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Ascorbic acid is among the most abundant antioxidants in the lung, where it likely plays a key role in the mechanism by which particulate air pollution initiates a biological response. Because ascorbic acid is a highly redox active species, it engages in a far more complex web of reactions than a typical organic molecule, reacting with oxidants such as the hydroxyl radical as well as redox-active transition metals such as iron and copper. The literature provides a solid outline for this chemistry, but there are large disagreements about mechanisms, stoichiometries and reaction rates, particularly for the transition metal reactions. Here we synthesize the literature, develop a chemical kinetics model, and use seven sets of laboratory measurements to constrain mechanisms for the iron and copper reactions and derive key rate constants. We find that micromolar concentrations of iron(III) and copper(II) are more important sinks for ascorbic acid (both AH2 and AH−) than reactive oxygen species. The iron and copper reactions are catalytic rather than redox reactions, and have unit stoichiometries: Fe(III)/Cu(II) + AH2/AH− + O2 → Fe(III)/Cu(II) + H2O2 + products. Rate constants are 5.7 × 104 and 4.7 × 104 M−2 s−1 for Fe(III) + AH2/AH− and 7.7 × 104 and 2.8 × 106 M−2 s−1 for Cu(II) + AH2/AH−, respectively. [ABSTRACT FROM AUTHOR]

In the present work, the chemical bath deposition technique was used to synthesize CuO electrodes. Their electrochemical properties were examined for non-enzymatic glucose sensors. In order to analyse, the crystallinity of prepared electrodes X-ray diffractometer (XRD) was used whereas Field Emission Scanning Microscope (FE-SEM) was for morphological study. The synthesized bundles of CuO nanosheets exhibited the monoclinic phase. For the study of electrochemical properties of prepared CuO electrodes, cyclic voltammetry and chronoamperometry techniques have been adopted. The developed CuO electrodes are the best candidates for non-enzymatic glucose sensing, showing excellent response. It shows high sensitivity 1594 µAmM−1cm−2 with potential of + 0.6V, active time period of approximately 5 s, and linear range 3 μm to 3 mM. The CuO electrode's selectivity toward interfering species such as ascorbic acid is also studied. The prepared electrode shows an excellent response to glucose compared to ascorbic acid. [ABSTRACT FROM AUTHOR]

Methylene blue intercalated layered MnO2 nanosheets (MB-MnO2) were synthesized through an ex-situ method at room temperature. Tetramethylammonium hydroxide (TMAOH) was used as a delaminating agent for the synthesis of nanosheet-like structures of MnO2. The prepared nanocomposites were analyzed by various instrumental techniques such as UV–visible, FTIR, XRD, FESEM, and EDX for the close examination of the morphology, structure, shape, crystallinity, and vibrational characterization. Typical two-dimensional layer sheet-like morphologies with multiple folds were observed for non-intercalated MnO2, whereas intercalated MnO2 showed more flattered and planar square-shaped and elongated ultrathin sheet-like structures with occasional folds and crinkles. MB intercalated MnO2nanosheets were used as an efficient electron mediator for the electrooxidation of the ascorbic acid to dehydroascorbic acid. Cyclic voltammetry and chronoamperometry confirmed the excellent electrocatalytic activity of the modified MB intercalated MnO2 nanosheets/GCE over a wide range of ascorbic acid concentrations in 0.1 M PBS. The detection limit was computed to be 0.05 μM. The effect of the scan rates and concentration of the ascorbic acid were also analyzed. [ABSTRACT FROM AUTHOR]

In summary, we have demonstrated that the Cu complex reported in the previous communication does not form oxalate via CO SB 2 sb reduction. Among the examples reported for the reductive coupling of CO SB 2 sb to oxalate is a dinuclear Cu complex introduced by some of us in 2014 (ref. [16]). Since the reaction seemed to require air for the formation of oxalate, we suggested that oxidation of the ascorbate might be the true origin of the oxalate. This was finally evidenced by the reaction conducted under an atmosphere of O SB 2 sb , giving rise to the same oxalate complex described earlier (ref.[16]) from which sodium oxalate was removed and identified by NMR spectroscopy. [Extracted from the article]

Selective detection of dopamine is still a challenge due to the strong interference from ascorbic acid (AA). A hybrid dopamine electrochemical sensor was fabricated by boron-doped diamond (BDD) film co-modified with gold nanoparticles and graphite-coated nickel nanoparticles (Au-C@Ni/BDD). Highly sensitive and selective detection toward dopamine was achieved by multiple electrochemical anodic polarization treatment (EAPT) with relatively mild voltage (+ 1.6 V vs. Ag/AgCl) on Au-C@Ni/BDD electrode. Specifically, the oxidation peak separation between ascorbic acid and dopamine reached 166 mV, and the limit of detection of dopamine was as low as 0.015 μM in a linear concentration range of 0.05–100 μM with the sensitivity up to 1.99 μA μM−1 cm−2 even in the presence of interference of high-level AA. These could be ascribed to the electrocatalytically active sites and functional oxygen-containing groups of the hybrid electrodes produced by the EAPT and the excellent catalytical activity of gold nanoparticles. [ABSTRACT FROM AUTHOR]

An organic crystal l-ascorbic acid known as vitamin C is grown by slow evaporation method and studied the properties of crystal under the influence of gamma radiation. Powder X-ray study and FTIR study have been carried out to see the effect of irradiation on crystallinity and chemical nature of the crystal. Energy gap and SHG conversion efficiency decreased exponentially upon increasing the gamma irradiation dosage. Dielectric studies for the crystal have been carried out both before and after irradiation in the frequency range 10 Hz to 8 MHz at room temperature; it is observed that dielectric constant and dielectric loss decreases and they became stable due to irradiation effect. The mechanical properties such as hardness number, elastic stiffness and yield strength were determined and these parameters are enhanced with the influence of gamma radiation. [ABSTRACT FROM AUTHOR]

The application of zinc oxide-based nanocomposite is one of the novel approaches utilized for the development of electronic devices. The sol-gel and auto combustion procedures were employed to synthesize porous PVA aided ZnO/Fe2O3 nanocomposite (PBNC). The n-type iron (III) oxide was successfully coupled with n-type ZnO. The characterizations conducted to explore the significant changes in the physical properties of as-synthesized materials revealed that the surface area, porosity, and charge transfer capability improvement on the PBNC, compared to ZnO. Using the DTG analysis, 500 °C was confirmed to be the optimal calcination temperature to degrade the PVA polymer after acting as a capping agent and impurities that have a boiling point of less than 500 °C. The XRD pattern and TEM image analysis validated the nanometer range size of the materials (10–70 nm). The SEM image and BET spectral analyses confirmed the porous nature of the PBNC, supporting results obtained from the HRTEM (IFFT) and SAED pattern analysis. The EDXS, XPS, and HRTEM analyses were appliedapplied for Zn, Fe, and O elemental composition and certainty of ZnO. The presence of improved charge transfer property for PBNC, compared to ZnO, has been evidenced by CV and EIS studies. The PBNC also showed enhanced ascorbic acid detection capability compared to ZnO. [ABSTRACT FROM AUTHOR]

