RESUMEN
BACKGROUND: Polyphenols extracted from plants are usually highly unstable and rapidly transformed into various reaction products during food and drug processing, thus limiting their applications. To improve the stability and solubility of polyphenols from the leaves of Chinese star anise (Illicium verum Hook. f.), and hence to expand their application to food and medicine, the extracted anise leaf polyphenols (ALPs) were microencapsulated using ß-cyclodextrin (ß-CD) and cyclodextrin-based metal-organic frameworks (ß-CD-MOFs). RESULTS: The optimum inclusion rate of ALP/ß-CD-MOFs was 97.80% at a core-wall ratio of 1:10. Meanwhile, the stabilities, solubilities and antioxidant activities of the polyphenols before and after inclusion were compared. The results showed both the stabilities and solubilities of ALP/ß-CD-MOFs were significantly improved compared with those of ALPs and ALP/ß-CD, suggesting the potential of ß-CD-MOFs as newer and better carriers than ß-CD for polyphenols in food industry applications. The free radical (including superoxide, hydroxyl and DPPH radicals) scavenging activities were also improved by microencapsulation. Superoxide radical scavenging reaction also showed slow-release property of ALP/ß-CD-MOFs. The formation of the inclusion complex was further confirmed using Fourier transform infrared spectral characterization. CONCLUSIONS: Microencapsulation with ß-CD-MOFs could expand the application scope of ALPs, and it is more effective than encapsulation with ß-CD. This is important for a better understanding and application of this useful traditional Chinese plant. As a new material with high efficiency and edibility, ß-CD-MOFs are not limited to the chemical field, but also have potential in new areas of food, medicine and healthcare products. © 2020 Society of Chemical Industry.
Asunto(s)
Antioxidantes/química , Illicium/química , Estructuras Metalorgánicas/química , Extractos Vegetales/química , Polifenoles/química , beta-Ciclodextrinas/química , Hojas de la Planta/químicaRESUMEN
BACKGROUND: Traditional chemical methods were mainly used to evaluate the total antioxidant activity of essential oils. How to determine the bioactivity of each compound in mixtures is an interesting research topic. Nowadays, an ultra-fast gas chromatography electronic nose (E-nose) has been gradually used in the detection of volatile compounds, but the screening of the active components of essential oils has not been reported. E-nose coupled with chemical methodology was established using the essential oil from rosemary (EOR) as a specific application example. The proposed method can both identify the chemical constituents of EOR and quickly screen the antioxidant by comparing the change of chromatographic peak area of every component in EOR before and after reaction with free radicals. RESULTS: Among all chemical constituents in EOR, verbenone, eucalyptol and o-cymene showed the strongest scavenging abilities in 1,1'-diphenyl-2-picrylhydrazine (DPPH·), 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulphonate) (ABTS·+ ) and hydroxyl (·OH) radicals, respectively, with scavenging rates of 67.9%, 39.5%, and 69.9%. The reliability and feasibility of using E-nose to identify chemical constituents of EOR were verified by gas chromatography-tandem mass spectrometry (GC-MS/MS). The GC-MS/MS results showed that the main components of EOR were α-pinene (422.2 µg g-1 ), p-cymene (208.4 µg g-1 ), camphor (203.5 µg g-1 ), verbenone (160.2 µg g-1 ), and eucalyptol (129.1 µg g-1 ). CONCLUSIONS: The E-nose methods can be used as a complementary method to traditional spectrophotometric techniques. Furthermore, this study will be of great significance for the rapid screening of antioxidant active components in essential oils from natural products. © 2020 Society of Chemical Industry.
