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51.
Determination of the total tannin of white and red rind pomegranate (Punica granatum L.) has been carried out by colorimetry method using reagent 1,10 phenantroline. This method is based on reduction of iron (III) into iron (II) by tannin at temperature 800C for 20 min. Then the formed of iron (II) was reacted with 1,10 phenantroline to form orange red colour complex that could be measured by spectrophotometer visible at maximum absorption wavelength of 508 nm. The limit of detection (LOD) and the limit of quantitation (LOQ) obtained were 0.34 μg/mL and 1.14 μg/mL, respectively. This result was found to be linier with R value of 0.9984; accuracy as percent recovery was 84.69 ± 0.85% and coefficient of variant (KV) was 1.003% for white rind pomegranate while red rind pomegranate percent recovery was 84.38 ± 0,45% and coefficient of variant (KV) was 0.53%. The total tannin of white rind pomegranate was 18.28 ± 0.072%b/b and red rind pomegranate was 17.33 ± 0.081%b/b 相似文献
52.
In the last years, the development of new methods for analyzing accurate and precise individual metalloproteins is of increasing importance, since numerous metalloproteins are excellent biomarkers of oxidative stress and diseases. In that way, methods based on the use of post column isotopic dilution analysis (IDA) or enriched protein standards are required to obtain a sufficient degree of accuracy, precision and high limits of detection. This paper reports the identification and absolute quantification of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) in cytosol and mitochondria from mice hepatic cells using a innovative column switching analytical approach. The method consisted of orthogonal chromatographic systems coupled to inductively coupling plasma-mass spectrometry equipped with a octopole reaction systems (ICP-ORS-MS) and UV detectors: size exclusion fractionation (SEC) of the cytosolic and mitochondrial extracts followed by online anion exchange chromatographic (AEC) separation of Cu/Zn containing species. After purification, Cu,Zn-SOD was identified after tryptic digestion by molecular mass spectrometry (MS). The MS/MS spectrum of a doubly charged peptide was used to obtain the sequence of the protein using the MASCOT searching engine. This optimized methodology reduces the time of analysis and avoids the use of sample preconcentration and clean-up procedures, such as cut-off centrifuged filters, solid phase extraction (SPE), precipitation procedures, off-line fractions insolates, etc. In this sense, the method is robust, reliable and fast with typical chromatographic run time less than 20 min. Precision in terms of relative standard deviation (n = 5) is of 3–5% and detection limits is 0.21 ng Cu g−1. 相似文献
53.
A glassy carbon electrode modified with poly(alizarin red)/electrodeposited graphene (PAR/EGR) composite film was prepared and applied to detect ciprofloxacin (CPFX) in the presence of ascorbic, uric acid and dopamine. The morphology and interface property of PAR/EGR films were examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrocatalytic oxidation of CPFX on AR/EGR was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The linearity ranged from 4 × 10−8 to 1.2 × 10−4 M with a detection limit (S/N = 3) of 0.01 μM. The modified electrode could be applied to the individual determination of CPFX as well as the simultaneous determination of CPFX, ascorbic acid, uric acid and dopamine. This method proved to be a simple, selective and rapid way to determine CPFX in pharmaceutical preparation and biological media. 相似文献
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A comparative study of the luminescent properties of Y2O3:Eu3+ phosphor powders and thin films sputtered from targets prepared from combustion synthesized powders is reported. Thin films of (Y0.96Eu0.04)2O3 were deposited on silicon substrates. Films deposited at 600 °C had both monoclinic and cubic phases of Y2O3, which developed to an oriented cubic phase after annealing. Films and powders showed a linear dependence of the intensity of the 5D7→7F2 (611 nm) transition with temperature in the range 26-660 °C with an average rate of change of 1.8×10−4 °C−1. The rate of change appears to be dependent on the Eu3+ concentration. This work shows that these thin films can be used as thermographic phosphors for remote temperature measurements. 相似文献
58.
