A new calcium 2,5-dihydroxybenzoate: Synthesis,characterization and antioxidant studies and stress mediated cytotoxity in MCF-7 cells

The structure and composition of the calcium 2,5-dihydroxybenzoate (calcium gentisate) were studied by single-crystal and powder X-ray diffraction. Single-crystal X-ray analysis revealed that the compound crystallizes in the orthorhombic space group Pbcn. The Ca(II) cation is coordinated in a monodentate fashion by two symmetry-related gentisate anions and five water molecules. The metal ion and one of the water molecules are located on a 2-fold rotation axis. The adjacent monomeric units are assembled into a 3-D supramolecular framework via O–H…O hydrogen bonds. Comparison of the experimental powder pattern with that simulated from single-crystal X-ray data confirmed the purity and homogeneity of the sample. The FT-IR, UV/VIS, ¹H and ¹³C NMR spectra of the calcium 2,5-dihydroxybenzoic acid were registered and analysed. Moreover the effect of calcium complex and 2,5-dihydroxybenzoic acid on basic oxidative stress parameters, such as thiol group content and lipid peroxidation in the human breast cancer cells MCF-7 was studied. The antiradical and ferric reducing power of these compounds was measured by DPPH, CUPRAC and FRAP methods. The chemical reactivity parameters (e.g. HOMO and LUMO orbitals, ionization potential, electron affinity) for Ca 2,5-dHB and 2,5-dHB were calculated at B3LYP/6-311++G7 level of theory and discussed in relation to their antioxidant properties.     

Kinetics of Natural Langbeinite Conversion in Magnesium Chloride Solutions

The mechanism of conversion of natural langbeinite with magnesium chloride solutions was studied. The dependence of the degree of conversion on the process time, temperature, MgCl₂ concentration in solution, and grain size of natural langbeinite was studied.     

Bis(benzo)triazinethionoaza-14-crown-4 ether and its complex with CoBr<Subscript>2</Subscript>: Synthesis and crystal structures

8,11,14-Trioxa-22,24,25-triazatetracyclo[19.3.1.0^2,7.0^15,20]pentacosa-2,4,6,15(20),16,18-hexaene-23-thione (L) containing a symmetric triazinethione subunit in its macrocycle and its complex with cobalt(II) bromide of the formula [CoL₂Br₂] · 0.5CHCl₃ (I) were obtained and examined by X-ray diffraction, IR and NMR spectroscopy, and mass spectrometry. It was found that the thiourea fragment in compound L is attached to the nitrogen macrocycle through the C(2) and C(19) atoms, thus forming a substantially nonplanar six-membered triazine ring in a slightly distorted sofa conformation. Its mean-square plane is nearly perpendicular to the mean-square plane of the macrocycle (the dihedral angle between them is 83.3°). Structure L is stabilized by two bifurcate endocyclic hydrogen bonds between the N(1) atom of the triazine ring and the O(1) and O(3) atoms. The size of the macrocyclic cavity is 4.07 Å. The coordination polyhedron of the Co atom is a distorted tetrahedron made up of the sulfur atoms of two monodentate terminal molecules L and two bromine atoms.     

Two polymorphs of morpholin‐4‐ium 2‐(5‐methyl‐1H‐1,2,4‐triazol‐3‐ylsulfanyl)acetate

Two polymorphs of the title organic salt (a very effective medicinal preparation with the commercial name thiotriazoline), C₄H₁₀NO⁺·C₅H₆N₃O₂S⁻, were obtained. The cations and anions are connected by hydrogen bonds and extend into two‐dimensional networks. The main packing motifs are an R₄⁴(12) cluster in the monoclinic form and a chain in the orthorhombic form.     

Spreading of Gas from a Line Source in the Flow over Two-dimensional Hill

Flow around the two-dimensional hill is of great interest in engineering application, namely in transport and dispersion of pollutants in atmosphere. A case of polynomial shaped 2D hill with the line source of tracer gas has been studied in detail. Experimental study of both, the time-averaged velocity field and the binary-mixture concentration field has been done. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

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Synthesis of 2,4,5-trisubstituted tetrahydropyrans as peptidomimetic scaffolds for melanocortin receptor ligands

[reaction: see text] We have synthesized a series of 2,4,5-trisubstituted tetrahydropyran derivatives to determine the utility of this scaffold as a peptidomimetic platform. The key synthetic steps involved a palladium-mediated cross-coupling reaction of a dihydropyran-4-one moiety to introduce R(2) followed by a sequential regio- and diastereoselective reduction of sp(2) carbon centers. Selected compounds have shown biological activity at melanocortin receptors, indicating that this scaffold may be useful in the design of peptidomimetics relating to a tripeptide structure.