Twenty-one different cultivars from four different species were examined. The highest dry weight was present in seeds (between 35 and 50%) and the average water content was 60%. Placenta and pericarp contained on average 86% water. Total sugars variation between species was 60%. The most concentrated in the various cultivar pericarps were ascorbic acid ranging from 368.1 to 2105.6 mg/100 g DW and citric acid ranging from 1464.3 to 9479.9 mg/100 g DW. Total phenolic content ranged from 2599.1 mg/100 DW in 'Chilli AS- Rot' to 7766.7 mg/100 g DW in 'Carolina Reaper'. The placenta had 23.5 times higher phenolic content than seeds. C. chinense and C. chinense × C. frutescens had 3.5 to 5 times higher capsaicinoid content compared to C. annuum and C. baccatum, with 'Carolina Reaper' having the highest content at 7334.3 mg/100 g DW and 'Chilli AS- Rot' the lowest (318.7 mg/100 g DW). [ABSTRACT FROM AUTHOR]

We developed a method for the selective and sensitive voltammetric determination of ascorbic and oxalic acids. A screen-printed electrode, modified by gold–palladium bimetallic system and exhibiting catalytic activity in the electrooxidation of the organic acids under consideration, was used as a detector. The difference between the potentials of oxidation peaks of these compounds was 400–500 mV. The proposed method enables an in situ voltammetric determination of ascorbic and oxalic acids in citrus fruits and orange juices without sample preparation. The results of the voltammetric determination are comparable with the data of iodometry and permanganometry, which are the recommended methods for the analysis of fruit juices. [ABSTRACT FROM AUTHOR]

Tungstate nanorods (WO3 -NRs) were synthesized by a facile hydrothermal method using sodium tungstate as a precursor while sodium sulfate and hydrochloric acid were used as stabilizing agents. Scanning electron microscopy (SEM) images showed outstanding growth of WO3-NRs with uniform surface morphology. The X-ray diffraction (XRD) analysis confirmed the purity and crystalline nature of the synthesized material. The material was further characterized by different tools such as TEM, EDX, FTIR, XPS, BET, and Raman spectroscopy. For the electrochemical response of WO3-NRs, cyclic voltammetry measurements were performed for the detection of vitamin C (ascorbic acid). The designed sensor shows a limit of detection of 0.56 µM and higher selectivity in the presence of its structural and functional analogs such as uric acid and lauric acid. Improved sensing properties of WO3-NRs are attributed to the synergistic effects involving the quantum effect, high surface area, fast electron transfer, and highly ordered 1-D nanostructure. Among them, the highly arranged 1-D growth of WO3 nanorods has a greater impact on the efficiency of the biosensor. These results provide a new insight for the synthesis of 1-D nanostructures of transition metal oxides for contributions in sensor devices, solar cells, and capacitor applications. [ABSTRACT FROM AUTHOR]

The encapsulation of ascorbic acid within chitosan nanoparticles (CHNs), embedded in a fibrous structure of a dexamethasone (Dex)-loaded PCL scaffold, provides a new plan for osteogenic differentiation of mesenchymal stem cells. This electrospun PCL fibrous scaffold can release Dex, as bone differentiation initiator, and ascorbic acid, as bone differentiation enhancer, in an approximately sustained release pattern for about 2 weeks. Ascorbic acid-loaded CHNs were prepared by electrospraying a mixture of chitosan and ascorbic acid, and Dex-containing PCL fibers were prepared by electrospinning a mixture of PCL and Dex. The final PCL/chitosan bilayer scaffolds were obtained by the sequential employment of electrospinning and electrospraying methods. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) confirmed that the CHNs were successfully incorporated into the fibrous PCL matrix. The improved proliferation of hMSCs cultured on the PCL/chitosan scaffolds was also verified. Osteogenic assays showed an increase in alkaline phosphatase activity and mineral deposits. The expression of bone-specific genes also confirmed the osteogenic differentiation of cells cultured on these PCL/chitosan bilayer scaffolds. Dual-drug-loaded PCL/chitosan scaffold enhanced the osteoblast differentiation of hMSC cells and can be served as a potential scaffold for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Hydrogen as a potential reductive gas has selective antioxidant capacity to remove the reactive oxygen species (ROS) which is harmful to human body. Introducing hydrogen to human body through hydrogen-rich water (HRW) is an effective strategy to alleviate the oxidation process dominated by ROS. Here, aeration method was adopted to prepare the hydrogen-rich water, and the effects of hydrogen pressure, injected water volume and temperature on the hydrogen concentration and bubble size were overall investigated to achieve the controllable synthesis of hydrogen bubbles. It was found that hydrogen-rich water with a concentration higher than 1000 ppb and nanoscale bubbles (300–600 nm) can be obtained by the present aeration processing method. Altering processing parameters can lead to various hydrogen solubilities and bubble sizes acquired. The hydrogen bubbles showed a high stability in the as-prepared water by keeping it in room temperature condition until 5 h. The scavenging experiments exhibited that the hydrogen-rich water showed a good antioxidant ability on different free radicals (DPPH, ·OH and ·O2−). In comparison to the conventional antioxidant of vitamin C (VC), the scavenging rate of hydrogen-rich water on ·O2− free radical is 4.3 times that of VC. Such hydrogen-rich water with a high hydrogen concentration and stability may play an important role in the field of hydrogen molecular medical therapy. [ABSTRACT FROM AUTHOR]

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Hydrogen atom transfer (HAT) hydrogenation has recently emerged as an indispensable method for the chemoselective reduction of unactivated alkenes. However, the hitherto reported systems basically require stoichiometric amounts of silanes and peroxides, which prevents wider applications, especially with respect to sustainability and safety concerns. Herein, we report a silane- and peroxide-free HAT hydrogenation using a combined cobalt/photoredox catalysis and ascorbic acid (vitamin C) as a sole stoichiometric reactant. A cobalt salophen complex is identified as the optimal cocatalyst for this environmentally benign HAT hydrogenation in aqueous media, which exhibits high functional-group tolerance. In addition to its applicability in the late-stage hydrogenation of amino-acid derivatives and drug molecules, this method offers unique advantage in direct transformation of unprotected sugar derivatives and allows the HAT hydrogenation of unprotected C-glycoside in higher yield compared to previously reported HAT hydrogenation protocols. The proposed mechanism is supported by experimental and theoretical studies. Hydrogen atom transfer (HAT) hydrogenation of alkenes usually requires stoichiometric silanes and peroxides. Here, the authors report a silane- and peroxide-free HAT hydrogenation method using a combined cobalt/photoredox catalysis and vitamin C as a sole stoichiometric reactant. [ABSTRACT FROM AUTHOR]

