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1.
J Agric Food Chem ; 67(38): 10734-10743, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31479252

RESUMO

Glutenin is the main protein of flour and is a very important source of protein nutrition for humans. Methylglyoxal (MGO) is an important product of the Maillard reaction that occurs during the hot-processing of flour products, and it reacts with glutenin to facilitate changes in glutenin properties. Here, the effects of MGO on glutenin digestion during the heating process were investigated using a simulated MGO-glutenin system. MGO significantly reduced the digestibility of glutenin. The structure of MGO-glutenin and physicochemical properties were studied to understand the mechanism of the decrease of digestibility. These data suggest that changes in digestibility were caused by decreases in surface hydrophobicity and increases in disulfide bonds. MGO induces strong aggregation of glutenin after heating that led to the masking of cleavage sites for proteases. Moreover, carbonyl oxidation induced by MGO leads to intermolecular cross-linking of glutenin that increasingly masks or even destroys cleavage sites, further decreasing digestibility.


Assuntos
Glutens/química , Aldeído Pirúvico/química , Culinária , Digestão , Farinha/análise , Glutens/metabolismo , Temperatura Alta , Humanos , Interações Hidrofóbicas e Hidrofílicas , Reação de Maillard , Oxirredução , Aldeído Pirúvico/metabolismo
2.
J Agric Food Chem ; 67(37): 10361-10372, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31487173

RESUMO

Alkyl di-/tri-/tetraoxyethyl ß-d-xylopyranosides as derivatives of alkyl xylosides are a class of non-ionic sugar-based surfactants. They were stereoselectively synthesized by the Helferich method. Their properties including hydrophilic-lipophilic balance number, water solubility, surface property, foam property, emulsifying property, and thermotropic liquid crystal property were mainly investigated. The results showed that their water solubility decreased with increasing the alkyl chain length and increasing the number of the oligooxyethyl fragment. The critical micelle concentration had a monotonous decreasing trend with increasing the alkyl chain length. Nonyl di-/tri-/tetraoxyethyl ß-d-xylopyranosides [-(OCH2CH2)m-, where m = 2, 3, and 4] exhibited the most excellent foaming ability and foam stability. In the n-octane/water system, dodecyl tetraoxyethyl ß-d-xylopyranosides and tetradecyl tetraoxyethyl ß-d-xylopyranosides had the strongest emulsion ability. In addition, some alkyl di-/tri-/tetraoxyethyl ß-d-xylopyranosides had thermotropic liquid crystal properties. Such sugar-based surfactants, alkyl di-/tri-/tetraoxyethyl ß-d-xylopyranosides, will be expected to develop for a variety of practical application.


Assuntos
Glicosídeos/química , Tensoativos/química , Glicosídeos/síntese química , Interações Hidrofóbicas e Hidrofílicas , Solubilidade , Propriedades de Superfície , Tensoativos/síntese química
3.
Pharm Res ; 36(11): 153, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31482243

RESUMO

The purpose of this review is to discuss the challenges associated with the development of nanoparticle-based quality drug products in adhering to the principles of quality by design (QbD) and defining appropriate quality parameters towards successful product development. With the advent of nanotechnology into the pharmaceutical field, the novel field of nanomedicine was born. Due to their unique properties in terms of size, conformation and targeted delivery, nanomedicines are able to overcome many drawbacks of conventional medicine. As nano-sized formulations have made their way into more and more therapies, it has became clear that these very unique properties create hurdles for nanomedicines in successfully traversing the regulatory pathways and there is a need to develop nanomedicines in a more controlled and consistent fashion. The elements of a QbD methodology explained in this review enable the development of nano-based formulations in a way that maximizes the possibility of success. The identification of critical quality attributes (CQA) of the drug product and its intermediates are discussed in detail with a focus on nanomaterial-based formulations. In conclusion, QbD and the identification and specification of CQAs at its core are critical to the design, development and growth of nanomaterials in pharmaceuticals.