Asunto(s)
Antioxidantes/química , Aceites Volátiles/química , Rosmarinus/química , Nariz Electrónica , Cromatografía de Gases y Espectrometría de Masas , Hojas de la Planta/químicaRESUMEN
Flavonoids are rich in Juglans regia L. leaves. They have potent antioxidant properties, which have been related to regulating immune function and enhancing anticancer activity. Herein, qualitative and quantitative determination of flavonoids from J. regia leaves was carried out using high performance liquid chromatography coupled with tandem mass spectrometry with electrospray ionization and negative ion detection (HPLC-ESI-MS/MS) by comparison of the retention times and mass spectral fragments with standard substances or related literatures. Seventeen compounds were identified and major components are quercetin-3-O-rhamnoside (453.11 µg/g, dry weight), quercetin-3-O-arabinoside (73.91 µg/g), quercetin-3-O-xyloside (70.04 µg/g), kaempferol-O-pentoside derivative (49.04 µg/g), quercetin-3-O-galactoside (48.61 µg/g), and kaempferol-O-pentoside (48.46 µg/g). The in vitro intracellular antioxidation indicated that flavonoids from J. regia leaves could reduce the reactive oxygen species (ROS) level in RAW264.7 cells and showed good radical scavenging activities. These results proved to be more related to the flavonoids that could be considered in the design of new formulations of dietary supplements or functional foods.
Asunto(s)
Flavonoides/farmacología , Depuradores de Radicales Libres/farmacología , Juglans/química , Extractos Vegetales/farmacología , Animales , Línea Celular , Flavonoides/química , Depuradores de Radicales Libres/química , Macrófagos/efectos de los fármacos , Ratones , Extractos Vegetales/química , Hojas de la Planta/químicaRESUMEN
The authentication of traditional herbal medicines in powder form is of great significance, as they are always of high values but vulnerable to adulteration. Based on the distinct fluorescence of protein tryptophan, phenolic acids and flavonoids, front-face synchronous fluorescence spectroscopy (FFSFS) was applied for the fast and non-invasive authentication of Panax notoginseng powder (PP) adulterated with the powder of rhizoma curcumae (CP), maize flour (MF) and whole wheat flour (WF). For either single or multiple adulterants in the range of 5-40% w/w, prediction models were built based on the combination of unfolded total synchronous fluorescence spectra and partial least square (PLS) regression, and were validated by both five-fold cross-validation and external validation. The constructed PLS2 models simultaneously predicted the contents of multiple adulterants in PP and gave suitable results, with most of the determination coefficients of prediction (Rp2) >0.9, the root mean square error of prediction (RMSEP) no >4% and residual predictive deviation (RPD) >2. The limits of detections (LODs) were 12.0, 9.1 and 7.6% for CP, MF and WF, respectively. All the relative prediction errors for simulated blind samples were between -22% and + 23%. FFSFS offers a novel alternative to the authentication of powdered herbal plants.
Asunto(s)
Panax notoginseng , Panax notoginseng/química , Polvos/química , Espectrometría de Fluorescencia/métodos , Harina , Triticum , Estructura Molecular , Zea maysRESUMEN
The applications of clove (Syzygium aromaticum) essential oil (CEO) are limited by instability, low solubility and high volatility. The present study aimed to improve the properties of CEO by microencapsulation with cyclodextrin metal organic frameworks (ß-CD-MOFs) to enhance the preservation effects on Chinese bacon (preserved meat products). The microencapsulated CEO by ß-CD-MOFs (CEO/ß-CD-MOFs) not only did not inhibit the antioxidant activities of CEO, but also showed significant improvements on their ROS scavenging abilities and thermo-/pH-stabilities. The increases of superoxide anion and hydroxyl radical scavenging activities were 20.74% and 12.84%, respectively. In addition, less lipid oxidation, including malondialdehyde (MDA) contents and peroxide values (POV), of Chinese bacon was found after the CEO/ß-CD-MOFs treatment than CEO and synthetic antioxidant (BHT) treatments. These results suggested the enhanced preservation effects of microencapsulated CEO on the processing of Chinese bacon and the great potential of ß-CD-MOFs as carriers for essential oils in food industry applications.
