Synthesis and characterization of new metal-free and metallophthalocyanines containing macrocyclic moieties

The synthesis and characterization of new metal-free 7 and metallophthalocyanines 8, 9 carrying macrocyclic N₂S₂O₄ donor groups on peripheral positions have been investigated. Phthalonitrile derivative 6 was synthesized according to Rosenmund von Braun procedure from compound 5. The novel compounds were characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV-Vis and MS spectra data.     

Antioxidant activity of some Turkish medicinal plants

DPPH, superoxide and nitric oxide radical scavenging activities and total phenolic content (TPC) of some less known plants, distributed in Burdur-Antalya provinces and consumed both as food and for the medicine, Asplenium ceterach L. (golden herb), Valeriana dioscoridis Sm. (valerian), Doronicum orientale Hoffm. (tiger herb), Cota pestalozzae (Boiss.) Boiss. (camomile), Eremurus spectabilis M. Bieb. (foxtail lily), Asphodeline lutea (L.) Rchb. (asphodel) and Smyrnium connatum Boiss. and Kotschy (hemlock) were investigated. As a result, the highest 2,2-diphenyl-1-picril hydrazyl (DPPH) radical scavenging activity was determined in C. pestalozzae extract (IC₅₀ = 18.66 μg mL^? 1), the highest superoxide and nitric oxide radical scavenging activity was determined in A. ceterach extract (IC₅₀ = 145.17 and 372.03 μg mL^? 1). The highest TPC was determined in A. ceterach extract (59,26 μg mL^? 1) as gallic acid equivalent. Further bioactivity and phytochemistry studies on these plants may enlighten new drug discovery researches.     

A new approach for the synthesis of spiro and gem-dimethyl-substituted 1,4-oxazepines from N-propargylic β-enaminones

An efficient and general method for the synthesis of spiro-1,4-oxazepines and 3,3-dimethyl-1,4-oxazepines is reported. When treated with ZnI₂ and AgSbF₆ in refluxing DCE, cyclohexane-embedded N-propargylic β-enaminones underwent 7-exo-dig cyclization to afford spiro-1,4-oxazepines, specifically 12-methylene-11-oxa-7-azaspiro[5.6]dodeca-7,9-dienes, in good to high yields. Accordingly, N-(1,1-dimethyl)propargylic β-enaminones produced 3,3-dimethyl-1,4-oxazepines. Cyclization was found to be general for a diverse range of N-propargylic β-enaminones with high efficiency and broad functional group tolerance. This operationally easy method might provide quick access to a library of functionalized spiro and gem-dimethyl-substituted 1,4-oxazepine derivatives of pharmacological interest.     

Uniaxial tensile testing of rubber-like materials

Experimental Techniques -     

137Cs, 40K, alkali–alkaline earth element and heavy metal concentrations in wild mushrooms from Turkey

In 2002, an extensive study was performed in forest sites of Izmir. This first study results led on the one hand, to quantify of ¹³⁷Cs and ⁴⁰K concentration in mushrooms collected in the Izmir region and to a first evaluation of dose in people due to the ingestion of radionuclide-contaminated mushrooms. The mushroom concentration values varied over a wide range from below detection limit to 401 ± 4 Bq kg^?1 (dry wt) for ¹³⁷Cs. The ⁴⁰K concentration values obtained for different species of mushrooms ranged from 588 ± 26 Bq kg^?1 to 2024 ± 63 Bq kg^?1 (dry wt). The annual effective dose values due to mushroom ingestion for ¹³⁷Cs are lower than the ICRP-2007’s reference level value of 1 mSv for “existing” exposure situation. Inductively coupled plasma-mass spectrometry was used to measure many alkali–alkaline earth elements and heavy metals in mushroom samples. The relationships among the concentrations of ¹³⁷Cs and the stable elements were presented and the occurrence of metals in mushrooms was evaluated.     

mTHPC-mediated photodynamic treatment up-regulates the cytokines VEGF and IL-1alpha

Photodynamic therapy (PDT) of cancer induces oxidative stress, which intervenes in the expression of cytokines by tumor cells. The cytokines might have either a positive or a negative impact on tumor eradication. Here, we studied the expression of cytokines vascular endothelial growth factor (VEGF) and interleukin-1alpha (IL-1alpha) in the human epidermoid carcinoma A-431 cells following m-tetra(3-hydroxyphenyl)-chlorin (mTHPC)-mediated PDT in vitro and assessed the IL-1alpha effect on VEGF expression. Quantitative polymerase chain reaction and enzyme-linked immunosorbent assay revealed the enhanced production of VEGF and IL-1alpha both on mRNA and protein levels by mTHPC-loaded cells after light exposure. The silencing of IL1A by small interfering RNA resulted in decreased production of IL-1alpha and a reduced amount of VEGF. Furthermore, exogenous recombinant IL-1alpha stimulated the VEGF expression after PDT. Thus, in addition to the cytotoxic action on the A-431 cells, mTHPC-mediated PDT stimulated the production of VEGF and IL-1alpha, and IL-1alpha contributed to the VEGF overexpression. These data establish IL-1alpha as a possible target of combined cancer treatment.     

Sensitive sepiolite-carbon nanotubes based disposable electrodes for direct detection of DNA and anticancer drug-DNA interactions

A new surface based on the natural clay mineral sepiolite and a single-walled carbon nanotubes-modified graphite electrode was developed for the electrochemical detection of DNA, and also for anticancer drug-DNA interactions.     

