Antioxidant,Antimicrobial, and Insecticidal Properties of a Chemically Characterized Essential Oil from the Leaves of Dittrichia viscosa L.

Since some synthetic insecticides cause damage to human health, compounds in plants can be viable alternatives to conventional synthetic pesticides. Dittrichia viscosa L. is a perennial Mediterranean plant known to possess biological activities, including insecticidal properties. The chemical composition of an essential oil (EOD) from D. viscosa, as well as its antioxidant, antimicrobial, and insecticidal effects on the cowpea weevil (Callosobruchus maculatus) were determined. Forty-one volatile compounds were identified in EOD, which accounted for 97.5% of its constituents. Bornyl acetate (41%) was a major compound, followed by borneol (9.3%), α-amorphene (6.6%), and caryophyllene oxide (5.7%). EOD exhibited significant antioxidant activity in all tests performed, with an IC₅₀ of 1.30 ± 0.05 mg/mL in the DPPH test and an EC₅₀ equal to 36.0 ± 2.5 mg/mL in the FRAP assay. In the phosphor-molybdenum test, EOD results ranged from 39.81 ± 0.7 to 192.1 ± 0.8 mg AAE/g E. EOD was active on E. coli (9.5 ± 0.5 mm), S. aureus (31.0 ± 1.5 mm), C. albicans (20.4 ± 0.5 mm), and S. cerevisiae (28.0 ± 1.0 mm), with MICs ranging from 0.1 mg/mL to 3.3 mg/mL. We found that 1 µL of EOD caused 97.5 ± 5.0% insect mortality after 96 h in the inhalation test and 60.0 ± 8.3% in the ingestion assay. The median lethal concentration (LC₅₀) was 7.8 ± 0.3 μL EO/L, while the effective concentration in the ingestion test (LC₅₀) was 15.0 ± 2.1 μL EO/L. We found that 20 µL of EOD caused a reduction of more than 91% of C. maculatus laid eggs.     

The Inhibition of the Dissolution of Aluminium in Sodium Hydroxide by Some Organic Phosphorus Compounds

The inhibition of the corrosion of aluminium in 1M sodium hydroxide solution by some cyclodiphosphazane derivatives has been studied using hydrogen evolution technique. The results indicate that the additives reduce the corrosion rate. The inhibitory character of these compounds depends upon the concentration of the inhibitor, as well as on its chemical composition.     

Theoretical conformational analysis of opiate peptides Leu-Enkephalin (H-Tyr-Gly-Gly-Phe-Leu-OH) and its two thioamide analogs (H-Tyr-Glyψ[CSNH]Gly-Phe-Leu-OH) and (H-Tyr-Gly-Glyψ[CSNH]Phe-Leu-OH)

In order to find informations on the native structure of the Leu-Enkephalin opiate peptide, the parent peptide and its two thioamide analogs (Thio-Gly2)Leu-Enkephalin and (Thio-Gly3)Leu-Enkephalin were studied by the theoretical method PEPSEA. This comparative conformational analysis showed that the active conformation is a β turn structure centered on Gly3 and Phe4. Moreover, this study showed also that the more active analog (Thio-Gly2)Leu-Enk has a lower tendency to adopt this structure. Consequently, its high activity can only be explained by its long lifetime due to its resistance to enzymatic hydrolysis, following the substitution of the amide linkage by the thioamide one. The weakly active analog (Thio-Gly3)Leu-Enk does not adopt this structure and prefers instead a β turn structure centered on Gly2 and Gly3. This study also confirmed the importance of the distances between the Tyr and Phe residues at positions 1 and 4, and that of the terminal Tyrosine N-H group which must be free of any intramolecular hydrogen bond in order to be available in the molecular recognition process.     

Ladder operators for Szego polynomials and related biorthogonal rational functions

We find the raising and lowering operators for orthogonal polynomials on the unit circle introduced by Szego and for their four parameter generalization to biorthogonal rational functions on the unit circle.

     

Chemical interactions between 2-mercaptobenzazoles and π-acceptors

Summary 2-Mercaptobenzazoles (1a–c) interact with several -acceptors such as tetracyanoethylene (TCNE) 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (CHL) dicyanomethyleneindane-1,3-dione (CNIND), 2,3-dicyano-1,4-naphthoquinone (DCNQ), 9-dicyanomethylene-2,4,7-trinitrofluorene (DTF), and 2,3-dichloro-1,4-naphthoquinone (DCHNQ)via the formation of charge-transfer (CT) complexes to yield various heterocyclic compounds.

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Chemische Wechselwirkungen zwischen 2-Mercaptobenzazolen und -Akzeptoren

Zusammenfassung Die 2-Mercaptobenzazole1a–c reagieren mit verschiedenen -Akzeptoren wie Tetracyanoethylen (TCNE), 2,3-Dichlor-5,6-dicyano-1,4-benzochinon (DDQ), 2,3,5,6-Tetrachlor-1,4-benzochinon (CHL), Dicyanomethylenindan-1,3-dion (CNIND), 2,3-Dicyano-1,4-naphthochinon (DCNQ), 9-Dicyanomethylen-2,4,7-trinitrofluoren (DTF) und 2,3-Dichlor-1,4-naphthochinon (DCHNQ) unter Ausbildung von charge transfer — Komplexen (CT) zu heterocyclischen Verbindungen.

     

Synthesis of imidazo[1,2-b]pyridazines: Fenbendazole,oxifenbendazole analogs and related derivatives

A series of imidazo[1,2-b]pyridazines has been prepared and evaluated for macrofilaricidal activity against Brugia pahangi or Acanthocheilonema viteae infections in jirds. The imidazo[1,2-b]pyridazine analogs of fen-bendazole and oxifenbendazole are reported. In addition, several 6-aminoimidazo[1,2-b]pyridazine derivatives have been prepared. None of these compounds possessed significant activity against human cytomega-lovirus (HCMV) or filarial infections.     

Reversible pH-Controlled Catenation of a Benzobisimidazole-Based Tetranuclear Rectangle

The development of methodologies to control on demand and reversibly supramolecular transformations from self-assembled metalla-structures requires the rational design of architectures able to answer to an applied stimulus. While solvent or concentration changes, light exposure or addition of a chemical have been largely explored to provide these transformations, the case of pH sensitive materials is less described. Herein, we report the first example of a pH-triggered dissociation of a coordination-driven self-assembled interlocked molecular link. It incorporates a pH sensitive benzobisimidazole-based ligand that can be selectively protonated on its bisimidazole moieties. This generates intermolecular electrostatic repulsions that reduces drastically the stability of the interlocked structure, leading to its dissociation without any sign of protonation of the pyridine moieties involved in the coordination bonds. Importantly, the dissociation process is reversible through addition of a base.     

Fast and accurate algorithm for cavities reconstruction in an elasticity problem

The aim of this work is to reconstruct the location and geometry of a cavity embedded in a linear isotropic material Ω via an exterior boundary measurement of the displacement field. The considered problem is governed by the linear elasticity system. This inverse problem of geometry reconstruction (ie, location and shape) is formulated as a topology optimization one and solved by minimizing a Kohn‐Vogelius type functional with the help of the topological sensitivity method. Some numerical results are presented using a noniterative geometric algorithm.