Kirsten Berger Johanna Josefine Ostberg-Potthoff Tamara Bakuradze Peter Winterhalter Elke Richling 《Molecules (Basel, Switzerland)》2020,25(22)
Red fruits and their juices are rich sources of polyphenols, especially anthocyanins. Some studies have shown that such polyphenols can inhibit enzymes of the carbohydrate metabolism, such as α-amylase and α-glucosidase, that indirectly regulate blood sugar levels. The presented study examined the in vitro inhibitory activity against α-amylase and α-glucosidase of various phenolic extracts prepared from direct juices, concentrates, and purees of nine different berries which differ in their anthocyanin and copigment profile. Generally, the extracts with the highest phenolic content—aronia (67.7 ± 3.2 g GAE/100 g; cyanidin 3-galactoside; chlorogenic acid), pomegranate (65.7 ± 7.9 g GAE/100 g; cyanidin 3,5-diglucoside; punicalin), and red grape (59.6 ± 2.5 g GAE/100 g; malvidin 3-glucoside; quercetin 3-glucuronide)—showed also one of the highest inhibitory activities against α-amylase (326.9 ± 75.8 μg/mL; 789.7 ± 220.9 μg/mL; 646.1 ± 81.8 μg/mL) and α-glucosidase (115.6 ± 32.5 μg/mL; 127.8 ± 20.1 μg/mL; 160.6 ± 68.4 μg/mL) and, partially, were even more potent inhibitors than acarbose (441 ± 30 μg/mL; 1439 ± 85 μg/mL). Additionally, the investigation of single anthocyanins and glycosylated flavonoids demonstrated a structure- and size-dependent inhibitory activity. In the future in vivo studies are envisaged. 相似文献
59.
Fernanda Cosme Alice Vilela Luís Moreira Carla Moura Jos A. P. Enríquez Luís Filipe-Ribeiro Fernando M. Nunes 《Molecules (Basel, Switzerland)》2020,25(24)
‘Mencía’/‘Jaen’ it’s an important red grape variety, exclusive of the Iberian Peninsula, used in wine production namely in Bierzo D.O. and Dão D.O., respectively. This work evaluates the effect of the two different “terroirs” on the phenolic composition and chromatic characteristics of ‘Mencía’/‘Jaen’ monovarietal wines produced at an industrial scale in the same vintage. Using Principal Component Analysis (PCA), Partial Least Squares-Discrimination Analysis (PLS-DA), and Orthogonal PLS-DA (OPLS-DA) it was found that peonidin-3-coumaroylglucoside, petunidin-3-glucoside, malvidin-3-coumaroylglucoside, peonidin-3-glucoside, malvidin-3-acetylglucoside, malvidin-3-glucoside, and ferulic acid were the phenolic compounds with the highest differences between the two regions. PLS regression allowed to correlate the differences in lightness (L*) and redness (a*) of wines from ‘Jaen’ and ‘Mencía’ to differences in colored anthocyanins, polymeric pigments, total pigments, total anthocyanins, cyanidin-3-acetylglucoside, delphinidin-3-acetylglucoside, delphinidin-3-glucoside, peonidin-3-coumaroylglucoside, petunidin-3-glucoside and malvidin-3-glucoside in wines, and the colorless ferulic, caffeic, and coutaric acids, and ethyl caffeate. The wines a* values were more affected by colored anthocyanins, ferulic acid, total anthocyanins, delphinidin-3-acetylglucoside, delphinidin-3-glucoside and petunidin-3-acetylglucoside, and catechin. The positive influence of ferulic acid in the a* values and ferulic, caffeic, coutaric acids, and ethyl caffeate on the L* values can be due to the co-pigmentation phenomena. The higher dryness and lower temperatures during the September nights in this vintage might explain the differences observed in the anthocyanin content and chromatic characteristics of the wines. 相似文献
60.
Ji‐Long Shi Rufan Chen Huimin Hao Cheng Wang Xianjun Lang 《Angewandte Chemie (International ed. in English)》2020,59(23):9088-9093
2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 carbon‐conjugated porphyrin‐based covalent organic framework (Por‐sp2c‐COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light‐emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π‐conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 ?C=C? double bonds linkage ensures the stability of Por‐sp2c‐COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por‐sp2c‐COF is pivotal for cooperative photocatalysis with (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis. 相似文献