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1.
EMBO Rep ; 24(4): e56932, 2023 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-36862324

RESUMO

Obesity is associated with metabolic disorders and chronic inflammation. However, the obesity-associated metabolic contribution to inflammatory induction remains elusive. Here, we show that, compared with lean mice, CD4+ T cells from obese mice exhibit elevated basal levels of fatty acid ß-oxidation (FAO), which promote T cell glycolysis and thus hyperactivation, leading to enhanced induction of inflammation. Mechanistically, the FAO rate-limiting enzyme carnitine palmitoyltransferase 1a (Cpt1a) stabilizes the mitochondrial E3 ubiquitin ligase Goliath, which mediates deubiquitination of calcineurin and thus enhances activation of NF-AT signaling, thereby promoting glycolysis and hyperactivation of CD4+ T cells in obesity. We also report the specific GOLIATH inhibitor DC-Gonib32, which blocks this FAO-glycolysis metabolic axis in CD4+ T cells of obese mice and reduces the induction of inflammation. Overall, these findings establish a role of a Goliath-bridged FAO-glycolysis axis in mediating CD4+ T cell hyperactivation and thus inflammation in obese mice.


Assuntos
Ácidos Graxos , Inflamação , Animais , Camundongos , Camundongos Obesos , Ácidos Graxos/metabolismo , Inflamação/metabolismo , Obesidade/metabolismo , Glicólise , Ubiquitina-Proteína Ligases/metabolismo , Oxirredução
2.
Br J Haematol ; 191(5): 906-919, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32729137

RESUMO

Severe acquired aplastic anaemia (AA) is a serious disease characterised by autoreactive T cells attacking haematopoietic stem cells, leading to marrow hypoplasia and pancytopenia. Immunosuppressive therapy combined with antithymocyte globulin and ciclosporin can rescue most patients with AA. However, the relapse after ciclosporin withdrawal and the severe side effects of long-term ciclosporin administration remain unresolved. As such, new strategies should be developed to supplement current therapeutics and treat AA. In this study, the possibility of all-trans-retinoic acid (ATRA) as an alternative AA treatment was tested by using an immune-mediated mouse model of AA. Results revealed that ATRA inhibited T-cell proliferation, activation and effector function. It also restrained the Fas/Fasl pathway, shifted Th1 towards Th2 cell development, rebalanced T-cell subsets at a relatively high level and corrected the Th1/Th2 ratio by targeting NFAT1 signalling. In addition, ATRA inhibited Th17 cell differentiation and promoted regulatory T-cell development. Therefore, ATRA was an effective agent to improve AA treatment outcomes.


Assuntos
Anemia Aplástica/imunologia , Diferenciação Celular/efeitos dos fármacos , Fatores de Transcrição NFATC/imunologia , Transdução de Sinais/imunologia , Células Th1/imunologia , Células Th2/imunologia , Tretinoína/farmacologia , Anemia Aplástica/patologia , Animais , Diferenciação Celular/imunologia , Feminino , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Transdução de Sinais/efeitos dos fármacos , Células Th1/patologia , Células Th17/imunologia , Células Th17/patologia , Células Th2/patologia
3.
Med Sci Monit ; 26: e923411, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32266878

RESUMO

BACKGROUND Acute lymphocytic leukemia (ALL) is a common blood cancer which induces high mortality in children. Bromodomains and extra-terminal (BET) protein inhibitors, such as JQ1 and ARV-825, are promising cancer therapeutic agents that can be used by targeting c-Myc. A recent work reported that JQ1 effectively attenuates ALL in vitro by suppressing cell proliferation and accelerating apoptosis. The purpose of this research was to probe into the potential mechanism of how JQ1 inhibits ALL cell proliferation in vitro. MATERIAL AND METHODS Cell viability of ALL cells were measured by CTG after treatment by JQ1. Cell cycle analysis was done by EdU and PI staining. Cell apoptosis was assessed by Annexin V/PI staining. Glycolysis was detected using Seahorse and LC-MS kits. The expression of glycolytic rate-limiting enzymes was assessed by RNA-seq, qRT-PCR, and Western blot. RESULTS JQ1 suppressed cell proliferation by arresting the cell cycle and inducing the apoptosis of acute lymphocytic leukemia cells. JQ1 inhibited cell proliferation of B-ALL cells by restraining glycolysis. Conversely, the cell cycle block of B-ALL cells induced by JQ1 was partially abolished after pretreatment with 2-Deoxy-D-glucose (2-DG), an inhibitor of glycolysis. Furthermore, JQ1 restrained the glycolysis of B-ALL cell lines by remarkably downregulating the rate-limiting enzymes of glycolysis, such as hexokinase 2, phosphofructokinase, and lactate dehydrogenase A. Moreover, the cell cycle arrest was reversed in B-ALL cells with overexpressed c-Myc treated by JQ1, which is involved in the enhancement of glycolysis. CONCLUSIONS The BET inhibitor JQ1 suppresses the proliferation of ALL by inhibiting c-Myc-mediated glycolysis, thus providing a new strategy for the treatment of ALL.


