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1.
J Zhejiang Univ Sci B ; 20(11): 868-876, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31595723

RESUMO

Acrolein, known as one of the most common reactive carbonyl species, is a toxic small molecule affecting human health in daily life. This study is focused on the scavenging abilities and mechanism of ferulic acid and some other phenolic acids against acrolein. Among the 13 phenolic compounds investigated, ferulic acid was found to have the highest efficiency in scavenging acrolein under physiological conditions. Ferulic acid remained at (3.04±1.89)% and acrolein remained at (29.51±4.44)% after being incubated with each other for 24 h. The molecular mechanism of the detoxifying process was also studied. Detoxifying products, namely 2-methoxy-4-vinylphenol (product 21) and 5-(4-hydroxy-3-methoxyphenyl)pent-4-enal (product 22), were identified though nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS), after the scavenging process. Ferulic acid showed significant activity in scavenging acrolein under physiological conditions. This study indicates a new method for inhibiting damage from acrolein.

2.
J Chromatogr A ; 1601: 335-339, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31155143

RESUMO

Sodium valproate is the most commonly used antiepileptic drug that patients need to keep taking over a long period of time or on a permanent basis. Its blood concentration should be accurately detected to avoid toxicity or side-effects, especially for children and the aged. Dried blood spot (DBS) sampling from finger prick is a minimally invasive and patient-friendly procedure for blood collection. However, there are few studies about rapid detection of sodium valproate in DBS samples in current literatures. In this work, we developed an ink auxiliary headspace gas chromatography mass spectrometry (GC-MS) strategy for direct detection of sodium valproate in DBS from epilepsy patients, which does not need extra solvent extraction or elution. It was discovered that carbon black ink could provide better capacity of heat absorption and dissociation, and higher quality of headspace sampling. The detection sensitivity has been improved with reported headspace GC-MS methods, and the limit of quantitation could reach to 200 ng/mL. Finally, this strategy was practically applied to quantify sodium valproate in DBS samples from 29 epilepsy patients. The result showed higher accuracy with lower relative errors by comparing with the clinical immunoassay results. In conclusion, we developed a direct detection method for DBS samples that is suitable for high-throughput clinical test with great potential for clinical application.


Assuntos
Teste em Amostras de Sangue Seco/métodos , Cromatografia Gasosa-Espectrometria de Massas , Ácido Valproico/análise , Anticonvulsivantes/análise , Anticonvulsivantes/sangue , Criança , Monitoramento de Medicamentos , Humanos , Manejo de Espécimes , Ácido Valproico/sangue
3.
Nat Chem ; 9(2): 188-193, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28282048

RESUMO

Developing homogeneous catalysts that convert CS2 and COS pollutants into environmentally benign products is important for both fundamental catalytic research and applied environmental science. Here we report a series of air-stable dimeric Pd complexes that mediate the facile hydrolytic cleavage of both CS2 carbon-sulfur bonds at 25 °C to produce CO2 and trimeric Pd complexes. Oxidation of the trimeric complexes with HNO3 regenerates the dimeric starting complexes with the release of SO2 and NO2. Isotopic labelling confirms that the carbon and oxygen atoms of CO2 originate from CS2 and H2O, respectively, and reaction intermediates were observed by gas-phase and electrospray ionization mass spectrometry, as well as by Fourier transform infrared spectroscopy. We also propose a plausible mechanistic scenario based on the experimentally observed intermediates. The mechanism involves intramolecular attack by a nucleophilic Pd-OH moiety on the carbon atom of coordinated µ-OCS2, which on deprotonation cleaves one C-S bond and simultaneously forms a C-O bond. Coupled C-S cleavage and CO2 release to yield [(bpy)3Pd3(µ3-S)2](NO3)2 (bpy, 2,2'-bipyridine) provides the thermodynamic driving force for the reaction.

