Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic...Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic variation for shelf life in MAP,but their variation for nutrient retention is not known.Fifty accessions were evaluated for initial content of ascorbic acid (AsA),carotenoids,and sugars and their retention in storage.Accessions with high content and/or good retention of one or more nutrients were identified.The romaine accession ‘Floricos’ had high levels of all the three nutrients.Accessions with relatively high retention of all the three nutrients were ‘Salinas 88’,‘Siskiyou’,‘Solar’,SM09A,‘Romance’,and ‘Green Towers’.Romaine cultivars,‘Balady Barrage’,‘Green Towers’,and ‘Darkland’ had relatively high initial levels of all tested nutrients and good rate of their retention.There was no clear correlation between initial AsA/carotene concentrations and their retention rates,suggesting that besides content,retention of nutrients should also be a breeding target in a lettuce nutritional improvement program.Statistical analyses with the Pearson's correlation coefficient determined a negative relationship between tissue deterioration(AUDePS) and retention of all tested nutrients[r of-0.52 (P<0.0001) for AsA,-0.27 (P<0.01) for total carotene,and-0.59 (P<0.0001) for total sugars],suggesting that an increase in tissue deterioration intensifies nutrient decay.Broad-sense heritability (H^(2)) across the experiments was0.15 for AsA,0.23 for total carotene,and 0.50 for total sugars.Identification of germplasm with high nutrient content,extended shelf life and good nutrient retention provides valuable information for the lettuce industry and associated breeding programs.展开更多
Compared with natural enzymes, nanozymes have the advantages of high stability and low cost;however,selectivity and sensitivity are key issues that prevent their further development. In this study, we report a cascade...Compared with natural enzymes, nanozymes have the advantages of high stability and low cost;however,selectivity and sensitivity are key issues that prevent their further development. In this study, we report a cascade nanozymatic system with significantly improved selectivity and sensitivity that combines more substrate-specific reactions and sensitive fiuorescence detection. Taking detection of ascorbic acid(AA)as an example, a cascade catalytic reaction system consisting of oxidase-like N-doped carbon nanocages(NC) and peroxidase-like copper oxide(Cu O) improved the reaction selectivity in transforming the substrate into the target product by more than 1200 times against the interference of uric acid. The cascade catalytic reaction system was also applicable for transfer from open reactors into a spatially confined microfiuidic device, increasing the slope of the calibration curves by approximately 1000-fold with a linear detection range of 2.5 nmol/L to 100 nmol/L and a low limit of detection of 0.77 nmol/L. This work offers a new strategy that achieves significant improvements in selectivity and sensitivity.展开更多
Objective:To investigate the potential of ascorbic acid in mitigating reproductive toxicity induced by di-(2-ethyl hexyl)phthalate(DEHP)in female Wistar rats,focusing on oxidative stress,hormone levels,and gonadotropi...Objective:To investigate the potential of ascorbic acid in mitigating reproductive toxicity induced by di-(2-ethyl hexyl)phthalate(DEHP)in female Wistar rats,focusing on oxidative stress,hormone levels,and gonadotropin receptors expression.Methods:Forty female Wistar rats[30 days old,weighing(60±10)g]were randomly divided into five groups(n=8 per group).Group 1 received corn oil(control).Groups 2 and 3 were administered DEHP at 10 and 100 mg/kg body weight(b.wt.),respectively.Groups 4 and 5 received DEHP at 10 and 100 mg/kg b.wt.,respectively,plus ascorbic acid 100 mg/kg b.wt..All treatments were given orally for 30 days.Blood and ovarian tissues were collected to assess serum reproductive hormones,gonadotropin receptor gene expression,oxidative stress markers,and apoptosis.Results:DEHP,particularly at the higher dose,significantly decreased hormone levels(follicle-stimulating hormone,luteinizing hormone,estradiol)and gonadotropin receptor gene expression(FSHR,LHR),while increasing oxidative stress and apoptosis.Co-treatment with ascorbic acid significantly improved these parameters,reducing oxidative stress and apoptosis,and restoring hormone levels and gonadotropin receptor expression.Histopathology revealed fewer atretic follicles and less disruption in ovarian structure in DEHP and ascorbic acid-treated groups compared to those treated with DEHP alone.Conclusions:Ascorbic acid demonstrates protective effects against DEHP-induced reproductive toxicity in female rats,likely through mitigating oxidative stress and normalizing hormone levels and ovarian function.展开更多
