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1.
Nanomedicine ; 58: 102751, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38705222

RESUMEN

Active targeting can enhance precision and efficacy of drug delivery systems (DDS) against cancers. Riboflavin (RF) is a promising ligand for active targeting due to its biocompatibility and high riboflavin-receptor expression in cancers. In this study, RF-targeted 4-arm polyethylene glycol (PEG) stars conjugated with Paclitaxel (PTX), named PEG PTX RF, were evaluated as a targeted DDS. In vitro, PEG PTX RF exhibited higher toxicity against tumor cells compared to the non-targeted counterpart (PEG PTX), while free PTX displayed the highest acute toxicity. In vivo, all treatments were similarly effective, but PEG PTX RF-treated tumors showed fewer proliferating cells, pointing to sustained therapy effects. Moreover, PTX-treated animals' body and liver weights were significantly reduced, whereas both remained stable in PEG PTX and PEG PTX RF-treated animals. Overall, our targeted and non-targeted DDS reduced PTX's adverse effects, with RF targeting promoted drug uptake in cancer cells for sustained therapeutic effect.


Asunto(s)
Sistemas de Liberación de Medicamentos , Paclitaxel , Polietilenglicoles , Riboflavina , Paclitaxel/farmacología , Paclitaxel/química , Riboflavina/farmacología , Riboflavina/química , Animales , Humanos , Ratones , Polietilenglicoles/química , Línea Celular Tumoral , Ratones Endogámicos BALB C , Polímeros/química , Antineoplásicos Fitogénicos/farmacología , Antineoplásicos Fitogénicos/química , Ratones Desnudos , Neoplasias/tratamiento farmacológico , Neoplasias/patología , Ensayos Antitumor por Modelo de Xenoinjerto , Femenino
2.
Int J Biol Macromol ; 270(Pt 2): 132313, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38740156

RESUMEN

The application of many hydrophilic and hydrophobic nutraceuticals is limited by their poor solubility, chemical stability, and/or bioaccessibility. In this study, a novel Pickering high internal phase double emulsion co-stabilized by modified pea protein isolate (PPI) and sodium alginate (SA) was developed for the co-encapsulation of model hydrophilic (riboflavin) and hydrophobic (ß-carotene) nutraceuticals. Initially, the effect of emulsifier type in the external water phase on emulsion formation and stability was examined, including commercial PPI (C-PPI), C-PPI-SA complex, homogenized and ultrasonicated PPI (HU-PPI), and HU-PPI-SA complex. The encapsulation and protective effects of these double emulsions on hydrophilic riboflavin and hydrophobic ß-carotene were then evaluated. The results demonstrated that the thermal and storage stabilities of the double emulsion formulated from HU-PPI-SA were high, which was attributed to the formation of a thick biopolymer coating around the oil droplets, as well as thickening of the aqueous phase. Encapsulation significantly improved the photostability of the two nutraceuticals. The double emulsion formulated from HU-PPI-SA significantly improved the in vitro bioaccessibility of ß-carotene, which was mainly attributed to inhibition of its chemical degradation under simulated acidic gastric conditions. The novel delivery system may therefore be used for the development of functional foods containing multiple nutraceuticals.


Asunto(s)
Alginatos , Emulsiones , Proteínas de Guisantes , Riboflavina , beta Caroteno , beta Caroteno/química , Alginatos/química , Riboflavina/química , Emulsiones/química , Proteínas de Guisantes/química , Composición de Medicamentos/métodos , Interacciones Hidrofóbicas e Hidrofílicas , Solubilidad , Estabilidad de Medicamentos , Cápsulas
3.
J Chem Inf Model ; 64(11): 4570-4586, 2024 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-38800845