4.
Plant Cell ; 24(11): 4731-47, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23204407

RESUMO

Xyloglucan endohydrolase (XEH) and xyloglucan endotransglucosylase (XET) activities, encoded by xyloglucan endotransglucosylase-hydrolase (XTH) genes, are involved in cell wall extension by cutting or cutting and rejoining xyloglucan chains, respectively. However, the physiological significance of this biochemical activity remains incompletely understood. Here, we find that an XTH31 T-DNA insertion mutant, xth31, is more Al resistant than the wild type. XTH31 is bound to the plasma membrane and the encoding gene is expressed in the root elongation zone and in nascent leaves, suggesting a role in cell expansion. XTH31 transcript accumulation is strongly downregulated by Al treatment. XTH31 expression in yeast yields a protein with an in vitro XEH:XET activity ratio of >5000:1. xth31 accumulates significantly less Al in the root apex and cell wall, shows remarkably lower in vivo XET action and extractable XET activity, has a lower xyloglucan content, and exhibits slower elongation. An exogenous supply of xyloglucan significantly ameliorates Al toxicity by reducing Al accumulation in the roots, owing to the formation of an Al-xyloglucan complex in the medium, as verified by an obvious change in chemical shift of (27)Al-NMR. Taken together, the data indicate that XTH31 affects Al sensitivity by modulating cell wall xyloglucan content and Al binding capacity.


Assuntos
Alumínio/toxicidade , Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Regulação Enzimológica da Expressão Gênica , Glucanos/metabolismo , Xilanos/metabolismo , Sequência de Aminoácidos , Arabidopsis/química , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Parede Celular/metabolismo , Quelantes/análise , Quelantes/metabolismo , Regulação para Baixo , Regulação da Expressão Gênica de Plantas , Glucanos/análise , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Mutagênese Insercional , Especificidade de Órgãos , Fenótipo , Filogenia , Folhas de Planta/química , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/enzimologia , Folhas de Planta/genética , Raízes de Plantas/química , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/enzimologia , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , Polissacarídeos/análise , Polissacarídeos/metabolismo , Proteínas Recombinantes de Fusão , Plântula/química , Plântula/efeitos dos fármacos , Plântula/enzimologia , Plântula/genética , Análise de Sequência de DNA , Xilanos/análise
6.
Molecules ; 16(3): 2551-60, 2011 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-21441860

RESUMO

The traditional methods used in natural product separation primarily target the major components and the minor components may thus be lost during the separation procedure. Consequently, it's necessary to develop efficient methods for the preparative separation and purification of relatively minor bioactive components. In this paper, a LC/MS method was applied to guide the separation of crude extract of lotus (Nelumbo nucifera Gaertn.) leaves whereby a minor component was identified in the LC/MS analysis. Afterwards, an optimized pH-zone-refining CCC method was performed to isolate this product, identified as N-demethylarmepavine. The separation procedure was carried out with a biphasic solvent system composed of hexane-ethyl acetate-methyl alcohol-water (1:6:1:6, v/v) with triethylamine (10 mM) added to the upper organic phase as a retainer and hydrochloric acid (5 mM) to the aqueous mobile phase eluent. Two structurally similar compounds--nuciferine and roemerine--were also obtained from the crude lotus leaves extract. In total 500 mg of crude extract furnished 7.4 mg of N-demethylarmepavine, 45.3 mg of nuciferine and 26.6 mg of roemerine with purities of 90%, 92% and 96%, respectively. Their structures were further identified by HPLC/ESI-MSn, FTICR/MS and the comparison with reference compounds.


Assuntos
Alcaloides/isolamento & purificação , Cromatografia Líquida/métodos , Distribuição Contracorrente/métodos , Espectrometria de Massas/métodos , Folhas de Planta/química , Cromatografia Líquida de Alta Pressão , Concentração de Íons de Hidrogênio
7.
Mol Divers ; 15(3): 809-15, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21222031

RESUMO

A highly efficient and catalyst-free method for the synthesis of substituted thiourea derivatives is presented. The synthesis is performed through the reaction of thiazolidine-2-thiones with various amines in water. A sound number of thioureas with both unsymmetrical and symmetrical architectures have been obtained in good to excellent yields.