A novel multiwall carbon nanotube-chitosan modified electrode has been prepared.The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbicacid into two well-defined peak by 212 mV. ...A novel multiwall carbon nanotube-chitosan modified electrode has been prepared.The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbicacid into two well-defined peak by 212 mV. The mechanism of discrimination of dopamine fromascorbic acid is discussed. Dopamine can be determined selectively with the carbonnanotube-chitosan modified electrode. The electrode shows good sensitivity, selectivity andstability.展开更多
BACKGROUND The current case report describes successful phacoemulsification with the aid of perioperative topical ascorbic acid(AA) in two patients with corneal endothelial disorders to prevent postoperative corneal e...BACKGROUND The current case report describes successful phacoemulsification with the aid of perioperative topical ascorbic acid(AA) in two patients with corneal endothelial disorders to prevent postoperative corneal endothelial decompensation.CASE SUMMARY Two eyes of two patients underwent phacoemulsification with pre-existing corneal endothelial disorders including Fuchs corneal endothelial dystrophy(Patient 1) and endotheliitis(Patient 2). Topical AA was applied to both patients at least one month before and after with a frequency of four times per day. After the surgery, both eyes improved best-corrected visual acuity(BCVA) and there was limited human corneal endothelial cell loss without signs of corneal endothelial decompensation, such as deteriorated BCVA or persistent corneal edema during the follow-up of at least two years.CONCLUSION Perioperative administration of topical AA may be an alternative therapy to the triple procedure in patients expecting to undergo cataract surgery.展开更多
Hydroponically-grown produce may be a way of helping to feed the world a variety of fruits and vegetables, regardless of soil quality, space availability or climate. The objective of this study was to determine whethe...Hydroponically-grown produce may be a way of helping to feed the world a variety of fruits and vegetables, regardless of soil quality, space availability or climate. The objective of this study was to determine whether hydroponicallygrown lettuce contains as much ascorbic acid and tocopherol as soil-grown lettuce. We analyzed four varieties of lettuce, including: Waldmann’s Dark Green, Red Lollo Antago, Red Romaine Annapolis, and Butterleaf. The tocopherol content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 229%, 497% and 492% higher, respectively, compared to their soil-grown counterpart. The ascorbic acid content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 93%, 171% and 216% higher, respectively, compared to their soil-grown counterparts. Hydroponically grown lettuce varieties are significantly higher in both ascorbic acid and tocopherol content than their soil-grown counterparts, and hydroponic gardening is a viable option for producing nutritious fruits and vegetables.展开更多
The aim of this study was to investigate the effect of storage conditions on the sensory quality, colour and texture of fresh-cut cabbage during the addition of ascorbic acid, citric acid and calcium chloride. Ascorbi...The aim of this study was to investigate the effect of storage conditions on the sensory quality, colour and texture of fresh-cut cabbage during the addition of ascorbic acid, citric acid and calcium chloride. Ascorbic acid maintained the overall quality for 14 days at 0℃ and 7 days at 5℃;no difference, however, was observed regarding browning of cut surface compared to the control sample at both storage temperatures. Calcium chloride maintained the overall quality and cut surface browning for 14 days at both storage temperatures. It was also found that citric acid 1% can be used for minimally processed cabbage. Soaking with citric acid helped retain the color and increased the overall acceptance and organoleptic quality of fresh cut cabbage;it reduced browning of the cut surface and protected against formation of black specks. Citric acid treatment combined with low temperature storage (0℃) prolonged the shelf life of minimally processed cabbage for 22 days, time sufficient for acceptable marketing of the product. The lightness of minimally processed cabbage decreased linearly from 70.94 ± 6 to 63.8 ± 8.5 - 61.3 ± 8 units for the chemical treatments during 22 days of storage at 0℃. Hue angle values during storage time were also significantly influenced by chemical treatments mainly at 0℃.展开更多