The paper presents the possibility of applying ultrasonic technology for inactivation of mesophilic aerobic microorganisms, lactic acid bacteria, coliform bacteria, and yeast with the maintenance of the chemical and structural properties of tomato juice. The research was conducted on fresh tomato juice obtained from the Apis F1 variety. Pressed juice was exposed to high power ultrasound and frequency 20 kHz with three operational parameters: ultrasound intensity (28 and 40 W cm−2), treatment time (2, 5, and 10 min), and product storage time (1, 4, 7 and 10 days). The temperature of the juice during the sonication ranged from 37 to 52 °C depending on the intensity of ultrasound and time of treatment. Effectiveness of the tested microorganisms eradication in the juice depended on the amplitude and duration of the ultrasound treatment. It was shown that the juice exposed to an ultrasonic field with an intensity of 40 W cm−2 for 10 min was microbiologically pure and free from spoilage microorganism even after 10 storage days. No statistically significant differences in pH were found between the untreated juice and the sonicated samples. The ultrasonic treatment was found to change the content of lycopene in small degree (both an increase and a decrease, depending on the processing time) and to induce a small decrease in the vitamin C content. The study suggests that the ultrasonic treatment can be successfully implemented on an industrial scale for the production of not-from-concentrate (NFC) tomato juice. [ABSTRACT FROM AUTHOR]

The integration of the enzymes on the solid electrode surfaces is an indispensable step for the construction of the bioelectrochemical electrode. In the current work, the blend nanofibers consisting of poly (vinyl alcohol) and poly(ethyleneimine) were deposited by the electrospinning method on an H2O2-sensitive modified glassy carbon electrode. Glucose oxidase was immobilized on the glutaraldehyde-activated blend nanofibers. Bioelectrochemical electrode displayed a good linear response to the glucose concentration ranges with two separate calibration curves, from 2 to 8 mmol L−1 and from 10 to 30 mmol L−1. Besides, it showed a high anti-interference performance against ascorbic and uric acids as well as long-term storage stability over 63 days. Moreover, analysis results in a diluted human serum sample showed that the prepared bioelectrochemical electrode has the ability to measure glucose in real samples. [ABSTRACT FROM AUTHOR]

The antioxidant composition from four samples, brewer's spent grain (BSG), brewer's spent yeast (BRY), a part of the process (POP—after hop addition), and craft beer (CRB) from five popular craft beers were evaluated. The total phenolics, flavonoids, tannins, and ascorbic acid, as well as the antioxidant capacity, were determined. Furthermore, phenolics content was determined by LC–MS/MS technique. The cytotoxicity of BRY on fibroblasts cells and the anti-tumor effect of craft beers on colon adenocarcinoma cells were determined by cell viability and membrane integrity assays. The darker samples presented the highest total phenolics and antioxidant capacities. Phenolics, tannins, and ascorbic acid showed a strong correlation with antioxidant activity. Moreover, among nine phenolics characterized, catechin, and ferulic and p-coumaric acids were the majority compounds. Besides, no cytotoxicity was detected by BRY samples, and the darker craft beers, American Ipa and Imperial Stout demonstrated antiproliferative activity in the tumor cell line. Therefore, the comprehensive vision of the antioxidants into the entire brewing process is useful to optimize and valorize the end product and residues. This study also enlightened the potential benefits to human health, pointing new approaches to increase the interest in craft beer and its bioproducts avoiding the high costs of discard and possible negative impacts on the environment. [ABSTRACT FROM AUTHOR]

The green space of parks with its vegetation population of trees and shrubs plays a key role in air purification and the absorption of air pollutions, thereby contributing to the alleviation of environmental pollutions. The present factorial experiment was carried out in urban parks with 18 treatments. The leaf samples of 18 ornamental species were collected in two sites [(1) the margin and (2) the downtown] of Rasht city in north of Iran. Then, they were subjected to the measurement of leaf relative water content, total chlorophyll content, leaf extract pH, and ascorbic acid content to evaluate their air pollution tolerance index (APTI). The tolerance of the species was assessed by two methods: the comparison of their APTI with the average APTI of all species and the use of a constant APTI as a standard. The results showed that the species differed in their tolerance in different sites. Among the studied 18 species, Yucca filamentosa and Berberis thunbergii were identified as air pollution-tolerant species, so they are recommended for the use in parks. Yucca had an APTI of 78.24 and Berberis had an APTI of 67.56. The lowest APTI was obtained from Fraxinus excesio and Ligustrum texanum. [ABSTRACT FROM AUTHOR]

Background: The influence of different biological agents on the rate of orthodontic tooth movement (OTM) has been extensively reviewed in animal studies with conflicting results. These findings cannot be extrapolated from animals to humans. Therefore, we aimed to systematically investigate the most up-to-date available evidence of human studies regarding the effect of the administration of different biological substances on the rate of orthodontic tooth movement. Methods: A total of 8 databases were searched until the 16th of June 2020 without restrictions. Controlled randomized and non-randomized human clinical studies assessing the effect of biological substances on the rate of OTM were included. ROBINS-I and the Cochrane Risk of Bias tools were used. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: A total of 11 studies (6 randomized clinical trials and 5 prospective clinical trials) were identified for inclusion. Local injections of prostaglandin E1 and vitamin C exerted a positive influence on the rate of OTM; vitamin D showed variable effects. The use of platelet-rich plasma and its derivatives showed inconsistent results, while the local use of human relaxin hormone showed no significant effects on the rate of OTM. Limitations: The limited and variable observation periods after the administration of the biological substances, the high and medium risk of bias assessment for some included studies, the variable concentrations of the assessed biological agents, the different experimental designs and teeth evaluated, and the variety of measurement tools have hampered the quantitative assessment of the results as originally planned. Conclusions and implications: Despite the methodological limitations of the included studies, this systematic review provides an important overview of the effects of a variety of biological agents on the rate of tooth movement and elucidates the deficiencies in the clinical studies that have been conducted so far to evaluate the effectiveness of these agents in humans, providing some guidelines for future robust research. Trial registration: PROSPERO (CRD42020168481, www.crd.york.ac.uk/prospero) [ABSTRACT FROM AUTHOR]

