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1.
Int J Mol Sci ; 21(15)2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32707773

RESUMO

NMR spectroscopy continues to provide important molecular level details of dynamics in different polymer materials, ranging from rubbers to highly crosslinked composites. It has been argued that thermoset polymers containing dynamic and chemical heterogeneities can be fully cured at temperatures well below the final glass transition temperature (Tg). In this paper, we described the use of static solid-state 1H NMR spectroscopy to measure the activation of different chain dynamics as a function of temperature. Near Tg, increasing polymer segmental chain fluctuations lead to dynamic averaging of the local homonuclear proton-proton (1H-1H) dipolar couplings, as reflected in the reduction of the NMR line shape second moment (M2) when motions are faster than the magnitude of the dipolar coupling. In general, for polymer systems, distributions in the dynamic correlation times are commonly expected. To help identify the limitations and pitfalls of M2 analyses, the impact of activation energy or, equivalently, correlation time distributions, on the analysis of 1H NMR M2 temperature variations is explored. It is shown by using normalized reference curves that the distributions in dynamic activation energies can be measured from the M2 temperature behavior. An example of the M2 analysis for a series of thermosetting polymers with systematically varied dynamic heterogeneity is presented and discussed.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Polímeros/química , Ciclodecanos/química , Simulação de Dinâmica Molecular , Movimento (Física) , Floroglucinol/química , Espectroscopia de Prótons por Ressonância Magnética/métodos , Prótons , Temperatura
2.
Nat Prod Res ; 34(4): 545-548, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30257572

RESUMO

The chemical composition of Tussilago farfara L. essential oil from the Saguenay-Lac-St-Jean region of Quebec, Canada was analyzed by gas chromatography-flame ionisation detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS), and the antibacterial activity of the oil was tested against Escherichia coli and Staphylococcus aureus. Forty-five (45) compounds were identified from the GC profile. The main components were 1-nonene (40.1%), α-phellandrene (26.0%) and ρ-cymene (6.6%). The essential oil demonstrated antibacterial activity against E. coli (MIC50 = 468 µg·mL-1; MIC90 = 6869 µg·mL-1) and S. aureus (MIC50 = 368 µg·mL-1; MIC90 = 773 µg·mL-1). Dodecanoic acid was found to be active against both bacteria having a MIC50 and MIC90 of 16.4 µg·mL-1 and 95 µg·mL-1, respectively for E. coli and a MIC50 and MIC90 of 9.8 µg·mL-1 and 27.3 µg·mL-1, respectively for S. aureus. In addition, 1-decene and (E)-cyclodecene were also found to be active against E. coli.


Assuntos
Antibacterianos/isolamento & purificação , Óleos Voláteis/química , Tussilago/química , Alcanos/análise , Alcanos/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Ciclodecanos/análise , Ciclodecanos/farmacologia , Monoterpenos Cicloexânicos/análise , Cimenos/análise , Escherichia coli/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Ácidos Láuricos/análise , Ácidos Láuricos/farmacologia , Testes de Sensibilidade Microbiana , Quebeque , Staphylococcus aureus/efeitos dos fármacos
3.
Macromol Biosci ; 18(12): e1800257, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30318738

RESUMO

Well-defined dihydroxy telechelic oligodepsipeptides (oDPs), which have a high application potential as building blocks for scaffold materials for tissue engineering applications or particulate carrier systems for drug delivery applications are synthesized by ring-opening polymerization (ROP) of morpholine-2,5-diones (MDs) catalyzed by 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecane (Sn(IV) alkoxide). In contrast to ROP catalyzed by Sn(Oct)2 , the usage of Sn(IV) alkoxide leads to oDPs, with less side products and well-defined end groups, which is crucial for potential pharmaceutical applications. A slightly faster reaction of the ROP catalyzed by Sn(IV) alkoxide compared to the ROP initiated by Sn(Oct)2 /EG is found. Copolymerization of different MDs resulted in amorphous copolymers with T g s between 44 and 54 °C depending on the molar comonomer ratios in the range from 25% to 75%. Based on the well-defined telechelic character of the Sn(IV) alkoxide synthesized oDPs as determined by matrix-assisted laser desorption/ionization time of flight measurements, they resemble interesting building blocks for subsequent postfunctionalization or multifunctional materials based on multiblock copolymer systems whereas the amorphous oDP-based copolymers are interesting building blocks for matrices of drug delivery systems.