In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrod...In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrode. Using this technique, the catalytic ability of cobalt hexacyanoferrate(CoHCF) microcrystalline toward AA oxidation was also studied. It was found that the dispersed CoHCF powder in the PEG paste can generate well shaped thin layer cyclic voltammetric waves with the peak height proportional to the scan rate, corresponding to the Fe centered redox reactions. This oxidation step catalyzed the AA oxidation. Also, this pasted CoHCF powder generated well resolved in situ MFTIRs spectra, by which a chemical interaction between CC bond of AA ring and CoHCF lattice was revealed. A corresponding surface docking mechanism for the catalytic reaction has been proposed.展开更多
The synergetic cytocidal effect of ascorbic acid and mitomycin C on Ehrlich as-cites tumor cells in culture was studied. The chain scission of DNA by Cu(Ⅱ)mitomycin C/ascorbic acid system,and the chemical kinetics of...The synergetic cytocidal effect of ascorbic acid and mitomycin C on Ehrlich as-cites tumor cells in culture was studied. The chain scission of DNA by Cu(Ⅱ)mitomycin C/ascorbic acid system,and the chemical kinetics of the Cu(Ⅱ) catalyzed aerobic oxidation of ascorbic acid in the presence of mitomycin C were also discussed. Experimental results showed that ascorbic acid and mitomycin C were synergetic in destroying Ehrlich ascites tumor cells.The effect is related to the breaking action of the Cu(Ⅱ)mitomycin C/ascorbic acid system on the DNA chain, and to the quantity of the system produced ·OH, and the speed of production which are both directly proportional to the concentration of ascorbic aci.These results imply that the ·OH produced in the aerobic oxidation of ascorbic acid,and·OH induced scission of DNA chain, are important factors to he synergetic cytocidal effect of ascorbic acid and mitomycin C on Ehrlich ascites tumor cells.展开更多
In this work,molybdenum disulfide quantum dots（MoS2 QDs） were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors,and applied in ascorbic acid detection.When joining MnO2 nan...In this work,molybdenum disulfide quantum dots（MoS2 QDs） were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors,and applied in ascorbic acid detection.When joining MnO2 nanosheets into MoS2 QDs solution,they produced an obvious fluorescence quenching,which should be due to inner filter effect（IFE）.Meanwhile,the fluorescent probe was formed,Interestingly,we found that this quenching phenomenon disappeared with the addition of ascorbic acid,In other words,the fluorescence gradually restored.This recovery phenomenon is mainly due to the reduction effect of ascorbic acid for MnO2 nanosheets.Under the optimum conditions,the limit of detection（LOD） of 39 nmol/L for ascorbic acid was achieved with a linear range of 0.33-5.00 μmol/L.The repeatability was better than 5.0% for ascorbic acid in both standard and fruit samples（n = 3）.Moreover,the as-fabricated fluorescent sensing system was successfully employed to detect the ascorbic acid levels in hawthorn and jujube with satisfactory results.展开更多
The exploitation of multifunctional nanocomposites is highly desired in environmental monitoring,biosensors,and medical diagnosis.In this paper,a simple approach has been proposed to fabricate MoS2 decorated N-doped c...The exploitation of multifunctional nanocomposites is highly desired in environmental monitoring,biosensors,and medical diagnosis.In this paper,a simple approach has been proposed to fabricate MoS2 decorated N-doped carbon nanotubes(NCNTs@MoS2)hybrid composites as efficient peroxidase-like mimics.The combination of the MoS2 and N-doped carbon nanotubes(NCNTs)brings about an enhanced synergistic effect,leading to remarkably decent intrinsic peroxidase-mimic activities than that of the single components.Due to the high catalytic efficiency of the resultant NCNTs@MoS2 hybrid nanotubes as peroxidase-like mimics,a co nvenient colorimetric approach for the sensitive determination of H2 O2 and ascorbic acid have been developed with a detection limit of about 0.14μmol/L and 0.12μmol/L,respectively.The work offers a new strategy for the fabrication of peroxidase-like nanomaterials with excellent catalytic activity,which indicates great promising applications in sensitive detections in real samples.展开更多