RESUMEN

It is nowadays clear that RNA molecules can play active roles in several biological processes. As a result, an increasing number of RNAs are gradually being identified as potentially druggable targets. In particular, noncoding RNAs can adopt highly organized conformations that are suitable for drug binding. However, RNAs are still considered challenging targets due to their complex structural dynamics and high charge density. Thus, elucidating relevant features of drug-RNA binding is fundamental for advancing drug discovery. Here, by using Molecular Dynamics simulations, we compare key features of ligand binding to proteins with those observed in RNA. Specifically, we explore similarities and differences in terms of (i) conformational flexibility of the target, (ii) electrostatic contribution to binding free energy, and (iii) water and ligand dynamics. As a test case, we examine binding of the same ligand, namely riboflavin, to protein and RNA targets, specifically the riboflavin (RF) kinase and flavin mononucleotide (FMN) riboswitch. The FMN riboswitch exhibited enhanced fluctuations and explored a wider conformational space, compared to the protein target, underscoring the importance of RNA flexibility in ligand binding. Conversely, a similar electrostatic contribution to the binding free energy of riboflavin was found. Finally, greater stability of water molecules was observed in the FMN riboswitch compared to the RF kinase, possibly due to the different shape and polarity of the pockets.


Asunto(s)
Simulación de Dinámica Molecular , ARN , Riboflavina , Riboswitch , Riboflavina/química , Riboflavina/metabolismo , Ligandos , ARN/química , ARN/metabolismo , Unión Proteica , Conformación de Ácido Nucleico , Termodinámica , Electricidad Estática , Conformación Proteica , Agua/química
4.
Biomater Adv ; 161: 213898, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38796957

RESUMEN

In this study, we report the preparation of bio-inspired binary CuO/ZnO nanocomposite (bb-CuO/ZnO nanocomposite) via the biological route using Bauhinia variegata flower extract following hydrothermal treatment. The prepared bb-CuO/ZnO nanocomposite was electrophoretically deposited (EPD) on indium tin oxide (ITO) substrate to develop bb-CuO/ZnO/ITO biosensing electrode which is employed for the determination of vitamin B2 (Riboflavin) through electrochemical techniques. Physicochemical assets of the prepared bb-CuO/ZnO nanocomposite have been extensively evaluated and make use of different characterization techniques including powder XRD, FT-IR, AFM, SEM, TEM, EDX, XPS, Raman, and TGA. Electrochemical characteristics of the bb-CuO/ZnO/ITO biosensing electrode have been studied towards vitamin B2 determination. Furthermore, different biosensing parameters such as response time, reusability, stability, interference, and real sample analysis were also estimated. From the linear plot of scan rate, charge transfer rate constant (Ks), surface concentration of electrode (γ), and diffusion coefficient (D) have been calculated, and these are found to be 6.56 × 10-1 s-1, 1.21 × 10-7 mol cm-2, and 6.99 × 10-3 cm2 s-1, respectively. This biosensor exhibits the linear range of vitamin B2 detection from 1 to 40 µM, including sensitivity and limit of detection (LOD) of 1.37 × 10-3 mA/µM cm2 and 0.254 µM, respectively. For higher concentration range detection linearity is 50-100 µM, with sensitivity and the LOD of 1.26 × 10-3 mA/µM cm2 and 0.145 µM, respectively. The results indicate that the bio-inspired nanomaterials are promising sustainable biosensing platforms for various food and health-based biosensing devices.


Asunto(s)
Bauhinia , Técnicas Biosensibles , Cobre , Técnicas Electroquímicas , Flores , Nanocompuestos , Extractos Vegetales , Riboflavina , Óxido de Zinc , Cobre/química , Cobre/análisis , Extractos Vegetales/química , Nanocompuestos/química , Técnicas Electroquímicas/métodos , Flores/química , Técnicas Biosensibles/métodos , Óxido de Zinc/química , Bauhinia/química , Riboflavina/análisis , Riboflavina/química , Electrodos , Límite de Detección
5.
Int J Pharm ; 656: 124090, 2024 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-38582101