Assuntos
Desenvolvimento de Medicamentos/métodos , Nanocápsulas/química , Nanotecnologia/métodos , Animais , Preparações de Ação Retardada/química , Composição de Medicamentos , Estabilidade de Medicamentos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Nanomedicina , Resultado do Tratamento
4.
Phys Chem Chem Phys ; 21(37): 20999-21006, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31528872

RESUMO

A substantial number of diseases leading to loss of neurologic functions such as Morbus Alzheimer, Morbus Parkinson, or Chorea Huntington are related to the fibrillation of particular amyloidogenic peptides. In vitro amyloid fibrillation strongly depends on admixture with other proteins and peptides, lipids, nanoparticles, surfactants and polymers. We investigated amyloid-beta 1-40 peptide (Aß1-40) fibrillation in mixture with thermoresponsive poly(oligo(ethylene glycol)macrylates), in which the polymer's hydrophobicity is tuned by variation of the number of ethylene glycol-units in the side chain (m = 1-9), the end groups (B = butoxy; C = carboxy; D = dodecyl; P = pyridyldisulfide) and the degree of polymerization (n) of the polymers. The polymers were prepared via RAFT-polymerization, obtaining a broad range of molecular masses (Mn = 700 to 14 600 g mol-1 kDa-1, polydispersity indices PDI = 1.10 to 1.25) and tunable cloud point temperatures (Tcp), ranging from 42.4 °C to 80 °C, respectively. Proper combination of hydrophobic end groups with hydrophilic side chains of the polymer allowed to alter the hydrophilicity/hydrophobicity of these polymers, which is shown to enhance Aß1-40 aggregation significantly in case of the endgroup D (with n = 16, 23, 56). We observed that the less hydrophilic polymers (m = 1-2) were able to both decrease and elongate the lag (tlag) and characteristic times (tchar) of Aß1-40 fibril formation in dependence of their end groups, molecular mass and hydrophilicity. On the other hand, highly hydrophilic polymers (m = 3, 5, 9) either decreased, or only marginally influenced the lag and characteristic times of Aß1-40 fibrillation, in all cases forming ß-sheet rich fibrils as observed by TEM and CD-spectroscopy. Our results support that balanced hydrophobic and hydrophilic interactions of a polymer with Aß1-40 is important for inhibiting amyloid-formation pathways.


Assuntos
Peptídeos beta-Amiloides/química , Fragmentos de Peptídeos/química , Polímeros/química , Amiloide/química , Amiloide/ultraestrutura , Peptídeos beta-Amiloides/ultraestrutura , Interações Hidrofóbicas e Hidrofílicas , Fragmentos de Peptídeos/ultraestrutura
5.
J Chem Phys ; 151(8): 085101, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31470695

RESUMO

Periodic molecular dynamics simulations of proteins may suffer from image interactions. Similarly, the hydrophobic effect required to keep a protein folded may not be enforced by small simulation cells. Accordingly, errors may arise both from the water concentration per se and the image interactions. Intrinsically disordered proteins are particularly sensitive, providing a worst-case estimate of the errors. Following this reasoning, we studied Aß40 (Aß), a disordered peptide central to Alzheimer's disease, by 100 different simulations with variable cell size from very large (20 Å) to very small (3 Å). Even for this very disordered peptide, most properties are not cell-size dependent, justifying the common use of modest-sized (10 Å) cells for simulating proteins. The radius of gyration, secondary structure, intrapeptide, and peptide-water hydrogen bonds are similar relative to standard deviations at any cell size. However, hydrophobic surface area increases significantly in small cells (confidence 95%, two-tailed t-test), as does the standard deviation in exposure and backbone conformations (>40% and >27%). Similar results were obtained for the force fields OPLS3e, Ambersb99-ILDN, and Charmm22*. The similar prevalence of structures and α-ß transitions in long and short simulations indicate small diffusion barriers, which we suggest is a defining hallmark of intrinsically disordered proteins. Whereas hydrophilic exposure dominates in large cells, hydrophobic exposure dominates in small cells, suggesting a weakening of the hydrophobic effect by image interactions and the few water layers available to keep the protein compact, with a critical limit of 2-3 water layers required to enforce the hydrophobic effect.