To counteract the effects of drought stress,scientists have adopted several approaches including the use of different chemicals both inorganic and organic,which is contemplated as a highly efficient and cost-effective...To counteract the effects of drought stress,scientists have adopted several approaches including the use of different chemicals both inorganic and organic,which is contemplated as a highly efficient and cost-effective shot-gun approach.Ascorbic acid(AsA)is a potential organic substance,which widely occurs in plants,and is considered to be an effective antioxidant to counteract reactive oxygen species(ROS).Thus,a pot experiment was performed to assess the relative mitigating impacts of synthetic AsA and naturally occurring AsA in the form of lemon juice(LJ)and orange juice(OJ)on two cultivars of okra(Abelmoschus esculentus L.)namely Sabz Pari and Bhindi Sanwali under varying water deficit conditions.After 30 days of seed germination,okra seedlings were subjected to different irrigation regimes,i.e.,water deficit stress[(65%and 50%F.C.)and control conditions(100%F.C.)].Different levels of AsA[control(no spray),14 mg L^(−1)LJ,24 mg L^(−1)OJ and 150 mg L^(−1)AsA]obtained from different sources were applied as a foliar spray to control and water-stressed plants.Drought stress prominently reduced plant growth and yield attributes of the okra cultivars.Water-deficit conditions(65%and 50%F.C.)substantially decreased the fruit chlorophyll(a,b)pigments and the activity of superoxide dismutase(SOD)enzyme,while an increase was observed in the contents of fruit’s hydrogen peroxide(H_(2)O_(2)),malondialdehyde(MDA),total phenolics,total soluble sugars,AsA,and total soluble proteins.Drought stress also increased the activities of antioxidant enzymes like peroxidase(POD)and catalase(CAT).However,plant growth and yield attributes,fruit chlorophyll pigments,total phenolics,total soluble sugars,total free amino acids,total soluble proteins,AsA,GB,H_(2)O_(2),and the activities of antioxidant enzymes(POD and CAT)were increased by the AsA exogenous treatment in both okra cultivars under water deficit and control conditions.Overall,LJ and OJ were more effective than the synthetic AsA in upregulating the physiological and metabolic processes of okra plants.So,cost-effective as well as multi-nutrient natural sources of AsA could be suggested for alleviating the harmful effects of water deficit stress on plants.展开更多
Edible zein-based films containing lysozyme(LY) and ascorbic acid(AA) were developed in the presence of polyethylene glycol 400(PEG 400), the combined effects of LY and AA on the microstructure, mechanical properties ...Edible zein-based films containing lysozyme(LY) and ascorbic acid(AA) were developed in the presence of polyethylene glycol 400(PEG 400), the combined effects of LY and AA on the microstructure, mechanical properties and release properties of developed zein films were investigated in detail. The results of microstructure characterization indicated that zein-based films became compact and smooth, and LY aggregates were well distributed in the zein matrix because of the simultaneous addition of LY and AA. The results of mechanical tests showed that because of the synergistic effects of LY and AA on zein film, elongation at break of zein-based film could be up to 138%, which was 34.5 times higher than that of zein control film. LY release tests showed that when the concentration of AA was less than 3.1 mg·cm^(-2), the release rate of LY significantly decreased by 33.7%, and the total release increased by 80.6%. While the release profiles of AA showed that the release rate and total release of AA from the films containing LY increased by approximately 68.9% and 61.7% than the films without LY. Good antioxidant and sustained antimicrobial activities were found for the developed zein films.展开更多