RESUMEN

Advancements in industrial technologies and the application of quality by design (QbD) guidelines are shifting the attention of manufacturers towards innovative production techniques. In the pharmaceutical field, there is a significant focus on the implementation of continuous processes, in which the production stages are carried out continuously, without the need to interrupt the process and store the production intermediates, as in traditional batch production. Such innovative production techniques also require the development of proper analytical methods able to analyze the products in-line, while still being processed. The present study aims to compare a traditional batch manufacturing process with an alternative continuous one. To this end, a real pharmaceutical formulation was used, substituting the active pharmaceutical ingredient (API) with riboflavin, at the concentration of 2 %w/w. Moreover, a direct and non-destructive analytical method based on UV-Vis reflectance spectroscopy was applied for the quantification of riboflavin in the final tablets, and compared with a traditional absorbance analysis. Good results were obtained in the comparison of both the two manufacturing processes and the two analytical methods, with R2 higher than 0.9 for all the calculated calibration models and predicted riboflavin concentrations that never significantly overcame the 15 % limits recommended by the pharmacopeia. The continuous production method demonstrated to be as reliable as the batch one, allowing to save time and money in the production step. Moreover, UV-Vis reflectance was proved to be an interesting alternative to absorption spectroscopy, which, with the proper technology, could be implemented for in-line process control.


Asunto(s)
Riboflavina , Espectrofotometría Ultravioleta , Comprimidos , Tecnología Farmacéutica , Riboflavina/análisis , Riboflavina/química , Tecnología Farmacéutica/métodos , Espectrofotometría Ultravioleta/métodos , Composición de Medicamentos/métodos , Química Farmacéutica/métodos
6.
ACS Appl Bio Mater ; 7(5): 2734-2740, 2024 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-38651321

RESUMEN

3D printing of a living bioanode holds the potential for the rapid and efficient production of bioelectrochemistry systems. However, the ink (such as sodium alginate, SA) that formed the matrix of the 3D-printed bioanode may hinder extracellular electron transfer (EET) between the microorganism and conductive materials. Here, we proposed a biomimetic design of a 3D-printed Shewanella bioanode, wherein riboflavin (RF) was modified on carbon black (CB) to serve as a redox substance for microbial EET. By introducing the medicated EET pathways, the 3D-printed bioanode obtained a maximum power density of 252 ± 12 mW/m2, which was 1.7 and 60.5 times higher than those of SA-CB (92 ± 10 mW/m2) and a bare carbon cloth anode (3.8 ± 0.4 mW/m2). Adding RF reduced the charge-transfer resistance of a 3D-printed bioanode by 75% (189.5 ± 18.7 vs 47.3 ± 7.8 Ω), indicating a significant acceleration in the EET efficiency within the bioanode. This work provided a fundamental and instrumental concept for constructing a 3D-printed bioanode.


Asunto(s)
Materiales Biocompatibles , Ensayo de Materiales , Impresión Tridimensional , Riboflavina , Shewanella , Riboflavina/química , Riboflavina/metabolismo , Shewanella/metabolismo , Transporte de Electrón , Materiales Biocompatibles/química , Fuentes de Energía Bioeléctrica , Electrodos , Hollín/química , Tamaño de la Partícula , Tinta
7.
Chem Res Toxicol ; 37(3): 455-464, 2024 03 18.
Artículo en Inglés | MEDLINE | ID: mdl-38452272

RESUMEN

(E)-Ethyl 2-cyano-3-(4'-(diphenyl amino)-[1,1'-biphenyl]-4-yl) acrylate (RSJ) is a novel luminogen based on triphenylamine. It has been fully synthesized and characterized, exhibiting an incredible photophysical phenomenon known as aggregation-induced emission (AIE). This work describes a fluorescent sensor that detects vitamin B2 in mixed aqueous media with high selectivity and a low limit of detection as well as a mechanism for reversible mechanochromic luminescence. Moreover, the molecule was validated for its nontoxicity in water using a histotoxicological study. Fish subjected to two different concentrations of the "novel luminogen" that displayed photophysical phenomena during sensing of vitamin B2 (riboflavin) in mixed aqueous media did not exhibit any significant differences in the structural makeup of their liver, kidney, gills, brain, and muscle tissues when compared with the control group.