Assuntos
Peptídeos beta-Amiloides/química , Tamanho Celular , Proteínas Intrinsicamente Desordenadas/química , Simulação de Dinâmica Molecular , Humanos , Interações Hidrofóbicas e Hidrofílicas , Conformação Proteica
6.
Bioresour Technol ; 293: 122009, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31493730

RESUMO

Here, we demonstrated the immobilization of bacterial feruloyl esterase (FAE) from Butyrivibrio sp. XPD2006, Lactobacillus crispatus, Butyrivibrio sp. AE2015, Ruminococcus albus, Cellulosilyticum ruminicola and Clostridium cellulovorans on SBA-15 and their ability to synthesize butyl ferulate (BFA). The BFae2 from Butyrivibrio sp. XPD2006 showed the best catalytic efficiency. High BFA yield was produced when the immobilization of BFae2 took place with a high protein loading and narrow pore sized SBA-15, suggesting alteration of enzyme behavior due to the crowding environment in SBA-15. Grafting of SBA-15 with octyl moieties led to shrinking pore size and resulted in 2.5-fold increment of BFA activity compared to the free enzyme and 70%mol BFA was achieved. The BFae2 encapsulated in hydrophobic-modified SBA-15 endured up to seven reaction cycles while the BFA activity remained above 60%. This is the first report showing the superior performance of hydrophobic-modified surface to entrap FAE to produce fatty phenolic esters.


Assuntos
Hidrolases de Éster Carboxílico , Dióxido de Silício , Catálise , Interações Hidrofóbicas e Hidrofílicas
7.
J Chem Theory Comput ; 15(9): 5154-5160, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31412199

RESUMO

Side-chain modeling plays a critical role in protein structure prediction. However, in many current methods, balancing the speed and accuracy is still challenging. In this paper, on the basis of our previous work OPUS-Rota (Protein Sci. 2008, 17, 1576-1585), we introduce a new side-chain modeling method, OPUS-Rota2, which is tested on both a 65-protein test set (DB65) in the OPUS-Rota paper and a 379-protein test set (DB379) in the SCWRL4 paper. If the main chain is native, OPUS-Rota2 is more accurate than OPUS-Rota, SCWRL4, and OSCAR-star but slightly less accurate than OSCAR-o. Also, if the main chain is non-native, OPUS-Rota2 is more accurate than any other method. Moreover, OPUS-Rota2 is significantly faster than any other method, in particular, 2 orders of magnitude faster than OSCAR-o. Thus, the combination of higher accuracy and speed of OPUS-Rota2 in modeling side chains on both the native and non-native main chains makes OPUS-Rota2 a very useful tool in protein structure modeling.


Assuntos
Modelos Moleculares , Proteínas/química , Algoritmos , Interações Hidrofóbicas e Hidrofílicas , Conformação Proteica
8.
Chem Commun (Camb) ; 55(66): 9829-9832, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31363730

RESUMO

Polyethylene glycol grafted pyrrole-based conjugated polymers are synthesized through a one-pot multicomponent methodology, the self-assemblies of which enable nanoparticle size-selective encapsulation of drug molecules and their sustained release. Efficient loading of curcumin through drug-nanoparticle core interactions is probed using FRET, and the inherently fluorescent nature of polypyrrole could be used to detect these nanocarriers intracellularly.