Background: Atherosclerosis is an important medical problem of modern society. High environmental tobacco smoke in casino is associated with an accelerated atherogenic process. We have previously shown vitamin B12 and C supplementation improves vascular reactivity and may be beneficial in vascular protection. Objective: To evaluate the impact of vitamin supplementation on atherosclerosis (brachial artery reactivity FMD and carotid intima-media thickness IMT) in subjects exposed to high environmental tobacco smoke. Design: Double-blind 2×2 factorial design fashion. Setting: Computer randomization in 4 treatment groups: placebo (n=24), vitamin B12 (n=21), vitamin C (n=23) and vitamin B12+C (n=23) groups. Participants: 91 passive-smoking casino employees (19.2% male, mean age 45.0±8.2 years). Intervention: Subjects were randomized to receive vitamin B12 (500µg daily), vitamin C (200mg daily), vitamin B12+C or image-matched placebo capsules for 1 year. Measurement: Brachial FMD and carotid IMT (surrogate atherosclerotic markers) were measured by ultrasound at baseline and on completion at 12 months. Methods: 91 passive smoking casino employees (19.2% male, mean age 45.0±8.2 years) were randomized to receive vitamin B12 (500µg daily), vitamin C (200mg daily), vitamin B12+C or image-matched placebo capsules in double-blind 2 × 2 factorial design fashion for 1 year. Brachial FMD and carotid IMT (surrogate atherosclerotic markers) were measured by ultrasound at baseline and 12 months. Results: Of the 78 (85.7%) passive-smoking employees completed the study, 11.5% had hypertension, 5.1% diabetes mellitus and 15.4% hypercholesterolemia. There were no significant changes in their blood pressures, lipid profiles, glucose and body mass index after supplementation for 1 year, but mild decrease in DBP (p<0.001) and blood creatinine (p<0.01) after combined vitamin B12 and C, and significant increase in blood B12 after vitamin B12 (p<0.01) and vitamin B12+C supplementations (p<0.001). Brachial FMD and cartotid IMT improved after the 3 vitamin supplementations (p<0.001), but not after placebo, being more significant after combined vitamin supplementations (p<0.0001). No adverse effects were reported. Conclusion: Vitamin B12 or C supplementation in passive smokers improved vascular reactivity and structures at 1 year, with implication in long term atherosclerosis prevention. [ABSTRACT FROM AUTHOR]

C5-glyceryl-methylcytosine (5gmC) is a novel DNA modification catalyzed by algal TET homologue CMD1 using vitamin C (VC) as co-substrate. Here, we report the structures of CMD1 in apo form and in complexes with VC or/and dsDNA. CMD1 exhibits comparable binding affinities for DNAs of different lengths, structures, and 5mC levels, and displays a moderate substrate preference for 5mCpG-containing DNA. CMD1 adopts the typical DSBH fold of Fe2+/2-OG-dependent dioxygenases. The lactone form of VC binds to the active site and mono-coordinates the Fe2+ in a manner different from 2-OG. The dsDNA binds to a positively charged cleft of CMD1 and the 5mC/C is inserted into the active site and recognized by CMD1 in a similar manner as the TET proteins. The functions of key residues are validated by mutagenesis and activity assay. Our structural and biochemical data together reveal the molecular mechanism for the VC-derived 5gmC DNA modification by CMD1. C5-glyceryl-methylcytosine is a DNA modification that plays a role in the regulation of green alga photosynthesis and is catalysed by CMD1, using vitamin C (VC) as a co-substrate. Here, the authors provide insights into the catalytic mechanism of CMD1 by determining the crystal structures of apo CMD1 and CMD1 bound to either VC or DNA, as well as the ternary CMD1/VC/DNA complex structure. [ABSTRACT FROM AUTHOR]

A new electrochemical sensor based on thionine (TH), an electroactive polymer, and CuO nanoparticle (CuONP)-modified pencil graphite electrode (PGE) has been developed. Poly(thionine) (PTH) was formed on the CuO/PGE surface by electropolymerisation in ethaline deep eutectic solvent (DES) containing acetic acid dopant to form PTHEthaline/CuO/PGE. Cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry were utilized to evaluate the fabrication process, electrochemical properties, and performance parameters of the modified electrodes. The analytical performance of the PTHEthaline/CuO/PGE was evaluated with respect to linear range, limit of detection, repeatability, and reproducibility for the detection of acetaminophen (APAP) by electrooxidation in the presence of ascorbic acid (AA). Analytical parameters such as pH were optimized. The combined use of PTH and CuONP led to enhanced performance towards APAP due to the large electroactive surface area and synergistic catalytic effect, with a wide linear working range and low detection limit. The reliability of the proposed sensor for the detection of APAP was successfully tested in pharmaceutical samples containing APAP and AA, with very good recoveries. [ABSTRACT FROM AUTHOR]

Vitamin C is a necessary micronutrient that is involved in many biological processes. In preserved human plasma and serum, vitamin C is most meaningfully analyzed as total ascorbic acid (TAA). From 1993 through 2015, the National Institute of Standards and Technology (NIST) coordinated 40 interlaboratory studies (ILS) devoted to improving the between-participant comparability of TAA measurements. The results from these ILS demonstrate that the concentration of TAA ([TAA]) is stable for at least 20 years in serum diluted 1 + 1 (volume fraction) with 10% mass concentration aqueous metaphosphoric acid (MPA) and stored at −80 °C. The between-participant relative reproducibility precision, expressed as a coefficient of variation (CV), improved from over 16% to under 9% over the course of the studies. Normalization of test samples (i.e., ex post-facto recalibrating the as-submitted results) using participant-prepared serum-free calibration solutions did not improve reproducibility. Normalization to one control sample having a similar serum-based matrix as the test samples improved the CV to 7%; normalization to two such controls reduced the CV to 4%. Multicenter studies that require the highest degree of measurement comparability among the participants should consider calibrating with materials that have a serum-based matrix as similar as possible to that of the samples of interest. [ABSTRACT FROM AUTHOR]

Background: Few specific medications have been proven effective for the treatment of patients with severe coronavirus disease 2019 (COVID-19). Here, we tested whether high-dose vitamin C infusion was effective for severe COVID-19. Methods: This randomized, controlled, clinical trial was performed at 3 hospitals in Hubei, China. Patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the ICU were randomly assigned in as 1:1 ratio to either the high-dose intravenous vitamin C (HDIVC) or the placebo. HDIVC group received 12 g of vitamin C/50 ml every 12 h for 7 days at a rate of 12 ml/hour, and the placebo group received bacteriostatic water for injection in the same way within 48 h of arrival to ICU. The primary outcome was invasive mechanical ventilation-free days in 28 days (IMVFD28). Secondary outcomes were 28-day mortality, organ failure (Sequential Organ Failure Assessment (SOFA) score), and inflammation progression (interleukin-6). Results: Only 56 critical COVID-19 patients were ultimately recruited due to the early control of the outbreak. There was no difference in IMVFD28 between two groups (26.0 [9.0–28.0] in HDIVC vs 22.0 [8.50–28.0] in control, p = 0.57). HDIVC failed to reduce 28-day mortality (P = 0.27). During the 7-day treatment period, patients in the HDIVC group had a steady rise in the PaO2/FiO2 (day 7: 229 vs. 151 mmHg, 95% CI 33 to 122, P = 0.01), which was not observed in the control group. IL-6 in the HDIVC group was lower than that in the control group (19.42 vs. 158.00; 95% CI -301.72 to -29.79; P = 0.04) on day 7. Conclusion: This pilot trial showed that HDIVC failed to improve IMVFD28, but might show a potential signal of benefit in oxygenation for critically ill patients with COVID-19 improving PaO2/FiO2 even though. [ABSTRACT FROM AUTHOR]

