Advances in 1,8-Naphthyridines Chemistry

This review reports a broad overview of the synthetic procedures of 1,8-naphthyridines, dibenzo[b,g][1,8]naphthyridine, dibenzo[c,f][1,8]naphthyridine, 1,8-naphthyridine-3-carboxylic acid, 1,8-naphthyridine-3-carboxamide, and 1,8-naphthyridine-3-carbohydrazide compounds and their reactions. The physical properties, spectral data, and biological importance of naphthyridines are discussed.     

Spectral characterization and biocidal activity of organotin(IV) (E)-3-[(2′,6′-dichlorophenylamido)]propenoates

Biocidal and spectroscopic aspects of organotin(IV) complexes with (E)-3-[(2′,6′-dichlorophenylamido)]propenoic acid are described with support of elemental analysis. IR, ¹H, ¹³C, ¹¹⁹Sn NMR and mass spectral data suggest that the ligand is bidentate, coordinating through oxygen atoms and that diorganotin(IV) complexes are six-coordinate. Triorganotin(IV) carboxylates exist as pentacoordinated trigonal bipyramidal complexes in the solid state and tetrahedral ones in solution. The complexes have been screened against bacteria, fungi and brine-shrimp larvae to assess their biological activity.     

Supramolecular lead(II) azide complex of 2,6-diacetylpyridine dihydrazone: synthesis,molecular structure,and biological activity

The complex of 2,6-diacetylpyridinedihydrazone (L) with lead(II) and azide has been characterized by elemental analyses, FTIR, and single-crystal X-ray analysis. The Pb(C₉H₁₃N₁₁) (1) crystallized in the monoclinic space group C2/c. The coordination of 1 exhibits a gap around the lead(II), possibly occupied by a stereochemically active electron lone pair on lead(II) resulting in a hemidirected complex. Antimicrobial activity of the complex is higher than the free ligand.     

In vivo pharmacokinetics of and tissue distribution study of physalin B after intravenous administration in rats by liquid chromatography with tandem mass spectrometry

A rapid and sensitive liquid chromatography tandem mass spectrometry quantitative analysis method was established for the pharmacokinetics and tissue distribution study of physalin B in rat. Physalin B and physalin H (internal standard, IS) were separated on an Agilent Eclips XDB C₈ column. MS detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction monitoring mode with a positive eletrospray ionization source. The assay was validated in the concentration ranges of 22.6–22600 ng/mL for heart and lung and 4.52–4520 ng/mL for other tissues. The intra‐ and inter‐day precisions (RSD) were ≤9.23 and ≤12.51%, respectively, with accuracy (%) in the range of 88.07–113.2%. A pharmacokinetic study showed that physalin B has a long dwell time with a half‐life of 321.2 ± 29.5 min and clearance of 175.4 ± 25.7 mL/min/kg after intravenous administration. Additionally, physalin B showed a wide tissue distribution with a special higher penetration in lung. The data presented in this study could provide useful information for the further study of physalin B. Copyright © 2016 John Wiley & Sons, Ltd.     

Structural studies and biological evaluation of Co (II), Ni (II) and Cu (II) complexes of carbohydrazone derived from ethyl acetoacetate in addition to crystallographic description of La (III) or Sm (III) catalytic activity abnormal product

New carbohydrazone ligand derived from the condensation of carbohydrazide and ethyl acetoacetate, diethyl 3,3′‐(carbonylbis (hydrazin‐2‐yl‐1‐ylidene))(3E,3′E)‐dibutyrate (H₄EBC), and its divalent Co, Ni and Cu chelates have been isolated and characterized utilizing convenient methods. ¹H‐NMR spectrum of H₄EBC revealed the abundance of the enol isomer in solution, which was the opposite to what was shown by the solid IR. This was supported by comparing the theoretical IR of both keto and enol forms. In [Ni(H₄EBC)Cl₂(H₂O)]·2H₂O, H₄EBC acts as a neutral NON tridentate ligand via the (C=O)_carbonyl oxygen atom besides the two (C=N)_azomethine nitrogen atoms, while in [Co(H₄EBC)Cl₂(2H₂O)]·2H₂O, H₄EBC behaves as a neutral NN bidentate ligand through the two azomethine groups. Magnetic measurements inherent to their electronic spectra show that both Ni (II) and Co (II) chelates have octahedron coordination frameworks. On the other hand, the ligand behaves as a binegative tetradentate in [Cu₂(H₄EBC)Cl₂]·H₂O via the deprotonated (C=O)_carbonyl groups of the ethyl acetoacetate framework and the two (C=N)_azomethine groups. In the latter complex, the carbonyl group of the carbohydrazide moiety is converted to hydroxyl group. Cu (II) complex has a tetrahedral geometry according to ESR and electronic spectral data. The reaction of H₄EBC with SmCl₃·6H₂O or LnCl₃·7H₂O gave single crystals of abnormal product (C₁₆H₁₆N₄O₄). The packing diagram of this crystal has a chain structure. The photoluminescence spectra of [Cu ₂ (H ₄ EBC)Cl ₂ ]·H ₂ O , [Co(H ₄ EBC)Cl ₂ (H ₂ O) ₂ ]·2H ₂ O and [Ni(H ₄ EBC)Cl ₂ (H ₂ O)]·2H ₂ O display emission broad‐bands at 342, 321 and 337 nm, respectively. The microbial behavior of the synthesized moieties was investigated against various bacterial and fungal strains. [Cu₂(H₄EBC)Cl₂]·H₂O complex shows the same activity as ampicillin towards Escherichia coli and Staphylococcus aureus with inhibition zones of 26 and 22 mm, respectively. Antioxidant activity is determined using bleomycin‐dependent DNA damage assay besides erythrocyte hemolysis. Finally, in vitro cytotoxic activities against two different cell lines have been examined.     

A rapid UPLC‐MS/MS method for the determination of oleanolic acid in rat plasma and liver tissue: application to plasma and liver pharmacokinetics

A reliable high‐throughput ultra‐high performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method was developed and validated for oleanolic acid (OA) determination in rat plasma and liver tissue using glycyrrhetic acid as the internal standard (IS). Plasma and liver homogenate samples were prepared using solid‐phase extraction. Chromatographic separation was achieved on a C₁₈ column using an isocratic mobile phase system. The detection was performed by multiple reaction monitoring mode via positive electrospray ionization interface. The calibration curves showed good linearity (R² > 0.9997) within the tested concentration ranges. The lower limit of quantification for plasma and liver tissue was ≤0.75 ng/mL. The intra‐ and inter‐day precision and accuracy deviations were within ±15% in plasma and liver tissue. The mean extraction recoveries ranged from 80.8 to 87.0%. In addition, the carryover, matrix effect, stability and robustness involved in the method were also validated. The method was successfully applied to the plasma and hepatic pharmacokinetics of OA after oral administration to rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Strain-dependent internal parameters in hyperelastic biological materials

The behavior of hyperelastic energies depending on an internal parameter, which is a function of the deformation gradient, is discussed. As an example, the analysis of two models where the parameter describes the activation of a tetanized skeletal muscle tissue is presented. In those models, the activation parameter depends on the strain and it is shown the importance of considering the derivative of the parameter with respect to the strain in order to capture the proper stress–strain relations.