Assuntos
Portadores de Fármacos , Nanopartículas/química , Polietilenoglicóis/química , Polímeros/química , Pirróis/química , Linhagem Celular Tumoral , Curcumina/administração & dosagem , Transferência Ressonante de Energia de Fluorescência , Humanos , Interações Hidrofóbicas e Hidrofílicas , Concentração Inibidora 50 , Microscopia Eletrônica de Transmissão , Espectrofotometria Ultravioleta
9.
J Agric Food Chem ; 67(35): 9926-9933, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31398027

RESUMO

Vitamins and flavonoids are two kinds of essential trace bioactives which are prone to photodegradation during food processing and storage. In this study, a particle-stabilized water-in-water (W/W) emulsion system composed of soy protein isolate (SPI) and guar gum (GG) was applied in loading riboflavin. Based on the significant binding affinity differences of SPI (Ka = 1.11 × 105 L mol-1) and GG (Ka = 9.00 × 103 L mol-1) to riboflavin, this hydrophilic and light-sensitive bioactive compound was loaded in SPI-rich droplets. Confocal images indicated that a stable microstructure of SPI-rich droplets suspended in GG-rich continuous phase was successfully constructed by manipulating the proportion of the two polymeric components and using zein-based particles (ZPs) as stabilizers. These negatively charged particles modified by pectin with a hydrodynamic diameter of 533 ± 5.7 nm were able to adsorb at the SPI/GG interface and subsequently stabilized the SPI-in-GG emulsion. Fluorescence spectra of riboflavin suggested that the formation of such W/W emulsion could effectively delay the photodegradation of riboflavin during an 8 h ultraviolet irradiation, and its color was maintained to a maximum extent. Therefore, this structured W/W emulsion could be a desired architecture for delivering light-sensitive cargo.


Assuntos
Riboflavina/química , Água/química , Zeína/química , Composição de Medicamentos , Emulsões/química , Excipientes/química , Galactanos/química , Interações Hidrofóbicas e Hidrofílicas , Cinética , Mananas/química , Tamanho da Partícula , Fotólise , Gomas Vegetais/química
10.
J Agric Food Chem ; 67(35): 9907-9915, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31436102

RESUMO

The impact of covalent or non-covalent bound gallic acid (GA) on the formation, physicochemical properties, and digestion of ovotransferrin (OTF) nanofibrils was comprehensively studied. Thioflavin T fluorescence results revealed that bound GA could inhibit OTF nanofibrillation and that the fibril-inhibitory activity of bound GA was dose dependent. Covalent bound GA exerted stronger inhibition on OTF nanofibrillation than an equal amount of non-covalent bound GA. Atomic force microscopy revealed that covalent bound GA shortened OTF nanofibrils significantly, while non-covalent bound GA did not change the contour length of OTF fibrils remarkably. Bound GA altered diameter of OTF nanofibrils. Both covalent and non-covalent bound GA could alter the zeta potential, surface hydrophobicity, and rheological properties of OTF nanofibrils. Bound GA endowed OTF nanofibrils with a strong antioxidant activity. In vitro gastrointestinal digestion results showed that covalent bound GA elevated the fibril digestion rate better than non-covalent bound GA. Polyphenol binding provided a new approach to modulating the physicochemical properties of protein nanofibrils.


Assuntos
Conalbumina/química , Ácido Gálico/química , Nanofibras/química , Animais , Antioxidantes/química , Antioxidantes/metabolismo , Galinhas , Conalbumina/metabolismo , Digestão , Ácido Gálico/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Microscopia de Força Atômica , Modelos Biológicos , Reologia
11.
Biomater Sci ; 7(9): 3866-3875, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31309204

RESUMO

Photothermal therapy (PTT) is emerging as a promising treatment for skin cancer. Plasmon-resonant gold-coated liposome nanoparticles (Au Lipos NPs) specifically absorb Near Infra-Red (NIR) light resulting in localized hyperthermia (PTT). In the current study, curcumin (a hydrophobic anticancer agent) was entrapped in Au Lipos NPs as nanocrystals to act as an adjuvant for the PTT of melanoma. NIR light irradiation on Au Lipos Cur NPs triggered the release of curcumin nanocrystals which coalesce to form curcumin microcrystals (CMCs). An in situ"nano to micro" transition in the crystal state of curcumin was observed. This in situ transition leads to the formation of CMCs. These CMCs exhibited sustained release of curcumin for a prolonged duration (>10 days). The localized availability of curcumin aids in enhancing PTT by inhibiting the growth and mobility of cancer cells that escape PTT. In the in vitro modified scratch assay, the Au Lipos Cur NP + Laser group showed >1.5 fold enhanced therapeutic coverage when compared with the Au Lipos NP + Laser group. In vivo PTT studies performed in a B16 tumor model using Au Lipos Cur NPs showed a significant reduction of the tumor volume along with the localized release of curcumin in the tumor environment. It was observed that the localized release of curcumin enables an immediate adjuvant effect resulting in the enhancement of PTT.


