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Chemical extraction

Xem 1-20 trên 141 kết quả Chemical extraction
  • In pursuit of evaluating the suitability of methods for determining the ability of soils to supply available nitrogen under different soil conditions, two biological aerobic and anaerobic incubation procedures and six chemical extraction methods were applied to 31 samples of soil collected from the Central Anatolian area.

    pdf9p aquaman27 15-01-2019 11 0   Download

  • Preparations derived from Lentinula edodes (Berk.) Pegl. mycelium are worldwide used as dietary supplements containing compounds active as immune system enhancers, demonstrating chemopreventive and anticancer activity. L. edodes mycelium enriched with organic forms of selenium like selenized yeast possess putative, higher cancer preventive properties. The objective of this study was to test the effect of enrichment in selenium on antioxidant, reducing and free radical scavenging activity of water and alcohol extracts from mycelium of L. edodes (Berk.).

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  • The electrophoretic deposition (EPD) method was adopted for a fabrication of nanocomposite layers composed of ZnO particles covered by the polythiopene shell in a reduced state. This composite was prepared by oxidative polymerization of thiophene monomer with iron (III) chloride as a catalyst in the presence of ZnO particles. After polymerization, polythiophene in oxidized form was reduced by the extraction in methanol. Electrochemical properties of the obtained composite were measured by cyclic voltammetry and electrochemical impedance spectroscopy.

    pdf6p uocvong02 24-09-2015 21 3   Download

  • Angelica sinensis (OLiv.) Diels ("Danggui") belongs to the family Umbelliferae. Its rhizomes are reputed to have marked restorative, antianaemic and haemagogic properties. From ethyl acetate and butanol extracts of rhizomes of this plant 8 nitrogen-containing compounds (1-8) have been isolated. Their structures were elucidated by means of MS and NMR spectroscopic methods as 5-oxo-proline, 5-oxo-prolin-ethylester, nicotinamide, tryptophane, perlolidine, 1,2,3,4-tetrahydro-1-methyl- -carboline-3-carboxylic acide, adenosine and uridine.

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  • 2-Amino-5-carboxymuconic 6-semialdehyde is an unstable intermediate in the meta-cleavage pathway of 4-amino-3-hydroxybenzoic acid inBordetellasp. strain 10d.In vitro, this compound is nonenzymatically converted to 2,5-pyrid-inedicarboxylic acid. Crude extracts of strain 10d grown on 4-amino-3-hydroxybenzoic acid converted 2-amino-5-car-boxymuconic 6-semialdehyde formed from 4-amino-3-hydroxybenzoic acid by the first enzyme in the pathway, 4-amino-3-hydroxybenzoate 2,3-dioxygenase, to a yellow compound (emax¼375 nm).

    pdf0p awards 05-04-2013 33 2   Download

  • -Sitosterol, stigmasterol, cardamomin (1), chalconaringenin 2-O-methyl ether (2), alpinetin (3), and naringenin 5-O-methyl ether (4) were isolated from the MeOH extract of Alpinia conchigera Griff. (Zingiberaceae). Their structures were determined on the basis of spectroscopic analyses. The antimicrobial and free radical scavenging activities of the isolates 1-4 were evaluated in correlation with those of the soluble fractions.

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  • Objectives of thesis: Determine the chemical composition and safety of TG extract; evaluate the effects of TG extract on CSUs in vitro rabbits; evaluate the clinical therapeutic efficacy of TG extract on CSUs stage II and III.

    doc35p change05 08-06-2016 46 2   Download

  • From the root of Calotropis gigantea, six compounds were isolated: 12-O-benzoyllineolon (1), 12-O-benzoyldeacetylmetaplexigenin (2), calotropone (3), 2,3-dimethoxyphenol (4), 2,5- dimethoxyphenol (5), 2-formyl-5-hydroxymethylfuran (6). The chemical structure of these compounds were elucidated by their NMR spectra and comparison with references.

    pdf5p estupendo5 31-08-2016 19 1   Download

  • Using combined chromatographic methods, four compounds were isolated from the nhexane and ethyl acetate extracts of the Ricinus communis in Melinh - Hanoi. Their structures were determined to be lupeol (1), epialeuritolic acid (2), ergosterol peroxide (3), and ricinine (4) by 1D-, 2D-NMR spectroscopic methods and in comparison with those reported in literature.

    pdf7p cumeo3000 01-08-2018 24 1   Download

  • The effect of chip size on hemicellulose extraction of wood and technological properties of flakeboard were investigated. Three different sizes of wood chips were treated with hot water in a digester at 170 °C for 90 min. After hydrothermal treatment, the wood chips were washed with water and then dried in a dryer.

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  • The natural product of tamanu oil is valuable in medicine and cosmetic. In this study, the tamanu oil was extracted by supercritical CO2 (sCO2) and Soxhlet (using hexane solvent) methods. The fatty acids and coumarins compound of the obtained tamanu oil were analyzed by gas chromatography–mass spectrometry (GC-MS). The antibacterial and anti-inflammatory activities were also investigated by the diffusion method and performed on the white mice ears (Swiss albino).

