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1.
Angew Chem Int Ed Engl ; : e202202089, 2022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35460153

RESUMO

Rational synthesis of hydrogen-bonded organic frameworks (HOFs) with predicted structure has been a long-term challenge. Herein, by using the efficient, simple, low-cost, and scalable mechanosynthesis, we demonstrate that reticular chemistry is applicable to HOF assemblies based on building blocks with different geometry, connectivity, and functionality. The obtained crystalline HOFs show uniform nano-sized morphology, which is challenging or unachievable for conventional solution-based methods. Furthermore, the one-pot mechanosynthesis generated a series of Pd@HOF composites with noticeably different CO oxidation activities. In situ DRIFTS studies indicate that the most efficient composite, counterintuitively, shows the weakest CO affinity to Pd sites while the strongest CO affinity to HOF matrix, revealing the vital role of porous matrix to the catalytic performance. This work paves a new avenue for rational synthesis of HOF and HOF-based composites for broad application potential.

2.
Angew Chem Int Ed Engl ; 61(6): e202115854, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34877789

RESUMO

Under topological guidance, the self-assembly process based on a tetratopic porphyrin synthon results in a hydrogen-bonded organic framework (HOF) with the predicted square layers topology (sql) but unsatisfied stability. Strikingly, simply introducing a transition metal in the porphyrin center does not change the network topology but drastically causes noticeable change on noncovalent interaction, orbital overlap, and molecular geometry, therefore ultimately giving rise to a series of metalloporphyrinic HOFs with high surface area, and excellent stability (intact after being soaked in boiling water, concentrated HCl, and heated to 270 °C). On integrating both photosensitizers and catalytic sites into robust backbones, this series of HOFs can effectively catalyze the photoreduction of CO2 to CO, and their catalytic performances greatly depend on the chelated metal species in the porphyrin centers. This work enriches the library of stable functional HOFs and expands their applications in photocatalytic CO2 reduction.

3.
World J Clin Cases ; 9(27): 8114-8119, 2021 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-34621869

RESUMO

BACKGROUND: Empyema is a severe complication following pneumonectomy that is associated with high morbidity and mortality rates. Although there are a wide variety of treatment options, successful management remains challenging when this condition is combined with a large cavity in very thin patients who had previously undergone a posterolateral thoracotomy. CASE SUMMARY: We reported the case of a thin, 63-year-old man with a progressive pulmonary cyst who underwent left pneumonectomy via posterolateral thoracotomy 23 years ago. After an initially uneventful postoperative course, he was readmitted with empyema and a large cavity 21 years after surgery. He was successfully treated with limited thoracoplasty, followed by free vastus lateralis musculocutaneous flap transposition. CONCLUSION: This case highlights that the treatment mode of limited thoracoplasty and free vastus lateralis musculocutaneous flap transposition is safe and effective for the management of postpneumonectomy empyema with a large cavity in thin patients who had previously undergone a posterolateral thoracotomy.

4.
Surg Laparosc Endosc Percutan Tech ; 29(4): 280-284, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30870313

RESUMO

It is currently unclear whether endoscopic papillary balloon dilation (EPBD) is associated with increased severe postendoscopic retrograde cholangiopancreatography pancreatitis (PEP)-related morbidity owing to conflicting reports. This study aimed to investigate whether EPBD increases the risk of PEP and hyperamylasemia. Clinical data of patients with choledocholithiasis, treated at the Second Affiliated Hospital of Harbin Medical University from January 2015 to December 2016 were analyzed. Patients were divided into the EPBD group and endoscopic sphincterotomy (EST)+EPBD group, and their characteristics and PEP and hyperamylasemia incidences were compared. Incidences related to dilated balloon diameter were also analyzed. There were no significant differences in patient characteristics and the incidences of PEP (2.6% vs. 0%; P=0.257) and hyperamylasemia (4.4% vs. 5.6%; P=0.954) between the 2 groups. Results were similar even with different balloon dilatations. EPBD without endoscopic sphincterotomy did not increase the risk of PEP and hyperamylasemia. It is a safe option for choledocholithiasis patients.