Assuntos
Adjuvantes Farmacêuticos/química , Antineoplásicos/química , Curcumina/química , Ouro/química , Lipossomos/química , Nanopartículas Metálicas/química , Adjuvantes Farmacêuticos/administração & dosagem , Animais , Antineoplásicos/administração & dosagem , Linhagem Celular Tumoral , Movimento Celular , Quimioterapia Adjuvante , Cristalização , Curcumina/administração & dosagem , Feminino , Humanos , Interações Hidrofóbicas e Hidrofílicas , Hipertermia Induzida , Raios Infravermelhos , Melanoma/terapia , Nanopartículas Metálicas/administração & dosagem , Camundongos Endogâmicos C57BL , Tamanho da Partícula , Fototerapia/métodos , Neoplasias Cutâneas/terapia , Microambiente Tumoral
12.
Biomater Sci ; 7(9): 3898-3905, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31317137

RESUMO

To target a response to a high oxidative stress environment of inflammatory or tumor sites, various reactive oxygen species (ROS) sensitive polymers have been developed as drug delivery systems. In this study, a novel oxidation sensitive copolymer, phenylboronic acid pinacol ester-functionalized methoxyl poly(ethylene glycol)-block-poly(phthalic anhydride-alter-glycidyl propargyl ether) (mPEG-b-P(PA-alt-GPBAe)), was designed and synthesized by ring-opening alternating copolymerization (ROAP) and click reaction. The copolymers could self-assemble into micelles in aqueous solution with an average size of 20.3 ± 9.3 nm, and are able to load hydrophobic anticancer drug (doxorubicin, DOX) with a high encapsulation efficiency of 75.2%. Interestingly, the encapsulated drug showed accelerated release in the trigger of H2O2, or at low pH values. The copolymers have low cytotoxicity indicated by the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay towards 4T1 cells, which showed cell viabilities of more than 80% with treatment of our copolymers at concentrations up to 0.5 mg mL-1. The effective uptake of the drug-loaded micelles by 4T1 cells was investigated by confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) analysis. Finally, compared with free DOX, the DOX-loaded nanoparticles exhibited a better antitumor effect and had lower systemic toxicity in 4T1 tumor-bearing mice. Therefore, this new kind of copolymer acting as a stimuli-responsive nanocarrier should represent a promising therapeutic platform for cancer therapy.


Assuntos
Antineoplásicos/administração & dosagem , Ácidos Borônicos/química , Doxorrubicina/administração & dosagem , Nanocápsulas/química , Polímeros/química , Animais , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular , Sobrevivência Celular/efeitos dos fármacos , Liberação Controlada de Fármacos , Ésteres/química , Humanos , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Camundongos , Micelas , Oxirredução , Polietilenoglicóis/química
13.
Food Chem ; 300: 125171, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31330369

