of QS-mediated molecules, and deregulation of QS gene expression. However, clinical applications of these molecules have not been fully covered, which limits their use against infectious diseases. Accordingly, the aim of the present work was to discuss the role of the QS system in bacteria and its involvement in virulence and resistance to antibiotics. In addition, the present review summarizes the most recent and relevant literature pertaining to the anti-quorum sensing of secondary metabolites and its relationship to antibacterial activity.     

Global existence of solutions to a parabolic–elliptic chemotaxis system with critical degenerate diffusion

This paper is devoted to the analysis of nonnegative solutions for a degenerate parabolic–elliptic Patlak–Keller–Segel system with critical nonlinear diffusion in a bounded domain with homogeneous Neumann boundary conditions. Our aim is to prove the existence of a global weak solution under a smallness condition on the mass of the initial data, thereby completing previous results on finite blow-up for large masses. Under some higher regularity condition on solutions, the uniqueness of solutions is proved by using a classical duality technique.     

Design of bacteria repellent PVC surfaces using the click chemistry

Novel bacteria repellent PVC surfaces were developed. hydroxyethyl cellulose, methylcellulose, dextran and PEG containing alkyne groups were successfully synthesized and characterized. These polymers were grafted on PVC surfaces bearing azide groups (PVC-N3) by the click Cu^I-catalyzed Huisgen 1,3-dipolar cycloaddition. The grafted surfaces were homogeneous with specific nanostructures, and presented high polarity and hydrophilicity. In these conditions, hydroxyethyl cellulose and methylcellulose surfaces displayed high repellent effect against Escherichia coli.     

On Elliptic Equations with General Non-Local Boundary Conditions in UMD Spaces

In this work, we give new results concerning existence, uniqueness and maximal regularity of the strict solution of a class of elliptic equations with non-local boundary conditions containing an unbounded linear operator. This study is performed in the framework of UMD Banach spaces.     

Existence of semilinear elliptic equations with prescribed limiting behaviour

In this paper, we consider semilinear elliptic equations of the form Δu + f(u) = 0 over a quarter space with Dirichlet boundary conditions. Given a suitable positive root z of f, we show how to construct a non‐negative bounded solution u converging to a one‐dimensional limiting profile V with V . This is established using Perron's method by constructing sub‐solutions and super‐solutions and employing a sliding argument. Copyright © 2016 John Wiley & Sons, Ltd.     

Iron-catalyzed benzamide formation. Application to the synthesis of moclobemide

A convenient and user-friendly method to yield benzamides from primary and secondary amines and various benzylic alcohols in the presence of a cheap iron salt (FeCl₂·4H₂O) and tert-butylhydroperoxide (70% in water) as a stoichiometric oxidant is described. Control experiments indicated that this reaction might involve radical species. This method proved to be general, generating a family of 30 benzamides and was applied to the preparative synthesis of anti-anxiety drug moclobemide.     

Pharmacological Effects of Grifolin: Focusing on Anticancer Mechanisms

Grifolin is a volatile compound contained in essential oils of several medicinal plants. Several studies show that this substance has been the subject of numerous pharmacological investigations, which have yielded interesting results. Grifolin demonstrated beneficial effects for health via its multiple pharmacological activities. It has anti-microbial properties against bacteria, fungi, and parasites. In addition, grifolin exhibited remarkable anti-cancer effects on different human cancer cells. The anticancer action of this molecule is related to its ability to act at cellular and molecular levels on different checkpoints controlling the signaling pathways of human cancer cell lines. Grifolin can induce apoptosis, cell cycle arrest, autophagy, and senescence in these cells. Despite its major pharmacological properties, grifolin has only been investigated in vitro and in vivo. Therefore, further investigations concerning pharmacodynamic and pharmacokinetic tests are required for any possible pharmaceutical application of this substance. Moreover, toxicological tests and other investigations involving humans as a study model are required to validate the safety and clinical applications of grifolin.