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1.
Ai-Qun Lin Lin Du Yu-Chun Fang Fa-Zuo Wang Tian-Jiao Zhu Qian-Qun Gu Wei-Ming Zhu 《Chemistry of Natural Compounds》2009,45(5):677-680
A new natural product, iso-α-cyclopiazonic acid (1), together with its isomer α-cyclopiazonic acid (2); three mycotoxins: aflatoxin B1 (AFB1) (3), aflatoxin Q1 (AFQ1) (4), and O-methylsterigmatocystin (OMST) (5); two diketopiperazine alkaloids: ditryptophenaline (6) and 3-[(1H-indol-3-yl)methyl]-6-benzylpiperazine-2,5-dione (7), were isolated from the marine-derived fungus Aspergillus flavus. Their structures were determined by analysis of spectroscopic data. The cytotoxicities of compounds 1 and 2 were studied using HL-60, MOLT-4, A-549, and BEL-7402 cell lines. 相似文献
2.
O. A. Luk’yanov G. A. Smirnov P. B. Gordeev 《Russian Journal of Organic Chemistry》2007,43(8):1228-1231
A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups. 相似文献
3.
Francisco Guzmán-Rodríguez Sergio Alatorre-Santamaría Lorena Gómez-Ruiz Gabriela Rodríguez-Serrano Mariano García-Garibay Alma Cruz-Guerrero 《Applied biochemistry and biotechnology》2018,186(3):681-691
Fucosylated oligosaccharides, such as 2′-fucosyllactose in human milk, have important biological functions such as prebiotics and preventing infection. In this work, the effect of an acceptor substrate (lactose) and the donor substrate 4-nitrophenyl-α-l-fucopyranoside (pNP-Fuc) on the synthesis of a fucosylated trisaccharide was studied in a transglycosylation reaction using α-l-fucosidase from Thermotoga maritima. Conducting a matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), it was demonstrated that synthesized oligosaccharide corresponded to a fucosylated trisaccharide, and high-performance liquid chromatography (HPLC) of the hydrolyzed compound confirmed it was fucosyllactose. As the concentration of the acceptor substrate increased, the concentration and synthesis rate of the fucosylated trisaccharide also increased, and the highest concentration obtained was 0.883 mM (25.2% yield) when using the higher initial lactose concentration (584 mM). Furthermore, the lower donor/acceptor ratio had the highest synthesis, so at the molar ratio of 0.001, a concentration of 0.286 mM was obtained (32.5% yield). 相似文献
4.
Bohumil Proksa Richard Hercek Tibor Liptaj Nada Prónayová 《Monatshefte für Chemie / Chemical Monthly》2009,140(5):485-487
Abstract A new compound was isolated from the reaction mixture after O-demethylation of 6-O-acetyl-10α-acetoxycodeine with boron tribromide. The structure of this compound, 10α-hydroxy-β-isomorphine, was elucidated by spectral data, and its spatial arrangement was deduced from an NOE experiment. Capillary zone
electrophoresis was used for separation of morphine and its 10-hydroxy analogues.
Graphical abstract
相似文献
5.
6.
Bruno Benoliel Marcio José Poças-Fonseca Fernando Araripe Gonçalves Torres Lidia Maria Pepe de Moraes 《Applied biochemistry and biotechnology》2010,160(7):2036-2044
A β-glucosidase gene (bgl4) from Humicola grisea var thermoidea was successfully expressed in Saccharomyces cerevisiae. The recombinant protein (BGL4
Sc
) was initially detected associated with yeast cells and later in the culture medium. BGL4
Sc
showed optimal pH and temperature of 6.0 and 40 °C, respectively, and an apparent molecular mass of 57 kDa. The enzyme showed
activity against cellobiose and synthetic substrates, and was inhibited more than 80% by Fe2+, Cu2+, Zn2+, and Al3+. Using p-nitrophenyl-β-d-glucopyranoside (pNPG) as substrate, BGL4
Sc
presented a V
max of 6.72 μmol min−1 mg total protein−1 and a K
m of 0.16 mM under optimal conditions. Most important, BGL4
Sc
is resistant to inhibition by glucose and the calculated K
i value for this sugar is 70 mM. This feature prompts BLG4
Sc
as an ideal enzyme to be used in the saccharification process of lignocellulosic materials for ethanol production. 相似文献
7.
Chiral imidazoquinazolines undergoing thermally induced reversible R ⇄ S enantiomerization have been synthesized by the interaction of 2-(o-aminophenyl)benzimidazoles with aldehydes and ketones. The benzimidazole fragment has been used for the first time as an indicator group in temperature-dependent 1H NMR spectra for determining the energy barrier of this rearrangement. The effects of nearby substituents on the kinetic and activation parameters, and on the recyclization mechanism have been investigated. 相似文献
8.