Assuntos
Azepinas/farmacologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Proteínas/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-myc/antagonistas & inibidores , Triazóis/farmacologia , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Glicólise/efeitos dos fármacos , Células HEK293 , Humanos , Proteínas Nucleares/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Fatores de Transcrição/metabolismo
4.
Biochem Biophys Res Commun ; 518(2): 212-218, 2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31434610

RESUMO

Aplastic anemia (AA) is a serious blood system disease that threatens human health. At present, the main cause of this disease is believed to be immune hyperfunction. However, the specific metabolic mode involved in the occurrence of lymphocytes in AA is still unknown. In addition, whether rapamycin, a specific blocker of the mTOR signaling pathway, plays a therapeutic role by inhibiting lymphocyte metabolism remains unclear. We induced an AA mouse model through the classical immune-mediated pathway and simultaneously administered rapamycin intervention therapy. First, the AA-associated phenotypic changes and the efficacy of rapamycin in the treatment of AA were discussed. Second, the proliferation and metabolic pathway of bone marrow (BM) lymphocytes in AA and the effect of rapamycin on this process were determined. Finally, the expression levels of mTOR pathway-related proteins were analyzed. By inhibiting the mTOR signaling pathway, rapamycin could ameliorate the phenotype of the immune-mediated AA model and inhibit the proliferation of T cells by preventing cell cycle transition from G0 to G1 phase. Moreover, we found that mitochondrial oxidative phosphorylation is involved in the metabolic reprogramming of T cells in AA and that rapamycin can inhibit this process. We confirmed that mitochondrial oxidative phosphorylation is involved in the metabolic reprogramming of T cells in AA and further extended the mechanism of rapamycin in treating AA by inhibiting the mTOR signaling pathway. This viewpoint may provide a new therapeutic idea for clinical applications.


Assuntos
Anemia Aplástica/tratamento farmacológico , Imunossupressores/farmacologia , Sirolimo/farmacologia , Linfócitos T/efeitos dos fármacos , Anemia Aplástica/imunologia , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Masculino , Camundongos , Camundongos Congênicos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Linfócitos T/imunologia , Linfócitos T/patologia
5.
Biochem Biophys Res Commun ; 519(1): 1-7, 2019 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-31500806

RESUMO

Leucine-rich repeat containing G-protein-coupled receptor 6 (LGR6) is a member of the rhodopsin-like 7-transmembrane domain receptor superfamily and has high homology to LGR4 and LGR5. LGR6 is highly expressed in osteoblastic progenitors, and LGR6-deficient mice show nail and bone regeneration defect. However, the effect of LGR6 on the osteogenic differentiation of osteoblastic progenitors and its underlying mechanisms are largely unknown. In this study, we overexpressed and knockdown LGR6 with lentivirus in the preosteoblastic cell MC3T3-E1 to observe the effect of LGR6 on osteogenic differentiation and explore its possible molecular mechanism. LGR6 overexpression promoted osteogenic differentiation and mineralization by stabilizing ß-catenin to potentiate the Wnt/ß-catenin signaling pathway in MC3T3-E1 cells. Conversely, LGR6 knockdown inhibited osteogenic differentiation and mineralization by enhancing ß-catenin degradation to inactivate the Wnt/ß-catenin signaling pathway. These results reveal that LGR6 is highly expressed in osteoblastic progenitors, and promotes osteogenesis by enhancing ß-catenin stability to strengthen the Wnt signaling pathway. This study provides an important reference into the exact mechanisms of osteogenic differentiation.