Assuntos
Colangiopancreatografia Retrógrada Endoscópica/efeitos adversos , Coledocolitíase/cirurgia , Hiperamilassemia/etiologia , Pancreatite/etiologia , Esfinterotomia Endoscópica/efeitos adversos , Adulto , Fatores Etários , Idoso , Colangiopancreatografia Retrógrada Endoscópica/métodos , Coledocolitíase/diagnóstico por imagem , Estudos de Coortes , Dilatação/instrumentação , Dilatação/métodos , Feminino , Hospitais Universitários , Humanos , Hiperamilassemia/epidemiologia , Incidência , Masculino , Pessoa de Meia-Idade , Pancreatite/epidemiologia , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/fisiopatologia , Prognóstico , Estudos Retrospectivos , Medição de Risco , Fatores Sexuais , Esfinterotomia Endoscópica/métodos , Resultado do Tratamento
5.
J Glob Antimicrob Resist ; 16: 262-265, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30339895

RESUMO

OBJECTIVES: Vancomycin resistance in Enterococcus spp., mediated mainly by the vanA resistance gene, has become a major health concern as it has spread worldwide. Therefore, a rapid method is urgently required to detect the vanA gene for timely and appropriate antimicrobial control of resistant Enterococcus infections. METHODS: The loop-mediated isothermal amplification (LAMP) assay was optimised for vanA detection in Enterococcus spp. isolates. RESULTS: The LAMP primer set designed in this study could reliably recognise seven distinct regions of the vanA gene and amplify the gene within 25min at an isothermal temperature of 65°C with high specificity. The sensitivity of the optimised assay was high, with a detection limit for vanA as low as 100pg/µL, which is 100-fold more sensitive than the PCR assay. A special advantage of this optimised LAMP method is that the vanA gene could be detected directly from clinical specimens. CONCLUSION: This optimised LAMP assay has great application potential for efficient detection of vanA in clinical diagnosis and epidemiological studies.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Carbono-Oxigênio Ligases/genética , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/genética , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/genética , Técnicas de Amplificação de Ácido Nucleico , Adolescente , Adulto , Enterococcus faecalis/isolamento & purificação , Enterococcus faecium/isolamento & purificação , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Temperatura , Resistência a Vancomicina/genética , Adulto Jovem
6.
Shanghai Kou Qiang Yi Xue ; 27(2): 150-155, 2018 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30146641

RESUMO

PURPOSE: The aim of this clinical study was to evaluate the changes of alveolar bone morphology before and after upper incisors retraction with mini implant anchorage using cone-beam CT (CBCT). METHODS: Twenty-two young patients with dentoalveolar maxillary protrusion and extraction of 2 maxillary first premolars were evaluated with CBCT. CBCT scans were obtained before treatment and 3 months after retraction of the incisors. The movement patterns of the upper incisors were assessed with Mimics15.0. The labial and palatal alveolar plates at crest level, midroot level, and apical level for bone-thickness changes and labial and palatal vertical bone level during retraction of the maxillary anterior segments were assessed with Invivo5.0. Paired t tests were used to evaluate the changes. RESULTS: The edge of the maxillary incisor and the root apex appeared lingual movement horizontally, but the moving distance was larger than the root apex. The edge of the incisors was moved downward, and the root apex was moved upward obviously. The palatal thickness and total thickness of the alveolar bone showed significant decrease at the crest level and midroot level after retraction while the apical level showed significant increase(P<0.05). The palatal vertical bone level also showed great loss (P<0.05). CONCLUSIONS: After extensive retraction of the maxillary incisors, tilt movements are controlled with high traction hooks and microscrew implants. The decreases in palatal bone thickness are much more significant compared with the increases in labial bone thickness. Alveolar bone remodeling doesn't follow the movement of tooth, suggesting that the limitation of anterior teeth retraction should be taken into consideration.


Assuntos
Incisivo , Maxila , Técnicas de Movimentação Dentária , Dente Pré-Molar , Tomografia Computadorizada de Feixe Cônico , Humanos , Maxila/diagnóstico por imagem
7.
Shanghai Kou Qiang Yi Xue ; 26(4): 414-418, 2017 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-29199337

RESUMO

PURPOSE: To study the aesthetic appearance of skeletal Class Ⅱ patients with maxillary protrusion and mandibular retrusion treated with different methods. METHODS: The facial profile photographs and lateral cephalometric radiographs of a Chinese woman suffering from skeletal Class Ⅱ with maxillary protrusion and mandibular retrusion was digitized.The digital images were modified to obtain orthodontic compensatory treatment, genioplasty with different advancement ranges and orthognathic treatment comprising 6 profiles by Photoshop software,orthodontic professionals and non-professionals were chosen to score the pictures. Post hoc tests were done with ANONA and the Student Keuls method to analyze the data Using SPSS22.0 software package. RESULTS: The profile with the highest score was the picture treated by orthognathic and orthodontic treatment. The profile with genioplasty (advancement of 4 mm) took the second place. When the advancement distance of genioplasty was 8 mm, the score was under the score of orthodontic compensatory treatment profile. CONCLUSIONS: Orthognathic-orthodontic treatment of skeletal Class Ⅱ is still the best treatment option to improve facial aesthetics. Genioplasty, as a adjuvant treatment, improves the appearance based on compensatory orthodontic treatment to some extent, but not comparable to orthognathic-orthodontic treatment.