Assuntos
Tioureia/análogos & derivados , Catálise , Tiazolidinedionas/química , Tionas/química , Tioureia/síntese química , Tioureia/química , Água
8.
J Agric Food Chem ; 58(16): 9020-7, 2010 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-20677737

RESUMO

Resveratrol and its oligomers, abundantly present in wine grapes, are believed to be effective phytoalexins for the phenomenon "French paradox" partially by virtue of their powerful antiradical properties. EPR spin-trapping technique was utilized, demonstrating all polyphenols were selective (1)O2 quenchers but not effective (•)OH and O2(•¯) scavengers. On the basis of the HPLC-ESI-MS(2) analysis for the simulated reactions of polyphenols with (1)O2, the molecular weights of the resulting photochemical products were 14 or 28 Da higher than those of their substrates. No fragment C2H2O (42 Da), which was rather distinctive of the resorcinol rings in these cases, had been observed, whereas their MS/MS spectra displayed characteristic neutral fragments including carbon monoxide (CO, 28 Da) and 2-hydroxy[1,4]benzoquinone (C6H4O3, 124 Da). Finally, PM3 semiempirical calculations and HR-FTICR-MS experiments were performed, supporting the assertion that their quenching mechanism involved physical and chemical pathways. Chemical quenching underwent an endoperoxide intermediate form to generate quinones.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Oxigênio/metabolismo , Polímeros/farmacologia , Espectrometria de Massas por Ionização por Electrospray/métodos , Estilbenos/farmacologia , Espectrometria de Massas em Tandem/métodos , Vitis/química , Espectroscopia de Ressonância de Spin Eletrônica , Polímeros/química , Resveratrol , Estilbenos/química
9.
Inorg Chem ; 49(17): 7783-92, 2010 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-20690696

RESUMO

By employing diimine ligands coordinated dimetallic clips ([(bpy)2Pd2(NO3)2](NO3)2 or [(phen)2Pd2(NO3)2](NO3)2, where bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) as the corner and anthracene-, naphthalene-, and benzene-based dipyrazolate dianions as the linker, a series of positively charged metallomacrocycles ([M4L2]4+ or [M8L4]8+) have been synthesized through a directed self-assembly method in aqueous solution. Every macrocycle has a cavity to bind solvent molecules or anions. The structures were characterized by elemental analysis, 1H and 13C NMR, electrospray ionization mass spectrometry, and single crystal X-ray diffraction analysis for compound 1 x 4 PF6(-) (1 = {[(bpy)Pd]4L(1)2}4+), 3 x 4 PF6(-) x 8 CH3CN x H2O (3 = {[(bpy)Pd]4L(2)2}4+), and 7 x 4 PF6(-) x 6 H2O (7 = {[(bpy)Pd]4L(5)2}4+). The 1:1 host-guest complexation for anthracene-based dipyrazolate-bridged macrocycles with aromatic guests was investigated via UV-vis and fluorescent titration.


Assuntos
Compostos Macrocíclicos/química , Compostos Organometálicos/química , Pirazóis/química , 2,2'-Dipiridil/síntese química , 2,2'-Dipiridil/química , Antracenos/síntese química , Antracenos/química , Compostos Macrocíclicos/síntese química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Naftalenos/síntese química , Naftalenos/química , Compostos Organometálicos/síntese química , Fenantrolinas/síntese química , Fenantrolinas/química , Pirazóis/síntese química , Espectrometria de Massas por Ionização por Electrospray , Difração de Raios X
10.
Dalton Trans ; 39(13): 3203-11, 2010 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-20449448

