共查询到20条相似文献,搜索用时 31 毫秒
1.
A. V. Lezov G. E. Polushina A. A. Lezov P. S. Vlasov N. S. Domnina 《Polymer Science Series A》2011,53(2):93-101
The hydrodynamic and conformational properties of molecules of poly(N,N-diallyl-N,N-dimethylammonium chloride) and N,N-diallyl-N,N-dimethylammonium chloride-maleic acid copolymers of different compositions in solutions with various ionic-strength and pH
values, as well as of the polyelectrolyte complex based on the copolymer with dodecyl sulfate anions in chloroform, are studied.
For poly(N,N-diallyl-N,N-dimethylammonium chloride) molecules in a 1 M NaCl solution, the Kuhn segment length and the hydrodynamic diameter of the
chain are estimated as A = 3.9 nm and d = 0.48 nm, respectively. In acidic solutions with pH 3.5, the copolymers demonstrate behavior typical for polyelectrolytes.
In an alkaline solution with pH 13, when 1 M NaCl is added to the solution of the copolymer containing 29 mol % maleic acid
units, there is an antipolyelectrolyte effect that manifests itself as an increase in the intrinsic viscosity of the copolymer
and in the hydrodynamic radius of its molecules. It is found that an increase in the fraction of maleic acid units in the
copolymer from 12 to 42 mol % brings about a reduction in the equilibrium rigidity of its macromolecules from 4.1 to 2.2 nm.
The equilibrium rigidity of polyelectrolyte-complex molecules is higher than that of initial copolymer molecules owing to
steric interactions arising between the aliphatic chains of dodecyl sulfate anions. In an electric field, the molecules of
the complex are oriented owing to the induced dipole moment resulting from the displacement of dodecyl sulfate anions along
the chain contour. 相似文献
2.
Chen Dong Guolin Li Zhuoqi Li Honglin Zhu Mingquan Zhou Zhongli Hu 《Applied biochemistry and biotechnology》2009,158(3):605-614
A rapid amplification cDNA end (RACE) assay was established to achieve the complete sequence of mitochondrial manganese-superoxide
dismutase (Mn-SOD) cDNA in Nelumbo nucifera. The obtained full-length cDNA of Mn-SOD was 926 bp and contained a 699-bp open reading frame encoding an Mn-SOD precursor of 233 amino acids. The recombinant of
Mn-SOD expressed by PET-32a vector in Escherichia coli BL21 was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blotting assays. A 3D structural
model of the Mn-SOD was constructed by homology modeling. Real-time polymerase chain reaction analysis revealed that Mn-SOD mRNA was expressed in young leaves, blossom, stems, and terminal buds during reproductive stage but with the highest expression
in young leaves. This significant difference demonstrated the differential expression of Mn-SOD in various organs of N. nucifera. 相似文献
3.
D. T. Asilbekova F. M. Tursunkhodzhaeva A. M. Nigmatullaev 《Chemistry of Natural Compounds》2009,45(3):322-324
The composition of lipids from the aerial parts of two species of halophytes from the family Chenopodiaceae, Halostachys caspica C. A. Mey. and Halocharis hispida Bge. was determined. Neutral lipids (NL, 62.1 and 54.2%, respectively) dominated the total lipids (TL) of these plants. More
than a third of the NL were esters of aliphatic alcohols and phytosterols (FAE). Fatty acids 16:0, 18:1, and 18:2 dominated
the acids of FAE; 16:0, 18:1, and 18:3, the phospholipids. The principal fatty acids of glycolipids were unsaturated acids
(68.3 and 75.1%) with linolenic acid dominating (44.9 and 43.5%).
Presented at the 7th International Symposium on the Chemistry of Natural Compounds, Tashkent, October 16–18, 2007.
Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 276–278, May–June, 2009. 相似文献
4.
S. Petrovic S. Sobajic S. Rakic A. Tomic J. Kukic 《Chemistry of Natural Compounds》2004,40(5):420-422
The kernel oils of Quercus robur and Quercus cerris were obtained by Soxhlet extraction using petroleum ether. Oil yields were found to be 5.2–5.6% and 4.3–4.8% for Q. robur and Q. cerris kernel, respectively (expressed in g per 100 g of dried plant material). The physical and chemical constants, unsaponifiable matter and total fatty acids were determined. The total fatty acid composition of oils was determined by GC in the methyl ester form. Considering the composition and content of fatty acids, the examined kernel oils were very similar. Seven fatty acid components were identified in both oils: palmitic, stearic, arachidic, palmitoleic, oleic, linoleic, and -linolenic. In Q. robur and Q. cerris kernel oils the principal acids were oleic (44.3% and 43.0%, respectively) and linoleic (37.2% and 32.6%, respectively), followed by a significant amount of palmitic acid.Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 347–348, September–October, 2004. 相似文献
5.