Assuntos
Técnicas de Química Sintética , Ciclodecanos/química , Depsipeptídeos/síntese química , Morfolinas/química , Oligopeptídeos/síntese química , Estanho/química , Catálise , Portadores de Fármacos/síntese química , Humanos , Cinética , Óxidos/química , Polimerização , Engenharia Tecidual/métodos , Tecidos Suporte/química
4.
Bioorg Med Chem Lett ; 27(21): 4898-4903, 2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-28947153

RESUMO

The chloroform extract of the Japanese cypress Chamaecyparis obtusa was found to kill PANC-1 human pancreatic cancer cells preferentially in the nutrient-deprived medium without causing toxicity in the nutrient rich condition. Phytochemical investigation on this extract led to the isolation of a new sesquiterpene (1), together with the six sesquiterpenes (2-7) and a lignan (8). The isolated compounds were tested for their preferential cytotoxicity activity against five different human pancreatic cancer cell lines [PANC-1, MIA PaCa2, CAPAN-1, PSN-1, and KLM-1] by utilizing an antiausterity strategy. Among them, α-cadinol (2) was identified as the most active constituent. α-Cadinol (2) was found to inhibit the activation of Akt/mTOR pathway, and the hyperactivation of autophagy leading to preferential PANC-1 cell death during nutrient-starvation.


Assuntos
Antineoplásicos Fitogênicos/química , Chamaecyparis/química , Ciclodecanos/química , Sesquiterpenos/química , Terpenos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/toxicidade , Autofagia/efeitos dos fármacos , Linhagem Celular Tumoral , Chamaecyparis/metabolismo , Ciclodecanos/isolamento & purificação , Ciclodecanos/toxicidade , Avaliação Pré-Clínica de Medicamentos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Espectroscopia de Ressonância Magnética , Microscopia de Fluorescência , Conformação Molecular , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/metabolismo , Sesquiterpenos/isolamento & purificação , Sesquiterpenos/toxicidade , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Terpenos/isolamento & purificação , Terpenos/toxicidade
5.
Bioorg Med Chem Lett ; 27(15): 3495-3498, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28602640

RESUMO

We designed and synthesized novel δ opioid receptor (DOR) agonists 3a-i with an azatricyclodecane skeleton, which was a novel structural class of DOR agonists. Among them, 3b exhibited high values of binding affinity and potent agonistic activity for the DOR that were approximately equivalent to those of 2 which bore an oxazatricyclodecane skeleton. In vitro assays using the blood-brain barrier (BBB) permeability test kit supported the idea that 3b achieved an excellent BBB permeability by converting an oxygen atom of 2 to a carbon atom (methylene group) in the core skeleton. As a result, 3b showed potent antinociceptive effects.


Assuntos
Analgésicos Opioides/farmacologia , Analgésicos Opioides/farmacocinética , Barreira Hematoencefálica/metabolismo , Ciclodecanos/farmacologia , Ciclodecanos/farmacocinética , Receptores Opioides delta/agonistas , Administração Cutânea , Analgésicos Opioides/síntese química , Analgésicos Opioides/química , Animais , Ciclodecanos/síntese química , Ciclodecanos/química , Desenho de Fármacos , Humanos , Camundongos , Receptores Opioides delta/metabolismo
6.
Chembiochem ; 18(8): 721-725, 2017 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-28186695

RESUMO

The farnesoid X receptor (FXR) is an important target for drug discovery. Small molecules induce a conformational change in FXR that modulates its binding to co-regulators, thus resulting in distinct FXR functional profiles. However, the mechanisms for selectively recruiting co-regulators by FXR remain elusive, partly because of the lack of FXR-selective modulators. We report the identification of two natural terpenoids, tschimgine and feroline, as novel FXR modulators. Remarkably, their crystal structures uncovered a secondary binding pocket important for ligand binding. Further, tschimgine or feroline induced dynamic conformational changes in the activation function 2 (AF-2) surface, thus leading to differential co-regulator recruiting profiles, modulated by both hydrophobic and selective hydrogen-bond interactions unique to specific co-regulators. Our findings thus provide a novel structure template for optimization for FXR-selective modulators of clinical value.