RESUMO

By employing different diimine complexes and a naphthanoimidazolate (L(1)) or benzoimidazolate (L(2)) anion ligand as linker, a series of trimetallo-macrocycles have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the ligands in aqueous solution. Some compounds, namely, [M(3)L(3)](NO(3))(3) (M = (18-crown-6-phen)Pt, 1 or 7; (15-crown-5-phen)Pt, 2; (benzo-24-crown-8-phen)Pt, 8; (benzo-24-crown-8-phen)Pd, 9; (15-crown-5-phen)Pd, 4 or 11; (18-crown-6-phen)Pd, 3 or 10; (dmbpy)Pd, 6 or 14; (bpy)Pd, 5 or 13; (bpy)Pt, 12; (N4-Phen)Pd, 15) were synthesized. In all of these compounds, the L(1)or L(2) anion ligands are in a syn, syn, syn orientation which result in a bowl-like cavity that can serve as a host to bind the methyl of a solvent CH(3)CN within the naphthanoimidazolate or benzoimidazolate-built cavity through C-H...pi hydrogen bonds in the crystal state. The structures are characterized by elemental analysis, (1)H NMR, ESI-MS, and in the cases of 4a, 11, 13, and 14a by single-crystal X-ray diffraction analysis.

11.
Chem Commun (Camb) ; (19): 2768-70, 2009 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-19532949

RESUMO

A novel and facile cascade Biginelli-like assembly employing enaminone, aldehyde and urea/thiourea has been developed, which provides a highly chemo- and regioselective synthesis of new dihydropyrimidinones, 1,3-thiazines and chromones by altering particular functional groups in the reactants.

12.
J Org Chem ; 74(7): 2862-5, 2009 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-19256480

RESUMO

The three-component sequential reaction of alpha,beta-unsaturated aldehydes, amines, and enaminones proceeded smoothly to give 1,3,4-trisubstituted 1,4-dihydropyridines in aqueous DMF. Moreover, the unexpected regioselective formation of 1,2-dihydropyridines has been observed for the first time in such an approach. On the basis of a systematic study, the novel regioselectivity could be assigned both to steric and electronic effects originating from the amine partner.


Assuntos
Di-Hidropiridinas/síntese química , Di-Hidropiridinas/química , Estrutura Molecular , Estereoisomerismo
13.
Zhongguo Zhong Yao Za Zhi ; 33(15): 1843-6, 2008 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-19007012

RESUMO

OBJECTIVE: To study the chemical constituents and the antibacterial activity from n-butanol extract of Sarcandra glabra. METHOD: The compounds were isolated by Diaion HP-20, Sephadex LH-20, MCI CHP-20 and silica gel column chromatographic methods. Their structures were identified on the basis of physicochemical and spectroscopic analysis. The antibacterial effect of the compounds were measured against Staphylococcus aureus by filterpaper slice method, finally the antibacterial ring in each group was recorded after 24 hours. RESULT: Seven constituents were isolated and elucidated as 5, 7, 3', 4'-tetrahydroxy-6-C-beta-D-glucopyranosylflavanone (1), kaempferol-3-O-beta-D-glucuronide (2), fraxidin (3), isofraxidin (4), isofraxidin-7-O-beta-D-glucopyranoside (5), kaempferol (6), pinostrobin (7). Diameters (in mm) of antibacterial ring in the compounds 2, 5, 6 were orderly recorded as follows: 14.67 +/- 0.08, 11.14 +/- 1.06, 8.26 +/- 1.26 and the compound 4 is not effective. CONCLUSION: Compounds 1-3 and 5 were isolated from S. glabra for the first time.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Butanóis/química , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/farmacologia , Magnoliopsida/química , Antibacterianos/isolamento & purificação , Medicamentos de Ervas Chinesas/isolamento & purificação , Espectroscopia de Ressonância Magnética , Staphylococcus aureus/efeitos dos fármacos
14.
J Zhejiang Univ Sci B ; 9(9): 721-7, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18763305

RESUMO

In order to investigate the antioxidant properties of the polysaccharides from the brown alga Sargassum fusiforme, the crude polysaccharides from S. fusiforme (SFPS) were extracted in hot water, and the lipid peroxidation inhibition assay exhibited that SFPS possessed a potential antioxidant activity. Hence, two purely polymeric fractions, SFPS-1 and SFPS-2 were isolated by the column of DEAE (2-diethylaminoethanol)-Sepharose Fast Flow, with their molecular weights of 51.4 and 30.3 kDa determined by high performance gel permeation chromatography (HPGPC). They were preliminarily characterized using chemical analysis in combination of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies and found to contain large amounts of uronic acids and beta-glycosidical linkages. The antioxidant activities of these two SFPS fractions were evaluated using superoxide and hydroxyl radical-scavenging assays. The results show that the antioxidant ability of SFPS-2 was higher than that of SFPS-1, probably correlating with the molecular weight and uronic acid content.