Asunto(s)
Riboflavina , Agua , Animales , Riboflavina/química , Agua/química , Colorantes Fluorescentes/química , Aminas
8.
Food Funct ; 15(3): 1527-1538, 2024 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-38231081

RESUMEN

Foods rich in riboflavin (Rf) are susceptible to degradation due to oxidative processes with the formation of radicals. Herein, we describe the features and stability of an Mg(II) complex containing ferulic acid (fer) and 1,10-phenanthroline (phen) as chelators: henceforth called Mg(phen)(fer). The electrochemical behavior of Mg(phen)(fer) is pH dependent and results from the stabilisation of the corresponding phenoxyl radical via complexation with Mg(II). This stabilisation enhances the antioxidant activity of Mg(phen)(fer) with respect to free fer and commercial antioxidants. Mg(phen)(fer) scavenges and neutralizes DPPH˙ (IC50 = 15.6 µmol L-1), ABTS˙+ (IC50 = 5.65 µmol L-1), peroxyl radical (IC50 = 5.64 µg L-1) and 1O2 (IC50 = 0.7 µg m-1). Mg(phen)(fer) effectively protects riboflavin (Rf) against photodegradation by quenching the singlet excited states of Rf regardless of the conditions. Also, the complex Mg(phen)(fer) was effectively incorporated into starch films, broadening its applications, as shown by microbiological studies. Thus, Mg(phen)(fer) has high potential for use in Rf-rich foods and to become a new alternative to the synthetic antioxidants currently used.


Asunto(s)
Antioxidantes , Quelantes , Antioxidantes/farmacología , Antioxidantes/química , Riboflavina/química , Ácidos Cumáricos
9.
Spectrochim Acta A Mol Biomol Spectrosc ; 309: 123813, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38198998

RESUMEN

Ascorbic acid (AH2) photoxidation sensitized by riboflavin (RF) has been studied between pH 2.0 and 12.0 in ambient air and anaerobic environment using UV and visible irradiation sources. The kinetics of AH2 degradation in aqueous medium along with RF is found to be first-order for its photodegradation. AH2 photolysis rate constants in aerobic and anaerobic conditions with RF (1.0-5.0 × 10-5 M) are 0.14-3.89 × 10-2 and 0.026-0.740 × 10-2 min-1, respectively. The rate constants (k2) of second-order kinetics for AH2 and RF photochemical interaction in aerobic and anaerobic conditions are in the range of 0.24-3.70 to 0.05-0.70 × 10-3 M-1 min-1, respectively, which manifests that increasing the RF concentration also increases the rate of photodegradation (photooxidation) of AH2. The k2 versus pH graph is bell-shaped which indicates that increasing the pH increases photolytic degradation rate of AH2 with RF. Increasing the pH results in the increased ionization of AH2 (ascorbyl anion, AH-) and redox potential which leads to the higher rates of photodegradation of AH2. Two-component spectrophotometric (243 and 266 nm, AH2 and RF, respectively) and high-performance liquid chromatography (HPLC) methods have been used to determine the concentration of AH2 and RF in pure and degraded solutions. The results obtained from these two methods are compared using a student t-test which showed no noteworthy difference between them.


Asunto(s)
Ácido Ascórbico , Riboflavina , Riboflavina/química , Ácido Ascórbico/química , Vitaminas , Fotólisis , Luz , Cinética
10.
Bioorg Med Chem Lett ; 96: 129529, 2023 11 15.
Artículo en Inglés | MEDLINE | ID: mdl-37858620

RESUMEN

Riboflavin, a member of the B vitamin family, is a water-soluble vitamin that participates in energy metabolism processes via two coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), in oxidized and reduced forms. Low levels of riboflavin have been associated with growth and developmental problems. In an effort to investigate the role of hydrogen bonding in the interactions between riboflavin and chicken riboflavin binding protein, the solid state geometry characteristics of a riboflavin derivative stripped of hydroxyl groups except the primary one, N-(6'-hydroxyhexyl)isoalloxazine, were investigated and found that π-stacking and hydrogen bonding involving the isoalloxazine rings are the primary intermolecular interactions. Subsequent comparative fluorescence studies showed that at neutral pH, in presence of the protein, quenching of N-(6'-hydroxyhexyl)isoalloxazine and riboflavin occurred similarly suggesting that the hydroxyl groups were not a key component of the vitamin protein interactions in the binding pocket.