The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fl...The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fluorescence intensity of SC4Bu quenched regularly upon the addition of AA. A 1:1 stoichiometry for the complexation was established and was verified by Job’s plot. The temperature-dependent inclusion constants were calculated, form which Δ H and ΔS values were calculated. Meanwhile the proposed interaction mechanism of the inclusion complex was discussed based on 1H NMR results. The various factors (ionic strength, and surfactants) effecting the inclusion process were examined in detail.展开更多
Study on NO2 absorption aimed at seeking a better NO2 absorption chemical at pH 4.5-7.0 for application to existing wet flue gas desulfurization （FGD）. The results from the double-stirred reactor indicated that asco...Study on NO2 absorption aimed at seeking a better NO2 absorption chemical at pH 4.5-7.0 for application to existing wet flue gas desulfurization （FGD）. The results from the double-stirred reactor indicated that ascorbic acid has very high absorption rate at this pH range. The rate constant of ascorbic acid reaction with NO2 （0～ 1000× 10^-6 mol/mol） is about 3.54× 10^6 mol/（L.s） at pH 5.4～6.5 at 55 ℃.展开更多
Objective: To determine the effect of ascorbic acid (AA) on DNA synthesis, intracellular accumulation of ADM and ADM resistance of tumor cell lines. Methods: K562, K562/ADM and KB cell lines were used to study the e...Objective: To determine the effect of ascorbic acid (AA) on DNA synthesis, intracellular accumulation of ADM and ADM resistance of tumor cell lines. Methods: K562, K562/ADM and KB cell lines were used to study the effect of ascorbic acid on DNA synthesis, intracellular accumulation of ADM and ADM resistance by fluid scintillometry, MTT method, spectrofluorophotometry and immunocytochemistry. Results: Results showed that AA was capable of inhibiting DNA synthesis of K562 and K562/ADM in a dosedependence fashion, but not KB cell line, and significantly reducing ADM sensitivity in K562 and KB cell lines, as well as potentiating obviously ADM resistance in K562/ADM cell line. Conclusion: These effects of AA may be closely correlated with significant elevation of intracellular accumulation of ADM in KB cell line, and significant reduction of that in K562 and K562/ADM cell lines but possibly not correlated with the expression of Pglycoprotein.展开更多
Dimethoate,an organophosphorus insecticidewas found to be mutagenic in various testsystems.Ascorbic acid showed antimutageniceffects in micro organisms,mouse,etc.Inthe present study the antimutagenic effectof ascorbic...Dimethoate,an organophosphorus insecticidewas found to be mutagenic in various testsystems.Ascorbic acid showed antimutageniceffects in micro organisms,mouse,etc.Inthe present study the antimutagenic effectof ascorbic acid was tested for dimethoateinduced cytogenetic damage in展开更多
In this study, the effect of ascorbic acid 2-phosphate (Asc2P) was tested on porcine and rat mature hepatocytes in vitro. a). Asc2P increased the porcine, but not rat, albumin secretion and mRNA expression. The enhanc...In this study, the effect of ascorbic acid 2-phosphate (Asc2P) was tested on porcine and rat mature hepatocytes in vitro. a). Asc2P increased the porcine, but not rat, albumin secretion and mRNA expression. The enhancing effect of Asc2P on porcine C/EBP alpha mRNA was observed in porcine mature hepatocytes. These data suggested that Asc2P played an important role in the regulation of porcine albumin mRNA level. b). The enhancing effect of Asc2P on ammonium metabolic activity was also observed in porcine, but not rat, mature hepatocytes. The porcine ornithine transcarbamylase (OTC) and arginase mRNAs were augmented by Asc2P, indicating that Asc2P had a direct effect on the urea cycle. c). The porcine collagen type I and type III mRNA, but not type XII mRNA, were detected as well, sugessting that Asc2P did not have the effect on the non-parenchymal hepatocytes to induce collagen type I and III mRNA expression. d). Our RT-PCR analysis demonstrated that the porcine hepatocytes expressed the sodium-ascorbate co-transporters SVCT1 and SVCT2, however, the intensities of porcine sodium-ascorbate co-transporters SVCT1 and SVCT2 bands were not changed markedly. These findings indicated that the Asc2P had no effect on SVCT1 and SVCT2 mRNA expression. e). The enhancing effect of Asc2P on porcine albumin mRNA was inhibited by staurosporine, a portein kinase inhibitor. We conclude that the enhanced albumin mRNA by Asc2P might be due to activation of tyrosine protein kinase and/or PKC and the Asc2P enhanced porcine albumin mRNA mainly at the transcriptional step.展开更多