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  • This research focuses on the isolation and characterization of eight natural compounds from the ethyl acetate extract of Scoparia dulcis L. collected in An Giang province, Vietnam. Six flavonoid compounds: apigenin (1), luteolin (2), baicalein (3), oroxylin A (4), oroxylin A 7-O-βD-glucoside (5) and vitexin (6) along with two nitrogen-containing compounds: 2,4-dihydroxy1,4-benzoxazin-3-one (7) and uracil (8) were successfully isolated via the methods of natural product extraction.

    pdf6p cumeo3000 01-08-2018 21 0   Download

  • From the methanol extract of Bischofia javanica Blume leaves, five compounds including 5'-β-D-glucopyranosyloxyjasmonic acid methyl ester (1), 2-(4-hydroxy-3-methoxyphenyl)ethylO-β-D-glucopyranoside (2), hexyl-O-β-D-glucopyranoside (3), friedelan-3-one (4), and gallic acid (5) were isolated. Their structures were elucidated by NMR spectra as well as in comparison with previously reported data. This is the first report on the isolation of 1, 2, and 3 from Bischofia javanica.

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  • Phytochemical studied on methanol extract of fruits Fissistigma oldhami (Hemsl.) Merr. (Annonaceae) led to the isolation of four flavonoids: 6-hydroxy-5,7,8-trimethoxy flavanone, 2’,5’-dihydroxy-3’,4’,6’-trimethoxy chalcone, quercetin, rutin and two steroids: -sitosterol (5) and -sitosterol-3-O- -D-glucopyranoside (6). The structures of the compounds were established on the basic of spectroscopic methods (UV, IR, MS, 1D-NMR and 2D-NMR) and comparison with literature data. This is first time the 6 compounds isolated from the plant.

    pdf4p giesumanh 04-11-2018 32 0   Download

  • Chemical investigation of an acidic methanol extract of the whole plant of Datura metel resulted in the isolation of seven compounds, including pterodontriol B (1), disciferitriol (2), scopolamine (3), adenosine (4), thymidine (5), ilekudinoside C (6), and dioscoroside D (7). Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D NMR and mass spectra and in comparison with reported data in the literature. Among the isolated compounds, pterodontriol B, disciferitriol, ilekudinoside C, and dioscoroside D were reported for the first time from the Datura genus.

    pdf8p giesumanh 10-11-2018 13 0   Download

  • Two triterpenes, an anthraquinone, two lignans and a phenolic compound were isolated from the n-hexane and ethyl acetate extracts of the aerial part of Chirita drakei Burtt collected in islands, on mountain slopes of Ha Long bay, Quang Ninh province. Their structures have been elucidated by mass, NMR spectroscopy and comparison with published data. There are no report on the chemical constituents of Chirita drakei before our study.

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  • From the ethyl acetate extract of the rhizomes from Belamcanda chinensis (Iridaceae) five compounds irisflorentin (1), tectorigenin (2), iristectorigenin A (3), irigenin (4), and acetovanillone(5) were isolated. Their structures were elucidated by spectroscopic methods. This is first report of 5 from B. chinensis.

    pdf5p giesumanh 13-11-2018 11 0   Download

  • The volatile fraction of S. dulcis was analyzed by GC-MS to show the accumulation of methyl esters of fatty acids. The useful compound methoxybenzoxazolinone (MBOA) was found to be localized in the CH2Cl2- soluble fraction of the MeOH extract. For the direct qualitative and quantitative evaluation of MBOA in the CH2Cl2-soluble fraction 1 H-NMR method was applied in this study.

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  • Knema is a genus of tropical evergreen trees of the family Myristicaceae found in South East Asian countries such as Vietnam, Thailand, and Malaysia. In this paper, four lignans, (+)-pinoresinol (1),(+) epi-pinoresinol (2), piperitol (3), and pluviatilol (4), were isolated from the ethyl acetate extract of the fruit of Knema pachycarpa, an indigenus tree in Vietnam. The chemical structures were determined by spectroscopic data and comparison with the reported literature. These compounds were isolated from Knema genus for the first time.

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  • Five fungal secondary metabolites named 1,2,4,5-tetrachloro-3,6-dimethoxybenzene (1); ergosterol (2); ergosterol peroxide (3); (E)- 4-(3,4-dihydroxyphenyl)but-3-en-2-one (4) and [bi1,4-cyclohexandien-1-yl]-3,3’,6,6’-tetrone, 4, 4’-dihydroxyl-2,2’,5,5’-tetramethyl (5) were purified from the ethyl acetate fraction extract of the methanol extract fruit bodies of Phellinus gilvus (Schwein.) Pat.

    pdf6p dannisa 16-12-2018 20 0   Download

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