Chemical composition,cytotoxicity, antimicrobial and antifungal activity of several essential oils

Essential oils (EOs) are known and used for their biological, antibacterial, antifungal and antioxidant properties. Numerous studies have shown that EOs exhibit a large spectrum of biological activities in vitro. The incidence of drug-resistant pathogens and the toxicity of antibiotics have drawn attention to the antimicrobial activity of natural products, encouraging the development of alternative treatments. The aim of this study was to analyse the phytochemical and the cytotoxic characteristic of 36 EOs; we then evaluated the antimicrobial activity of the less-toxic EOs on Gram-positive, Gram-negative and fungi strains. The results showed low cytotoxicity in seven EOs and good activity against Gram-negative and Candida spp. strains. Based on our results, EOs could be proposed as a novel group of therapeutic agents. Further experiments are necessary to confirm their pharmacological effectiveness, and to determine potential toxic effects and the mechanism of their activity in in vivo models.     

Novel copolymers of styrene. 8. Phenoxy ring-substituted butyl 2-cyano-3-phenyl-2-propenoates

Novel trisubstituted ethylenes, phenoxy ring-substituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH = C(CN)CO₂C₄H₉ (where R is 2-(4-chlorophenoxy), 3-(4-chlorophenoxy), 4-(3-chlorophenoxy), 4-(4-chlorophenoxy), 4-(4-fluorophenoxy), 2-(3-methoxyphenoxy), 2-(4-methoxyphenoxy), 3-(4-methoxyphenoxy), 4-(4-methoxyphenoxy), 3-(4-methylphenoxy) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and butyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C-NMR. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500°C range with residue (3.1-6.5% wt), which then decomposed in the 500-800°C range.     

Electrochemistry on Paper‐based Analytical Devices: A Review

Even though they were introduced less than a decade ago, electrochemical paper‐based devices (ePADs) have attracted widespread attention because of their inherent advantages in many applications. ePADs combine the advantages of microfluidic paper‐based devices (low cost, ease of use, equipment free pumping, etc.) for sample handling and processing with the advantages of sensitive and selective detection provided by electrochemistry. As a result, ePADs provide simplicity, portability, reproducibility, low cost and high selectivity and sensitivity for analytical measurements in a variety of applications ranging from clinical diagnostics to environmental sensing. Herein, recent advances in ePAD development and application are reviewed, focusing on electrode fabrication techniques and examples of applications specially focused on environmental monitoring, biological applications and clinical assays. Finally, a summary and prospective directions for ePAD research are also provided.     

Crystallinity and crystalline phase orientation of poly(1,4‐cis‐isoprene) from Hevea brasiliensis and Taraxacum kok‐saghyz

Crystallization is studied for poly(isoprene‐1,4‐cis) from Hevea brasiliensis (natural rubber [NR]) and from taraxacum kok‐saghyz, mainly by collecting wide‐angle X‐ray diffraction patterns after processing and stretching. Although rubber samples before stretching are generally fully amorphous, crystallization can be induced in NR samples by processing at room temperature under moderate pressure. This phenomenon is possibly associated with nucleation by saturated fatty acid components. For rubber samples being fully amorphous in the undeformed state, strain‐induced crystallization occurs only at high strain ratios (α > 4), leading to high degrees of crystalline phase orientation (f_c > 0.9 for α = 5). Rubber samples presenting some crystallinity already in the unstretched state, on the contrary, reach much lower degrees of axial orientation, even for high strain ratios (f_c < 0.7 for α = 5). These differences in crystallinity and in crystalline phase orientations produce large differences in stress–strain behavior of the rubber. By room temperature processing, the considered NR samples can also develop an unreported disordered crystalline modification, with low intensity of 120 and 121 reflections. This disordered crystalline modification, which is also maintained after axial stretching procedures, can rationalized by a structural disorder along the b axis, possibly associated with statistical sequences of A⁺TA^? or A^?T A⁺ conformations for poly(isoprene‐1,4‐cis) chains. Copyright © 2016 John Wiley & Sons, Ltd.     

How relevant is the lack of reciprocity in pairwise comparisons? An experiment with AHP

We consider the 1-median problem with euclidean distances with uncertainty in the weights, expressed as possible changes within given bounds and a single budget constraint on the total cost of change. The upgrading (resp. downgrading) problem consists of minimizing (resp. maximizing) the optimal 1-median objective value over these weight changes. The upgrading problem is shown to belong to the family of continuous single facility location-allocation problems, whereas the downgrading problem reduces to a convex but highly non-differentiable optimization problem. Several structural properties of the optimal solution are proven for both problems, using novel planar partitions, the knapsack Voronoi diagrams, and lead to polynomial time solution algorithms.     