A sensitive and selective method for the determination of ascorbic acid（AA） using [Cu（phen）2]2＋/multiwalled carbon nanotubes modified glassy carbon electrode was developed. Electrochemical behavior and surface ch...A sensitive and selective method for the determination of ascorbic acid（AA） using [Cu（phen）2]2＋/multiwalled carbon nanotubes modified glassy carbon electrode was developed. Electrochemical behavior and surface characteristics of the modified electrode were studied using scanning electrode microscopy（SEM）, electrochemical impedance spectroscopy（EIS） and cyclic voltammetry（CV）. The experimental results showed that the modified electrode enhanced the electrochemical response of AA and exhibited good analytical performance for AA determination from 10 to 1 042 ？mol/L with a low detection limit of 9.67μmol/L（S/N=3）. The modified electrode was also applied to the determination of AA in the Vitamin tablets and showed good recovery.展开更多
基金supported by the Specialty Crop Block Grant Program of the U.S. Department of Agriculture's (USDA), Agricultural Marketing Service (AMS) through the California Department of Food and Agriculture (SCB15015)partly also by funding from the California Leafy Greens Research Board and by Oak Ridge Institute for Science and Education (ORISE) Research Participation Program。
文摘Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic variation for shelf life in MAP,but their variation for nutrient retention is not known.Fifty accessions were evaluated for initial content of ascorbic acid (AsA),carotenoids,and sugars and their retention in storage.Accessions with high content and/or good retention of one or more nutrients were identified.The romaine accession ‘Floricos’ had high levels of all the three nutrients.Accessions with relatively high retention of all the three nutrients were ‘Salinas 88’,‘Siskiyou’,‘Solar’,SM09A,‘Romance’,and ‘Green Towers’.Romaine cultivars,‘Balady Barrage’,‘Green Towers’,and ‘Darkland’ had relatively high initial levels of all tested nutrients and good rate of their retention.There was no clear correlation between initial AsA/carotene concentrations and their retention rates,suggesting that besides content,retention of nutrients should also be a breeding target in a lettuce nutritional improvement program.Statistical analyses with the Pearson's correlation coefficient determined a negative relationship between tissue deterioration(AUDePS) and retention of all tested nutrients[r of-0.52 (P<0.0001) for AsA,-0.27 (P<0.01) for total carotene,and-0.59 (P<0.0001) for total sugars],suggesting that an increase in tissue deterioration intensifies nutrient decay.Broad-sense heritability (H^(2)) across the experiments was0.15 for AsA,0.23 for total carotene,and 0.50 for total sugars.Identification of germplasm with high nutrient content,extended shelf life and good nutrient retention provides valuable information for the lettuce industry and associated breeding programs.
基金supported by the National Natural Science Foundation of China (Nos. 22174014 and 22074015)。
文摘Compared with natural enzymes, nanozymes have the advantages of high stability and low cost;however,selectivity and sensitivity are key issues that prevent their further development. In this study, we report a cascade nanozymatic system with significantly improved selectivity and sensitivity that combines more substrate-specific reactions and sensitive fiuorescence detection. Taking detection of ascorbic acid(AA)as an example, a cascade catalytic reaction system consisting of oxidase-like N-doped carbon nanocages(NC) and peroxidase-like copper oxide(Cu O) improved the reaction selectivity in transforming the substrate into the target product by more than 1200 times against the interference of uric acid. The cascade catalytic reaction system was also applicable for transfer from open reactors into a spatially confined microfiuidic device, increasing the slope of the calibration curves by approximately 1000-fold with a linear detection range of 2.5 nmol/L to 100 nmol/L and a low limit of detection of 0.77 nmol/L. This work offers a new strategy that achieves significant improvements in selectivity and sensitivity.
