RESUMO
Whey protein isolate (WPI)-based nanodelivery systems have recently attracted an increasing amount of attention. Despite this, research focusing on milk protein concentrate (MPC) and micellar casein (MCC) as carriers loaded in hydrophobic compounds is lacking. This study investigated the mediated effect of docosahexaenoic acid (DHA) in 3 different milk proteins for the embedding of astaxanthin (ASTA) after ultrasound-assisted pH-shifting treatment. We then evaluated the application of milk protein carriers in cheese processing by comparing MPC, MCC, and WPI. The particle size, polydispersity index, and zeta potential results of the milk protein-DHA complex suggested that the addition of 0.36 µmol/mL DHA optimized the delivery of milk protein to ASTA. All 3 DHA-mediated milk proteins induced an improvement in encapsulation efficiency and antioxidant properties of ASTA. Furthermore, the DHA-mediated MPC and MCC played a stronger role in improving the bioaccessibility and thermal and storage stability of ASTA than those without DHA. Tests conducted to examine the application in cheese production indicated that MCC carrier had a positive effect on the texture of cheeses. However, the delivery effect was dependent on the milk protein variety, and MCC exhibited the best protection ability of ASTA, followed by MPC and WPI. The simulated digestion and storage stability results of cheese further confirmed that the protein encapsulation mediated by DHA was more conducive to ASTA absorption. These findings suggested that the DHA-mediated milk protein complexes studied here may be suitable hydrophilic delivery carriers for the hydrophobic nutrient ASTA, potentially playing different roles in improving its storage stability and bioaccessibility.
Assuntos
Queijo , Ácidos Docosa-Hexaenoicos , Proteínas do Leite , Xantofilas , Animais , Concentração de Íons de Hidrogênio , Proteínas do Soro do Leite , CaseínasRESUMO
Two fluorescent diboronic acid compounds (6a and 6b) with a dipeptide linker were synthesized as potential sensors for cell surface saccharide Lewis X (Le(X)). Compound 6a with a dipeptide (H-Asp-Ala-) as the linker was found to selectively label CHOFUT4 cells, which express Le(x), at micromolar concentrations, while non-Le(x)-expressing control cells were not labeled.
Assuntos
Antracenos/química , Ácidos Borônicos/química , Corantes Fluorescentes/química , Oligossacarídeos/metabolismo , Animais , Antracenos/síntese química , Antracenos/metabolismo , Ácidos Borônicos/síntese química , Ácidos Borônicos/metabolismo , Células CHO , Cricetinae , Cricetulus , Dipeptídeos/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/metabolismo , Fucosiltransferases/química , Fucosiltransferases/metabolismo , Antígenos do Grupo Sanguíneo de Lewis , Microscopia de Fluorescência , Oligossacarídeos/genéticaRESUMO
In this research, the characteristic ions' abundance ratio between two isomers A and B in MS/MS mass spectra was defined as a parameter for discriminating diastereomers. Through this ratio, the discrimination of four pairs of cyclic peptide (CP) diastereomers was successfully achieved. Furthermore, in the analysis of diastereomers' mixtures, both calibration curve and calculational methods were substantiated to have high precision and accuracy. The average absolute errors of the two methods were 2.0 and 2.5% in the 48 measurements of 16 samples, respectively. This research provided a promising approach for the analysis of the CP diastereomers in the fields of asymmetrical synthesis, chiral natural products and structural biology by ESI-MS/MS.
Assuntos
Mapeamento de Peptídeos/métodos , Peptídeos Cíclicos/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Medicamentos de Ervas Chinesas/química , Reprodutibilidade dos Testes , Estereoisomerismo , Espectrometria de Massas em TandemRESUMO
The boronic acid functional group plays very important roles in sugar recognition, catalysis, organic synthesis, and supramolecular assembly. Therefore, understanding the unique properties of this functional group is very important. 8-Quinolineboronic acid (8-QBA) is found to be capable of self-assembling in solid state through a unique intermolecular B-N bond mechanism reinforced by intermolecular boronic anhydride formation, π-π stacking, and hydrogen bond formation. NMR NOE and diffusion studies indicate that intermolecular B-N interaction also exists in solution with 8-QBA. In contrast, a positional isomer of 8-QBA, 5-quinolineboronic acid (5-QBA) showed very different behaviors in crystal packing and in solution and therefore different supramolecular network. Understanding the structural features of this unique 8-QBA assembly could be very helpful for the future design of new sugar sensors, molecular catalysts, and supramolecular assemblies.
RESUMO
Maintaining a proper balance of metal concentrations is critical to the survival of bacteria. We have designed and synthesized a series of conjugates of metal chelators and efflux transporter substrates aimed at disrupting bacterial metal homeostasis to achieve bacterial killing. Biological studies showed that two of the compounds had very significant antimicrobial effect with an MIC value of 7.8 microg/mL against Gram-positive Bacillus subtilis.
Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Quelantes/síntese química , Quelantes/farmacologia , Bacillus subtilis/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Desenho de Fármacos , Farmacorresistência Bacteriana Múltipla , Escherichia coli/efeitos dos fármacos , Indicadores e Reagentes , Metais/metabolismo , Testes de Sensibilidade Microbiana , Relação Estrutura-AtividadeRESUMO
Four new naphthalene-based boronic acid compounds (1-4) were synthesized. The effect of various carbohydrates on their fluorescence properties has been studied in aqueous phosphate buffer at pH 7.4. Different substitutions on the aniline group of the naphthalene ring resulted in significant differences in fluorescence properties for these four compounds. Compound 1 shows ratiometric fluorescence changes upon addition of a sugar. Compounds 2 and 3 do not show ratiometric fluorescence changes but show very large fluorescence intensity changes (about 70-fold fluorescence intensity increase). In addition to the quantifiable fluorescence property changes upon sugar addition, the fluorescence color changes of 1-3 are also visible to the naked eye. However, amidation of the aniline nitrogen atom significantly diminishes the fluorescence intensity of compound 4. The crystal structure of one boronic acid provided some insight into the structural features that are important for the fluorescence properties of these compounds.