Asunto(s)
Proteínas Portadoras , Pollos , Animales , Pollos/metabolismo , Riboflavina/química , Flavina-Adenina Dinucleótido/química , Flavina-Adenina Dinucleótido/metabolismo , Vitaminas
11.
Arch Biochem Biophys ; 748: 109762, 2023 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-37739114

RESUMEN

The rapid resistance of pathogens to antibiotics has emerged as a major threat to global health. Identification of new antibiotic targets is thus needed for developing alternative drugs. Genes encoding enzymes involved in the biosynthesis of riboflavin and flavin cofactors (FMN/FAD) are attractive targets because these enzymatic reactions are necessary for most bacteria to synthesize flavin cofactors for use in their central metabolic reactions. Moreover, humans lack most of these enzymes because we uptake riboflavin from our diet. This review discusses the current knowledge of enzymes involved in bacterial biosynthesis of riboflavin and other flavin cofactors, as well as the functions of the FMN riboswitch. Here, we highlight recent progress in the structural and mechanistic characterization, and inhibition of GTP cyclohydrolase II (GCH II), lumazine synthase (LS), riboflavin synthase (RFS), FAD synthetase (FADS), and FMN riboswitch, which have been identified as plausible antibiotic targets. As the structures and functions of these enzymes and regulatory systems are not completely understood, they are attractive as subjects for future in-depth biochemical and biophysical analysis.


Asunto(s)
Antibacterianos , Riboswitch , Humanos , Mononucleótido de Flavina/metabolismo , Riboflavina/química , Flavina-Adenina Dinucleótido/metabolismo
12.
FEBS J ; 290(19): 4777-4791, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37403630

RESUMEN

The thioredoxin pathway is an antioxidant system present in most organisms. Electrons flow from a thioredoxin reductase to thioredoxin at the expense of a specific electron donor. Most known thioredoxin reductases rely on NADPH as a reducing cofactor. Yet, in 2016, a new type of thioredoxin reductase was discovered in Archaea which utilize instead a reduced deazaflavin cofactor (F420 H2 ). For this reason, the respective enzyme was named deazaflavin-dependent flavin-containing thioredoxin reductase (DFTR). To have a broader understanding of the biochemistry of DFTRs, we identified and characterized two other archaeal representatives. A detailed kinetic study, which included pre-steady state kinetic analyses, revealed that these two DFTRs are highly specific for F420 H2 while displaying marginal activity with NADPH. Nevertheless, they share mechanistic features with the canonical thioredoxin reductases that are dependent on NADPH (NTRs). A detailed structural analysis led to the identification of two key residues that tune cofactor specificity of DFTRs. This allowed us to propose a DFTR-specific sequence motif that enabled for the first time the identification and experimental characterization of a bacterial DFTR.


Asunto(s)
Archaea , Reductasa de Tiorredoxina-Disulfuro , Reductasa de Tiorredoxina-Disulfuro/genética , Reductasa de Tiorredoxina-Disulfuro/química , Reductasa de Tiorredoxina-Disulfuro/metabolismo , Archaea/genética , Archaea/metabolismo , NADP/metabolismo , Bacterias/metabolismo , Riboflavina/química , Riboflavina/metabolismo , Tiorredoxinas/genética , Tiorredoxinas/metabolismo , Oxidación-Reducción
13.
J Chem Inf Model ; 63(12): 3903-3910, 2023 06 26.
Artículo en Inglés | MEDLINE | ID: mdl-37310018