Assuntos
Compostos Bicíclicos com Pontes/farmacologia , Ciclodecanos/farmacologia , Hidroxibenzoatos/farmacologia , Parabenos/farmacologia , Receptores Citoplasmáticos e Nucleares/agonistas , Animais , Sítios de Ligação , Haplorrinos , Células Hep G2 , Humanos , Interleucina-16/metabolismo , Ligantes , Óxido Nítrico Sintase Tipo II/metabolismo , Mutação Puntual , Estrutura Terciária de Proteína , Receptores Citoplasmáticos e Nucleares/química , Receptores Citoplasmáticos e Nucleares/genética , Fator de Necrose Tumoral alfa/metabolismo
7.
Org Lett ; 17(14): 3379-81, 2015 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-26118407

RESUMO

An efficient synthesis of the tricyclo[4,3,1,0(1, 5)]decane core (B/C/D rings) of plumisclerin A, a unique cytotoxic marine diterpenoid, is described. A Pauson-Khand reaction and a SmI2-mediated radical 1,4-conjugate addition successfully served as key reactions for construction of the fully functionalized 5,6-fused rings and the highly strained cyclobutanol moiety with correct relative stereochemistries, respectively.


Assuntos
Ciclodecanos/síntese química , Diterpenos/síntese química , Ciclização , Ciclodecanos/química , Diterpenos/química , Estrutura Molecular , Estereoisomerismo
8.
Org Lett ; 15(16): 4238-41, 2013 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-23923982

RESUMO

Highly enantio- and diastereoselective transannular ketone-ene reactions are catalyzed by a new chromium(III) triflate tridentate Schiff base complex. Electronically unactivated keto-olefins undergo heteroene reactions at ambient temperature to afford enantioenriched bicyclic alcohols, common structural motifs in natural products. The kinetic resolution of a configurationally stable planar-chiral cyclodecenone is also described.


Assuntos
Alcenos/química , Cromo/química , Cetonas/química , Mesilatos/química , Bases de Schiff/química , Álcoois/química , Catálise , Ciclodecanos/química , Estereoisomerismo
9.
J Med Chem ; 56(1): 301-19, 2013 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-23234271

RESUMO

A series of GPR119 agonists based on a 2,6-diazatricyclo[3.3.1.1∼3,7∼]decane ring system is described. Also provided is a detailed account of the development of a multigram scale synthesis of the diazatricyclic ring system, which was achieved using a Hofmann-Löffler-Freytag reaction as the key step. The basis for the use of this complex framework lies in an attempt to constrain one end of the molecule in the "agonist conformation" as was previously described for 3-oxa-7-aza-bicyclo[3.3.1]nonanes. Optimization of carbamate analogues of the diazatricylic compounds led to the identification of 32i as a potent agonist of the GPR119 receptor with low unbound human liver microsomal clearance. The use of an agonist response weighted ligand lipophilic efficiency (LLE) termed AgLLE is discussed along with the issues of applying efficiency measures to agonist programs. Ultimately, solubility limited absorption and poor exposure reduced further interest in these molecules.


Assuntos
Compostos Aza/síntese química , Hidrocarbonetos Aromáticos com Pontes/síntese química , Ciclodecanos/síntese química , Receptores Acoplados a Proteínas G/agonistas , Animais , Compostos Aza/química , Compostos Aza/farmacologia , Disponibilidade Biológica , Hidrocarbonetos Aromáticos com Pontes/química , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Cristalografia por Raios X , Ciclodecanos/química , Ciclodecanos/farmacologia , Cães , Desenho de Fármacos , Humanos , Masculino , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Pirimidinas/síntese química , Pirimidinas/química , Pirimidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Acoplados a Proteínas G/química , Solubilidade , Estereoisomerismo , Relação Estrutura-Atividade
10.
Nat Prod Res ; 27(7): 603-8, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22548364