RESUMO

This study aimed to examine the modification effect of whey protein concentrate (WPC), WPC-gum arabic (WPC-GA) or WPC-high methoxyl pectin (WPC-PEC) complex to tailor-modify W/O/W emulsion for secondary microencapsulation of hydrophilic arbutin and hydrophobic coumaric acid. The stability and rheological properties of coated emulsions, encapsulation yield, release and degradation kinetics of arbutin and coumaric acid were investigated. Results revealed that WPC-PEC complex (at the ratio of 1:3) coating W/O/W emulsion exhibited the highest viscosity and stability, with the highest encapsulation yield of 91.08% for arbutin and 80.92% for coumaric acid, respectively. Tighter coating structure of the WPC-PEC complex (1:3) forming a stronger gel network structure was confirmed, accounting for the larger mean particle size of 569.67 nm. Moreover, the WPC-PEC (1:3) coating W/O/W emulsion also showed controlled release of arbutin and coumaric acid in simulated conditions. The k value of degradation kinetics for arbutin (7.99 × 10-4 at pH = 1.2, 4.19 × 10-4 at 90 °C and 7.52 × 10-4 at UV-C treatment) and coumaric acid (5.18 × 10-4 at pH = 1.2, 3.24 × 10-4 at 90 °C and 6.90 × 10-4 at UV-C treatment) indicated low degradation rate. The present study revealed that the WPC-PEC (1:3) coating W/O/W emulsion could provide a better synergistic effect on higher encapsulation yield and stability of arbutin and coumaric acid.


Assuntos
Arbutina/química , Cápsulas/química , Ácidos Cumáricos/química , Emulsões/química , Polissacarídeos/química , Arbutina/farmacocinética , Composição de Medicamentos , Goma Arábica/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Pectinas/química , Reologia , Temperatura Ambiente , Raios Ultravioleta , Viscosidade , Proteínas do Soro do Leite/química
14.
J Enzyme Inhib Med Chem ; 34(1): 1186-1192, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31282228

RESUMO

A series of sixteen benzenesulfonamide derivatives has been synthesised and tested as inhibitors of Vibrio cholerae carbonic anhydrase (CA) enzymes, belonging to α-CA, ß-CA, and γ-CA classes (VchCAα, VchCAß, and VchCAγ). The determined Ki values were compared to those of selected human CA isoforms (hCA I and hCA II). Structure-affinity relationship analysis highlighted that all tested compounds proved to be active inhibitors of VchCAα at nanomolar concentration. The VchCAß activity was lower to respect inhibitory efficacy toward VchCAα, whereas, these benzenesulfonamide derivatives failed to inhibit VchCAγ. Interestingly, compound 7e combined the best activity toward VchCAα and VchCAß. In order to obtain a model for binding mode of our inhibitors toward bacterial CAs, we carried out docking simulations by using the available crystal structures of VchCAß.


Assuntos
Inibidores da Anidrase Carbônica/uso terapêutico , Cólera/tratamento farmacológico , Isoenzimas/antagonistas & inibidores , Sulfonamidas/uso terapêutico , Inibidores da Anidrase Carbônica/química , Cólera/enzimologia , Humanos , Interações Hidrofóbicas e Hidrofílicas , Simulação de Acoplamento Molecular , Relação Estrutura-Atividade , Sulfonamidas/química , Vibrio cholerae/enzimologia
15.
J Agric Food Chem ; 67(33): 9325-9334, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31318196

RESUMO

In vitro dynamic aroma release over oil-in-water (o/w) and water-in-oil-in-water (w/o/w) emulsions stabilized with Tween 20 or octenyl succinic anhydride (OSA) starch as a hydrophilic emulsifier and polyglycerol polyricinoleate (PGPR) as a hydrophobic emulsifier was investigated. The equal-molecular-weight hydrophilic aroma diacetyl (2,3-butanedione) or relatively more-hydrophobic 3-pentanone was added to the emulsions prepared by high speed mixing, or membrane emulsification followed by thickened with xanthan gum removing droplet size distribution and creaming as variables affecting dynamic release. Results showed the differences of w/o/w emulsions in the dynamic release compared to o/w emulsions mainly depended on aroma hydrophobicity, emulsion type, emulsifier-aroma interactions, and creaming. Xanthan led to a reduced headspace replenishment. Interfacially adsorbed OSA starch and xanthan-OSA starch interaction influenced on diacetyl release over emulsions. OSA starch alone interacted with 3-pentanone. This study demonstrates the potential impact of emulsifying and thickening systems on aroma release systems and highlights that specific interactions may compromise product quality.