Assuntos
Estética Dentária , Mentoplastia , Cefalometria , Feminino , Humanos , Maxila , Retrognatismo/cirurgia , Resultado do Tratamento
8.
PLoS One ; 12(9): e0184849, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28910417

RESUMO

Diatoms are important components of marine ecosystems and contribute greatly to the world's primary production. Despite their important roles in ecosystems, the molecular basis of how diatoms cope with oxidative stress caused by nutrient fluctuations remains largely unknown. Here, an isobaric tags for relative and absolute quantitation (iTRAQ) proteomic method was coupled with a series of physiological and biochemical techniques to explore oxidative stress- and cell fate decision-related cellular and metabolic responses of the diatom Thalassiosira pseudonana to nitrate (N) and inorganic phosphate (P) stresses. A total of 1151 proteins were detected; 122 and 56 were significantly differentially expressed from control under N- and P-limited conditions, respectively. In N-limited cells, responsive proteins were related to reactive oxygen species (ROS) accumulation, oxidative stress responses and cell death, corresponding to a significant decrease in photosynthetic efficiency, marked intracellular ROS accumulation, and caspase-mediated programmed cell death activation. None of these responses were identified in P-limited cells; however, a significant up-regulation of alkaline phosphatase proteins was observed, which could be the major contributor for P-limited cells to cope with ambient P deficiency. These findings demonstrate that fundamentally different metabolic responses and cellular regulations are employed by the diatom in response to different nutrient stresses and to keep the cells viable.


Assuntos
Diatomáceas/crescimento & desenvolvimento , Nitratos/metabolismo , Fosfatos/metabolismo , Proteômica/métodos , Organismos Aquáticos , Diatomáceas/genética , Diatomáceas/metabolismo , Regulação da Expressão Gênica , Estresse Oxidativo , Fotossíntese , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico
9.
ACS Omega ; 2(9): 5850-5860, 2017 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31457842

RESUMO

With the aim of revealing the catalytic role of atypically coordinated (3His-1Glu) active site mononuclear non-heme Fe(II)-dependent quercetin 2,4-dioxygenase (Fe-2,4-QD) and the electronic effects of the model ligands on the reactivity toward dioxygen, a set of p/m-R-substituted carboxylate-containing ligand-supported Fe(II)-3-hydroxyflavonolate complexes, [FeIILR(fla)] (LRH: 2-{[bis(pyridin-2-ylmethyl)amino]methyl}-p/m-R-benzoic acid; R: p-OMe (1), p-Me (2), m-Br (4), and m-NO2 (5); fla: 3-hydroxyflavonolate), were synthesized and characterized as structural and functional models for the ES (enzyme-substrate) complexes of Fe-2,4-QD. [FeIILR(fla)] show relatively high enzyme-type reactivity (dioxygenative ring opening of the coordinated substrate fla, single-turnover reaction) at low temperatures (30-65 °C). The reaction shows a linear Hammett plot (ρ = -1.21), and electron donating groups enhance the reaction rates. The notable difference on the reactivity can be rationalized from the electronic nature of the substituent in the ligands, which could tune the reactivity via tuning Lewis acidity of the Fe(II) ion, electron density, and the redox potential of fla. The properties and the reactivity show approximately linear correlations between λmax or E 1/2 of fla and the reaction rate constant k. This work sheds light not only on understanding of electronic effects of the ligands and the property-reactivity relationship but also on the role of the catalytic reaction by Fe-2,4-QD.