T. F. Ibragimov M. G. Levkovich V. A. Saprykina Kh. M. Shakhidoyatov 《Chemistry of Natural Compounds》2010,46(5):767-770
N-Chloroacetylcytisine was synthesized by acylation of (–)-cytisine. Stable Z- and E-conformers with respect to rotational isomerism around the N-12–CO bond were found in PMR spectra at room temperature. The
point at which PMR resonances of the Z- and E-conformers coalesced upon heating was measured. The transition barrier between the conformers was estimated. 相似文献
6.
Sunisa Suwancharoen Orawan Chonvanich Sophon Roengsumran Surachai Pornpakakul 《Chemistry of Natural Compounds》2012,48(4):583-586
A new seco-kaurane type diterpenoid, ent-3,4-seco-17-oxo-kaur-4(19),15(16)-dien-3-oic acid, and a known compound, ent-3,4-seco-kaur-4(19),16(17)-dien-3-oic acid, were isolated from the stem bark of Croton oblongifolius. The structures of these compounds were established on the basis of spectroscopic data. 相似文献
7.
U. S. Makhmudov Sh. B. Rakhimov B. Tashkhodzhaev M. G. Levkovich V. I. Vinogradova 《Chemistry of Natural Compounds》2008,44(2):208-212
The molecular structures of N-(o-and p-hydroxybenzyl)cytisine were investigated by NMR spectroscopy, x-ray structure analysis, and molecular modeling. It was found
that NMR resonances of the OH and aromatic protons in N-(o-hydroxybenzyl)cytisine were doubled because of the presence of two conformers in solution.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 165–168, March–April, 2008. 相似文献
8.
Qiong-ming Xu Quan Li Yan-li Liu Yu-lin Feng Shi-lin Yang Xiao-ran Li 《Chemistry of Natural Compounds》2010,46(3):366-369
In the search for platelet-activating-factor (PAF) antagonists, two new lignan compounds were isolated from the leaves of
Syringa reticulata Hara var. mandshurica. Their structures were elucidated as (7R,8S, 8'S)-3,4,3',4'-dimethylenedioxy-8,9-dihydroxy-8.8', 7-O-9'-lignan (mandshuricol A) and (7R,8S,8'S)-3',4'methylenedioxy-4-methoxy-3,8,9-trihydroxy-8.8', 7-O-9'-lignan (mandshuricol B), Mandshuricol A and B showed antagonistic activity on PAF in the [3H] PAF receptor binding assay with IC50 values of 4.8 × 10–5 M and 3.5 × 10–5 M, respectively. 相似文献
9.
Oil pumpkin (Cucurbita pepo L. var. Styriaca) is an economically important horticultural plant cultivated for oil production. After harvesting seeds, the residual biomass
has a limited application and is usually left in the field. An experimental study was performed to evaluate the chemical composition
of the seeded fruit oil pumpkin biomass (OP) dried by solvent-exchange using ethanol. The sugar composition of polysaccharides
obtained by sequential extraction with water and dilute alkali indicated the prevalence of pectic polysaccharides. Hemicelulloses
were released in higher amounts in the alkaline step. The chemical composition of OP and its individual tissues (peel, flesh
and hairy flesh) was investigated and compared to the corresponding preparations of standard pumpkin (SP, Cucurbita pepo L.). The content of components (on oven-dry basis), calculated from the analysis data of the individual tissues, was estimated
for OP: 7.9 % ash, 7.6 % Klason lignin, 19.3 % pectin (as uronic acids), 34.1 % neutral carbohydrates, and 27.4 % α-cellulose
and for SP: 6.4 % ash, 4.0 % Klason lignin, 20.9% pectin (as uronic acids), 38.1% neutral carbohydrates, and 29.2 % α-cellulose,
respectively. The OP biomass showed a higher proportion of hemicelluloses. 相似文献
10.
Jian-Chao?Chen Zhong-Zhi?Xu Li-Xin?Yang Xiu-Yun?He Cui?Chen Gao-Hong?Zhang Yong-Tang?Zheng Ming-Hua?Qiu
A new cucurbitacin, endecaphyllacin C, was isolated from the tubers of Hemsleya endecaphylla. The structure was elucidated as 2β,16α,20β,25-tetrahydroxy-24-acetylaminocucurbita-5-en-3,11,22-trione (1) on the basis of extensive 1D and 2D NMR techniques, including COSY, HMBC, HMQC, and NOESY correlations, as well as HR-FAB-MS analysis. 相似文献
11.