Assuntos
Osteogênese , Receptores Acoplados a Proteínas G/metabolismo , Via de Sinalização Wnt , Animais , Calcificação Fisiológica , Diferenciação Celular , Linhagem Celular , Técnicas de Silenciamento de Genes , Camundongos , Estabilidade Proteica , Proteólise , beta Catenina/metabolismo
6.
Angew Chem Int Ed Engl ; 53(12): 3158-62, 2014 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-24677438

RESUMO

Hydrazonyl radicals are known for their p-electronic structures; however, their s-electronic structures have not been reported as yet. Herein, we show that readily accessible b,g- and g,d-unsaturated N-trichloroacetyl and Ntrifluoroacetyl hydrazones can be conveniently converted into hydrazonyl s radicals, which subsequently undergo 5-exo-trig radical cyclization at the N1 or N2 atom to form pyrazolines and azomethine imines, respectively.

7.
Transplantation ; 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38773837

RESUMO

BACKGROUND: Stimulation of myeloid-derived suppressor cell (MDSC) formation represents a potential curative therapeutic approach for graft-versus-host disease (GVHD), which significantly impacts the prognosis of allogeneic hematopoietic stem cell transplantation. However, the lack of an effective strategy for inducing MDSC production in vivo has hindered their clinical application. In our previous study, MDSC expansion was observed in interleukin (IL)-27-treated mice. METHODS: In this study, we overexpressed exogenous IL-27 in mice using a recombinant adeno-associated virus vector to investigate its therapeutic and exacerbating effects in murine GVHD models. RESULTS: In our study, we demonstrated that exogenous administration of IL-27 significantly suppressed GVHD development in a mouse model. We found that IL-27 treatment indirectly inhibited the proliferation and activation of donor T cells by rapidly expanding recipient and donor myeloid cells, which act as MDSCs after irradiation or under inflammatory conditions, rather than through regulatory T-cell expansion. Additionally, IL-27 stimulated MDSC expansion by enhancing granulocyte-monocyte progenitor generation. Notably, we verified that IL-27 signaling in donor T cells exerted an antagonistic effect on GVHD prevention and treatment. Further investigation revealed that combination therapy involving IL-27 and T-cell depletion exhibited remarkable preventive effects on GVHD in both mouse and xenogeneic GVHD models. CONCLUSIONS: Collectively, these findings suggest that IL-27 promotes MDSC generation to reduce the incidence of GVHD, whereas targeted activation of IL-27 signaling in myeloid progenitors or its combination with T-cell depletion represents a potential strategy for GVHD therapy.

8.
Nat Cell Biol ; 24(3): 353-363, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35256775

RESUMO

As one of the most induced genes in activated macrophages, immune-responsive gene 1 (IRG1) encodes a mitochondrial metabolic enzyme catalysing the production of itaconic acid (ITA). Although ITA has an anti-inflammatory property, the underlying mechanisms are not fully understood. Here we show that ITA is a potent inhibitor of the TET-family DNA dioxygenases. ITA binds to the same site on TET2 as the co-substrate α-ketoglutarate, inhibiting TET2 catalytic activity. Lipopolysaccharide treatment, which induces Irg1 expression and ITA accumulation, inhibits Tet activity in macrophages. Transcriptome analysis reveals that TET2 is a major target of ITA in suppressing lipopolysaccharide-induced genes, including those regulated by the NF-κB and STAT signalling pathways. In vivo, ITA decreases the levels of 5-hydroxymethylcytosine, reduces lipopolysaccharide-induced acute pulmonary oedema as well as lung and liver injury, and protects mice against lethal endotoxaemia, depending on the catalytic activity of Tet2. Our study thus identifies ITA as an immune modulatory metabolite that selectively inhibits TET enzymes to dampen the inflammatory responses.