RESUMO

A novel secondary metabolite, N-trans-cinnamoyl 2-amino-3a,4,5,6,7,8,9,10,11,12,13,13a-dodecahydrocyclododeca[d]oxazole (1), was isolated from Streptomyces spp. CIBYL1, along with five known compounds, pimprinine (2), (3R,4S,5R,6R)-3,4,5,6-tetrahydro-4-hydroxy-3,5,6-trimethyl-2H-pyran-2-one (3), indolyl-3-carboxylic acid (4), 2-phenylacetamide (5) and di(1H-pyrrol-2-yl)methanone (6). The structures of these metabolites were elucidated on the basis of extensive analysis of spectroscopic data, including OR, IR, HRMS, 1D and 2D NMR data and chemical derivation.


Assuntos
Oxazóis/química , Streptomyces/química , Ciclodecanos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular
11.
Clin Oral Investig ; 17(1): 251-7, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22411263

RESUMO

OBJECTIVES: Nanohybrid resin-based composites (RBCs) containing new types of matrix monomers such as dimer acid-based dimethacrylate or tricyclodecane-urethane are assumed to show decreased water uptake and therefore better resistance to hydrolytic degradation than RBCs using bisphenol A diglycidyl methacrylate (BisGMA) due to their hydropobic nature. Our study aimed to analyze the effect of aging on six nanohybrid RBCs, of which two are using these new types of monomers, with regard to differences in the mechanical properties of the materials. MATERIALS AND METHODS: Diametral tensile strength (DTS), Vickers hardness (HV), and creep were measured. Mechanical tests were performed after storing samples for 24 h in distilled water, as well as after aging (thermocycling for 5,000 cycles at 5-55°C and storage for 4 weeks either in distilled water, artificial saliva, or ethanol). RESULTS: The effect of aging on all test parameters was lower than the effect of the material. This information was provided by a general linear model, showing higher partial η(2) values for the influence factor material than for the factor aging. The influence of aging on the micromechanical properties HV and creep was proven to be more sensitive than on the macromechanical property (DTS). This was also illustrated by lower η(2) values for the variable aging for DTS. An increase of the creep of all materials was observed after storage in alcohol. CONCLUSIONS: The use of new types of monomers could not be shown to be a significant advantage to the other examined materials containing BisGMA. CLINICAL RELEVANCE: Nanohybrid composites can be recommended as universal filling materials, whether based on new or conventional monomers.


Assuntos
Resinas Compostas/química , Materiais Dentários/química , Nanocompostos/química , Bis-Fenol A-Glicidil Metacrilato/química , Ácidos Carboxílicos/química , Química Farmacêutica , Ciclodecanos/química , Etanol/química , Dureza , Humanos , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Fenômenos Mecânicos , Metacrilatos/química , Saliva Artificial/química , Solventes/química , Estresse Mecânico , Propriedades de Superfície , Temperatura , Resistência à Tração , Fatores de Tempo , Uretana/química , Água/química
12.
Clin Oral Investig ; 17(2): 635-42, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22552591

RESUMO

OBJECTIVES: This study aimed to determine the degree of conversion (DC) of two nano-hybrid resin-based composites (RBCs) with novel monomer composition based on dimer acid derivates (hydrogenated dimer acid) and tricyclodecane-urethane structure compared to three nano-hybrid materials containing conventional matrices. DC was evaluated at 0.1, 2, and 6 mm depth at varying irradiation times (10, 20, and 40 s) and layering techniques (bulk and incremental). MATERIALS AND METHODS: DC was measured in real time by a Fourier transform infrared spectroscopy (FTIR) spectrometer with attenuated total reflectance accessory. The FTIR spectra were recorded on the bottom of the samples in real time for 5 min from photoinitiation. Results were compared using one- and multiple-way ANOVA, Tukey's HSD post hoc test (α = 0.05), and partial eta-squared statistic. RESULTS: After 5 min of measurement, DC showed no significant difference by varying cure time for specimens of 0.1 mm thickness. At 2 mm depth, the DC significantly increased after a cure time of 20 s compared to 10 s, remaining equal after 40 s of irradiation. At 6 mm depth, bulk curing showed significantly lower DC compared to incremental curing for all polymerization times. Specimen geometry revealed a strong effect on DC (η (2) = 0.90) followed by curing time (η (2) = 0.39). CONCLUSIONS: The RBCs containing the dimer acid and tricyclodecane-urethane structure showed a relatively low decrease of DC with increasing incremental thickness compared to the conventionally formulated materials. The former reached the highest DC among the tested materials. CLINICAL RELEVANCE: For the tested RBCs, increments of 2 mm and irradiation time of at least 20 s may be recommended for clinical practice. The two materials containing novel monomer composition might be applied for enlarged increments because of the low decrease of DC they demonstrated for 6-mm increments.