Assuntos
Antioxidantes/química , Polissacarídeos/química , Sargassum/metabolismo , Concentração de Íons de Hidrogênio , Peso Molecular , Projetos Piloto
15.
Chem Biodivers ; 5(7): 1298-303, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18649316

RESUMO

Chemical investigation of the leaves and stems of Chloranthus henryi resulted in the isolation and characterization of two new eudesmane-type sesquiterpenes, and two new germacrane-type sesquiterpenes, together with two known compounds. The inhibitory activities against tyrosinase of all isolates were also evaluated.


Assuntos
Medicamentos de Ervas Chinesas/isolamento & purificação , Inibidores Enzimáticos/isolamento & purificação , Monofenol Mono-Oxigenase/antagonistas & inibidores , Sesquiterpenos/isolamento & purificação , Medicamentos de Ervas Chinesas/química , Inibidores Enzimáticos/química , Ressonância Magnética Nuclear Biomolecular , Sesquiterpenos/química
16.
Zhongguo Zhong Yao Za Zhi ; 33(4): 424-7, 2008 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-18533503

RESUMO

OBJECTIVE: To investigate the changes of MDA, SOD, LDH of cultured hippocampal neurons injury induced by amyloid-beta protein (Abeta 25-35) and the protective effect of puerarin and ligustrazine. METHOD: Primary hippocampal neurons were cultured and induced by Abeta 25-35. The concentrations of MDA, SOD and LDH in cultured hippocampal neurons were measured after exposed to Abeta 25-35, puerarin and ligustrazine. RESULT: The Alzheimer disease (AD) model was successfully established in cultured hippocampal neurons. AD group has remarkably increased MDA and LDH level, and decreased SOD level, Piracetan group and combined application group of have remarkably decreased MDA and LDH level and increased SOD level, compared with AD group (P < 0.01). Ligustrazine together with puerarin group has remarkably decreased MDA and LDH level and increased SOD level, compared with ligustrazine group and puerarin group (P < 0.05). CONCLUSION: Abeta 25-35 can induce cultured hippocampal neurons injury, combined application of ligustrazine, and puerarin can alleviate the injury.


Assuntos
Peptídeos beta-Amiloides/farmacologia , Hipocampo/citologia , Isoflavonas/farmacologia , Neurônios/efeitos dos fármacos , Pirazinas/farmacologia , Animais , Células Cultivadas , Ratos
17.
Inorg Chem ; 47(6): 2142-54, 2008 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-18271506

RESUMO

By employing functional diimine ligands coordinated dipalladium(II,II) or diplatinum(II,II) clips as corners and the coplanar 4,4'-bipyrazolate dianion (L(2-)) ligand as linker, a series of bipyrazolate-bridged metallo-macrocycles, namely, [M8L4](NO3)8 (M = Pd(dmbpy), 1; Pd(bpy), 2; Pt(bpy), 3a; Pd(phen), 4; Pt(phen), 5; Pd(15-crown-5-phen), 6; Pd(18-crown-6-phen), 8; Pd(benzo-24-crown-8-phen), 10a; Pt(15-crown-5-phen), 7a, Pt(18-crown-6-phen), 9a; Pt(benzo-24-crown-8-phen), 11a) and [M6L3](NO3)6 (M = Pt(bpy), 3b; Pt(15-crown-5-phen), 7b; Pt(18-crown-6-phen), 9b; Pd(benzo-24-crown-8-phen), 10b; Pt(benzo-24-crown-8-phen), 11b), have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the 1H-bipyrazolyl ligands in aqueous solution. All these compounds have a crown-shaped cavity that can serve as host to solvent molecules and anions. The structures are characterized by elemental analysis, (1)H and (13)C NMR, ESI-MS, and in the cases of 1a (the BF4(-) salt of 1), 2a (the BF4(-) salt of 2), and 3b by single-crystal X-ray diffraction analysis. Photophysical properties for complexes 1 and 2 are discussed.

