Synthesis of New Phenolic Derivatives of Quinazolin-4(3H)-One as Potential Antioxidant Agents—In Vitro Evaluation and Quantum Studies

Considering the important damage caused by the reactive oxygen (ROS) and nitrogen (RNS) species in the human organism, the need for new therapeutic agents, with superior efficacy to the known natural and synthetic antioxidants, is crucial. Quinazolin-4-ones are known for their wide range of biological activities, and phenolic compounds display an important antioxidant effect. Linking the two active pharmacophores may lead to an increase of the antioxidant activity. Therefore, we synthesized four series of new hybrid molecules bearing the quinazolin-4-one and phenol scaffolds. Their antioxidant potential was evaluated in vitro, considering different possible mechanisms of action: hydrogen atom transfer, ability to donate electrons and metal ions chelation. Theoretical quantum and thermodynamical calculations were also performed. Some compounds, especially the ortho diphenolic ones, exerted a stronger antioxidant effect than ascorbic acid and Trolox.     

Polymorphism and stability of norfloxacin, (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinil)-3-quinolinocarboxylic acid

Norfloxacin was studied by thermal methods (TG and DSC), X-ray powder diffraction, and by FT-IR, UV-VIS and NMR spectroscopy. The drug substance can be prepared in two different crystalline forms and in amorphous state, depending on the experimental conditions of preparation. DSC examinations were carried out at various heating rates and by cycling the samples in the temperature range 50°–250°C. The unstable crystalline form undergoes two irreversible solid-solid phase transitions at 176.5° and 197.6°C. The polymorph melts in the temperature range 218.5°–220.0°C.

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uote> Zusammenfassung Norfloxacin wurde mittels thermischer Methoden (TG und DSC), weiterhin mittels der Debye-Scherrer-Methode und FTIR-, UV-VIS-und NMR-Spektroskopie untersucht. Je nach den experimentellen Bedingungen bei der Herstellung kann die Wirkstoffsubstanz in zwei verschiedenen kristallinen und in einer amorphen Form hergestellt werden. Die DSC-Untersuchungen wurden bei zahlreichen Aufheizgeschwindigkeiten und durch abwechselnden Temperaturwechsel zwischen Raum- und Schmelztemperatur durchgeführt. Die unstabile kristalline Form unterliegt zwei irreversiblen Feststoff-Feststoff-Umwandlungen bei 176.5° und bei 195.6°C. Das polymorphe Material schmilzt im Temperaturbereich 218.5°–220.0°C. uote>     

Examination of performance of glassy carbon paste electrode modified with gold nanoparticle and xanthine oxidase for xanthine and hypoxanthine detection

A composite electrode was prepared by modifying glassy carbon microparticles with gold nanoparticles (Au-nps) and xanthine oxidase enzyme (XOD) for xanthine (X) and hypoxanthine (Hx) detection. After the optimization of the system for X, the biosensor was characterized for X and Hx. A linearity was obtained in the concentration range between 5.00 × 10up>−7up> and 1.00 × 10up>−5up> M for X with equation of y = 0.24x + 0.712 and 5.00 × 10up>−6up> to 1.50 × 10up>−4up> M for Hx, with equation of y = 0.014x + 0.575, respectively. Obtained results were compared to X and/or Hx biosensors including/not including Au-np in the structure. The developed system was also applied for detection of Hx in canned tuna fish sample and very promising results were obtained.     

On congruences of groupoids closely connected with quasigroups

Conditions when a congruence of a left (right) division groupoid and a left (right) cancellation groupoid is closed (“normal”) are given. Conditions for the simplicity of the above-mentioned groupoids are obtained.     

Limiting the Number of Potential Binding Modes by Introducing Symmetry into Ligands: Structure‐Based Design of Inhibitors for Trypsin‐Like Serine Proteases

In the absence of X‐ray data, the exploration of compound binding modes continues to be a challenging task. For structure‐based design, specific features of active sites in different targets play a major role in rationalizing ligand binding characteristics. For example, dibasic compounds have been reported as potent inhibitors of various trypsin‐like serine proteases, the active sites of which contain several binding pockets that can be targeted by cationic moieties. This results in several possible orientations within the active site, complicating the binding mode prediction of such compounds by docking tools. Therefore, we introduced symmetry in bi‐ and tribasic compounds to reduce conformational space in docking calculations and to simplify binding mode selection by limiting the number of possible pocket occupations. Asymmetric bisbenzamidines were used as starting points for a multistage and structure‐guided optimization. A series of 24 final compounds with either two or three benzamidine substructures was ultimately synthesized and evaluated as inhibitors of five serine proteases, leading to potent symmetric inhibitors for the pharmaceutical drug targets matriptase, matriptase‐2, thrombin and factor Xa. This study underlines the relevance of ligand symmetry for chemical biology.     

Hamilton-Poisson formulation for the rotational motion of a rigid body in the presence of an axisymmetric force field and a gyroscopic torque

We give sufficient conditions for the rigid body in the presence of an axisymmetric force field and a gyroscopic torque to admit a Hamilton-Poisson formulation. Even if by adding a gyroscopic torque we initially lose one of the conserved Casimirs, we recover another conservation law as a Casimir function for a modified Poisson structure. We apply this frame to several well-known results in the literature.     

New approach for numerical solution of configuration-space Faddeev equations

A new computational scheme for solving the bound state configuration-space Faddeev equations is applied. The scheme is based on the spline-approximation and the adiabatic limit of Faddeev equations. An ordering of variables being in agreement with the limit was chosen. As a result the matrix of the eigenvalue problem has a sparse block structure. Calculations of the bound states of µpp, µdd, µtt mesic molecules and ¯pdd, ¯ptt antiprotonic ones, were performed. To check the method, calculations of the binding energies for such systems as the positronium ion Psub>–ub>,up>3up>H andup>3up>He were carried out. The results are compared with the best results of other authors.     

Crystallization of amorphous metal films within and without magnetic field

Assuming that the conduction electrons of an amorphous metal contribute to the binding, we investigate whether a magnetic field will influence the transition from the amorphous to the crystalline state. Measurements taken on amorphous Bi, Ga and Yb films show no change in the crystallization temperatures within an accuracy of ±0.1 K due to a magnetic field of 18.5 T parallel to the surface of the films.Dedicated to Prof. Dr. W. Buckel on the occasion of his 60th birthday