RESUMEN

8-Demethyl-8-dimethylaminoriboflavin (Roseoflavin or RoF) is a natural riboflavin analogue found in Streptomyces davaonensis and Streptomyces cinnabarinus. RoF displays potent antibiotic properties because it affects FMN riboswitches and flavoproteins of cellular targets. N,N-8-Demethyl-8-aminoriboflavin dimethyltransferase (RosA) is an enzyme that catalyzes the last step of RoF biosynthesis, a consecutive dimethylation of 8-demethyl-8-aminoriboflavin (AF) to generate RoF. Thus, understanding mechanistic insights into RosA structures and mechanisms could lead to the improvement of the RoF product yield. Herein, mechanistic insights into roseoflavin synthesis by RosA were evaluated using molecular dynamics simulations. The obtained results revealed that RosA possibly catalyzes the reaction by positioning the substrate binding to have proper distance and orientation to the methyl group donor, S-adenosylmethionine. No direct participation of catalytic residues in the reaction was identified. The enzyme's active site structures change drastically to accommodate the ligand binding. On the basis of the MM/GBSA calculations and conservation analysis, the amino acid residues involved in substrate binding were identified. The structural information obtained from this study could be beneficial in designing RosA to efficiently produce roseoflavin.


Asunto(s)
Simulación de Dinámica Molecular , Rosa , Rosa/metabolismo , Riboflavina/química , Riboflavina/metabolismo
14.
Bioelectrochemistry ; 152: 108439, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37060705

RESUMEN

Riboflavin has been proposed to serve as an electron shuttle in photoelectrochemical systems. However, riboflavin was also observed for abiotic photolysis under illumination. Such conflicting reports raise the necessity for further investigation. In this study, riboflavin secreted by Rhodopseudomonas palustris was studied to clarify its stability and electron shuttle function under illumination. The data of high-performance liquid chromatography-mass spectrometry showed that the riboflavin was photolyzed to lumichrome in microbial photoelectrochemical systems. In addition, the anodic current increased by 75% after adding lumichrome compared with that of the control; it further demonstrated that lumichrome, not riboflavin, as an electron shuttle could facilitate microbial electron transfer. This study clarifies the mechanism of the interface process in microbial photoelectrochemical systems.


Asunto(s)
Electrones , Riboflavina , Fotólisis , Riboflavina/química , Flavinas/metabolismo , Transporte de Electrón
15.
Nat Chem Biol ; 19(6): 695-702, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-36658338

RESUMEN

Methanogenic archaea are main actors in the carbon cycle but are sensitive to reactive sulfite. Some methanogens use a sulfite detoxification system that combines an F420H2-oxidase with a sulfite reductase, both of which are proposed precursors of modern enzymes. Here, we present snapshots of this coupled system, named coenzyme F420-dependent sulfite reductase (Group I Fsr), obtained from two marine methanogens. Fsr organizes as a homotetramer, harboring an intertwined six-[4Fe-4S] cluster relay characterized by spectroscopy. The wire, spanning 5.4 nm, electronically connects the flavin to the siroheme center. Despite a structural architecture similar to dissimilatory sulfite reductases, Fsr shows a siroheme coordination and a reaction mechanism identical to assimilatory sulfite reductases. Accordingly, the reaction of Fsr is unidirectional, reducing sulfite or nitrite with F420H2. Our results provide structural insights into this unique fusion, in which a primitive sulfite reductase turns a poison into an elementary block of life.