Assuntos
Compostos de Boro/química , Ácidos Borônicos/química , Oligossacarídeos/análise , Técnicas Biossensoriais , Compostos de Boro/síntese química , Ácidos Borônicos/síntese química , Cristalografia por Raios X , Fluorescência , Estrutura Molecular , Oligossacarídeos/químicaRESUMO
Carbohydrate antigens with subterminal fucosylation have been implicated in the development and progression of several cancers, including hepatocellular carcinoma (HCC). Fluorescent sensors targeting fucosylated carbohydrate antigens could potentially be used for diagnostic and other applications. We have designed and synthesized a series of 26 diboronic acid compounds as potential fluorescent sensors for such carbohydrates. Among these compounds, 7q was able to fluorescently label cells expressing high levels of sLex (HEPG2) within a concentration range of 0.5 to 10 microM. This compound (7q) did not label cells expressing Lewis Y (HEP3B), nor cells without fucosylated antigens (COS7). This represents the first example of a fluorescent compound labeling cells based on cell surface carbohydrate structures.
Assuntos
Ácidos Borônicos/química , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Oligossacarídeos/análise , Oligossacarídeos/genética , Animais , Ácidos Borônicos/síntese química , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/imunologia , Linhagem Celular , Fluorescência , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/imunologia , Estrutura Molecular , Oligossacarídeos/química , Antígeno Sialil Lewis XRESUMO
[structure: see text] A new boronic acid fluorescent on-off reporter compound (1) was synthesized. This fluorescent sensor shows a 41-fold emission intensity increase upon addition of 50 mM fructose in 0.1 M aqueous phosphate buffer at pH 7.4.
Assuntos
1-Naftilamina/síntese química , Ácidos Borônicos/química , Ácidos Borônicos/síntese química , Naftalenos/química , 1-Naftilamina/análogos & derivados , 1-Naftilamina/química , Boro/química , Carboidratos/química , Fluorescência , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Espectrometria de Fluorescência , TitulometriaRESUMO
Boronic acid compounds have been used, because of their unique structural features, for the development of potent enzyme inhibitors, boron neutron capture agents for cancer therapy, and as antibody mimics that recognize biologically important saccharides. Consequently, there has been a surge of interests in boronic acid compounds. This study reviews the recent development in this area during the last six years.
Assuntos
Compostos de Boro/farmacologia , Ácidos/química , Ácidos/farmacologia , Compostos de Boro/química , Terapia por Captura de Nêutron de Boro , Sistemas de Liberação de Medicamentos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , HumanosRESUMO
A glucose selective diphenylboronic acid fluorescent sensor (10a) with a K(a) of 1472M(-1) has been synthesized and evaluated. This sensor shows a 43- and 49-fold selectivity for glucose over fructose and galactose, respectively. The binding affinity improvement is about 300-fold and the selectivity improvement for glucose over fructose is about 1400-fold compared with the monoboronic acid compound, phenylboronic acid. 1H NMR studies indicate that sensor 10a binds with alpha-D-glucofuranose in a bidentate manner (1:1 ratio).
Assuntos
Técnicas Biossensoriais/métodos , Compostos de Boro/química , Corantes Fluorescentes/química , Glucose/análise , Compostos de Boro/síntese química , Fluorescência , Corantes Fluorescentes/síntese química , Glucose/análogos & derivados , Espectroscopia de Ressonância Magnética , Sensibilidade e Especificidade , Espectrometria de FluorescênciaRESUMO
Six cyclic pentapeptides containing two or three non-protein amino acids have been synthesized by cyclization of linear precursors in dilute solution and characterized by TLC. HPLC, NMR, melting point. specific rotation etc. A total of 72 cyclization reactions were carried out to study the factors that influence head-to-tail cyclization: linear precursor sequence, coupling reagent, residue configuration, the proportion of DMAP additive, concentration, reaction temperature and reaction time. The cyclic pentapeptides will be modified by active moieties and evaluated as LHRH antagonists.
Assuntos
Hormônio Liberador de Gonadotropina/antagonistas & inibidores , Oligopeptídeos/síntese química , Oligopeptídeos/farmacologia , Peptídeos Cíclicos/síntese química , Peptídeos Cíclicos/farmacologia , Sequência de Aminoácidos , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Indicadores e Reagentes , Ressonância Magnética Nuclear Biomolecular , Oligopeptídeos/química , Peptídeos Cíclicos/química , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas de Bombardeamento Rápido de Átomos , TemperaturaRESUMO
A series of fluorescent diboronic acids was synthesized in nine steps as potential sensors for sialyl Lewis X (sLex). The fluorescent binding studies of these sensors with sLex were carried out in a mixed aqueous solution. Compound 7e was found to show the strongest fluorescence enhancement upon binding with sLex. Using cell cultures, 7e was shown to label sLex-expressing HEPG2 cells at 1 microM, while non-sLex-expressing cells were not labeled.