10.
Zhongguo Ying Yong Sheng Li Xue Za Zhi ; 33(3): 197-201, 2017 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-29931932

RESUMO

OBJECTIVE: To analyze the expression and its promoter methylation of chemokine CXC ligand 14 (CXCL14) in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE). METHODS: The RNAs of PBMCs from 28 SLE patients and 20 healthy controls were isolated and reversely transcribed into cDNAs. Using GAPDH as the internal reference, the levels of CXCL14 ex-pression were detected by real-time polymerase chain reaction (PCR). The correlation between CXCL14 expression and the clinic pathological fe atures of SLE were further analyzed. DNA methylation was analyzed by bisulfite sequencing PCR (BSP). RESULTS: Our data indicated that the level of CXCL14 in the PBMC of SLE patients was statistically lower than that in healthy controls (P < 0.05). Further analysis showed that CXCL14 expression was negatively correlated with anti-Sj gren syndrome B antibody(anti-SSB antibody, P < 0.01) and albuminuria(P < 0.05). However, CXCL14 expression was not significantly correlated with the indexes of SLE activity, renal damage, the level of anti-ds-DNA antibodies, complement C3 and C-reactive protein. In addition, we further demonstrated that the CXCL14 promoter hypermethylation expres-sion was significant higher than healthy controls. CONCLUSIONS: Down-regulated of CXCL14 expression in PBMC maybe involved in the occur-rence or development of SLE disease. The loss of CXCL14 expression was regulated by promoter hypermethylation.


Assuntos
Quimiocinas CXC/genética , Metilação de DNA , Lúpus Eritematoso Sistêmico/genética , Regiões Promotoras Genéticas , Estudos de Casos e Controles , Humanos , Leucócitos Mononucleares
11.
Dalton Trans ; 44(31): 13926-38, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26153684

RESUMO

In order to get insights into the metal ion effects and the carboxylate effects on enzymatic activity, a series of the carboxylate ligand supported transition metal complexes [M(II)L(OAc)] (M = Mn (), Fe (), Co (), Ni (), Cu () and Zn (); LH = 2-{[bis-(pyridin-2-ylmethyl)amino]methyl}-4-methoxy benzoic acid) were synthesized and characterized as structural and functional models for the active sites of various M(II)-substituted resting quercetin 2,3-dioxygenases (2,3-QD). Their structures, spectroscopic features, redox properties, as well as the catalytic reactivity toward the substrate flavonol and O2 have been investigated in detail. The model complexes show higher enzymatic reactivities in the catalytic dioxygenation (oxidative ring opening) of the substrate flavonol at lower temperatures (55-100 °C), presumably caused by the carboxylate group in the supporting model ligand, which could lower the redox potential of the bound substrate flavonolate by electron donation. The catalytic reactivity of [M(II)L(OAc)] exhibits notable differences and it is in a metal ion dependent order of Co () > Ni () > Zn () > Fe () > Mn () > Cu (). The differences in the reactivities among them could be ascribed to the redox potential of the bound substrate flavonolate, which was drastically influenced by the metal ions via tuning the electron density of flavonolate, providing important insights into the metal ion effects and the carboxylate effects on the enzymatic activity of various M(II)-substituted 2,3-QD. Our model complexes [M(II)L(OAc)] are the first examples of a series of structural and functional models of various M(II)-substituted resting 2,3-QD.


Assuntos
Materiais Biomiméticos/química , Complexos de Coordenação/química , Dioxigenases/metabolismo , Flavonóis/química , Oxigênio/química , Ácido Benzoico/química , Catálise , Cobalto/química , Cobre/química , Eletroquímica , Ferro/química , Manganês/química , Níquel/química , Zinco/química
12.
Dalton Trans ; 43(17): 6480-9, 2014 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-24622725

RESUMO

Ni(II)-flavonolate complexes [Ni(II)L(R)(fla)] (L(R)H: 2-{[bis(pyridin-2-ylmethyl)amino]methyl}-p/m-R-benzoic acid, R: p-OMe (1), p-Me (2), m-Br (4) and m-NO2 (5), fla: flavonolate) were synthesized and characterized with relevance to structural and functional models for the ES (enzyme-substrate) adduct of the Ni(II)-containing quercetin 2,3-dioxygenase (2,3-QD). Their structures, spectroscopic features, redox properties and the reactivity toward molecular oxygen have been investigated. The complexes show a similar distorted octahedral structure and higher enzyme-type dioxygenation reactivity than other reported metal-flavonolate complexes in the oxidative O-heterocyclic ring-opening of the bound substrate flavonolate at lower temperature owing to the introduced carboxylate group in the supporting model ligands. The reaction rate shows first-order dependence on both of the complex and O2 and the second-order rate constant k fits a Hammett linear free energy relationship (ρ = -0.71) for the substituent group in the supporting model ligand L(R). The complexes exhibit substituent group dependent structures, properties and reactivity and there are some relationship among them, which could be ascribed to the electronic nature of the substituent group via the benzoate, Ni(II) ion and O(4)=C(27)-C(21)=C(22) "electron conduit". In a word, the stronger electron donating group could induce a smaller torsion angle, larger λ(max) and lower redox potential of the bound flavonolate, making a higher reactivity finally. This study is the first example of a series of structural and functional ES models of the Ni(II)-containing 2,3-QD, providing important insights into the structure-property-reactivity relationship, the electronic substituent effects and carboxylate effects on the enzymatic reactivity and the catalytic role of the Ni(II)-containing 2,3-QD.