D. A. Köse G. Gökçe S. Gökçe İ. Uzun 《Journal of Thermal Analysis and Calorimetry》2009,95(1):247-251
Three novel mixed ligand complexes of Ni(II), Zn(II) and Cd(II) with p-chlorobenzote and N,N-diethylnicotinamide were synthesised and characterized on the basis of elemental analysis, FTIR spectroscopic
analysis, solid state UV-Vis spectrometric and magnetic susceptibility data. The thermal behavior of the complexes was studied
by simultaneous TG-DTA methods in static air atmosphere and the mass spectra data were recorded.
According to microanalytical results, formulas of complexes are C34H40N4O8ClNi, C34H40N4O8ClZn and C34H44N4O10ClCd. The complexes contain two moles of coordination waters, two moles p-chlorobenzoate and two mole N,N-diethylnicotinamide (dena) ligands per formula unit. In these complexes, the p-chlorobenzoate and N,N-diethylnicotinamide behave as monodentate ligand through acidic oxygen and nitrogen of pyridine ring.
The decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data. The final
decomposition products were found to be as metal oxides. 相似文献
12.
K. N. Semenov N. A. Charykov V. N. Postnov O. A. Krokhina E. G. Gruzinskaya 《Russian Journal of General Chemistry》2010,80(12):2443-2449
Available published data on isothermal solubility (at 20°C) of individual light fullerenes in a homologous series of n-alkanes, n-alkanols, n-alkylcarboxylic acids, and arenas were systematized. A correlation between the parameter of Hildebrand’s cohesion and the
logarithm of the mole fraction of the fullerene in the saturated solution was revealed. 相似文献
13.
Nicole Dalonso Rafaela Souza Márcia Luciane Lange Silveira Ângelo Adolfo Ruzza Theodoro Marcel Wagner Elisabeth Wisbeck Sandra Aparecida Furlan 《Applied biochemistry and biotechnology》2010,160(8):2265-2274
Fungi of the Pleurotus genus present a great industrial interest due to their possibility of producing pharmacological compounds, pigments, aromas,
organic acids, polysaccharides, enzymes, vitamins, amino acids, etc. Among the therapeutic products, we can highlight those
with antineoplasic activity, attributed to the fungi cell wall components. Based on this, the objective of this work was to
study the antineoplasic capacity of the polysaccharidic fractions obtained from Pleurotus sajor-caju fruiting bodies. Female Swiss mice were inoculated with the Ehrlich ascitic tumor (5 × 106 cells/animal) in ascitic form. The polysaccharidic fractions were administered intraperitoneally, during a 6-day period.
Fractions FI and FII presented a lower volume of ascitic liquid (3.1 and 1.8 mL, respectively) and a higher reduction in the
number of neoplasic cells present in the ascitic liquid (86.2% and 85%, respectively), when compared to the positive control
(group inoculated with the tumor but without treatment). These fractions were characterized in terms of monosaccharide composition.
Glucose was the major component detected, followed by galactose and mannose. The anomeric carbon configuration of the β-glucan
was confirmed by the 13C NMR (δ 103.7). Substituted and free C3 and C6 were also detected. Protein bands were confirmed through infrared analysis. 相似文献
14.
G. V. Mokrov A. M. Likhosherstov V. S. Troitskaya T. A. Gudasheva 《Russian Journal of Organic Chemistry》2009,45(12):1829-1833
New procedures have been developed for the synthesis of α-(2-formyl-1H-pyrrol-1-yl)-substituted carboxylic acids, α-(2-R-aminomethyl-1H-pyrrol-1-yl)-substituted carboxylic acids, and 1,2-dihydropyrrolo-[1,2-a]pyrazin-3(4H)-ones on the basis of furfurol and α-amino acids. 相似文献
15.
L. M. Korul’kina G. E. Zhusupova E. E. Shul’ts K. B. Erzhanov 《Chemistry of Natural Compounds》2004,40(5):417-419
The fatty-acid composition of two Limonium plant species (Plumbaginaceae), including both saturated and polyunsaturated acids, was determined for the first time using chromatography—mass-spectrometry. High contents of palmitic, oleic, linolenic, and linoleic acids were found. Methyl esters of fatty acids in Limonium Popovii were identified by mass spectrometry as hexadecanedioic, eicosanedioic, and docosanedioic acids.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 344–346, September–October, 2004. 相似文献
16.