Asunto(s)
Euryarchaeota , Methanococcales , Methanococcales/metabolismo , Oxidorreductasas actuantes sobre Donantes de Grupos Sulfuro , Riboflavina/química , Riboflavina/metabolismo , Sulfitos , Oxidación-Reducción
16.
Macromol Rapid Commun ; 44(6): e2200826, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36414542

RESUMEN

Polymers of intrinsic microporosity (PIMs) are a class of microporous organic materials that contain interconnected pores of less than 2 nm in diameter. Such materials are of great potential used in membranes for molecular separation, such as drug fractionation in pharmaceutical industry. However, the PIMs membranes are often susceptible to low separation selectivity toward different molecules due to their wide pore size distribution. Herein, a linear polyimide, Matrimid, is incorporated with PIM-1 (a typical member of PIMs) by solution blending, and the blends are dip-coated onto a polyimide P84 support membrane to prepare thin-film composite (TFC) membranes to control pore size distribution while keep high microporosity. The component miscibility, pore characteristics, and molecular separation performances of the Matrimid/PIM-1 TFC membranes are investigated in detail. The Matrimid and PIM-1 are partially miscible due to their similar Hansen solubility parameters. The Matrimid endows the selective layers (coatings) with narrower pore size distribution due to more compact chain packing. The prepared Matrimid/PIM-1 TFC membranes show high selectivity for separation of riboflavin (80% of retention) and isatin (only 5% of retention). The developed membranes exhibit great potential for separating molecules with different molecular weights.


Asunto(s)
Fraccionamiento Químico , Membranas Artificiales , Polímeros , Solventes , Fraccionamiento Químico/métodos , Isatina/química , Isatina/aislamiento & purificación , Permeabilidad , Polímeros/química , Porosidad , Riboflavina/química , Riboflavina/aislamiento & purificación , Solubilidad , Solventes/química
17.
Sci Rep ; 12(1): 18276, 2022 10 31.
Artículo en Inglés | MEDLINE | ID: mdl-36316402

RESUMEN

A novel metal-doped Zn/Cl carbon quantum dots (Zn/Cl-CQDs) was developed successfully as ratiometric fluorescent probes for the sequential on-off-on detection of riboflavin, Cu2+ ion and thiamine. The excellent catalytic performance of the Zn/Cl-CQDs nanozyme serves as an ideal platform for sensitive detection of thiamine. Due to the addition of riboflavin to the Zn/Cl-CQDs, the blue emission peak of Zn/Cl-CQDs at 440 nm remains unaffected and used as an internal reference approach, while the green emission peak of riboflavin at 520 nm appeared and increased remarkably. Following the presence of Cu2+, a quenching blue fluorescence signal of Zn/Cl-CQDs was observed which resulted in consequent fluorescent 'turn-off' response toward Cu2+ ion. Finally, upon the addition of thiamine to the above solution under alkaline condition, the blue emission of Zn/Cl-CQDs was gradually recovered. The prepared Zn/Cl-CQDs could act as a nanozyme catalyst for directly catalyzing the oxidation of non-fluorescent substrate of thiamine to produce highly fluorescent substrate of thiochrome. As a result, the blue fluorescence emission peak at 440 nm was recovered. Eventually, the sequential detection properties of ratiometric probes for riboflavin, Cu2+ ion and thiamine were successfully applied in VB2 tablets, drinking water and VB1 tablet with good recoveries of 96.21%, 98.25% and 98.44%, respectively.


Asunto(s)
Puntos Cuánticos , Puntos Cuánticos/química , Carbono/química , Colorantes Fluorescentes/química , Riboflavina/química , Tiamina , Halógenos , Zinc
18.
J Am Chem Soc ; 144(28): 12769-12780, 2022 07 20.
Artículo en Inglés | MEDLINE | ID: mdl-35802469