Asunto(s)
Productos de la Carne , Estructuras Metalorgánicas , Aceites Volátiles , Carne de Cerdo , Syzygium , beta-Ciclodextrinas , Aceites Volátiles/farmacología , Antioxidantes/farmacología , China , Aceite de Clavo/farmacologíaRESUMEN
Capsanthin is the major natural carotenoid pigment in red chili pepper possessing important bioactivity. Its conventional determination method is high performance liquid chromatography (HPLC) with complex and tedious sample pretreatment. In this study, synchronous front-face fluorescence spectroscopy (FFFS) was applied for the fast and non-invasive detection of free capsanthin in chili powders. Although capsanthin was only weak fluorescent in solution state, it showed strong fluorescence in two separated regions in front-face geometry which could also be clearly observed in chili powders. The mechanisms of these emissions are revealed to be aggregation-induced emission (AIE) and J-aggregate formation (JAF). The free capsanthin in 85 chili powder samples were determined by HPLC as in the range of 0.6-3.0 mg/g. The total synchronous FFFS spectra of these samples were scanned. Simple first-order models were built by partial least square regression (PLSR), and were validated by 5-fold cross-validation and external validation. The coefficients of determination (R2) were higher than 0.9, and the root mean square errors (RMSE) were less than 0.2 mg/g. The relative error of prediction (REP) was 9.9%, and the residual predictive deviation (RPD) was 3.7. The method was applied for the estimation of free capsanthin in several real-world samples with satisfactory analytical results. The average relative error to HPLC reference values was -11.8%.
Asunto(s)
Capsicum , Carotenoides , Polvos , Espectrometría de Fluorescencia , XantófilasRESUMEN
Ethnopharmacological Relevance: Pepper essential oils have potential immunomodulatory, anti-tumor, and anti-cancer activities. Pepper exhibits the potential to prevent or attenuate carcinogenesis as therapeutic tools. However, the related mechanism remains unelucidated. Aim of the Study: The present study aims to provide reasonable information for the explanation of the dissimilarity of the essential oils from white (WPEO) and black pepper (BPEO). Materials and Methods: WPEO, BPEO, and their single active component, as well as synthetic antioxidants, were compared by the cell model methods and chemical methods, including intracellular antioxidant activity (CAA), total antioxidant activities (TAA), superoxide radical (SR), hydroxyl radical (HR), DPPH radical (DR) scavenging activities and inhibition ability of lipoprotein lipid peroxidation (ILLP). Results: The median effective concentration (EC50) values (mg/mL) of the WPEO and BPEO of SR, HR, DR, and ILLP were 0.437 and 0.327, 0.486 and 0.204, 7.332 and 6.348, 0.688, and 0.624 mg/mL, respectively. The CAA units of WPEO and BPEO were 50.644 and 54.806, respectively. CAA, DR, and TAA of BPEO were significantly higher than those of WPEO (p < 0.05). The BPEO and WPEO can be differentiated as the former have higher correlations with 3-carene, α-pinene, ß-pinene, and limonene while the latter has a higher caryophyllene correlation. The WPEO and BPEO show a good intracellular scavenging ability of reactive oxygen species in HeLa cells. Conclusion: Generally, pepper oil has stronger activities than single components, indicating that pepper is a broad-spectrum natural antioxidant.
RESUMEN
The fate of polybrominated diphenyl ethers (PBDEs) from polyethylene mesh knitted fabrics (PMKFs) to mulched soil and nearby plants was studied. PBDEs in the soil sample collected from Tianjin University of Commerce in April 2019 increased significantly after 6 months of PMKF mulching owing to PMKFs as the main input source. The compositional profiles/congener patterns of the PBDEs in the soil and PMKFs became similar after 6 months. High correlations were found between ΣPBDEs in the soil and PMKFs in October 2019, with no significant correlation in April. Plants could take up, accumulate and biotransform PBDEs in contaminated soil. The uptake of BDE-209 by plants was the highest compared with other lesser brominated PBDE congeners, due to its higher log Kow value and molecular weight or size. BDE-47 taken up in the plant was biotransformed via hydroxylation. These results prove that the government's PMKF solution to haze is causing environmental problems in bare soil, i.e., PBDE pollution in both soil and nearby plants. The present study provides important pieces of evidence for government and policymakers, and it is recommended that one environmental problem is not solved by creating another.