Ferreira JA Dias E Rocha SM Coimbra MA 《Analytical and bioanalytical chemistry》2011,401(6):1889-1898
Helicobacter pylori diagnosis is fundamental in the management of gastrointestinal pathologies, whose current clinical guidelines support a non-invasive
‘test-and-treat’ strategy. As such, the present work reports the basis of a new, low-cost, specific breath test based on the
detection of volatile carboxylic acids resulting from the hydrolysis of short-chain aliphatic amides by H. pylori amidases. Propionamide and butyramide, which are metabolized by amidases to propionic and butyric acids, were elected for
this study. Conditions for the extraction of these acids from a vapour phase were optimized concerning the use of solid-phase
microextraction (SPME) followed by gas chromatography–quadrupole mass spectrometry (GC–qMS) analysis. SPME–GC–qMS was then
used to detect the acids released into a vapour phase upon incubation of a H. pylori reference strain J99 or a clinical specimen with the amides. These experiments have demonstrated that the administration
of less than 9 mg of propionamide and/or butyramide to H. pylori cultures, in loads recognized to cause infection (106–109 cells), resulted in the formation of detectable and/or quantifiable amounts of propionic and/or butyric acids after 30 min
incubation. As such, propionic and butyric acids can be used as biomarkers for H. pylori upon incubation with the corresponding amides. SPME–GC–qMS was also used to verify the hepatic stability of the acids. These
experiments were conducted in mouse liver cells and revealed no signs of metabolization that could compromise their bioavailability
in future in vivo assays. Moreover, SPME–GC–qMS permitted the detection of both acids in amounts as low as 0.8 μg in systems
mimicking exhaled breath, demonstrating the sensitivity of the method for these compounds. 相似文献
17.
A novel plasma membrane intrinsic, LcPIP1, was isolated from Leymus chinensis using RACE method. The LcPIP1 has 288 amino acids with an estimated molecular mass of 30.6 kDa. Semi RT-PCR analysis indicated that the expression level
of LcPIP1 was obviously higher in leaf than root. The LcPIP1 was also found to be induced by salt stress. In addition, transformed with the LcPIP1, Saccharomyces cerevisiae could increase tolerance to salt stress. These results indicate that the LcPIP1 gene seems to play a role in resistance against salt stress. 相似文献
18.
The protective antigen (PA) of Bacillus anthracis is a potent immunogen and an important candidate vaccine. In addition, it is used in monitoring systems like enzyme-linked
immunosorbent assay to assess antibodies against PA in immunized subjects. The low level of PA production in B. anthracis and the difficulty of separating it from other bacterial components have made the researchers do different studies with the
aim of producing recombinant PA (rPA). In this study, to produce rPA as a recombinant protein vaccine, the partial sequence
of protective antigen of B. anthracis, amino acids 175–764, as a potent immunogenic target was inserted in pET21b(+). This is a prokaryotic plasmid that carries
an N-terminal T7.tag sequence. The integrity of constructed plasmid was confirmed using restriction enzyme mapping. rPA was
expressed after induction with isopropyl β-d-1-thiogalactopyranoside in Escherichia coli BL21. Purification of rPA was done with an affinity system using anti T7.tag antibody. Electrophoresis and Western blotting
confirmed the specificity of the expressed protein. BALB/c mice were immunized with obtained PA protein and evaluation of
specific immunoglobulin G antibodies against PA in sera using Western blotting method and showed that rPA is immunogenic.
The challenge of immunized mice with virulent strain of B. anthracis showed that rPA is functional to protect against pathogenic strain. 相似文献
19.
A new flavonoid, kaempferol-3,4′-di-O-α-L-rhamnopyranoside (1), and three known flavonoids (2–4) were isolated from the aerial parts of T. communis L. The structure of the new compound was elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed significant antioxidant activity (IC50 187.151 ± 0.821 μM, and 92.079±0.513 μM, respectively), whereas compounds 3 and 4 showed moderate activity in DPPH free radical scavenging assays.
Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 295–297, May–June, 2009. 相似文献
20.
Microorganisms producing lipase were isolated from soil and sewage samples and screened for enantioselective resolution of
(R,S)-methyl mandelate to (R)-mandelic acid. A strain designated as GXU56 was obtained and identified as Burkholderia sp. Preparing immobilized GXU56 lipase by simple adsorption on octyl sepharose CL-4B, the optimum temperature was shifted
from 40 °C (free lipase) to 50 °C (immobilized lipase), and the optimum pH was shifted from 8.0 (free lipase) to 7.2 (immobilized
lipase). The immobilized enzyme displayed excellent stability in the pH range of 5.0–8.0, at the temperatures below 50 °C
and in organic solvents compared with free enzyme. Enantioselectivity ratio for (R)-mandelic acid (E) was dramatically improved from 29.2 to more than 300 by applying immobilized lipase in the resolution of (R,S)-methyl mandelate. After five cycles of use of immobilized lipase, conversion and enantiomeric excess of (R)-mandelic acid were 34.5% and 98.5%, respectively, with enantioselectivity ratio for (R)-mandelic acid (E) of 230. Thus, octyl-sepharose-immobilized GXU56 lipase can be used as a bio-resolution reagent for producing (R)-mandelic acid. 相似文献