Assuntos
Dioxigenases , Animais , DNA , Dioxigenases/metabolismo , Lipopolissacarídeos/toxicidade , Camundongos , Succinatos/metabolismo , Succinatos/farmacologia
9.
Front Oncol ; 11: 663360, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33889549

RESUMO

B-cell acute lymphocytic leukemia (B-ALL) is a malignant blood cancer that develops in children and adults and leads to high mortality. THZ1, a covalent cyclin-dependent kinase 7 (CDK7) inhibitor, shows anti-tumor effects in various cancers by inhibiting cell proliferation and inducing apoptosis. However, whether THZ1 has an inhibitory effect on B-ALL cells and the underlying mechanism remains obscure. In this study, we showed that THZ1 arrested the cell cycle of B-ALL cells in vitro in a low concentration, while inducing the apoptosis of B-ALL cells in vitro in a high concentration by activating the apoptotic pathways. In addition, RNA-SEQ results revealed that THZ1 disrupted the cellular metabolic pathways of B-ALL cells. Moreover, THZ1 suppressed the cellular metabolism and blocked the production of cellular metabolic intermediates in B-ALL cells. Mechanistically, THZ1 inhibited the cellular metabolism of B-ALL by downregulating the expression of c-MYC-mediated metabolic enzymes. However, THZ1 treatment enhanced cell apoptosis in over-expressed c-MYC B-ALL cells, which was involved in the upregulation of p53 expression. Collectively, our data demonstrated that CDK7 inhibitor THZ1 induced the apoptosis of B-ALL cells by perturbing c-MYC-mediated cellular metabolism, thereby providing a novel treatment option for B-ALL.

10.
Front Cell Dev Biol ; 9: 641271, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33748130

RESUMO

B-cell acute lymphocytic leukemia (B-ALL), a common blood cancer in children, leads to high mortality. Cyclin-dependent kinase 9 inhibitor (CDK9i) effectively attenuates acute myeloid leukemia and chronic lymphoblastic leukemia by inducing apoptosis and inhibiting cell proliferation. However, the effect of CDK9i on B-ALL cells and the underlying mechanisms remain unclear. In this study, we showed that CDK9i induced the apoptosis of B-ALL cells in vitro by activating the apoptotic pathways. In addition, CDK9i restrained the glycolytic metabolism of B-ALL cells, and CDK9i-induced apoptosis was enhanced by co-treatment with glycolysis inhibitors. Furthermore, CDK9i restained the glycolysis of B-ALL cell lines by markedly downregulating the expression of glucose transporter type 1 (GLUT1) and the key rate-limiting enzymes of glycolysis, such as hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA). Moreover, cell apoptosis was rescued in B-ALL cells with over-expressed c-Myc after treatment with CDK9i, which is involved in the enhancement of glycolytic metabolism. In summary, our findings suggest that CDK9 inhibitors induce the apoptosis of B-ALL cells by inhibiting c-Myc-mediated glycolytic metabolism, thus providing a new strategy for the treatment of B-ALL.

11.
Int J Anal Chem ; 2020: 8892696, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33061977

RESUMO

Simple and rapid high-performance liquid chromatography methods were developed for the determination of berberine (BB) in various rat tissues so as to evaluate a P-gp inhibitor, glycyrrhetinic acid (GA), on BB's oral bioavailability. Acetonitrile was used to extract BB from tissues and showed different extraction recoveries in diverse tissues. The intra- and interday precision and accuracy were less than 10%. Long-term stability, pre (post) -preparative stability, and freeze-thaw stability were evaluated, and the results showed it could meet the need of this study. The proposed methods were subsequently applied to investigate the possible drug-drug interaction of GA and BB in vivo from the aspect of tissue distribution. The results showed that no significant difference was found between the group of low dose and high dose at the same time point. The tissue distributions show a saturated model, i.e., the content of BB in tissue tends to be constant while its dose is more than 200 mg/kg. Besides, the contents of BB ranged from high to low according to the order of the liver, kidney, and spleen. The BB content in the liver is especially high as compared to other tissues.