Asunto(s)
Éteres Difenilos Halogenados , Contaminantes del Suelo , China , Monitoreo del Ambiente , Éteres Difenilos Halogenados/análisis , Polietileno , Suelo , Contaminantes del Suelo/análisisRESUMEN
The chemical components of an edible spice, sweet ginger (Alpinia coriandriodora D. Fang) essential oil (AEO) were identified by an ultra-fast gas chromatography electronic nose (E-nose) and the main components were ß-pinene (27.9%), 1,8-cineole (17.3%), p-cymene (13.5%), camphene (7.3%), myrcene (5.4%), and pseudolimonene (4.3%). The antioxidant activity of each component was evaluated and the mechanisms of scavenging free radical were studied by E-nose combined with chemical methodology. Decanal and α-copaene in AEO showed strong scavenging activities against DPPH radical, and the scavenging rates were over 85%. Decanal had a strong scavenging activity for ABTS radical and the scavenging rate was more than 60%. Similarly, terpinen-4-ol and eugenol had strong scavenging abilities to OH radical and the scavenging rates were more than 50%. Gas chromatography-mass spectrography results showed that it was feasible to identify the chemical components of essential oil by E-nose, and the similarity reached 88.9%. PRACTICAL APPLICATIONS: Many essential oils have antioxidant activities and can be used in functional foods. In the present work, the antioxidant active components in AEO were identified and screened by ultra-fast GC E-nose. We aimed to target the components with strong antioxidant activity quickly and efficiently through the analysis of the reaction process of DPPH, ABTS and OH radicals with a high scavenging rate in a short time. These results indicate that ultra-fast GC E-nose can be used to screen the antioxidant active components in the essential oil.
Asunto(s)
Alpinia , Aceites Volátiles , Zingiber officinale , Antioxidantes , Cromatografía de Gases y Espectrometría de Masas , Aceites Volátiles/farmacologíaRESUMEN
As a member of flavonoids, the application of quercetin has been mainly focused on antioxidation study. Fabrication of multifunctional nanoplatforms with quercetin is limited. In the present study, water-soluble quercetin derived nanoparticles (QFNPs) were fabricated through the one pot synthesis strategy with Fe3+, quercetin and poly (vinyl pyrrolidone) (PVP). The raw materials were dissolved in absolute ethanol and the mixed together. After stirring at room temperature for 6â¯h, the QFNPs could be simply harvested by centrifugation without the need of time-consuming dialysis procedure. Due to the protective effect of PVP, the synthesized nanoparticles could be well dispersed in water with the hydrodynamic size about 23â¯nm. DPPH free radical scavenging capacity assay showed QFNPs could act as efficient antioxidant. Besides antioxidation activity, the QFNPs also exhibited good photothermal capacity. Temperature stability result suggested the good stability of QFNPs between 35 and 95⯰C. MTT and hemolysis assay showed the good biocompatibility of QFNPs. What's more, the QFNPs showed good cellular antioxidation activity and efficient photothermal killing effect to cancer cells (4T1 cells). The QFNPs could be promising nanoplatform for biomedical application.