Reactions of N-arylsulfonyl(acyl)arenesulfenamide sodium salts with phenyl isothiocyanate afforded N-arylsulfanyl-N-arylsulfonyl(acyl)-N-phenylthioura sodium salts which were found to increase thermal stability of finely dispersed poly(vinyl chloride).Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1532–1535.Original Russian Text Copyright © 2004 by Koval, Oleinik. 相似文献
9.
V. L. Korolev V. V. Toporov N. L. Merkulova V. M. Danilenko V. P. Ivshin T. S. Pivina 《Russian Chemical Bulletin》2017,66(7):1250-1255
A method for the synthesis of imidazo[4,5-e]benzo[1,2-c;3,4-c´]difuroxanes, potential nitric oxide donors, has been developed. The synthesized compounds were characterized by IR and NMR spectroscopy, high resolution mass spectrometry, and elemental analysis. 相似文献
10.
The sodium salt of N-(6-chloronicotinoyl)-γ-aminobutyric acid, a structural analog of the known nootropic and vasidilating drug picamilon, was synthesized via Schotten–Baumann
acylation of γ-aminobutyric acid with 6-chloronicotinoyl chloride and subsequent neutralization of the N-(6-chloronicotinoyl)-γ-aminobutyric acid that was obtained in >60% yield. 相似文献
11.
We report a ‘one-pot’ synthetic approach for TEMPO (2,2,6,6-tetramethyl-piperidin-1-oxyl) oxidized cellulose nanofibrils (TOCN) surface amidation by coupling up to 70% of superficial carboxylic units in TOCN with long alkyl chain primary amines (dodecylamine and octadecylamine) using TBTU [O-(1H-benzotriazol-1-yl)-N,N,N’,N’-tetramethyluronium tetrafluoroborate] uronium salt as coupling agent. Raw TOCNs were produced from commercial microcrystalline cellulose and have an elongated highly tangled morphology with nanometric diameters and lengths up to several micrometers with a crystallinity of 62%. TOCN´s degree of oxidation was 1.25 mmol –COOH groups/g cellulose. The TOCN-amidated products named TOCN-AMDC12 and TOCN-AMDC18 depending upon to the primary amine used for the synthesis (dodecylamine –C12– for the former and octadecylamine –C18– for the latter), were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy with attenuated total reflectance and X-ray diffraction. After amidation the hydrated gel-like TOCNs become a cream-colored gel insoluble in water and soluble in toluene. IR data indicates formation of an amide bond after the reaction, and FESEM images suggest a slight increase in fibril width as a result of the long-chain amide derivatives grafted onto the TOCN’s surface. Thermal stability and hydrophobicity of the products were determined using thermogravimetrical analysis and contact angle (CA) measurements. The TOCN-amidated products showed improved thermal properties with maximum decomposition temperatures of 347 and 358 °C, for TOCN-AMDC12 and TOCN-AMDC18 respectively, when compared to the raw TOCN (Td 340 °C); and high hydrophobicity with CA of 61° and 67°, respectively. Finally, the proposed method for TOCN amidation has advantages over current amidation approaches in that it is performed in aqueous media, does not require heating and occurs rapidly (2 h). 相似文献
12.
β-Methoxycarbonyl-γ-butyrolactones bearing a γ-aromatic substituent were prepared via copper-catalyzed reductive aldol addition/lactonization domino reactions of ketones with α,β-unsaturated dicarboxylate esters and a silane under ambient temperature. The reaction has advantage of using readily available reagents, mild conditions and high efficiency. 相似文献
13.
Background
Since chitin is a highly abundant natural biopolymer, many attempts have been made to convert this insoluble polysaccharide into commercially valuable products using chitinases and β-N-acetylglucosaminidases (GlcNAcases). We have previously reported the structure and function of chitinase A from Vibrio harveyi 650. This study t reports the identification of two GlcNAcases from the same organism and their detailed functional characterization. 相似文献14.
Lobodin VV Fedotov AN Dem'yanov PI Lebedev AT Ovcharenko VV Pihlaja K Blumenthal T 《Journal of the American Society for Mass Spectrometry》2005,16(11):1739-1749
Electron ionization (EI), chemical ionization (CI), tandem mass spectrometry, high-resolution measurements, and labeling studies as well as quantum chemical calculations were used to understand the behavior of the molecular radical cations (EI) and protonated molecules (CI) of substituted N-(ortho-cyclopropylphenyl)-N'-aryl ureas and N-(ortho-cyclopropylphenyl)-N'-aryl thioureas in a mass spectrometer. Fragmentation schemes and possible mechanisms of primary isomerization were proposed. According to the fragmentation pattern, formation of the corresponding benzoxazines and benzothiazines was considered as the major process of isomerization of the original M(+.) and MH(+), although some portions of these ions definitely transformed into other structures. The treatment of N-(ortho-cyclopropylphenyl)-N'-phenyl urea and N-(ortho-cyclopropylphenyl)-N'-phenylthiourea in solution with strong acids formed predicted 4-ethyl-N-phenyl-4H-3,1-benzoxazin-2-amin and 4-ethyl-N-phenyl-4H-3,1-benzothiazin-2-amine as principal products. 相似文献
15.