Assuntos
Emulsificantes/química , Odorantes/análise , Amido/química , Emulsões/química , Glicerol/análogos & derivados , Glicerol/química , Interações Hidrofóbicas e Hidrofílicas , Polissacarídeos Bacterianos/química , Polissorbatos/química , Ácidos Ricinoleicos/química , Anidridos Succínicos/química , Água/química
16.
J Agric Food Chem ; 67(33): 9344-9353, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31361957

RESUMO

Anthocyanins determine the color and potential health-promoting properties of red fruit juices, but the juices contain remarkably less anthocyanins than the fruits, which is partly caused by the interactions of anthocyanins with the residues of cell wall polysaccharides like pectin. In this study, pectin was modified by ultrasound and enzyme treatments to residues of polysaccharides and oligosaccharides widely differing in their molecular weight. Modifications decreased viscosity and degrees of acetylation and methylation and released smooth and hairy region fragments. Native and modified pectin induced different effects on the concentrations of individual anthocyanins after short-term and long-term incubation caused by both hydrophobic and hydrophilic interactions. Results indicate that both pectin and anthocyanin structure influence these interactions. Linear polymers generated by ultrasound formed insoluble anthocyanin complexes, whereas oligosaccharides produced by enzymes formed soluble complexes with protective properties. The structure of the anthocyanin aglycone apparently influenced interactions more than the sugar moiety.


Assuntos
Antocianinas/química , Beta vulgaris/química , Pectinas/química , Acetilação , Cor , Frutas/química , Sucos de Frutas e Vegetais/análise , Interações Hidrofóbicas e Hidrofílicas , Metilação , Peso Molecular , Ultrassom , Viscosidade
17.
Eur Biophys J ; 48(6): 549-558, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31327019

RESUMO

Liposomes are spherical vesicles enclosed by phospholipid bilayers. Nanoscale liposomes are widely employed for drug delivery in the pharmaceutical industry. In this study, nanoscale liposomes are fabricated using the microfluidic hydrodynamic focusing (MHF) approach, and the effects of flow rate ratio (FRR) on liposome size and drug loading efficiency are studied. Fluorescein isothiocyanate modified dextran is used as a hydrophilic drug simulant and Nile red is used as a hydrophobic drug simulant. The experiment results show that hydrophilic drug simulant loading efficiency increases as FRR increases and eventually plateaues at around 90% loading efficiency. The hydrophobic drug simulant loading efficiency and FRR have a positive linear correlation when FRR varies from 10 to 50. Concurrent loading of both hydrophilic and hydrophobic drug simulants maintains the same loading efficiencies as those of loading each drug simulant alone. A negative correlation between liposome size and FRR is also confirmed. Unloaded liposomes and hydrophilic drug-loaded liposomes are of the same sizes, and are smaller than the ones loaded with the hydrophobic drug simulants alone or combined. The results suggest tunable liposome size and drug loading efficiency with the MHF technique. This provides evidence to encourage further studies of microfluidic liposome fabrication in the pharmaceutical industry.


Assuntos
Hidrodinâmica , Dispositivos Lab-On-A-Chip , Lipossomos/química , Preparações Farmacêuticas/química , Interações Hidrofóbicas e Hidrofílicas , Oxazinas/química
18.
Adv Exp Med Biol ; 1140: 289-298, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31347054

RESUMO

Membrane proteins are of utmost importance in different cellular processes including: cell signaling, substrate transport, homeostasis control, immune surveillance, etc. In addition, they represent between 60% and 70% of the therapeutic targets currently used. Therefore, the identification and characterization of these proteins is crucial in many fields of research. Although proteomics has undergone an extraordinary advance in recent years thanks to the development of mass spectrometry, the methods used for the identification and quantification of soluble proteins generally fail to be used for membrane proteins, mainly due to their hydrophobic character.In this chapter, we revised the different alternatives, modifications and improvements that have been developed over the years with the aim of adapting the methods used in proteomics to the particular study of membrane proteins, thus allowing to increase the number of membrane proteins identified, as well as their coverage.