Asunto(s)
Antioxidantes/farmacología , Portadores de Fármacos , Células Epiteliales/efectos de los fármacos , Nanopartículas Multifuncionales/química , Povidona/química , Quercetina/farmacología , Animales , Antioxidantes/química , Antioxidantes/efectos de la radiación , Compuestos de Bifenilo/antagonistas & inhibidores , Compuestos de Bifenilo/química , Línea Celular Tumoral , Células Epiteliales/patología , Células Epiteliales/efectos de la radiación , Femenino , Calor , Hipertermia Inducida/métodos , Luz , Glándulas Mamarias Animales/patología , Ratones , Nanopartículas Multifuncionales/efectos de la radiación , Nanopartículas Multifuncionales/ultraestructura , Tamaño de la Partícula , Picratos/antagonistas & inhibidores , Picratos/química , Quercetina/química , Quercetina/efectos de la radiación , Solubilidad , Agua/químicaRESUMEN
Rosemary ethanol extract (REE) from Rosmarinus officinalis was identified by LC-ESI-MS/MS and 12 compounds were found. Among them, rosmarinic acid (389.78 µg/mg in REE), luteolin-3'-O-glucuronide (325.58 µg/mg), luteolin-5-O-glucuronide (120.92 µg/mg), and geniposide (120.83 µg/mg) are the major components. The antioxidant activity evaluation of REE by off-line HPLC methods indicated that among the 12 compounds, rosmarinic acid had the strongest scavenging activities in both DPPH· and ·OH. The cytotoxicity experiment showed that REE with the concentration ranges from 1 to 100 µg/ml did not significantly affect the cell viability of HeLa, while inhibitory rate reduced to 62.3% when the concentration was increased to 1,000 µg/ml. The results of intracellular antioxidation assay showed that the ability of REE in reducing the reactive oxygen species (ROS) in HeLa cells was higher than rosmanol, and lower than rosmarinic acid without cell toxicity. PRACTICAL APPLICATIONS: Plant polyphenols are essential components of functional foods, due to their antioxidant and enzyme inhibition activities. This paper is the first study about the quantification of antioxidant compounds, antioxidant activity evaluation, and their cellular antioxidant activity of polyphenols extract from R. officinalis toward HeLa cells. We aimed to elucidate the chemical composition and recognition of antioxidant components with DPPH and OH free radicals scavenging activity. In addition, the polyphenols dose-response correlations with cellular antioxidant activity were also determined. These results indicated that off-line HPLC method with DPPH and OH free radicals as markers is available for screening antioxidant activity of polyphenols from the mixture.
Asunto(s)
Antioxidantes , Extractos Vegetales , Polifenoles , Rosmarinus/química , Abietanos/metabolismo , Abietanos/toxicidad , Antioxidantes/análisis , Antioxidantes/farmacología , Antioxidantes/toxicidad , Cromatografía Líquida de Alta Presión , Cinamatos/metabolismo , Cinamatos/toxicidad , Depsidos/metabolismo , Depsidos/toxicidad , Etanol , Depuradores de Radicales Libres , Células HeLa , Humanos , Extractos Vegetales/análisis , Extractos Vegetales/farmacología , Extractos Vegetales/toxicidad , Hojas de la Planta/química , Polifenoles/análisis , Polifenoles/farmacología , Polifenoles/toxicidad , Especies Reactivas de Oxígeno/metabolismo , Ácido RosmarínicoRESUMEN
The complexation reactions of brilliant cresyl blue (BCB) with beta-cyclodextrin (beta-CD), mono[2-O-(2-hydroxypropyl)]-beta-CD (2-HP-beta-CD), mono[2-O-(2-hydroxyethyl)]-beta-CD (2-HE-beta-CD), and heptakis(2,6-di-methyl) -beta-CD (DM-beta-CD) were investigated using UV-vis and fluorospectrometry. The complexation between BCB and CDs could inhibit the aggregation of BCB molecules and could cause its absorbance at 634nm gradually increasing. The fluorescence of BCB was also enhanced with the addition of CDs. The fluorescence enhancement was more notable in neutral and acidic media than in basic media. Hildebrand-Benesi equation was used to calculate the formation constants of beta-CDs with BCB based on the fluorescence differences in the CDs solution. The stoichiometry ratio was found to be 1:1. The complexing capacities of beta-CD and its three derivatives were compared and the results followed the order: 2-HP-beta-CD>2-HE-beta-CD>DM-beta-CD>beta-CD. The effect of temperature on the formation of BCB-beta-CD inclusion complexes has also been examined. The results revealed that the formation constants decreased with the increase of temperature from 1038.9 to 491.6l/mol. Enthalpy and entropy values were calculated and the values were -25.77kJ/mol and 35.04J/kmol, respectively. The thermodynamic measurements suggest that the inclusive process was enthalpic favor. The release of high-energy water molecules and Van der Waals force played an important role in the inclusive process.