18.
Appl Microbiol Biotechnol ; 78(6): 947-53, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18286279

RESUMO

Apidaecins are heat-stable, nonhelical antibacterial peptides isolated from lymph fluid of the honeybee (Apis mellifera). These peptides are active against a wide range of gram-negative bacteria and they are the most prominent components of the honeybee humoral defense against microbial invasion. In the present study, one isoform of apidaecin, apidaecin Ho, was expressed extracellularly in the food-grade bacterium Lactococcus lactis. Results showed that expression driven by the lactococcal nisA promoter and Usp45 signal peptide resulted in efficient secretion of apidaecin in L. lactis subsp. cremoris NZ9000. Recombinant apidaecin was purified by gel filtration and semipreparative RP-HPLC, and about 10 mg active recombinant apidaecin was obtained from 1,000 ml culture. This is the first report on the nisin-controlled extracellular production of active apidaecin in L. lacits. The expression and delivery of apidaecin in the food-grade L. lactis may provide a clue to facilitate the widespread application of apidaecin in the control and prevention of gram-negative bacteria infections of human and animals.


Assuntos
Peptídeos Catiônicos Antimicrobianos/metabolismo , Engenharia Genética , Lactococcus lactis/genética , Lactococcus lactis/metabolismo , Nisina/genética , Animais , Antibacterianos/análise , Antibacterianos/isolamento & purificação , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/análise , Peptídeos Catiônicos Antimicrobianos/isolamento & purificação , Peptídeos Catiônicos Antimicrobianos/farmacologia , Abelhas/química , Células CACO-2 , Escherichia coli/efeitos dos fármacos , Vetores Genéticos , Humanos , Espectrometria de Massas , Regiões Promotoras Genéticas , Proteínas Recombinantes/análise , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia
19.
J Pept Sci ; 14(6): 697-707, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18076126

RESUMO

Two aspects were studied to elucidate the functional and structural characterization of apidaecin and its N-terminal and C-terminal fragments: (i) Functions of the N-terminal and C-terminal fragments of apidaecin were first studied by measuring their antibacterial activity, their ability to enter Escherichia coli cells and their effects on the activities of beta-galactosidase and alkaline phosphatase. The results indicate that neither the N-terminal nor the C-terminal of apidaecin contains intracellular delivery unit or active segment. (ii) The effect of apidaecin on the ATPase activity of DnaK, and the interactions of apidaecin with E.coli lidless DnaK and DnaK D-E helix were studied. Results showed that apidaecin could interact with the E.coli lidless DnaK protein and stimulate its ATPase activity, but not with E.coli DnaK D-E helix. This indicated that the antimicrobial activity of apidaecin may be shown by stimulating the ATPase activity of DnaK by binding to its conventional substrate-binding site, to decrease its cellular concentration of DnaK by competing with natural substrates and inhibit the enzymes' activities of E. coli cells. It is the first study to suggest that the apidaecin-binding site of DnaK is the conventional substrate binging site.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Adenosina Trifosfatases/metabolismo , Sequência de Aminoácidos , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , Dados de Sequência Molecular , Dobramento de Proteína , Espectrometria de Massas por Ionização por Electrospray
20.
Zhongguo Zhong Yao Za Zhi ; 32(15): 1539-41, 2007 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-17972583

RESUMO

OBJECTIVE: To study the chemical constituents of Microtropis triflora. METHOD: The compounds were isolated by chromatography on silica gel and Sephadex LH-20. There structures were elucidatedby by chemical methods and spectral analysis. RESULT: Five triterpenoids were isolated and elucidated as friedelin (1), 3-oxo-28-friedelanoic acid (2), 29-hydroxy-3-friedelanone (3), salaspermic acid (4), orthosphenic acid (5). CONCLUSION: Compounds 1-5 are all isolated from M. triflora for the first time.


Assuntos
Celastraceae/química , Plantas Medicinais/química , Triterpenos/isolamento & purificação , Caules de Planta/química , Triterpenos/química
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