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31.
32.
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
33.
In this study, a molecularly imprinted sensor technology is engineered to detect glucose in real blood samples by chronoimpedimetrically. The imprinting process of glucose (Glc) was carried out by electrochemical polymerization of aminophenylboronic acid (APBA) and pyrrole (Py) by performing cyclic voltammetry (CV). Afterwards, glucose molecule was removed from imprinted surface by 5 % acetic acid to reveal glucose imprinted cavities. Electrochemical Impedance Spectroscopy (EIS) was used to characterize sensor modification steps and glucose removal. Glucose monitoring process was carried out chronoimpedimetrically(CI) for the first time in real blood samples. Calibration curve was prepared between 20–800 mg/dL. The standard deviations of the 18 calibration curves R2 were calculated as 0.9866±0.0066 to assess reproducibility. Recovery was calculated by using 105 mg/dL Glc Serum Sample, which was monitored by auto analyzer and into this sample 50 mg/dL Glc added and our sensor response was 147.92±2.43 mg/dL, 98.6±1.62 % (n=5). Non‐imprinted (NIP) sensor gave no signal for the glucose concentration. 相似文献
34.
应用壳聚糖将葡萄糖氧化酶固定于鸡蛋膜上,结合氧电极制得葡萄糖传感器.实验表明,壳聚糖比戊二醛能更好地固定葡萄糖氧化酶,最佳条件为壳聚糖浓度0.3%、固定化酶量0.8 mg、 pH 7.0、缓冲溶液浓度300 mmol/L和温度25 ℃.本葡萄糖传感器的线性范围为0.016~1.10 mmol/L;检出限为8.0 μmol/L(S/N=3), 响应时间<60 s,有很好的稳定性,寿命>3个月.同一个传感器重复使用以及同方法制作的不同传感器之间都有很好的重现性,RSD分别为2.5%(n=10)和4.7%(n=4).实际样品中可能存在的烟酰胺、 VB6、 VB12、 VE、Ca2+、 Mg2+、 K+和Zn2+等对葡萄糖的测定不产生干扰.本传感器已成功地应用于市售饮料中葡萄糖含量的测定. 相似文献
35.
The direct electrochemistry of glucose oxidase (GOD) was achieved based on the immobilization of GOD on a natural nano‐structural attapulgite (ATP) clay film modified glassy carbon (GC) electrode. The immobilized GOD displayed a pair of well‐defined quasi‐reversible redox peaks with a formal potential (E0′) of ?457.5 mV (vs. SCE) in 0.1 mol·L?1 pH 7.0 phosphate buffer solution. The peak current was linearly dependent on the scan rate, indicating that the direct electrochemistry of GOD in that case was a surface‐controlled process. The immobilized glucose oxidase could retain bioactivity and catalyze the oxidation of glucose in the presence of ferrocene monocarboxylic acid (FMCA) as a mediator with the apparent Michaelis‐Menten constant Kappm of 1.16 mmol·L?1. The electrocatalytic response showed a linear dependence on the glucose concentration ranging widely from 5.0×10?6 to 6.0×10?4 mol·L?1 (with correlation coefficient of 0.9960). This work demonstrated that the nano‐structural attapulgite clay was a good candidate material for the direct electrochemistry of the redox‐active enzyme and the construction of the related enzyme biosensors. The proposed biosensors were applied to determine the glucose in blood and urine samples with satisfactory results. 相似文献
36.
37.
An amperometric glucose biosensor was developed based on the immobilization of glucose oxidase in the organically modified
silicate (ormosil)-polyvinyl acetate (PVA) matrix onto a Prussian Blue (PB)-modified glassy carbon electrode. A higher stability
PB-modified electrode was prepared by the electrochemical deposition of FeCl3, K3[Fe(CN)6] and ethylenediamine tetraacetic acid (EDTA) under cyclic voltammetric (CV) conditions. The effects of the potential range
of CV conditions, electrolyte cations, applied potential, pH, temperature and co-existing substances were investigated. The
detection limit of the glucose biosensor was 8.1 μmol·L−1 (S/N = 3) with a linear range from 20 μmol·L−1 to 2 mmol·L−1 (R = 0.9965). The biosensor presented a fast response and good selectivity. Additionally, excellent reproducibility and stability
of the biosensor were observed.
Supported by the National High Technical Development Project (863 project) Foundation (Grant No. 2006AA09Z160) and the National
Natural Science Foundation of China (Grant No. 20775064) 相似文献
38.
《中国化学》2017,35(11):1739-1748
The development of novel methods to obtain biofuels and chemicals from biomass has been an immediate issue in both academic and industrial communities. In this work, a series of novel catalysts were prepared and characterized by FT‐IR , TGA , XRD , SEM , TEM , ICP‐AES , NH3‐TPD and BET , which were applied for the conversion of hexose to 5‐hydroxymethylfurfural (HMF ). The Cr(Salten)‐MCM ‐41‐[(CH2 )3SO3HVIm ]HSO4 catalyst was the most active catalyst, and a glucose conversion of 99.8% with 50.2% HMF yield was obtained at 140 °C for 4 h in dimethyl sulfoxide (DMSO ). The effects of reaction temperature, reaction time, solvents and catalyst dosages were investigated in detail. MCM ‐41 immobilized acidic functional ionic liquid and chromium(III ) Schiff base complexes as heterogeneous catalysts can be easily recovered by simple filter treatment, exhibiting excellent stability and activity towards hexose conversion. Thus the heterogeneous catalysts were environment‐friendly for transforming biomass carbohydrates into fine chemicals. 相似文献
39.
40.
Mika Tiainen Hannu Maaheimo Pasi Soininen Reino Laatikainen 《Magnetic resonance in chemistry : MRC》2010,48(2):117-122
The one‐ and two‐bond 13C isotope shifts, typically ?1.5 to ?2.5 ppb and ?0.7 ppb respectively, in non‐cyclic aliphatic systems and up to ?4.4 ppb and ?1.0 ppb in glucose cause effects that need to be taken into account in the adaptive NMR spectral library‐based quantification of the isotopomer mixtures. In this work, NMR spectral analyses of some 13C‐labelled amino acids, D ‐glucose and other small compounds were performed in order to obtain rules for prediction of the 13C isotope effects on 1H chemical shifts. It is proposed that using the additivity rules, the isotope effects can be predicted with a sufficient accuracy for amino acid isotopomer applications. For glucose the effects were found strongly non‐additive. The complete spectral analysis of fully 13C‐labelled D ‐glucose made it also possible to assign the exocyclic proton signals of the glucose. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献