12.
Sci Rep ; 9(1): 11308, 2019 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-31383927

RESUMO

A simple validated high performance liquid chromatography method was developed for the evaluation of the effect of three kinds of active ingredients in traditional Chinese medicine (TCM) on the pharmacokinetics of glycyrrhetinic acid (GA),a kind of active component from the most commonly used TCM licorice. Our results revealed that all of the calibration curves displayed good linearity. Intra- and inter-day precision for GA ranged from 2.54 to 3.98% and from 4.95 to 7.08%, respectively. The recovery rates for GA were determined to be 96.3-106.4%. All the samples showed satisfactory precision and accuracy in various stability tests. Plasma pharmacokinetic parameters including area under the concentration-time curve (AUC), elimination half-life (t1/2), time to peak concentration(Tmax) and peak concentration Cmax were calculated. No significant difference was found as compared the groups administrating GA with and without other ingredients from TCM.


Assuntos
Anti-Inflamatórios/farmacocinética , Medicamentos de Ervas Chinesas/farmacologia , Ácido Glicirretínico/farmacocinética , Interações Ervas-Drogas , Animais , Anti-Inflamatórios/farmacologia , Medicamentos de Ervas Chinesas/química , Feminino , Ácido Glicirretínico/farmacologia , Glycyrrhiza/química , Masculino , Ratos Sprague-Dawley
13.
J Chromatogr Sci ; 46(10): 848-53, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19007490

RESUMO

A rapid, simple, and specific liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for the determination of lisinopril in human plasma. Enalaprilat was used as the internal standard (IS). Sample preparation of the serum involved deproteination with methanol twice, repeatedly. Samples were separated using a Thermo Hypersil-HyPURITY C18 reversed-phase column (150 x 2.1 mm i.d., 5 microm). Mobile phase consisted of formic acid solution (pH 2.9)-methanol-acetonitrile (58:25:17, v/v). Lisinopril and its internal standard were measured by electrospray ion source in positive selected ion monitoring mode. The method was validated with a linear range of 2.5-320 ng/mL and the lowest limits of quantitation were 2.5 ng/mL for lisinopril. The extraction efficiencies were approximately 80% and recoveries of method were in range of 94.4-98.2%. The intra-day relative standard deviation (RSD) was less than 8.8% and inter-day RSD was within 10.3%. QC samples were stable when kept at ambient temperature for 24 h, at -20 degrees C for 30 days and after four freeze/thaw cycles. The method has been successfully applied to the evaluation of pharmacokinetics and bioequivalence of 2 lisinopril formulations in 18 healthy Chinese volunteers after an oral dose of 20 mg.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/sangue , Cromatografia Líquida/métodos , Lisinopril/sangue , Espectrometria de Massas por Ionização por Electrospray/métodos , Adulto , Inibidores da Enzima Conversora de Angiotensina/administração & dosagem , Inibidores da Enzima Conversora de Angiotensina/farmacocinética , Feminino , Humanos , Lisinopril/administração & dosagem , Lisinopril/farmacocinética , Masculino , Estrutura Molecular , Reprodutibilidade dos Testes , Equivalência Terapêutica , Adulto Jovem
14.
J Pharm Biomed Anal ; 43(4): 1519-25, 2007 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-17156962

RESUMO

A sensitive liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method is developed and validated for rapid determination of amantadine in human plasma. Desloratadine was used as the internal standard (I.S.). Human plasma (0.2 mL) was first alkalified with 100 microL of sodium hydroxide (3M) and then extracted with 1 mL of n-hexane containing 1% isopropanol (v/v) and 10% dichloromethane (v/v) by vortex-mixer for 3 min. The mixture was centrifuged at 14,000 rpm for 5 min. The supernatant was evaporated to dryness and the residue was dissolved in mobile phase. Samples were separated using a Thermo Hypersil-HyPURITYC18 reversed-phase column (150 mm x 2.1 mm i.d., 5 microm). Mobile phase consisted of methanol-acetonitrile-20 mM ammonium acetate (45:10:45, v/v/v) containing 1% acetic acid with pH 4.0. Amantadine and I.S. were measured by electrospray ion source in positive selective ion monitoring mode. The good linearity ranged from 3.9 to 1000 ng/mL and the lowest limit of quantification was 3.9 ng/mL. The extraction efficiencies were approximately 70% and recoveries of method ranged from 98.53 to 103.24%. The intra-day relative standard deviations (R.S.D.) were less than 8.43% and inter-day R.S.D. below 10.59%. The quality control samples were stable when kept at room temperature for 12h, at -20 degrees C for 30 days and after four freeze/thaw cycles. The method has been successfully used to evaluation of the pharmacokinetics and bioequivalence of amantadine in 20 healthy volunteers after an oral dose of 100 mg amantadine.