Assuntos
Complexos de Coordenação/química , Dioxigenases/metabolismo , Níquel/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Complexos de Coordenação/síntese química , Cristalografia por Raios X , Dioxigenases/química , Cinética , Magnetismo , Modelos Moleculares , Conformação Molecular , Oxirredução , Especificidade por Substrato
13.
Inorg Chem ; 53(6): 2932-42, 2014 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-24601533

RESUMO

A series of mononuclear Co(II)-flavonolate complexes [Co(II)L(R)(fla)] (L(R)H = 2-{[bis(pyridin-2-ylmethyl)amino]methyl}-p/m-R-benzoic acid; R = p-OMe (1), p-Me (2), m-Br (4), and m-NO2 (5); fla = flavonolate) were designed and synthesized as structural and functional models for the ES (enzyme-substrate) complexes to mimic the active site of the Co(II)-containing quercetin 2,3-dioxygenase (Co-2,3-QD). The metal center Co(II) ion in each complex shows a similar distorted octahedral geometry. The model complexes display high enzyme-type dioxygenation reactivity (oxidative O-heterocyclic ring opening of the coordinated substrate flavonolate) at low temperature, presumably due to the attached carboxylate group in the ligands. The reactivity exhibits a substituent group dependent order of -OMe (1) > -Me (2) > -H (3)14b > -Br (4) > -NO2 (5), and the Hammett plot is linear (ρ = -0.78). This can be explained as the electronic nature of the substituent group in the ligands may influence the conformation and redox potential of the bound flavonolate and finally bring different reactivity. The structures, properties, and reactivity of the model complexes show some dependence on the substituent group in the supporting model ligands, and there is some relationship among them. This study is the first example of a series of structural and functional ES models of Co-2,3-QD, with focus on the effects of the electronic nature of substituted groups and the carboxylate group of the ligands to the dioxygenation reactivity, that will provide important insights into the structure-property-reactivity relationship and the catalytic role of Co-2,3-QD.


Assuntos
Cobalto/química , Dioxigenases/química , Modelos Moleculares , Cristalografia por Raios X , Especificidade por Substrato
14.
Asian Pac J Cancer Prev ; 15(2): 847-53, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24568506

RESUMO

There is a lot of debate on the relationship between vitamin D receptor polymorphisms and risk of breast cancer. Herein, we quantitatively analyzed the published case-control studies on this relationship by meta- analysis, performing a bibliographic search from Pubmed and CNKI up to July 31, 2013. The included case- control studies for Fok1, Bsm1, Taq1, Apa1, Cdx2 and Poly-A were 16, 19, 20, 10, 4, 6, respectively. Crude and adjusted odd ratios and 95% confidence intervals were calculated to present and compare the strength of any associations. The results of combined analyses indicated that Fok1, Bsm1, Apa1, Cdx2 and Poly-A were not significantly associated with the risk of breast cancer. In contrast, the tt genotype of Taq1 was a modest risk factor for breast cancer development (tt vs. TT: OR = 1.21, 95% CI: 1.01-1.44). To further confirm the above results, adjusted effects for the six polymorphisms were pooled based on adjusted ORs reported in the original studies. Adjusted ORs of Fok1, Apa1, Cdx2 and Poly-A were similar to the crude ORs. However, Bsm1 and Taq1 showed inconsistent results. For Bsm1, OR for BB vs. bb was 0.85, 95% CI: 0.74-0.98; for Taq1, OR for tt vs. TT was 1.03, 95% CI: 0.92-1.15, and not associated with risk. Subgroup analyses for crude ORs showed some association between Bsm1, Taq1 and breast cancer in Caucasians only, but for adjusted ORs, no associations were found. This meta-analysis suggests that the roles that Fok1, Apa1, Cdx2 and Poly-A polymorphisms play in breast cancer risk are negligible, with Bsm1 and Taq1 as possible exceptions. To be conservative, we still assumed that they may play a modest role in determining breast cancer risk. Further studies are needed to validate our findings.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias da Mama/genética , Polimorfismo Genético/genética , Receptores de Calcitriol/genética , Neoplasias da Mama/patologia , Estudos de Casos e Controles , Feminino , Predisposição Genética para Doença , Humanos , Razão de Chances , Prognóstico
15.
Inorg Chem ; 52(19): 10936-48, 2013 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-24044415

