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991.
We have synthesized twelve 2-substituted benzimidazole, benzothiazole and indole derivatives using on both microwave irradiation and conventional heating methods. The microwave method was observed to be more beneficial as it provides an increase of yield from 3% to 113% and a 95 to 98 % reduction in time. All compounds were tested by a stains-all assay at pH 7 and by a Morgan-Elson assay at pH 3.5 for hyaluronidase inhibitory activity at a concentration of 100 microM. The most potent compound was 2-(4-hydroxyphenyl)-3-phenylindole (12) with an IC(50) value of 107 microM at both pH 7 and 3.5. 相似文献
992.
Gören AC Akçicek E Dirmenci T Kilic T Mozioğlu E Yilmaz H 《Natural product research》2012,26(1):84-90
The fatty acid composition of the seed oil of 23 Stachys taxa was analysed by GC/MS. The main compounds were found to be linoleic (27.1-64.3%), oleic (20.25-48.1%), palmitic (4.3-9.1%), stearic (trace to 5.2%) and 6-octadecynoic (2.2-34.1%) acids. The latter compound could be used as a chemotaxonomic marker of the genus Stachys. A cluster analysis was performed for comparison and characterisation of the seed oil from Stachys species. 相似文献
993.
Ozcan Kocyigit Serkan Erdemir Mustafa Yilmaz 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):137-147
This study contains the synthesis of silica gel-immobilized calix[4]arene derivative (TR-CL[4]P) as a new sorbent and its sorption studies towards Cu (II) ion in aqueous solution. The aldehyde pointed calix[4]arene derivative 5 was synthesized and then it was immobilized onto 3-aminopropilsilica gel (APS). In batch sorption experiments, the experimental results showed that TR-CL[4]P is effective sorbent towards Cu (II) ion. Therefore, the effect of solution pH, sorption time, temperature and initial metal ion concentration onto Cu (II) sorption was investigated. Maximum Cu(II) removal was obtained at 30?°C, 30?min and pH 6.0 for TR-CL[4]P and the batch sorption capacity was found as 17.8?mg/g. The characteristics of the sorption process for Cu (II) ion were evaluated by using the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption isotherms. Also, thermodynamic parameters, i.e., ΔG, ΔS, and ΔH were calculated for the system. 相似文献
994.
Candida rugosa lipase was encapsulated within a chemically inert sol–gel support prepared by polycondensation with tetraethoxysilane and
octyltriethoxysilane in the presence of β-cyclodextrin-based polymer. The catalytic activity of the encapsulated lipases was
evaluated both in the hydrolysis of p-nitrophenylpalmitate and the enantioselective hydrolysis of racemic Naproxen methyl ester. It has been observed that the
percent activity yield of the encapsulated lipase was 65 U/g, which is 7.5 times higher than that of the covalently immobilized
lipase. The β-cyclodextrin-based encapsulated lipases had higher conversion and enantioselectivity compared with covalently
immobilized lipase. The study confirms an excellent enantioselectivity (E >300) for the encapsulated lipase with an enantiomeric excess value of 98% for S-naproxen. 相似文献
995.
Gam-Derouich S Lamouri A Redeuilh C Decorse P Maurel F Carbonnier B Beyazıt S Yilmaz G Yagci Y Chehimi MM 《Langmuir : the ACS journal of surfaces and colloids》2012,28(21):8035-8045
In this paper we describe a novel methodology for grafting polymers via radical photopolymerization initiated on gold surfaces by aryl layers from diazonium salt precursors. The parent 4-(dimethylamino)benzenediazonium salt was electroreduced on a gold surface to provide 4-(dimethylamino)phenyl (DMA) hydrogen donor layers; free benzophenone in solution was used as a photosensitizer to strip hydrogen from the grafted DMA. This system permitted efficient surface initiation of photopolymerization of 2-hydroxyethyl methacrylate. The resulting poly(2-hydroxyethyl methacrylate) (PHEMA) grafts were found to be very adherent to the surface as they resist total failure after being soaked in the well-known paint stripper methyl ethyl ketone. The PHEMA grafts were reacted with 1,1'-carbonyldiimidazole to yield carbamate groups that are able to react readily with amino groups from proteins. The final surface consisted of protein-functionalized PHEMA grafts where bovine serum albumin (BSA) protein is specifically linked to the grafts by covalent bonds. We used X-ray photoelectron spectroscopy to monitor the chemical changes at the gold surface all along the process from the neat gold to the end-protein-functionalized polymer grafts: the PHEMA graft thickness ranged from 7 to 27 nm, and the activation by 1,1'-carbonyldiimidazole reached 37% of the OH groups, which was sufficient for 90% surface coverage of the grafts by BSA. This work conclusively provides a new approach for bridging reactive and functional polymers to surfaces via aryl diazonium salts in a simple, fast, and efficient approach of importance in biomedical and other applications. 相似文献
996.
997.