Assuntos
Amantadina/sangue , Antiparkinsonianos/sangue , Antivirais/sangue , Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Amantadina/química , Amantadina/farmacocinética , Antiparkinsonianos/farmacocinética , Antivirais/farmacocinética , Humanos , Estrutura Molecular , Reprodutibilidade dos Testes
15.
Anal Chim Acta ; 970: 38-46, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28433057

RESUMO

Aflatoxins (AFs) are highly toxic, mutagenic, carcinogenic, and teratogenic secondary metabolites produced by the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus. AFs tend to contaminate a wide range of foods which is a serious and recurring food safety problem worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, IAC method is limited in the large-scale food analysis because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming. Herein, to achieve the cost-effective determination of AFs in edible oils, we developed a promising solid-phase extraction (SPE) method based on commercially available humic acid-bonded silica (HAS) sorbent, followed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) analysis. In HAS-SPE, AFs can be captured by the HAS sorbent with both hydrophobic and hydrophilic interactions, whereas the oil matrix was captured only with the hydrophobic interactions. The oil matrix can be sufficiently washed off with isopropanol, while the AFs were still retained on the SPE packing, thus achieving selective extraction of AFs and clean-up of oil matrices. Under the optimal conditions of HAS-SPE, satisfactory recoveries ranging from 82% to 106% for four AFs (B1, B2, G1, and G2) were achieved in various oil matrices, containing blended oil, tea oil, rapeseed oil, peanut oil, sunflower seed oil, corn oil, blended olive oil, rice oil, soybean oil, and sesame oil. Only minor matrix effects ranging from 99% to 105% for four AFs were observed. Moreover, the LODs of AFs between 0.012 and 0.035 µg/kg completely meet the regulatory levels fixed by the EU, China or other countries. The methodology was further validated for assaying the naturally contaminated peanut oils, and consistent results between the HAS-SPE and the referenced IAC were obtained. In addition, HAS-SPE can directly treat diluted oil sample without liquid-liquid extraction and is automatable, thus making it simple and convenient for the large-scale determination of AFs in edible oils. Using this method, we successfully detected four AFs in the naturally contaminated peanut oils, which is, to the best of our knowledge, the first report about the determination of AFs in edible oils using HA-based SPE.


Assuntos
Aflatoxinas/análise , Substâncias Húmicas , Óleos de Plantas/análise , Dióxido de Silício , Extração em Fase Sólida , China , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas em Tandem
16.
Org Lett ; 16(24): 6476-9, 2014 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-25489721

RESUMO

Readily accessible ß,γ-unsaturated ketoximes reacted with 2-arylphenylisonitriles under the conditions of t-BuOOH and n-Bu4NI to give isoxazoline functionalized phenanthridines via tandem intramolecular/intermolecular C-O/C-C/C-C bond formation. The reaction involves the initial generation of iminoxyl radicals from the oxidation of ß,γ-unsaturated ketoximes by t-BuOOH and n-Bu4NI followed a cascade radical cyclization/addition/cyclization sequence.

17.
Artigo em Inglês | MEDLINE | ID: mdl-22503873

RESUMO

A new method based on enhancement effect of room temperature ionic liquids for cloud point extraction trace amounts of nickel combined with UV-vis spectrophotometric determination was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagent and chelating reagent, respectively. The addition of room temperature ionic liquids leads to 3.0 times improvement in the determination of nickel. The nonionic surfactant Triton X-100 was used as the extractant. When the temperature of the system was higher than the cloud point of Triton X-100, Ni-DTC complex was extracted into Triton X-100 and separation of the analyte from the matrix was achieved. Some parameters that influenced cloud point extraction and subsequent determination were evaluated in detail, such as the concentrations of RTILs, DDTC and Triton X-100; pH of sample solution, as well as interferences. Under optimized conditions, an enrichment factor of 72 could be obtained, and the detection limit (LOD) for Ni was 0.5ng mL(-1). Relative standard deviations for five replicate determinations of the standard solution containing 50ng mL(-1) Ni was 3.9%. The proposed method was successfully applied to the determination of nickel in certified reference materials with satisfactory results.