RESUMO

A series of flavonolate complexes [M(II)L(fla)] (M = Mn (1), Fe (2), Co (3), Ni (4), Cu (5), and Zn (6), LH: 2-{[bis(pyridin-2-ylmethyl)amino]methyl}benzoic acid, fla: flavonolate) have been synthesized as structural and functional models for the ES (enzyme-substrate) complexes of the active site of various M(II)-containing quercetin 2,3-dioxygenase (2,3-QD) and their structures, spectroscopic features, and redox properties, as well as the reactivity toward molecular oxygen, have been investigated. The metal centers of [Fe(II)L(fla)]·H2O (2), [Co(II)L(fla)]·CH3OH (3), and [Ni(II)L(fla)] (4) exhibit a distorted octahedral geometry with two oxygen atoms of fla, one oxygen atom of the benzoate group of ligand L, and three nitrogen atoms of ligand L, in which oxygen atom of the carbonyl group of fla and one of the pyridine nitrogen atoms occupy the axial positions. The complexes [M(II)L(fla)] exhibit relatively high reactivity in the oxidative ring-opening of the bound flavonolate at lower temperature, presumably due to the existing carboxylate group in the supporting ligand. Thus, our complexes act as good functional ES models of various metal(II)-containing 2,3-QD. In addition, complexes [Fe(II)L(fla)]·H2O (2), [Co(II)L(fla)]·CH3OH (3), and [Ni(II)L(fla)] (4) are the first structurally characterized Fe(II)-, Co(II)-, and Ni(II)-flavonolate complexes, as an active site ES model of Fe(II)-, Co(II)-, and Ni(II)-containing 2,3-QD, respectively. The model complexes exhibit notably different reactivity in the order of Fe (2) > Cu (5) > Co (3) > Ni (4) > Zn (6) > Mn (1). The differences in the reactivity among them may be attributed to the redox potential of the coordinated flavonolate of the complexes, which are remarkably influenced by the Lewis acidity of the metal ion and its coordination environment. Our study is the first example of the metal ion effects on the enzyme-like dioxygenation reactivity, providing important insights into the metal ion effects on the enzymatic reactivity of various metal(II)-containing 2,3-QD.


Assuntos
Complexos de Coordenação/química , Dioxigenases/química , Modelos Biológicos , Regulação Alostérica , Cobalto/química , Complexos de Coordenação/síntese química , Cobre/química , Cristalografia por Raios X , Ferro/química , Manganês/química , Estrutura Molecular , Níquel/química , Ligação Proteica , Espectrometria de Massas por Ionização por Electrospray , Zinco/química
16.
Guang Pu Xue Yu Guang Pu Fen Xi ; 29(9): 2425-8, 2009 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-19950644

RESUMO

The objective of the present study was to develop a method for rapid determination of baicalin and total flavonoids in radix scutellariae by near infrared diffuse reflectance spectroscopy. Sixty one samples of radix scutellariae from different areas containing baicalin of 12.24%-21.34% and total flavonoids of 16.08%-26.52% were used. The range of 8000-4000 cm(-1) of near infrared spectra (NIRS) was selected. Calibration models were established using the PLS(partial least squares). Different spectra pretreatment methods were compared and the optimal model was selected. The study showed that first derivative pretreatments and minimum-maximum normalization methods can be used to extracted spectra information thoroughly to analyze the contents of baicalin and total flavonoids, respectively. The correlation coefficient (r) of baicalin was 0.9024, SEC was 1.01 (standard deviation of the calibration sets) and SEP was 0.8764 (standarddeviation ofthe prediction sets). The correlation coefficient(r) of total flavonoids was 0.9527, SEC was 0.7850 and SEP was 0.5211. Results indicated that near infrared diffuse reflectance spectroscopy method can be used to analyze the main active components in radix scutellariae rapidly.


Assuntos
Flavonoides/análise , Scutellaria baicalensis/química , Espectroscopia de Luz Próxima ao Infravermelho , Calibragem , Análise dos Mínimos Quadrados , Modelos Teóricos
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