Aruna P. Maharolkar A. G. Murugkar P. W. Khirade S. C. Mehrotra 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(9):1710-1716
The refraction, dielectric, viscosity, density, data of the binary mixtures of N,N-dimethylacetamide (DMA) with n-butanol at 308.15 and 313.15 K. The measured parameters used to obtain derived properties like Bruggeman factor, molar refraction and excess static dielectric constant, excess inverse relaxation time, excess molar volume and excess viscosity, excess molar refraction. The variation in magnitude with composition and temperature of these quantities has been used to discuss the type, strength and nature of binary interactions. Results confirm that there are strong hydrogen-bond interactions between unlike molecules of DMA+ n-butanol mixtures and that 1: 1 complexes are formed and strength of intermolecular interaction increases with temperature. 相似文献
16.
The crystalline modifications and of polypropylene (PP) were studied by using polarized light microscopy (PLM), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). Typically crystals surrounded by spherulites were observed at low temperature. With increasing temperature the crystals melted and a new crystal appeared. More interestingly, the melting temperature of the new crystal was about 5 ° higher than that of spherulites originally present in the sample formed isothermally. It was assumed that this new crystal was the recrystalline crystal. This assumption was supported by the DSC results. Furthermore, the crystallization kinetics of the PP used was studied on the basis of the traditional Avrami analysis. As a result, the Avrami exponents of crystallization temperature from 120 to 130 °C ranged between 4.21 and 3.60, indicating that the crystallization mechanism of PP order melt was spherulitic growth and random nucleation. 相似文献
17.
V.?R.?Akhmetova E.?M.?Bikbulatova N.?S.?Akhmadiev V.?M.?Yanybin T.?F.?Boiko R.?V.?Kunakova A.?G.?Ibragimov
Catalytic aminomethylation of pyrrole and indole with N,N,N′,N′-tetramethylmethanediamine in the presence of 5 mol % of ZrOCl2·8H2O proceeds selectively at the positions 2, 5 of pyrrole and 1, 3 of indole. Carbazole under the same conditions affords 3-formyl-9-aminomethyl derivative. The reaction in the presence of 5 mol % of K2CO3 occurs as monoaminomethylation: for pyrrole at the position 2, for indole at the position 3, and for carbazole at the nitrogen atom of the substrate. Water-soluble 1,1′-(1H-pyrrole-2,5-diyl)bis(N,N-dimethylmethanamine) exhibits a fungistatic activity with respect to phytopathogenic fungi Rhizoctonia solani. 相似文献
18.
A. A. Yartseva L. Sh. Koldrov S. S. Galibeev V. P. Arkhireev N. I. Naumkina I. A. Litvinov A. T. Gubaidullin 《Journal of Structural Chemistry》2007,48(6):1138-1144
The molecular complexes of 1,3,5-tris-m-chlorophenylisocyanurate and ε-caprolactone were synthesized by the reaction of the latter with 3-chlorophenylisocyanate in the presence of triethylamine. Single crystals were grown, and the molecular and crystal structures of the synthesized complexes were investigated. 相似文献
19.
A. A. Shamitov I. K. Garkushin A. V. Kolyado E. P. Petrov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(2):300-303
The n-decane–n-hexadecane–cyclododecane, n-decane–cyclododecane, and n-hexadecane–cyclododecane systems are studied by means of low-temperature differential thermal analysis using a differential scanning heat flow calorimeter. It is noted that all studied systems belong to the eutectic type. It is concluded that in the n-decane–n-hexadecane–cyclododecane system, the eutectic composition contains 85.0 wt % n-С10Н22, 4.0 wt % n-С16Н34, and 11.0 wt % С12Н24. It has a melting point of ?35.0°C. 相似文献
20.
Guo-Quan Zhu 《Chemical Papers》2010,64(1):34-39
Poly(ethylene glycol)-block-poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) (PEG-block-PBLG-graft-PEG) copolymer was synthesized by the ester exchange reaction of PBLG-block-PEG copolymer with a PEG chain. Surface morphology of the PEG-block-PBLG-graft-PEG copolymer membrane was characterized by atomic force microscopy (AFM). Mechanical and chemical properties of the PEG-block-PBLG-graft-PEG copolymer membrane were investigated by tensile testing and contact angle testing. The effects of grafting ratio on the
properties of PEG-block-PBLG-graft-PEG copolymer membrane were primarilly studied. 相似文献