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排序方式: 共有163条查询结果,搜索用时 390 毫秒
101.
El Sayed H. El Ashry Nagwa Rashed Ahmed Mousaad 《Journal of carbohydrate chemistry》2013,32(4):599-607
Abstract Dehydrative cyclization of the condensation product of 2, 3, 4, 5-tetra-O-acetyl-galactaryl chloride with anthranilic acid gave 1, 2, 3, 4-tetra-O-acetyl-1, 4-bis(4H-benzoxazin-4-one-2-yl)-galacto-tetritol. Its reaction with aniline in the presence of phosphorus trichloride afforded 1, 4-bis (3-phenylquinazolin-4-one-2-yl)-1, 2, 3, 4-tetra-O-acetyl-galacto-tetritol. 相似文献
102.
Saponifiable and unsaponifiable fractions of Ficus microcarpa leaves hexane extract have been phytochemically studied and evaluated for its hypolipidaemic and antioxidant effects in hypercholesterolemic rats. The effect of the extract on the lipid profile was assessed by measuring the levels of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, phospho and total lipids. Lipid peroxides, glutathione and superoxide dismutase were measured as antioxidants. The work was extended to evaluate liver function indices as well as the histopathological picture of the liver after treatment. Treatment with leaves extract (500 mg kg?1 body weight) 5 times/week for 9 weeks at the same time of cholesterol administration (30 mg/0.3 mL 0.7% tween/animal) recorded an improvement of lipid profile, antioxidants, liver function enzymes and the liver histopathological picture. The lipoidal matters of the unsaponifiable fraction of the hexane extract by GC/MS led to the identification of 22 compounds, while saponifiable fraction by (MS/MS) technique led to identification of 13 unsaturated and saturated fatty acid methyl ester derivatives. It can be concluded that the hexane extract of F. microcarpa L has been proved to have hypolipidaemic and antioxidant effects in hypercholesterolemic rats through its role in counteracting LDL oxidation, enhancement of HDL synthesis and inhibition of lipid peroxidation. 相似文献
103.
A series of 3,5-disubstituted pyrazole-1-carboxamides were obtained by treatment of chalcones with semicarbazide hydrochloride in dioxane containing sodium acetate/acetic acid as a buffer solution. N-acetyl derivatives of pyrazole-1-carboxamides were isolated in good yields either by treatment of the carboxamide derivatives with acetic anhydride or refluxing chalcones with semicarbazide in ethanol containing few drops of acetic acid to give the corresponding hydrazones. Subsequent treatment of hydrazones with acetic anhydride gave the desired N-acetyl pyrazole-1-carboxamides derivatives. When chalcones were refluxed with dioxane containing few drops of acetic acid, 4,5-dihydropyrazole-1-carboxamides were isolated, which were subsequently oxidized using 5% sodium hypochlorite in dioxane to afford pyrazole-1-carboxamides. The structures of isolated compounds were confirmed by elemental analyses and spectral methods. The isolated compounds were tested for their antimicrobial activities. 相似文献
104.
Nagwa M. Fawzy Khadiga M. Ahmed Heba M. Abo-Salem Magdy S. Aly 《Journal of heterocyclic chemistry》2020,57(7):2748-2761
Based on the considerable features of the multicomponent reactions (MCRs) in the field of organic and medicinal chemistry, the present work was designed to synthesize a new series of imidazole, pyridine, and pyrimidine derivatives using MCRs to obtain new anti-proliferative agent beside exploration of their interaction mechanism by molecular docking technique. MCRs of furochromone carbaldehyde 1 , benzoin, and ammonium acetate afforded the corresponding 2,4,5-trisubstituted imidazole 2 . However, MCRs of 1 with benzoin, amine derivatives, and ammonium acetate yielded the corresponding 1,2,4,5-tetrasubstituted imidazole 3a,b . In addition, pyridine 4a,b-5a,b and pyrimidine derivatives 6a,d were synthesized via condensation of 1 with different carbonyl compounds and ammonium acetate or benzyl urea, respectively. The in-vitro anti-Proliferative activities of the new furochromone derivatives were screened toward MCF-7 and HepG-2 cancer cell lines as well as the normal cell line (human normal melanocyte, HFB4) in comparison to the known anticancer drugs: 5-fluorouracil and doxorubicin using MTT assay. Compounds 5a and 5b revealed effective anti-proliferative activity against MCF-7 cell lines with IC 50 18 and 22 μg/mL, respectively, compared to 5-fluorouracil (IC 50 of 13 μg/mL). However, compounds 6a-d exhibited potent activity against HepG-2 cancer cell lines of IC 50 ranging from 18 to 20 μg/mL compared to doxorubicin (IC 50 of 14 μg/mL). Moreover, the binding mode of the most active furochromones 5a,b and 6a-d inside the active site of the epidermal growth factor receptor (EGFR) kinase enzyme (PDB ID: 5CAV) were studied using molecular docking technique. Compounds 6b,c showed excellent docking results compared to the known EGFR inhibitors ( 4ZQ ). 相似文献
105.