Chitosan coating (B/CH) in addition with nano-material films as silicon (B/CH/Nano-SiO2) and titanium (B/CH/Nano-TiO2) dioxides were developed and applied to detect potential changes on fresh blueberry fruits in commercial storage temperature. Physical, mechanical parameters (weight loss, decay rate, colour index and firmness), phytochemical contents (ascorbic acid, acidity, soluble solids concentration, titratable acidity, and repining index), phenolic enzymes (peroxidase and polyphenoloxidase), pigments (anthocyanin) and microbiological analysis (mesophilic aerobic, yeasts and molds populations) were detected every other day until the end of the experiment. Nano-coating based on (Nano-TiO2) established the most suitable values for weight loss (2.22%), titratable acidity (0.45% citric acid), and repining index. (B/CH/Nano-TiO2) reported a gradual increase in polyphenoloxidase and peroxidase enzyme activities (659.45 U/min g) and (20.39 U/min g), respectively. While, (B/CH/Nano-SiO2) established the slightest change in acidity (2.61), anthocyanin (105.19 cyanidin-3-O-glucoside mg/100 g FW) and minimized the growth of mesophilic aerobic, yeasts, and molds populations (3.73–3.98 log CFU/g), respectively. (B/CH) films maintained lightness (6.80% loss) and recorded the highest ascorbic acid content (7.34 g/100 g FW). Therefore, chitosan nano-material films can maintain nutrients and control the microbial growth for extending the shelf life of fresh blueberry fruits. [ABSTRACT FROM AUTHOR]

In this study, quality parameters (color, soluble solids content, titratable acidity), levels of sugars, organic acids, vitamin C, polyphenols and volatiles were determined during two successive years in Gariguette strawberries harvested at two stages of maturity (turning stage and fully ripe). Fruits were analyzed at harvest and after 2 days of storage at 10 °C. The descriptive sensory analyses of the samples were also performed by a trained panel. Whether at harvest or after storage, no significant difference was observed for sugars between samples, but strawberries harvested fully ripe had lower organic acids and higher levels of volatiles. Consistent with these results, strawberries harvested fully ripe were significantly noted sweeter and more aromatic than those harvested 75% red. No significant difference was observed for total vitamin C between samples, but strawberries harvested fully ripe were overall richer in polyphenols, particularly in hydroxycinnamic acids. This suggests strawberries harvested fully ripe could potentially have a greater impact on health. [ABSTRACT FROM AUTHOR]

Most of the food packaging is mainly petroleum-based, and new forms of food packaging have emerged, such as active, intelligent, and biodegradable packaging to extend the shelf life of fresh vegetables. The aim was to develop a biodegradable active packaging and senescence indicator label for fresh broccoli florets (Brassica oleracea L. var. italica), to increase shelf life and to monitor the decay of the vegetable. The biodegradable active packagings (BAP) were produced by blown extrusion containing zeolite as ethylene scavenger, and their mechanical properties, water vapor permeability, and water sorption isotherms were determined. Fresh broccoli florets were packed in perforated and non-perforated BAP and stored at 12 °C, and their weight loss, vitamin C content, color, and texture were evaluated during the storage. BAPs were efficient in reducing the metabolism of fresh broccoli florets stored at 12 °C, preserving the color, and vitamin C content for 7 days. The senescence indicator labels were able to detect CO2 in packages without perforations. [ABSTRACT FROM AUTHOR]

Background: Barberry has long been used as an herbal remedy since ancient times which is found throughout temperate and subtropical regions of the world. Given the short harvesting season and limited shelf life of the barberry, we evaluated the possibility of using modified atmosphere packaging and oxygen-scavenger sachets to increase its storage period. For this purpose, the physicochemical characterization (antioxidant activity, anthocyanin, phenolic compounds, and ascorbic acid content, acidity, firmness, color, and decay incident) of fresh barberry samples packaged within different atmospheres was investigated over 4 weeks of storage at 4 and 25 °C. The barberries were packaged with low-density polyethylene/polyester (LDPE/PET) films under natural atmosphere (C), N2 gas (N), vacuum (V), or in the presence of an oxygen scavenger (OS). Results: The results revealed that with increased storage period, the O2 and CO2 levels inside the packages decreased and increased, respectively. The antioxidant activity and amounts of anthocyanin, phenolic compounds, and ascorbic acid all decreased with increasing storage period. Among the studied atmospheres, the OS and, subsequently, V packages were most capable of maintaining the quality of fresh barberries, with the decay incidence being approximately 30 times lower inside these packages relative to the control. Increasing the storage temperature accelerated the intensity of chemical changes and decay across all samples. Conclusion: The barberries inside the OS packages stored at 4 °C (and even at 25 °C) still had good sensory properties in terms of chemical properties, texture, and color after 4 weeks. Fortunately, it seems that this packaging technology makes the exportation and delayed consumption of the fresh barberry possible by maintaining its quality. [ABSTRACT FROM AUTHOR]

Minimizing the post-harvest losses in fruits and vegetables is one of the challenging tasks in agriculture. To address this issue, we report nano-net of Cu-chitosan nanoparticles (Cu-chitosan NPs) which has the ability to extend the shelf-life of stored tomato. The application of Cu-chitosan NPs (0.01–0.04%) significantly curtailed microbial decay (< 5 versus > 50% in control), physiological loss in weight (14.36 versus 28.13% in control), respiration rate (0.01173 versus 0.01879 g CO2 kg−1 h−1) and maintained fruit firmness (34.0 versus 17.33 N in control) during storage. Further, these NPs significantly retarded loss of titratable acidity, retained total soluble solids, total and reducing sugars, lycopene, ascorbic acid and inhibited polyphenol oxidase. Likewise, NPs effectively preserved L* (lightness), a* (red/green) and b* (blue/yellow) values and maintained organoleptic score. Scanning electron microscopy study confirmed that Cu-chitosan NPs orchestrate into an invisible-intangible nano-net over tomato surface which may plausibly act as a potential barrier at all possible openings (stem scar, cuticle wax, lenticels, and aquaporins) to control microbial infection, moisture loss, gas exchanges and respiration rate. Overall, nano-net extended keeping quality of tomatoes up to 21 days at room temperature (27 ± 2 °C, 55 ± 2% relative humidity). [ABSTRACT FROM AUTHOR]

We developed a dual-modal colorimetric and photothermal assay for glutathione (GSH) using MnO2 nanosheets prepared with environmentally friendly materials. The nanosheets were synthesized by using ascorbic acid present abundantly in lemon and orange juices to reduce KMnO4. The as-prepared MnO2 nanosheets display oxidase-like activity and can catalyze the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB), yielding a blue oxidative product (oxTMB) that exhibits a UV–Vis absorption peak at 652 nm. In the presence of GSH, the MnO2 nanosheets are reduced and decomposed, resulting in a decrease in the peak intensity. The colorimetric assay offers a wide dynamic range (0.1–100 μM) and a detection limit of 100 nM. The MnO2 nanosheets are also efficient in converting photoenergy to thermal energy, with a photothermal conversion efficiency of 23.3%. The temperature change, after near-infrared (NIR) irradiation at 808 nm, can be easily measured by an inexpensive pen-type thermometer. This effect can also be used for GSH quantification and expands the GSH concentration detection to the range from 6.0 to 200 μM. The viability of our dual-modal assay for clinical applications was demonstrated with successful analyses of GSH in human serum samples. [ABSTRACT FROM AUTHOR]