RESUMEN

RibB (3,4-dihydroxy-2-butanone 4-phosphate synthase) is a magnesium-dependent enzyme that excises the C4 of d-ribulose-5-phosphate (d-Ru5P) as formate. RibB generates the four-carbon substrate for lumazine synthase that is incorporated into the xylene moiety of lumazine and ultimately the riboflavin isoalloxazine. The reaction was first identified by Bacher and co-workers in the 1990s, and their chemical mechanism hypothesis became canonical despite minimal direct evidence. X-ray crystal structures of RibB typically show two metal ions when solved in the presence of non-native metals and/or liganding non-substrate analogues, and the consensus hypothetical mechanism has incorporated this cofactor set. We have used a variety of biochemical approaches to further characterize the chemistry catalyzed by RibB from Vibrio cholera (VcRibB). We show that full activity is achieved at metal ion concentrations equal to the enzyme concentration. This was confirmed by electron paramagnetic resonance of the enzyme reconstituted with manganese and crystal structures liganded with Mn2+ and a variety of sugar phosphates. Two transient species prior to the formation of products were identified using acid quench of single turnover reactions in combination with NMR for singly and fully 13C-labeled d-Ru5P. These data indicate that dehydration of C1 forms the first transient species, which undergoes rearrangement by a 1,2 migration, fusing C5 to C3 and generating a hydrated C4 that is poised for elimination as formate. Structures determined from time-dependent Mn2+ soaks of VcRibB-d-Ru5P crystals show accumulation in crystallo of the same intermediates. Collectively, these data reveal for the first time crucial transient chemical states in the mechanism of RibB.


Asunto(s)
Transferasas Intramoleculares , Riboflavina , Butanonas , Formiatos , Transferasas Intramoleculares/química , Fosfatos , Riboflavina/biosíntesis , Riboflavina/química , Riboflavina Sintasa/química
19.
Food Res Int ; 158: 111508, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-35840217

RESUMEN

The impact of photosensitizer and wavelength on photooxidation of phytosterols (PS) in soymilk and the oxidative stability of lipid and protein was determined. The oxidation of lipid and the consumption of dissolved oxygen showed a close relationship with PS oxidation. Riboflavin (Rb) leads to extra oxidation of both lipid and protein, and chlorophyll (Chl) prefer to absorb to and change the structure of protein. The influence of Rb and Chl on PS degradation under different wavelengths of light in the range of 365-665 nm was measured. Original soymilk emulsion placed under UVA (365-375 nm) and violet (400-410 nm) light underwent the most PS deterioration, whereas riboflavin was responsible for oxidation around blue (465-475 nm) region and extra formation of 6ß-OH sterols, and chlorophyll enriched emulsion was vulnerable under red (645-665 nm) light. The wavelength of light (UVA > violet > blue > green > red > yellow) showed a great different effect in oxidation of PS and formation of phytosterol oxidation products (POPs). The UVA, violet, blue and red light gives rise to the prior five kind oxides of phytosterol: 6α-OH, 7α-OH, 7ß-OH, 5,6ß-epoxy and 7-keto.


Asunto(s)
Fitosteroles , Clorofila/química , Emulsiones , Fármacos Fotosensibilizantes/química , Fitosteroles/química , Riboflavina/química
20.
J Fluoresc ; 32(5): 1913-1919, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35751749

RESUMEN

A simple uracil-appended fluorescent sensor (1) has been developed by one pot reaction and characterized by using common spectroscopic methods such as UV-vis, Fluorescence, HRMS and FT-IR analyses. Upon addition of various metal ions to the CH3CN solution of sensor 1, the fluorescence was quenched in the presence of Cu2+ / Hg2+ ions. The limit of detection for Cu2+ and Hg2+ was calculated to be 3.31 and 0.316 µM, respectively. Further, the sensor was applied for real-life applications in the determination of Vitamin B2 (riboflavin) and its presence in milk products. With the incorporation of different sources of vitamin-B to acetonitrile solution of it, there was discernible fluorescence enhancement only in the presence of vitamin B2. Also, it has been successfully applied for the detection of Vitamin B2 (riboflavin) in milk and curd. Moreover, based on the fluorescent color changes, the sensor was utilized for invisible ink applications.


Asunto(s)
Cobre/análisis , Mercurio , Riboflavina , Animales , Colorantes/análisis , Colorantes Fluorescentes/química , Tinta , Iones , Mercurio/análisis , Leche/química , Riboflavina/química , Espectroscopía Infrarroja por Transformada de Fourier , Uracilo/análisis , Vitaminas/análisis
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