Assuntos
Resinas Compostas/química , Materiais Dentários/química , Nanocompostos/química , Bis-Fenol A-Glicidil Metacrilato/química , Química Farmacêutica , Resinas Compostas/efeitos da radiação , Ciclodecanos/química , Ciclodecanos/efeitos da radiação , Materiais Dentários/efeitos da radiação , Humanos , Hidrogenação , Teste de Materiais , Metacrilatos/química , Metacrilatos/efeitos da radiação , Nanocompostos/efeitos da radiação , Polietilenoglicóis/química , Polimerização , Ácidos Polimetacrílicos/química , Poliuretanos/química , Poliuretanos/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Fatores de Tempo
13.
J Phys Chem A ; 116(38): 9507-15, 2012 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-22971012

RESUMO

Rate constants for the reactions of OH radicals with four C(6)-C(10) cycloalkenes have been measured at 297 ± 2 K using a relative rate technique. The rate constants (in units of 10(-11) cm(3) molecule(-1) s(-1)) were cyclohexene, 6.35 ± 0.12; cis-cyclooctene, 5.16 ± 0.15; cis-cyclodecene, 4.18 ± 0.06; and 1-methyl-1-cyclohexene, 9.81 ± 0.18, where the indicated errors are two least-squares standard deviations and do not include uncertainties in the rate constant for the reference compound 1,3,5-trimethylbenzene. In addition, a rate constant of (4.8 ± 1.3) × 10(-11) cm(3) molecule(-1) s(-1) was derived for the reaction of OH radicals with 1,6-hexanedial, relative to our measured rate constant for OH + cyclohexene. Analyses of products of the OH + cyclohexene, 1-methyl-1-cyclohexene, and cis-cyclooctene reactions by direct air sampling atmospheric pressure ionization mass spectrometry and/or by combined gas chromatography-mass spectrometry showed the presence of products attributed to cyclic 1,2-hydroxynitrates and the dicarbonyls 1,6-hexanedial, 6-oxo-heptanal, and 1,8-octanedial, respectively. These dicarbonyl products, which are those formed after decomposition of the intermediate cyclic 1,2-hydroxyalkoxy radicals, were quantified as their dioximes, with molar formation yields of 76 ± 10%, 82 ± 12%, and 84 ± 18% from the cyclohexene, 1-methyl-1-cyclohexene, and cis-cyclooctene reactions, respectively. Combined with literature data concerning 1,2-hydroxynitrate formation from OH + alkenes and the estimated fractions of the overall reactions proceeding by H-atom abstraction, 90 ± 12%, 95 ± 13% and 108 ± 20% of the products or reaction pathways from the OH radical-initiated reactions of cyclohexene, 1-methyl-1-cyclohexene, and cis-cyclooctene in the presence of NO are accounted for.