We report the fabrication of silver nanoparticles evenly imbedded into TiN submicrospheres via one-pot solvothermal reaction and subsequent nitridation for electrochemical detecting of hydrogen peroxide. The precursor of TiO2 submicrospheres and high dispersion of silver nanoparticles are regulated by the alcoholysis of tetrabutyl titanate and reducibility of enol in vitamin C. The ion nitriding promoted the conductivity and micro-nano porous structure on the surface of TiN submicrospheres, which increase the dispersity of silver nanoparticles and make contributions to avoid aggregations. More importantly, the electrochemical response of Ag-TiN submicrospheres to H2O2 was remarkably enhanced due to the co-effects of Ag and N-doping. It provides a superior sensing performance for electrochemical detection of hydrogen peroxide at − 0.3 V with a high sensitivity of 33.25 μA mmol L−1 cm−2, wide linear range of 0.05–2100 μM and low detection limit of 7.7 nM. The fabricated sensor also reliably applied in detection of H2O2 in milk samples with good reproducibility, repeatability and storage stability. [ABSTRACT FROM AUTHOR]

The effects of ultraviolet-C light (UVC) on vitamin C and phenolic compounds in acerola during postharvest storage were investigated in order to elucidate the mechanism inducing the antioxidant systems. The fruits, stored at 10 °C for 7 days after a hormetic UVC irradiation (two pulses of 0.3 J/cm2), showed significantly less degradation of vitamin C and phenolic compounds than the control without the UVC challenge. UVC activated the L-galactono-1,4-lactone dehydrogenase (GalDH), a key enzyme for vitamin C biosynthesis, and altered the composition of phenolic compounds, through phenolic biosynthesis, in acerola during postharvest storage. UVC also induced reactive oxygen species (ROS) productions at immediate (day 0) and late (day 7) times during postharvest storage through the mitochondrial electron transport chain and NADPH oxidase, respectively. Results suggest that UVC helps in the retention of vitamin C and phenolic content in acerola by altering ascorbic acid and phenolic metabolism through an increase in mitochondrial activity and a ROS-mediated mechanism. Data showed the beneficial effects of UVC on maintenance of nutraceutical quality in acerola during postharvest storage and supplied new insights into understanding the mechanism by which UVC irradiation enhance the antioxidant system in fruits. [ABSTRACT FROM AUTHOR]

In this work, zinc oxide nanoparticles (ZnO-NPs) were synthesized by a chemical precipitation method. A precursor zinc nitrate hexahydrate, polyvinylpyrrolidone (PVP), as a surfactant stabilizing agent and ascorbic acid (AA) as a reducing agent were used. Molar ratios of ascorbic acid to zinc nitrate hexahydrate were changed from 1 to 4 during preparation processes and under the same conditions. Morphology, crystallinity, and particle sizes calculations were studied using Transmission electron microscopy (TEM) and X-ray diffraction. The particle sizes were estimated at 57 nm, 66 nm, 53 nm, 47 nm, and 33 nm and crystalline sizes at 30.05 nm, 26.26 nm, 26.38 nm, 26.53 nm, and 20.80 nm when the ratio of (AA:Zn) was 1, 1.5, 3, 3.5, and 4, respectively. The difference between the particle and crystalline size values because of particle size consist of several crystalline. The results illustrated the effect of different concentrations of (AA:Zn) on the formation and agglomeration of (ZnO - NPs) . Fourier transform infrared spectroscopy results showed that the characteristic transmittance bands of (ZnO - NPs) are closer to 455 c m - 1 . UV - vis spectra results show the absorption band seen at 368 nm , 374 nm , 364 nm , 358 nm , and 352 nm and optical band gap calculated at 3.64 eV , 3.58 eV , 3.70 eV , 3.74 eV , and 3.69 eV when the ratio of (AA:Zn) was 1, 1.5, 3, 3.5, and 4, respectively. These results clarified the effect of quantum sizes effect on the optical band gap of (ZnO - NPs) . [ABSTRACT FROM AUTHOR]

Biofortified maize varieties form an essential part of a nutritious diet; available evidence suggests that different processing methods may affect the final food products. The study aimed to evaluate the effects of processing (roasting) and harvesting time on the bioactive components (lutein, zeaxanthin, β-cryptoxanthin, phytate, tannin and vitamin C) and colour properties (L*, a*, b*), of biofortified orange maize. The orange maize hybrids used for the study were obtained from the International Institute of Tropical Agriculture (IITA) diverse lines with high provitamin A (PVA) content. The results showed that harvesting time and roasting methods significantly (P ≤ 0.001) affected the colour properties. The positive values of ∆b* 30.7, 36.0 and 38.1 at 20 days after pollination (DAP), 27DAP and 34DAP, respectively showed that the intensity of orange colour increased with delay in harvesting time. In unprocessed freshly harvested orange hybrid maize; lutein, zeaxanthin, β-cryptoxanthin, tannin and vitamin C increased with an increase in harvesting time. For roasted hybrid, the mean concentrations of all the bioactive components increased with increases in harvesting time except for tannin and vitamin C that showed a decrease at 20DAP and 27DAP. The results revealed that processing and time of harvest affect the levels of non-provitamin A carotenoids, tannins, phytic acid, Vitamin C and the colour properties of biofortified maize genotypes. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AA, vitamin C) serves as a cofactor for ten-eleven translocation (TET) enzymes and induces DNA demethylation in vitro. However, its role in DNA demethylation in vivo remains unclear. We previously reported that DNA demethylation in the mouse liver was enhanced during the suckling period. Therefore, we hypothesized that DNA demethylation is enhanced in an AA-dependent manner during the suckling period. To examine our hypothesis, we employed wild-type (WT) mice, which synthesize AA, and senescence marker protein-30/gluconolactonase (SMP30/GNL) knockout (KO) mice, which cannot synthesize AA, and analyzed the DNA methylation status in the livers of offspring in both the suckling period and adulthood. SMP30/GNL KO offspring showed DNA hypermethylation in the liver possibly due to low plasma and hepatic AA levels during the suckling period despite the administration of rescue-dose AA to dams. Furthermore, DNA hypermethylation of the fibroblast growth factor 21 gene (Fgf21), a PPARα target gene, persisted into adulthood. In contrast, a high-dose AA administration to SMP30/GNL KO dams during the lactation period restored DNA demethylation in the livers of offspring. Even though a slight increase was observed in plasma AA levels with the administration of rescue-dose AA to WT dams during the gestation and lactation periods, DNA demethylation in the livers of offspring was minimally enhanced. The present results demonstrate that AA intake during the suckling period is required for proper DNA demethylation in the liver. [ABSTRACT FROM AUTHOR]