Asunto(s)
Oxazinas/química , beta-Ciclodextrinas/química , Concentración de Iones de Hidrógeno , Cinética , Soluciones , Espectrometría de Fluorescencia , Espectrofotometría Ultravioleta , Temperatura , TermodinámicaRESUMEN
This study aimed to determine the effects of Metschnikowia pulcherrima yeast on storage quality of 'Tainong' mango, and elucidate it's possible anti-disease mechanism. The results showed that M. pulcherrima could inhibit the changes in peel colour, fruit firmness, the contents of total soluble solids, total acid and vitamin C, and maintain the storage quality of mango fruits. An investigation of the mechanism showed that M. pulcherrima competed not only for the primary carbon source, but also for living space with Colletotrichum gloeosporioides. In addition, M. pulcherrima promoted the activities of defence-related enzymes, including ß-1,3-glucanase(GLU) and chitinase (CHT), and secreted a small amount of antimicrobial substances composed of volatile and nonvolatile anti-fungal compounds. The results strongly demonstrated that antagonistic yeast M. pulcherrima could be applied as a biocontrol agent for deducing the spoilage and decay of mango fruit.
RESUMEN
An off-line high performance liquid chromatography (HPLC) coupled with chemical methods has been developed to evaluate antioxidant activity of 11 standard polyphenol compounds (SPCs) and vitamin C (Vc) in terms of radical scavenging abilities. The structure-activity relationships of each SPC were also discussed. SPCs showed different abilities in scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethyl-benzthiazoline-6-sulphonate (ABTS+) and hydroxyl (OH) free radicals. Among SPCs, quercetin and kaempferol, as typical flavonoids, displayed the greatest radical-scavenging activities and even exhibited higher activity in OH radical removal ability than that of Vc. Furthermore, the proposed method was also applied to screening polyphenolic antioxidant components from Cichorium endivia L. (C. endivia) seed extract. The results indicated that cynarin in the extract was a more active compound to scavenge DPPH and ABTS+ radicals than chlorogenic acid, while chlorogenic acid had stronger capacity in scavenging OH free radicals.
Asunto(s)
Antioxidantes/análisis , Ácido Ascórbico/análisis , Cromatografía Líquida de Alta Presión/métodos , Flavonoides/análisis , Polifenoles/análisis , Cichorium intybus/química , Extractos Vegetales/química , Semillas/químicaRESUMEN
Synchronous front-face fluorescence spectroscopy has been developed for the discrimination of used frying oil (UFO) from edible vegetable oil (EVO), the estimation of the using time of UFO, and the determination of the adulteration of EVO with UFO. Both the heating time of laboratory prepared UFO and the adulteration of EVO with UFO could be determined by partial least squares regression (PLSR). To simulate the EVO adulteration with UFO, for each kind of oil, fifty adulterated samples at the adulterant amounts range of 1-50% were prepared. PLSR was then adopted to build the model and both full (leave-one-out) cross-validation and external validation were performed to evaluate the predictive ability. Under the optimum condition, the plots of observed versus predicted values exhibited high linearity (R(2)>0.96). The root mean square error of cross-validation (RMSECV) and root mean square error of prediction (RMSEP) were both lower than 3%.
Asunto(s)
Contaminación de Alimentos/análisis , Aceites de Plantas/química , Espectrometría de Fluorescencia/métodosRESUMEN
A sensitive method for the preconcentration and determination of trace amounts of Co, Cu and Zn by energy-dispersive X-ray fluorescence spectrometry (EDXRF) has been developed. The method is based on the fact that 4-(2-pyridylazo)-resorcinol (PAR) loaded Dowex anion-exchange resin (PAR-resin) can effectively adsorb Co, Cu and Zn at pH 9.0 to form PAR-metal complexes. The detection limits for Co, Cu and Zn were 1.53, 0.31 and 0.21 ppb, respectively. The precisions for five replicate measurements of the three metals were 3.4, 2.7 and 2.1% RSD, and the calibration curves were linear up to 75 microg with correlation coefficients of 0.9975, 0.9980 and 0.9985, respectively. The method was successfully applied for the simultaneous determination of Co, Cu and Zn in seawater samples at ppb levels.