Reductive reactivity of the organolanthanide hydrides, [(C5Me5)2LnH]x, leads to ansa-allyl cyclopentadienyl (eta(5)-C5Me4CH2-C5Me4CH2-eta(3))2- and trianionic cyclooctatetraenyl (C8H7)3- ligands

The reductive reactivity of lanthanide hydride ligands in the [(C5Me5)2LnH]x complexes (Ln = Sm, La, Y) was examined to see if these hydride ligands would react like the actinide hydrides in [(C5Me5)2AnH2]2 (An = U, Th) and [(C5Me5)2UH]2. Each lanthanide hydride complex reduces PhSSPh to make [(C5Me5)2Ln(mu-SPh)]2 in approximately 90% yield. [(C5Me5)2SmH]2 reduces phenazine and anthracene to make [(C5Me5)2Sm]2(mu-eta(3):eta(3)-C12H8N2) and [(C5Me5)2Sm]2(mu-eta(3):eta(3)-C10H14), respectively, but the analogous [(C5Me5)2LaH]x and [(C5Me5)2YH]2 reactions are more complicated. All three lanthanide hydrides reduce C8H8 to make (C5Me5)Ln(C8H8) and (C5Me5)3Ln, a reaction that constitutes another synthetic route to (C5Me5)3Ln complexes. In the reaction of [(C5Me5)2YH]2 with C8H8, two unusual byproducts are obtained. In benzene, a (C5Me5)Y[(eta(5)-C5Me4CH2-C5Me4CH2-eta(3))] complex forms in which two (C5Me5)(1-) rings are linked to make a new type of ansa-allyl-cyclopentadienyl dianion that binds as a pentahapto-trihapto chelate. In cyclohexane, a (C5Me5)2Y(mu-eta(8):eta(1)-C8H7)Y(C5Me5) complex forms in which a (C8H8)(2-) ring is metalated to form a bridging (C8H7)(3-) trianion.     

Electrochemical urea biosensor based on Proteus mirabilis urease immobilized over polyaniline PANi-Glassy carbon electrode

In this study, a novel, sensitive electrochemical enzyme-based biosensor for urea detection was presented. This biosensor combines a three-electrode system consisting of a classic Glassy Carbon Electrode (GCE) as the working electrode, a platinum counter electrode, and Ag/AgCl as the reference electrode. To construct this urea platform, a GCE was modified with a polyaniline (PANi) film. Then, bacterial urease from Proteus mirabilis was immobilized on the modified GCE (P_m-Urease-PANi-GCE). For the characterization of surface modification, Cyclic Voltammetry (CV) and Scanning Electron Microscope (SEM) were applied, while the Square Wave Voltammetry (SWV) technique was performed for urea detection. The main analytical characteristics of the P_m-Urease-PANi-GCE biosensor showed a good linear range from 0.1 to 10 mM of urea, a limit of detection (LOD) of 0.1 mM, a Michaelis-Menten K_m of 0.23 mM, and a sensitivity value 46 μA/mM/cm². This biosensor allows the detection of urea in solutions, and it could be improved for further medical, environmental, or engineering applications.     

Pyrene-Based Covalent Organic Frameworks for Photocatalytic Hydrogen Peroxide Production

Four highly porous covalent organic frameworks (COFs) containing pyrene units were prepared and explored for photocatalytic H₂O₂ production. The experimental studies are complemented by density functional theory calculations, proving that the pyrene unit is more active for H₂O₂ production than the bipyridine and (diarylamino)benzene units reported previously. H₂O₂ decomposition experiments verified that the distribution of pyrene units over a large surface area of COFs plays an important role in catalytic performance. The Py-Py-COF though contains more pyrene units than other COFs which induces a high H₂O₂ decomposition due to a dense concentration of pyrene in close proximity over a limited surface area. Therefore, a two-phase reaction system (water-benzyl alcohol) was employed to inhibit H₂O₂ decomposition. This is the first report on applying pyrene-based COFs in a two-phase system for photocatalytic H₂O₂ generation.     

Translating Planar Heterocycles into Three-Dimensional Analogs by Photoinduced Hydrocarboxylation**

The rapid preparation of complex three-dimensional (3D) heterocyclic scaffolds is a key challenge in modern medicinal chemistry. Despite the increased probability of clinical success for small molecule therapeutic candidates with increased 3D complexity, new drug targets remain dominated by flat molecules due to the abundance of coupling reactions available for their construction. In principle, heteroarene hydrofunctionalization reactions offer an opportunity to transform readily accessible planar molecules into more three-dimensionally complex analogs through the introduction of a single molecular vector. Unfortunately, dearomative hydrofunctionalization reactions remain limited. Herein, we report a new strategy to enable the dearomative hydrocarboxylation of indoles and related heterocycles. This reaction represents a rare example of a heteroarene hydrofunctionalization that meets the numerous requirements for broad implementation in drug discovery. The transformation is highly chemoselective, broad in scope, operationally simple, and readily amenable to high-throughput experimentation (HTE). Accordingly, this process will allow existing libraries of heteroaromatic compounds to be translated into diverse 3D analogs and enable exploration of new classes of medicinally relevant molecules.     

Exploitation of Dimeric Cyclic Cysteine as Helix Inducer in Ultra-Short Peptides for Cu(II)-Catalyzed Asymmetric Michael Addition on Chalcones

A dimeric cyclic cysteine analogue, i.e. (1R,1′R,2R,2′R)-2,2′-disulfanediylbis (aminocyclohexane-1-carboxylic acid), was used as a constrained unnatural amino acid and as a folding inducer in ultra-short Leu-Val-containing peptide. Our results showed that both free dimer amino acid L1 and its peptide derivative L2 are able to chelate Cu(II). The obtained complexes resulted to be catalytically active in Michael addition reaction of nitromethane on different types of chalcones. L1-Cu(II) was shown more reactive in terms of conversion, while, in neat conditions, L2-Cu(II) allows to obtain an interesting 60 % e.e. on pyridine chalcone.