Assuntos
Espectrometria de Massas , Proteínas de Membrana/análise , Proteômica , Interações Hidrofóbicas e Hidrofílicas
19.
Molecules ; 24(13)2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31288444

RESUMO

Recently, we have found that calcium binding proteins of the EF-hand superfamily (i.e., a large family of proteins containing helix-loop-helix calcium binding motif or EF-hand) contain two types of conserved clusters called cluster I ('black' cluster) and cluster II ('grey' cluster), which provide a supporting scaffold for the Ca2+ binding loops and contribute to the hydrophobic core of the EF-hand domains. Cluster I is more conservative and mostly incorporates aromatic amino acids, whereas cluster II includes a mix of aromatic, hydrophobic, and polar amino acids of different sizes. Recoverin is EF-hand Ca2+-binding protein containing two 'black' clusters comprised of F35, F83, Y86 (N-terminal domain) and F106, E169, F172 (C-terminal domain) as well as two 'gray' clusters comprised of F70, Q46, F49 (N-terminal domain) and W156, K119, V122 (C-terminal domain). To understand a role of these residues in structure and function of human recoverin, we sequentially substituted them for alanine and studied the resulting mutants by a set of biophysical methods. Under metal-free conditions, the 'black' clusters mutants (except for F35A and E169A) were characterized by an increase in the α-helical content, whereas the 'gray' cluster mutants (except for K119A) exhibited the opposite behavior. By contrast, in Ca2+-loaded mutants the α-helical content was always elevated. In the absence of calcium, the substitutions only slightly affected multimerization of recoverin regardless of their localization (except for K119A). Meanwhile, in the presence of calcium mutations in N-terminal domain of the protein significantly suppressed this process, indicating that surface properties of Ca2+-bound recoverin are highly affected by N-terminal cluster residues. The substitutions in C-terminal clusters generally reduced thermal stability of recoverin with F172A ('black' cluster) as well as W156A and K119A ('gray' cluster) being the most efficacious in this respect. In contrast, the mutations in the N-terminal clusters caused less pronounced differently directed changes in thermal stability of the protein. The substitutions of F172, W156, and K119 in C-terminal domain of recoverin together with substitution of Q46 in its N-terminal domain provoked significant but diverse changes in free energy associated with Ca2+ binding to the protein: the mutant K119A demonstrated significantly improved calcium binding, whereas F172A and W156A showed decrease in the calcium affinity and Q46A exhibited no ion coordination in one of the Ca2+-binding sites. The most of the N-terminal clusters mutations suppressed membrane binding of recoverin and its inhibitory activity towards rhodopsin kinase (GRK1). Surprisingly, the mutant W156A aberrantly activated rhodopsin phosphorylation regardless of the presence of calcium. Taken together, these data confirm the scaffolding function of several cluster-forming residues and point to their critical role in supporting physiological activity of recoverin.


Assuntos
Recoverina/química , Recoverina/metabolismo , Alanina/química , Motivos de Aminoácidos , Substituição de Aminoácidos , Cálcio/metabolismo , Receptor Quinase 1 Acoplada a Proteína G/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cinética , Modelos Moleculares , Mutação , Fosforilação , Ligação Proteica , Recoverina/genética , Rodopsina/metabolismo
20.
Chem Commun (Camb) ; 55(66): 9797-9800, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31360962

RESUMO

Molecular tubes with hydrogen bonding donors in their deep hydrophobic cavities are able to selectively bind organophosphorus compounds in water through hydrogen bonding and the hydrophobic effect. They can also be used as a fluorescent sensor for nerve agent simulants and as an inhibitor to reduce the toxicity of paraoxon to acetylcholinesterase.


Assuntos
Acetilcolinesterase/efeitos dos fármacos , Inibidores da Colinesterase/química , Inibidores da Colinesterase/toxicidade , Agentes Neurotóxicos/química , Agentes Neurotóxicos/toxicidade , Paraoxon/química , Paraoxon/toxicidade , Calorimetria , Corantes Fluorescentes/química , Ligações de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Espectroscopia de Ressonância Magnética/métodos , Termodinâmica , Água/química
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