Assuntos
Técnicas de Química Analítica/métodos , Poluentes Ambientais/análise , Líquidos Iônicos/química , Níquel/análise , Temperatura , Absorção , Ditiocarb/química , Concentração de Íons de Hidrogênio , Íons , Octoxinol/química , Padrões de Referência , Solventes/química , Espectrofotometria Ultravioleta , Fatores de Tempo
18.
J Hazard Mater ; 237-238: 365-70, 2012 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-22981284

RESUMO

A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO(4) and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL(-1) and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL(-1), n=5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results.


Assuntos
Cromo/química , Poluentes Químicos da Água/química , Resíduos Industriais , Líquidos Iônicos/química , Microextração em Fase Líquida/métodos , Rios , Espectrofotometria Atômica/métodos , Temperatura , Águas Residuárias
19.
J Pharm Biomed Anal ; 52(2): 265-72, 2010 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-20092977

RESUMO

Metabolic fingerprinting is a powerful tool for exploring systemic metabolic perturbations and potential biomarkers, thus may shed light on the pathophysiological mechanism of diseases. In this work, a new strategy of metabolic fingerprinting was proposed to exploit the disturbances of metabolic patterns and biomarker candidates of childhood obesity. Plasma samples from children with normal weight, overweight and obesity were first profiled by GC/MS. ULDA (uncorrelated linear discriminant analysis) then revealed that the metabolic patterns of the three groups were different. Furthermore, several metabolites, say isoleucine, glyceric acid, serine, 2,3,4-trihydroxybutyric acid and phenylalanine were screened as potential biomarkers of childhood obesity by both ULDA and CCA (canonical correlation analysis). CCA also shows satisfactory correlation between the metabolic patterns and clinical parameters, and the results further suggest that WHR (waist-hip ratio) together with TG (total triglycerides), TC (total cholesterol), HDL (high density lipoprotein) and LDL (low density lipoprotein) were the most important parameters which are associated closely with the metabolic perturbations of childhood obesity, so as to be paid more attention for dealing with metabolic disturbances of childhood obesity in clinical practice rather than regularly monitored BMI (body-mass index). The results have demonstrated that the proposed metabolic fingerprinting approach may be a useful tool for discovering metabolic abnormalities and possible biomarkers for childhood obesity.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Obesidade/sangue , Obesidade/metabolismo , Criança , China , Colesterol/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Feminino , Humanos , Masculino , Análise Multivariada , Análise de Componente Principal , Triglicerídeos/sangue , Relação Cintura-Quadril
20.
Biomed Chromatogr ; 22(3): 223-31, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18059056

RESUMO

Licorice is the most widely used crude drug in traditional Chinese medicine. Glycyrrhetinic acid (GA) is the metabolite of glycyrrhizic acid, which is the main bioactive ingredient of licorice. In this work, capillary electrophoresis-frontal analysis (CE-FA) was applied to study the binding of bovine serum albumin with GA and two diuretics: furosemide (FU) and hydrochlorothiazide (HZ). The binding parameters of GA were determined by Scatchard analysis, which showed that there are two kinds of binding sites in bovine serum albumin for GA. However, the results showed that the CE-FA method was not suitable for the interaction study of FU and HZ. Therefore, utracentrifugation-CE was used to probe the binding characteristic of these two drugs and the results showed only one kind of binding site for them under the studied conditions. Displacement interactions between these drugs were also investigated by utracentrifugation-CE method and the results showed that GA hardly displaces HZ while it can slightly displace FU and FU can slightly displace HZ. For comparison, the binding of these drugs was also studied by the fluorescence quenching method and the data were processed by the Stern-Volmer quenching equation. Results showed that the binding constants were basically consistent for two methods for all drugs studied. The number of binding sites on one protein molecule was well consistent for FU and HZ while it was quite different for GA.


Assuntos
Eletroforese Capilar/métodos , Furosemida/química , Ácido Glicirretínico/química , Hidroclorotiazida/química , Soroalbumina Bovina/química , Espectrometria de Fluorescência/métodos , Animais , Bovinos , Espectrofotometria Ultravioleta
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