Taskin T Yilmaz S Yildiz I Yalcin I Aki E 《SAR and QSAR in environmental research》2012,23(3-4):345-355
Etoposide is effective as an anti-tumour drug by inhibiting eukaryotic DNA topoisomerase II via establishing a covalent complex with DNA. Unfortunately, its wide therapeutic application is often hindered by multidrug resistance (MDR), low water solubility and toxicity. In our previous study, new derivatives of benzoxazoles, benzimidazoles and related fused heterocyclic compounds, which exhibited significant eukaryotic DNA topoisomerase II inhibitory activity, were synthesized and exhibited better inhibitory activity compared with the drug etoposide itself. To expose the binding interactions between the eukaryotic topoisomerase II and the active heterocyclic compounds, docking studies were performed, using the software Discovery Studio 2.1, based on the crystal structure of the Topo IIA-bound G-segment DNA (PDB ID: 2RGR). The research was conducted on a selected set of 31 fused heterocyclic compounds with variation in structure and activity. The structural analyses indicate coordinate and hydrogen bonding interactions, van der Waals interactions and hydrophobic interactions between ligands and the protein, as Topo IIA-bound G-segment DNA are responsible for the preference of inhibition and potency. Collectively, the results demonstrate that the compounds 1a, 1c, 3b, 3c, 3e and 4a are significant anti-tumour drug candidates that should be further studied. 相似文献
998.
Halil İbrahim Ulusoy Ramazan Gürkan Öznur Yılmaz Mehmet Akçay 《Journal of Analytical Chemistry》2012,67(2):131-139
A sensitive and selective method has been developed for the determination of chromium in water samples based on using cloud
point extraction (CPE) preconcentration and determination by flame atomic absorption spectrometry (FAAS). The method is based on the complexation of Cr(III) ions with Brilliant Cresyl Blue (BCB) in the presence of non-ionic surfactant Triton X-114. Under the optimum conditions, the preconcentration of 50 mL of water
sample in the presence of 0.5 g/L Triton X-114 and 1.2 × 10−5 M BCB permitted the detection of 0.42 μg/L chromium(III). The calibration graph was linear in the range of 1.5–70 μg/L, and
the recovery of more than 99% was achieved. The proposed method was used in FAAS determination of Cr(III) in water samples
and certified water samples. In addition, the developed CPE-FAAS method was also used for speciation of the inorganic chromium
species after reduction of Cr(VI) to Cr(III) using a thiosulphate solution of 120 mg/L in the presence of Hg(II) ion as a
stabilizer. 相似文献
999.
In this research, a comprehensive theoretical investigation of the thermal rearrangements of 1-ethynyl-2-methylcyclopropane is carried out employing density functional theory (DFT), with the B3LYP functional, and high-level ab initio methods, such as the complete active space self-consistent field (CASSCF), multireference second-order M?ller-Plesset perturbation theory (MRMP2), and coupled-cluster singles and doubles with perturbative triples [CCSD(T)]. In all computations Pople's polarized triple-ζ split valence basis set, 6-311G(d,p), is utilized. The potential energy surface (PES) for the relevant system is explored to provide a theoretical account of the experiments by Hopf, Ellis and Frey, Huntsman et al., and Berson. The computational results herein on the target system show that the thermal aromatization reaction does not proceed via conversion of 1,2,5-hexatriene (2) to 1,3,5-hexatriene (10a) as proposed by Hopf. Indeed, the reaction proceeds via conversion of 5 and 6 to bicyclo[3.1.0]hexene (9) as suggested by Huntsman et al. 相似文献
1000.
Nuran Kahriman Nagihan Yilmaz Iskender Murat Yücel Nurettin Yayli Emine Demir Zihni Demirbağ 《Journal of heterocyclic chemistry》2012,49(1):71-79
A simple environmentally friendly solid‐phase microwave‐assisted method was used to synthesis of the 1,3′‐diazaflavanone ( 2 ) and 1,3′‐diazaflavone ( 3 ) from the cyclization of 2′‐amino (E)‐3″‐azachalcone ( 1 ). Ten new N‐alkyl (C5–12,14,15)‐substituted 1,3′‐diazaflavanonium bromides ( 2a–j ) were prepared from compound 2 with corresponding alkyl halides in acetonitrile under reflux. In addition, nine new N,N′‐dialkyl (C5–12,14)‐substituted 1,3′‐diazaflavonium bromides ( 3a–i ) were also synthesized from compound 3 with corresponding alkyl halides using basic silica in acetonitrile. The antimicrobial activities of compounds 1–3 , 2a–j , and 3a–i were tested against Gram‐positive (G+) (Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus aureus, and Enterococcus faecalis) and Gram‐negative (G?) (Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Proteus vulgaris, Salmonella typhimirium, Yersinia pseudotuberculosis, and Enterobacter cloaceae) microorganisms. They showed good antimicrobial activity against the Gram‐positive bacteria tested with the minimal inhibitory concentration values less than 7.8 μg/mL in most cases. The optimum length of the alkyl chain for better and broader activity is situated in the range of 9–12 carbon atoms in the series of compounds 2a–j and five to six carbon atoms in the series of compounds 3a–i . The nonalkylated compounds 1–3 were not effective, as were the ones alkylated with five or six C alkyl groups ( 2a and 2b ) and 8–13 C alkyl groups for N,N′‐dialkyl compounds ( 3c–3i ). The antimicrobial activity increased as the length of the alkyl substitution increased from 8 to 12 carbons in compounds 2a–j . However, antimicrobial activity decreased as the length of the alkyl substitution increased from 7 to 13 carbons in compounds 3c–i . J. Heterocyclic Chem., (2012) 相似文献