106.
Al-Dirbashi OY Santa T Al-Qahtani K Al-Amoudi M Rashed MS 《Rapid communications in mass spectrometry : RCM》2007,21(13):1984-1990
We describe a new approach applicable to the determination of organic acids that serve as diagnostic markers for several inherited metabolic disorders. We utilized liquid chromatography/tandem mass spectrometry for analysis of organic acid derivatives of a recently described benzofurazan reagent. The derivatization step was necessary to obtain organic acid derivatives suitable for analysis by reversed-phase liquid chromatography with high ionization efficiency for mass spectrometry in the positive-ion mode. In this work, a group of related dicarboxylic acid markers containing five or six carbon atoms were analyzed and validation was performed for glutaric and 3-hydroxyglutaric acids, the specific markers for glutaric acidemia type 1. Derivatization was achieved by reacting untreated urine with the derivatization reagent under mild conditions. The reaction mixture was analyzed on a C18 ultra-performance liquid chromatography (UPLC) column (50x2.1 mm, 1.7 microm) and detected in the multiple reaction monitoring mode in 5 min. Calibration curves were linear up to at least 1000 microM with detection limits for glutaric and 3-hydroxyglutaric acids of 0.025 and 0.02 microM, respectively (signal-to-noise ratio of 3). Intra-day (n=11) and inter-day (n=6) coefficients of variation were better than 11.2%. The assay was successfully applied to control (n=134) and glutaric acidemia type 1 (n=55) urine samples. 相似文献
107.
Suzuki H Aly NS Wataya Y Kim HS Tamai I Kita M Uemura D 《Chemical & pharmaceutical bulletin》2007,55(5):821-824
Quinoline hexose analogs are expected to be useful as novel agents for treatment of chloroquine-resistant malaria. Here, we report preparation of 4-hydroxy quinoline-beta-glucosides from anilines in 4 steps. 相似文献
108.
109.
This paper presents a new boundary element formulation for free vibration analysis of two-dimensional elastic structures. The dual reciprocity method (DRM) is introduced using the multiquadric radial basis functions (MQ). The required particular solution kernels for displacement and traction are derived and smoothed using simple mathematical trick; hence the limiting values of these kernels are computed. The eigen-problem of displacement is formulated and solved to obtain the required frequencies of different vibration modes. Finally, several numerical problems are studied to demonstrate the validity and accuracy of the developed formulation. The results are compared to those obtained from other interpolation functions, and finite element analysis to demonstrate the validity and superiority of the present formulation. 相似文献
110.
Sikder Sunbeam Islam Mohammad Rashed Iqbal Faruque Mohammad Tariqul Islam 《Applied Physics A: Materials Science & Processing》2014,116(2):723-733
This paper reveals the design and analysis of a new split-H-shaped metamaterial unit cell structure that is applicable for multi-band frequency range, and it shows negative permeability and permittivity at those frequency bands. In the basic design, the two separate split square resonators have been added by a metal link to form H-shape unit structure. Moreover, the analyses and comparison of the 1 × 1-array, 2 × 2-array structures and 1 × 1, 2 × 2 unit cell configurations have been investigated. All these configurations demonstrate its multi-band operating frequency (S-band, C-band, X-band, K u -band) with double negative characteristics. The equivalent circuit model for the unit cell is presented to demonstrate the validation of the resonant behavior. The commercially available finite-difference time-domain based simulation software CST microwave studio has been used to get the reflection and transmission parameters of the unit cell. In summation, the material also exhibits single negative characteristics in the multi-band frequency range if it is projected on the 20 × 20 mm2 substrates. The simplicity, scalability, double negative characteristics, and multi-band operations have made this design novel in the electromagnetic paradigm. 相似文献