RESUMEN
We report an application of data fusion for chemometric classification of 135 canned samples of Chinese lager beers by manufacturer based on the combination of fluorescence, UV and visible spectroscopies. Right-angle synchronous fluorescence spectra (SFS) at three wavelength difference Δλ=30, 60 and 80 nm and visible spectra in the range 380-700 nm of undiluted beers were recorded. UV spectra in the range 240-400 nm of diluted beers were measured. A classification model was built using principal component analysis (PCA) and linear discriminant analysis (LDA). LDA with cross-validation showed that the data fusion could achieve 78.5-86.7% correct classification (sensitivity), while those rates using individual spectroscopies ranged from 42.2% to 70.4%. The results demonstrated that the fluorescence, UV and visible spectroscopies complemented each other, yielding higher synergic effect.
Asunto(s)
Cerveza/análisis , Espectrometría de Fluorescencia/métodos , Espectrofotometría Ultravioleta/métodos , Cerveza/clasificación , China , Análisis Discriminante , Análisis de Componente PrincipalRESUMEN
The influence of solvation interactions on the surface charge of titania powders was studied by means of linear solvation energy relationships (LSER). The zeta potential (ZP) of titania powders and the effect of water content were determined in a series of alcohols, including methanol, ethanol, 1-propanol, isopropanol, and 1-butanol. The ZPs against the solvents' 13 LSER descriptors were analyzed by principal component analysis (PCA), cluster analysis, multiple linear regression (MLR), and stepwise multiple regression (SMR). Very good correlation between ZP and LSER parameter was obtained. One LSER parameter, relative dielectric constant, epsilon, was used to establish the LSER equation. The ZP of titania powders in pure alcohols can be reasonably calculated by an empirical formula: ZP=13.43-213.63.1/epsilon. The results show that epsilon is the most important factor governing the ZP of titania powders. The results also suggest that the effect of solvation interactions on ZP is a result of the electrostatic interactions between powders and solvents.
Asunto(s)
Solventes/química , Titanio/química , Alcoholes/química , Polvos/química , Agua/químicaRESUMEN
Design of chemical sensor arrays that can discriminate real-world samples has been highly attractive in recent years. Herein a fluorescent indicator-displacement sensor array for discrimination of fresh fruit juices was developed. By coupling the unique high affinity of titania to electron-donating anions and the cross-reactivity of molecularly imprinted materials to structurally similar species, a small array was fabricated using only one rhodamine-based fluorescent dye and three synthesized materials. Citric, malic, succinic and tartaric acids were chosen as indices. The recognition mechanism was investigated by spectrofluorimetric titration using a non-linear Langmuir-type adsorption model. The proposed method was applied to discriminate thirteen fruit juices through their carboxylic acid contents. Principal component analysis of the data clearly grouped the thirteen juices with the first principal component owning 98.2% of the total variation. The comparison of the sensor array with HPLC determination of the carboxylic acids was finally made.
Asunto(s)
Ácidos Carboxílicos/química , Frutas/química , Impresión Molecular/métodos , Titanio/química , Bebidas , Cromatografía Líquida de Alta Presión , Colorantes FluorescentesRESUMEN
High performance liquid chromatography coupled with tandem mass spectrometry with electrospray ionization and negative ion detection (HPLC-ESI-MS/MS) was used to identify the polyphenols from the leaves of a traditional vegetable and spice, Zanthoxylum bungeanum Maxim., in China by comparison of the retention times and mass spectral fragment with standard substances or related literature. A phenolic acid glucoside, two acids, and eight flavonoids were determined including vanillic acid-4-glucoside (22.75 µg/g, dry weight of leaves), quinic acid (58.58 µg/g), chlorogenic acid (2515.96 µg/g), epicatechin (77.80 µg/g), 5-feruloyquinic acid (16.63 µg/g), syringetin-3-glucoside (103.23 µg/g), rutin (89.41 µg/g), hyperoside (886.36 µg/g), quercetin-3-arabinoside (118.75 µg/g), quercitrin (645.82 µg/g), and isorhamnetin-3-glucoside (104.27 µg/g). The obtained polyphenols show good radical scavenging activities in DPPH and superoxide anion. Through the intracellular antioxidation assay, the result shows that the polyphenols could reduce the ROS in HT-29 cells without cell toxicity.