Assuntos
Ciclodecanos/química , Cicloexenos/química , Ciclo-Octanos/química , Radical Hidroxila/química , Cinética , Estrutura Molecular , Estereoisomerismo
14.
Int Arch Occup Environ Health ; 84(4): 371-4, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21082189

RESUMO

PURPOSE: Recent work practices in the conservation and restoration involve the use of cyclododecane (CDD, CAS 294-62-2) to protect fragile artifacts during their handling or transportation. Little is known about its toxicity, and no previous exposure has been reported. A short field investigation was conducted to characterize the exposure conditions to both CDD vapors and aerosols. METHODS: Measurements were conducted in the laboratory of conservation and restoration of the archeological service in Bern (Switzerland). Three indoor and four outdoor typical work situations, either during brush or spray gun applications, were investigated. Measurements were performed on charcoal adsorbent tube and analyzed by a gas chromatograph equipped with a flame ionization detector. RESULTS: Measurements have been conducted during both brush and spray gun applications. Indoor exposures were of 0.75-15.5 mg/m(3), while outdoors exposures were 19.5-53.9 mg/m(3). Exposures appear to be extremely localized due to both physicochemical properties and application methods of the CDD. Vapor exposure increases dramatically with the confinement of the workplace. CONCLUSION: Preventive measures should be undertaken to limit as much as possible these exposures. Field work in confined areas (ditches, underground) is of particular concern. CDD-coated artifacts or materials should be stored in ventilated areas to avoid delayed exposures.


Assuntos
Poluentes Ocupacionais do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Arte , Ciclodecanos/análise , Exposição Ocupacional/análise , Poluentes Ocupacionais do Ar/toxicidade , Ciclodecanos/toxicidade , Monitoramento Ambiental , Humanos , Exposição por Inalação/análise , Doenças Profissionais/etiologia , Doenças Profissionais/prevenção & controle , Exposição Ocupacional/efeitos adversos , Volatilização
15.
Chemistry ; 16(28): 8446-65, 2010 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-20540046

RESUMO

Complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H(6)do2a2p, H(6)L) with transition metal and lanthanide(III) ions were investigated. The stability constant values of the divalent and trivalent metal-ion complexes are between the corresponding values of H(4)dota and H(8)dotp complexes, as a consequence of the ligand basicity. The solid-state structures of the ligand and of nine lanthanide(III) complexes were determined by X-ray diffraction. All the complexes are present as twisted-square-antiprismatic isomers and their structures can be divided into two series. The first one involves nona-coordinated complexes of the large lanthanide(III) ions (Ce, Nd, Sm) with a coordinated water molecule. In the series of Sm, Eu, Tb, Dy, Er, Yb, the complexes are octa-coordinated only by the ligand donor atoms and their coordination cages are more irregular. The formation kinetics and the acid-assisted dissociation of several Ln(III)-H(6)L complexes were investigated at different temperatures and compared with analogous data for complexes of other dota-like ligands. The [Ce(L)(H(2)O)](3-) complex is the most kinetically inert among complexes of the investigated lanthanide(III) ions (Ce, Eu, Gd, Yb). Among mixed phosphonate-acetate dota analogues, kinetic inertness of the cerium(III) complexes is increased with a higher number of phosphonate arms in the ligand, whereas the opposite is true for europium(III) complexes. According to the (1)H NMR spectroscopic pseudo-contact shifts for the Ce-Eu and Tb-Yb series, the solution structures of the complexes reflect the structures of the [Ce(HL)(H(2)O)](2-) and [Yb(HL)](2-) anions, respectively, found in the solid state. However, these solution NMR spectroscopic studies showed that there is no unambiguous relation between (31)P/(1)H lanthanide-induced shift (LIS) values and coordination of water in the complexes; the values rather express a relative position of the central ions between the N(4) and O(4) planes.


Assuntos
Compostos Aza/química , Ciclodecanos/química , Íons/química , Elementos da Série dos Lantanídeos/química , Compostos Organometálicos/química , Soluções/química , Água/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular
16.
Biomacromolecules ; 10(5): 1025-31, 2009 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-19351154

RESUMO

Polymer-shelled microbubbles are applied as ultrasound contrast agents. To investigate the effect of the polymer on microbubble preparation and acoustic properties, polylactides with systematic variations in molecular weight, crystallinity, and end-group hydrophobicity were used. Polymer-shelled cyclodecane filled capsules were prepared by emulsification, and the cyclodecane was removed by lyophilization to obtain hollow capsules. Complete removal of cyclodecane from the microcapsules was only achieved for short chain (about M(w) 6000) crystalline polymers. The pressure threshold for acoustic destruction of the microbubbles was found to increase with molecular weight. Noncrystalline polymers showed a higher threshold for destruction than crystalline polymers. Hydrophobically modified short chain crystalline polymers showed the steepest increase in acoustic destruction after the threshold as a function of the applied pressure, which is a favorable characteristic for ultrasound mediated drug delivery. Microcapsules made with such polymers had an inhomogeneous surface including pores through which cyclodecane was lyophilized efficiently.