Hardy kiwifruits (Actinidia arguta) contain various bioactive compounds such as vitamin C and phenolics and can withstand cold temperatures. Changes in soluble solid, vitamin C, total phenolic, and total flavonoid content, and antioxidant capacity of three cultivars of hardy kiwifruits (A. arguta × A. deliciosa cv. Mansu, A. arguta cv. Haeyeon, and A. arguta cv. Chiak) were comparatively evaluated for 8 weeks of storage at 1 ± 0.5 °C. After the 8 weeks of storage, soluble solid content of three cultivars increased, whereas their vitamin C content decreased. Throughout this storage period, total phenolic and flavonoid content of cv. Mansu and cv. Haeyeon remained the same, while antioxidant capacity of these two cultivars also remained similar but with slightly more variations. Cv. Chiak, however, showed a decrease in total phenolic and flavonoid content and antioxidant capacity. These results suggest that cold storage of the hardy kiwifruits maintains levels of bioactive compounds. [ABSTRACT FROM AUTHOR]

Copyright of Gesunde Pflanzen is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Citrus reticulata is one of the most cultivated fruit with great benefits for humans in the world. Citrus reticulata peel has several biological activities within them hypoglycemic, hepatoprotective, antimicrobial and antioxidant. The present study emphasizes on the in vivo wound healing and in vitro antimicrobial and antioxidant activities of Citrus reticulata peel extract. Methods: Forty albino mice (23–29 g) of either sex were divided into four groups. The test groups were treated with experimental ointment (0.5% and 10% of methanolic extract), negative control were treated with Vaseline and the positive control were treated with silver sulfadiazine. Burn wounds were induced on dorsal area of mice bodies. Wound area measurement was carried out every day during 22 days. Biochemical screening was performed to identify possible compounds. Antioxidant and antimicrobial activities were also determined. Results: Significant wound healing activity was observed with topical application of Citrus reticulata peel extract. Wound area reduction at day 16 of treatment was 100% for both treated groups (0.5% and 10%) when compared to positive and negative control it was 100% and 98.32% respectively at day 22. Furthermore higher rate of wound contraction (100% on 16th day) was observed for both treated groups. The result of biochemical screening showed that C. reticulata peel is characterized by highest amount of total polyphenols (13.19 mg/g), flavonoids (4.07 mg/g), vitamin C (13.20 mg/g), carotenoids (0.032 mg/g) and lowest content of macronutrients (Proteins: 0.40%, reducing sugars: 7.21%; lipids: 1.5%). Additionally C. reticulata peel exhibited remarkable antioxidant activity using DPPH and phosphomolybdate methods as well as the extract possess antimicrobial effect against pathogen bactria. Conclusion: The findings from this research indicated that Citrus reticulata peel extract is effective in inhibiting the growth of pathogen bacteria and could be of therapeutic potentials for wound healing. [ABSTRACT FROM AUTHOR]

A simple Co3O4 modified carbon paste electrode (CPE) was developed as an electrochemical sensor for the selective detection and quantification of dopamine (DA) via fastest synthesis and fabrication methods. The solution combustion method and bulk modification techniques were sequentially used for the preparation of the sensor. The modifier was characterized using different techniques such as PXRD, FT-IR, SEM and TG-DSC. The fabricated sensor shows a wide linear dynamic range of 80 µM-300 nM, low detection limit, excellent reproducibility and high stability. The differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques were extensively used for the electrochemical studies. The same electrode was used for detecting DA in the solution of coexisting ascorbic acid (AA) and uric acid (UA). Well resolved peaks and good current sensitivity of this electrochemical sensor extended its utility in determining DA in blood serum at physiological pH. [ABSTRACT FROM AUTHOR]

The abnormal expression of microRNAs (miRNAs) has been reported in many diseases, so it is of great interest to develop simple and accurate methods for the detection and analysis of miRNA expression. We have developed a novel biosensor to detect miRNAs. This method is based on a polymeric double-stranded DNA (dsDNA) copper nanoparticle (CuNP) template that is synthesised by a polymerase. When Cu2+ and ascorbic acid are added to the system, the dsDNA template (which is rich in A-T bases) promotes the formation of CuNPs, resulting in high fluorescence intensity. This system provides sensitive analysis of miRNA expression with a limit of detection down to 17.8 pmol/L, due to significant changes in the fluorescence signal of the system before and after the addition of the target. The linear range between F0-F and concentration of miR-122 is 80.0 pmol/L to 4.50 nmol/L, and the recovery rate in spiked HepG2 cell lysates is 93.33–102.53%. This method expands the applications of fluorescent DNA-CuNPs in the field of biosensor analysis, and can be used to detect and analyse any miRNA marker by changing the target recognition sequence. [ABSTRACT FROM AUTHOR]

The present study suggested three different highly sensitive luminescent systems based on the employment of silver nanoparticles (NPs), copper oxide nanoparticles and gold nanoparticles in the presence of micellar medium sodium dodecyl sulfate (SDS) for the detection of ascorbic acid in some fruit juices. The fluorescence spectral behavior of ascorbic acid was detected at λem of 420 nm after λex at 350 nm in the presence of acetate buffer (pH 3). Under optimized experimental conditions, the suggested spectroflourimetric systems displayed excellent linearity over concentration ranges of 1.0 × 10–9–1.0 × 10–2, 1.0 × 10–7–1.0 × 10–3 and 1.0 × 10–6–1.0 × 10–3 M with lower limits of detection of 1.0 × 10–10, 5 × 10–8 and 5 × 10–7 M for SDS−AgNPs, SDS−CuONPs and SDS−AuNPs systems, respectively. The suggested approaches were successfully used to detect ascorbic acid in its bulk powder and in some commercial fruit juices. [ABSTRACT FROM AUTHOR]

In this work, UV/Vis spectroelectrochemistry (SEC), in a thin-layer regime and parallel configuration, is selected to solve a complex mixture that contains dopamine (DA), ascorbic acid (AA) and uric acid (UA). These molecules, like many other biological compounds, are assuming a highly important place in analytical and biomedical fields due to the fundamental role that they play in human metabolism. In addition, low or high levels of these compounds are associated with diseases such as Parkinson's disease. For this reason, the quantification of these biomolecules is becoming increasingly critical. However, some drawbacks must be overcome, because the three molecules coexist in the human body, and the species are subject to mutual interference. In fact, they are all oxidized at similar potentials, and their UV/Vis absorption bands overlap, greatly complicating their quantification. For this reason, derivative SEC together with suitable chemometric tools such as PARAFAC are proposed to solve this complex matrix. This technique allows us to separate the contribution of each of these molecules present in a sample and to quantify all of them, achieving high resolution and reproducibility. Besides, detection limits at the micromolar level are achieved for DA, AA and UA in mixture solutions. This work thus demonstrates the great potential for derivative potentiodynamic SEC combined with the appropriate chemometric tools in solving complex mixtures, a field where SEC is still taking the first steps. [ABSTRACT FROM AUTHOR]