Synthesis and Reactivity of Organosamarium Diarylpnictide Complexes: Cleavage Reactions of Group 15 E-E and E-C Bonds by Samarium(II)

(C(5)Me(5))(2)Sm (2 equiv) reacts with Ph(2)EEPh(2) to give (C(5)Me(5))(2)SmEPh(2) (E: P, 1; As, 2), while (C(5)Me(5))(2)Sm(THF)(2) (2 equiv) reacts with Ph(2)EEPh(2) to give (C(5)Me(5))(2)Sm(EPh(2))(THF) (E: P, 3; As, 4). 3 and 4 are also available from the reactions of 1 and 2 with THF. 3 and 4 undergo further reaction to produce the THF ring-opened products (C(5)Me(5))(2)Sm[O(CH(2))(4)EPh(2)](THF) (E: P, 5; As, 6).(C(5)Me(5))(2)Sm (4 equiv) reacts with Ph(2)EEPh(2) to give the mixed-valent (C(5)Me(5))(2)Sm(&mgr;-EPh(2))Sm(C(5)Me(5))(2) (E: P, 7; As, 8). These compounds are also available from the reaction of 1 and 2 with (C(5)Me(5))(2)Sm. The X-ray crystal structure of 2, crystallized from hexanes (P2(1)/n; a = 26.188(24) ?, b = 9.911(10) ?, c = 23.280(23) ?, beta = 97.150(12) degrees, V = 5995(2) ?(3), D(calcd) = 1.488 Mg/m(3); Z = 8; T = 156 K), revealed, in addition to a conventional seven-coordinate bent metallocene geometry with 2.698 ? Sm-C(C(5)Me(5)) and 2.970 ? Sm-As average distances, two very different Sm-As-C(Ph) angles, 74.2 and 118.7 degrees. As a result, one phenyl group is closer to the metal (2.901 ? minimum Sm-C distance). 4, crystallized from toluene (P2(1)/n; a = 10.713(9) ?, b = 14.143(11) ?, c = 21.620(16) ?, beta = 101.08(6) degrees, V = 3215(4) ?(3), D(calcd) = 1.492 Mg/m(3); Z = 4; T = 163 K), and 6, crystallized from hexanes (P2(1)/n; a = 9.3958(16) ?, b = 22.245(3) ?, c = 17.931(3) ?, beta = 96.497(11) degrees, V = 3724(1) ?(3), D(calcd) = 1.416 Mg/m(3); Z = 4; T = 163 K), have conventional eight-coordinate, bent metallocene structures.     

Functional and mechanistic analyses of biomimetic aminoacyl transfer reactions in de novo designed coiled coil peptides via rational active site engineering

Ribosomes and nonribosomal peptide synthetases (NRPSs) carry out instructed peptide synthesis through a series of directed intermodular aminoacyl transfer reactions. We recently reported the design of coiled-coil assemblies that could functionally mimic the elementary aminoacyl loading and intermodular aminoacyl transfer steps of NRPSs. These peptides were designed initially to accelerate aminoacyl transfer mainly through catalysis by approximation by closely juxtaposing four active site moieties, two each from adjacent noncovalently associated helical modules. In our designs peptide self-assembly positions a cysteine residue that is used to covalently capture substrates from solution via transthiolesterification (substrate loading step to generate the aminoacyl donor site) adjacent to an aminoacyl acceptor site provided by a covalently tethered amino acid or modeled by the epsilon-amine of an active site lysine. However, through systematic functional analyses of 48 rationally designed peptide sequences, we have now determined that the substrate loading and intermodular aminoacyl transfer steps can be significantly influenced (up to approximately 103-fold) by engineering changes in the active site microenvironment through amino acid substitutions and variations in the inter-residue distances and geometry. Mechanistic studies based on 15N NMR and kinetic analysis further indicate that certain active site constellations furnish an unexpectedly large pK(a) depression (1.5 pH units) of the aminoacyl-acceptor moiety, helping to explain the observed high rates of aminoacyl transfer in those constructs. Taken together, our studies demonstrate the feasibility of engineering efficient de novo peptide sequences possessing active sites and functions reminiscent of those in natural enzymes.     

Adsorption of Methylene Blue from Aqueous Solution on High Lime Fly Ash: Kinetic,Equilibrium, and Thermodynamic Studies

Kinetic, equilibrium, and thermodynamic studies were performed for the batch adsorption of methylene blue (MB) on the high lime fly ash as a low cost adsorbent material. The studied operating variables were adsorbent amount, contact time, dye concentration, and temperature. The kinetic data were analyzed using the pseudo-first order and pseudo-second order kinetic models and the adsorption kinetic was followed well by the pseudo-second order kinetic model. The equilibrium data were fitted with the Freundlich, Langmuir, and Dubinin Radushkevich (D–R) isotherms and the equilibrium data were found to be well represented by the Freundlich and D–R isotherms. Based on these two isotherms MB is taken by chemical ion exchange and active sites on the high lime fly ash have different affinities to MB molecules. Various thermodynamic parameters such as enthalpy of adsorption (ΔH°), free energy change (ΔG°), and entropy change (ΔS°) were investigated. The positive value of ΔH° and negative value of ΔG° indicate that the adsorption is endothermic and spontaneous. The positive value of ΔS° shows the increased randomness at the solid–liquid interface during the adsorption. A single-stage batch adsorber was also designed based on the Freundlich isotherm for the removal of MB by the high lime fly ash.