Assuntos
Meios de Contraste/química , Ácido Láctico/química , Microbolhas , Ácido Poliglicólico/química , Acústica , Cápsulas/química , Cristalização , Ciclodecanos/química , Interações Hidrofóbicas e Hidrofílicas , Ácido Láctico/síntese química , Microscopia Eletrônica , Peso Molecular , Tamanho da Partícula , Poliésteres/química , Ácido Poliglicólico/síntese química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Porosidade , Pressão , Propriedades de Superfície , Temperatura
17.
J Control Release ; 133(2): 109-18, 2009 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-18951931

RESUMO

The use of ultrasound contrast agents as local drug delivery systems continues to grow. Current limitations are the amount of drug that can be incorporated as well as the efficiency of drug release upon insonification. This study focuses on the synthesis and characterisation of novel polymeric microcapsules for ultrasound-triggered delivery of lipophilic drugs. Microcapsules with a shell of fluorinated end-capped poly(L-lactic acid) were made through pre-mix membrane emulsification and contained, apart from a gaseous phase, different amounts of hexadecane oil as a drug-carrier reservoir. Mean number weighted diameters were between 1.22 microm and 1.31 microm. High-speed imaging at approximately 10 million fames per second showed that for low acoustic pressures (1 MHz, 0.24 MPa) microcapsules compressed but remained intact. At higher diagnostic pressures of 0.51 MPa, microcapsules cracked, thereby releasing the encapsulated gas and model lipophilic drug. Using conventional ultrasound B-mode imaging at a frequency of 2.5 MHz, a marked enhancement of scatter intensity over a tissue-mimicking phantom was observed for all differently loaded microcapsules. The partially oil-filled microcapsules with high drug loads and well-defined acoustic activation thresholds have great potential for ultrasound-triggered local delivery of lipophilic drugs under ultrasound image-guidance.


Assuntos
Alcanos/química , Sistemas de Liberação de Medicamentos/métodos , Preparações Farmacêuticas/administração & dosagem , Ultrassom , Alcanos/análise , Varredura Diferencial de Calorimetria , Cápsulas , Ciclodecanos/análise , Ciclodecanos/química , Fluorcarbonetos/química , Cromatografia Gasosa-Espectrometria de Massas , Gases/análise , Gases/química , Interações Hidrofóbicas e Hidrofílicas , Ácido Láctico/química , Microscopia Eletrônica , Tamanho da Partícula , Imagens de Fantasmas , Preparações Farmacêuticas/química , Poliésteres , Polímeros/química , Álcool de Polivinil/química , Propriedades de Superfície , Ultrassonografia
19.
Food Chem Toxicol ; 46 Suppl 12: S97-9, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18845211

RESUMO

A toxicologic and dermatologic review of tricyclodecanyl acetate when used as a fragrance ingredient is presented.


Assuntos
Acetatos/química , Acetatos/toxicidade , Perfumes/química , Perfumes/toxicidade , Acetatos/farmacocinética , Animais , Ciclodecanos/química , Ciclodecanos/farmacocinética , Ciclodecanos/toxicidade , Humanos , Perfumes/farmacocinética , Pele/efeitos dos fármacos , Pele/metabolismo
20.
Food Chem Toxicol ; 46 Suppl 12: S93-6, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18845216

RESUMO

A toxicologic and dermatologic review of tricyclodecenyl acetate when used as a fragrance ingredient is presented.


Assuntos
Acetatos/química , Acetatos/toxicidade , Ciclodecanos/química , Perfumes/química , Perfumes/toxicidade , Acetatos/farmacocinética , Animais , Ciclodecanos/farmacocinética , Ciclodecanos/toxicidade , Humanos , Perfumes/farmacocinética , Pele/efeitos dos fármacos , Pele/metabolismo
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