An amperometric l-ascorbic acid biosensor utilizing ascorbate oxidase (AOx) immobilized onto poly(l-aspartic acid) (P(l-Asp)) film was fabricated on carbon nanofiber (CNF) and nanodiamond particle (ND)-modified glassy carbon electrode (GCE). Effects of AOx, ND, and CNF amounts were investigated by monitoring the response currents of the biosensor at different amounts of AOx, ND, and CNF. The electropolymerization step of l-aspartic acid on CNF-ND/GCE surface was also optimized. Scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques were used to enlighten the modification steps of the biosensor. The effects of pH and applied potential were studied in detail to achieve the best analytical performance. Under optimized experimental conditions, the AOx/P(L-Asp)/ND-CNF/GCE biosensor showed a linear response to l-ascorbic acid in the range of 2.0 × 10−7–1.8 × 10−3 M with a detection limit of 1.0 × 10−7 M and sensitivity of 105.0 μAmM−1 cm−2. The novel biosensing platform showed good reproducibility and selectivity. The strong interaction between AOx and the P(l-Asp)/ND-CNF matrix was revealed by the high repeatability (3.4%) and good operational stability. The AOx/P(l-Asp)/ND-CNF/GCE biosensor was successfully applied to the determination of l-ascorbic acid in vitamin C effervescent tablet and pharmaceutical powder containing ascorbic acid with good results, which makes it a promising approach for quantification of l-ascorbic acid. [ABSTRACT FROM AUTHOR]

Copyright of Gesunde Pflanzen is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Antioxidants have protective capacity, and can be used combinedly with other substances. Both, ascorbic acid (AA) and phytol (PHY) have many important biological activities, including antioxidant, anti-inflammatory, and organ protective activity. Recently, PHY has been found to exert an anti-pyretic effect in a mouse model. This study aims to evaluate the combined effects of AA and/or PHY with paracetamol (PARA) in Brewer's yeast-induced fever mice model. Methods: AA (125 mg/kg) and/or PHY (200 mg/kg) were orally co-treated with the PARA (100 mg/kg, p.o.) in Brewer's yeast-induced fever Swiss mice. Data were analyzed by using GraphPadPrism software (version: 6.0), considering p < 0.05 at 95% confidence interval, and using one-way analysis of variance (ANOVA) through time, followed by Dunnett's post hoc multiple comparison test. Results: PARA alone and with PHY and/or AA significantly (p < 0.05) reduced rectal temperature at 1st h of observation. PHY reduced rectal temperature at 2nd h, then maintained basal temperature over the observation period (4 h). AA showed an insignificant anti-pyretic effect in experimental animals. However, in combination groups, AA (i.e., with PHY or PARA) did not found to interfere the PHY and PARA mediated reduction of rectal temperature in the animals. Furthermore, AA when co-treated with the PARA + PHY, it caused a slight hypothermic temperature at 1st h, which was then started to restablish from 2nd to 3rd h, and normalized at 4th h. Conclusion: Taken together, AA did not interfere anti-pyretic effects of PARA and PHY, suggesting its possible use as a combination substance. [ABSTRACT FROM AUTHOR]

A flexible ascorbic acid (AA)-imprinted poly(o-phenylenediamine) (ploy(o-PD))/zeolite imidazole frameworks-67 (ZIF-67)/carbon cloth (CC) electrode was prepared for electrochemical sensing AA. The flexible AA-imprinted poly(o-PD)/ZIF-67/CC electrode was prepared by growing ZIF-67 on flexible CC, electropolymerization of o-PD with AA on ZIF-67/CC and eluting template molecules AA. The results showed that the spherical ZIF-67 crystals were arranged evenly and firmly on the fibers of CC surface. The diameter of spherical ZIF-67 crystals was approximately 500–600 nm, and the spherical ZIF-67 crystals catalyzed the oxidation of AA well. A layer of poly(o-PD) with AA-imprinted pores was covered on the ZIF-67/CC electrode, so the AA-imprinted poly(o-PD)/ZIF-67/CC electrode exhibited better selectivity toward AA detection and good stability. The molecularly imprinted sensor exhibits high sensitivity, and the sensitivity could reach 959.9 μA/mM−1 cm−2, the detection limit was 0.019 μM, and the concentration range of AA was 0.057 μM–11.4 0 mM. The AA-imprinted poly(o-PD)/ZIF-67/CC electrode also showed higher stability and repeatability. The results proved that the spherical ZIF-67 crystals were good electrode materials for electrochemical AA biosensors. [ABSTRACT FROM AUTHOR]

We proposed a method for the selective and highly sensitive amperometric determination of dopamine and adrenaline in the presence of ascorbic and uric acids in a flow-injection system. Screen-printed electrodes modified with palladium nanoparticles, exhibiting catalytic activity in the electrooxidation of catecholamines, were used as a detector. The difference between the oxidation peak potentials of these compounds is 200 mV. A linear bilogarithmic dependence of the analytical signal on the concentration of dopamine and adrenaline is observed in the ranges from 5 × 10–12 to 5 × 10–8 M and from 1 × 10–9 to 1 × 10–5 M, respectively. For simultaneous two-component analysis, screen-printed electrodes with two working electrodes were used, that is, dual screen-printed electrodes modified with palladium nanoparticles, which enable two substances to be determined simultaneously at two different potentials. The proposed method for the joint flow-injection amperometric determination of dopamine and adrenaline using a modified dual screen-printed electrode was tested in the analysis of urine. [ABSTRACT FROM AUTHOR]

Au/CuO nanoparticles with a size range of 20–40 nm directly synthesized by solution plasma method in water have been successfully applied to the non-enzyme detection of glucose. The electrocatalytic activities of Au/CuO nanoparticles toward glucose were evaluated in an alkaline solution by cyclic voltammetry and real-time current method. Research results demonstrate that the biosensor modified by Au/CuO catalysts has a fast reaction time (< 3 s) and low detection limit (0.22 µM). There are two specific linear ranges of 0.22 µM–1 mM and 3 mM–18 mM, with the sensitivities of 172.45 µA mM−1 cm−2 and 63.66 µA mM−1 cm−2, respectively. Moreover, it also exhibited remarkable current response, good stability (87% after 50 days), superior reproducibility, and excellent selectivity in interfering species (such as D-fructose, ascorbic acid and uric acid). Therefore, the Au/CuO nanoparticles directly synthesized by solution plasma method can be implemented to the enzyme-free detection of glucose. [ABSTRACT FROM AUTHOR]

A liquid chromatography−mass spectrometry method was developed for the simultaneous quantitation of (2R,3R)-Dihydromyricetin and Myricetin in rat plasma samples to facilitate analysis of samples collected after administration of SenDeng-4 medicine. The plasma was subjected to protein precipitation with HCl (containing 10% ascorbic acid) and analyzed using electrospray ionization mass spectrometry in selected ion monitoring mode with Paeoniflorin as an internal standard. Good linearity for the two compounds was observed. The intra- and inter-day precision of analysis was <10% for each compound. The present method was suitable for determining (2R,3R)-Dihydromyricetin and Myricetin in rat plasma after intravenous administration of SenDeng-4 to rats with sufficient sensitivity. [ABSTRACT FROM AUTHOR]