文摘Objective:To investigate the potential of ascorbic acid in mitigating reproductive toxicity induced by di-(2-ethyl hexyl)phthalate(DEHP)in female Wistar rats,focusing on oxidative stress,hormone levels,and gonadotropin receptors expression.Methods:Forty female Wistar rats[30 days old,weighing(60±10)g]were randomly divided into five groups(n=8 per group).Group 1 received corn oil(control).Groups 2 and 3 were administered DEHP at 10 and 100 mg/kg body weight(b.wt.),respectively.Groups 4 and 5 received DEHP at 10 and 100 mg/kg b.wt.,respectively,plus ascorbic acid 100 mg/kg b.wt..All treatments were given orally for 30 days.Blood and ovarian tissues were collected to assess serum reproductive hormones,gonadotropin receptor gene expression,oxidative stress markers,and apoptosis.Results:DEHP,particularly at the higher dose,significantly decreased hormone levels(follicle-stimulating hormone,luteinizing hormone,estradiol)and gonadotropin receptor gene expression(FSHR,LHR),while increasing oxidative stress and apoptosis.Co-treatment with ascorbic acid significantly improved these parameters,reducing oxidative stress and apoptosis,and restoring hormone levels and gonadotropin receptor expression.Histopathology revealed fewer atretic follicles and less disruption in ovarian structure in DEHP and ascorbic acid-treated groups compared to those treated with DEHP alone.Conclusions:Ascorbic acid demonstrates protective effects against DEHP-induced reproductive toxicity in female rats,likely through mitigating oxidative stress and normalizing hormone levels and ovarian function.
文摘A novel multiwall carbon nanotube-chitosan modified electrode has been prepared.The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbicacid into two well-defined peak by 212 mV. The mechanism of discrimination of dopamine fromascorbic acid is discussed. Dopamine can be determined selectively with the carbonnanotube-chitosan modified electrode. The electrode shows good sensitivity, selectivity andstability.
基金Supported by the Chang Gung Memorial Hospital,No.CMRPG3F1471~2 and No.CMRPG3G0031~3the Ministry of Science and Technology No.MOST106-2314-B-182A-042-34 and No.MOST 107-2314-B-182A-088-MY3
文摘BACKGROUND The current case report describes successful phacoemulsification with the aid of perioperative topical ascorbic acid(AA) in two patients with corneal endothelial disorders to prevent postoperative corneal endothelial decompensation.CASE SUMMARY Two eyes of two patients underwent phacoemulsification with pre-existing corneal endothelial disorders including Fuchs corneal endothelial dystrophy(Patient 1) and endotheliitis(Patient 2). Topical AA was applied to both patients at least one month before and after with a frequency of four times per day. After the surgery, both eyes improved best-corrected visual acuity(BCVA) and there was limited human corneal endothelial cell loss without signs of corneal endothelial decompensation, such as deteriorated BCVA or persistent corneal edema during the follow-up of at least two years.CONCLUSION Perioperative administration of topical AA may be an alternative therapy to the triple procedure in patients expecting to undergo cataract surgery.
文摘Hydroponically-grown produce may be a way of helping to feed the world a variety of fruits and vegetables, regardless of soil quality, space availability or climate. The objective of this study was to determine whether hydroponicallygrown lettuce contains as much ascorbic acid and tocopherol as soil-grown lettuce. We analyzed four varieties of lettuce, including: Waldmann’s Dark Green, Red Lollo Antago, Red Romaine Annapolis, and Butterleaf. The tocopherol content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 229%, 497% and 492% higher, respectively, compared to their soil-grown counterpart. The ascorbic acid content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 93%, 171% and 216% higher, respectively, compared to their soil-grown counterparts. Hydroponically grown lettuce varieties are significantly higher in both ascorbic acid and tocopherol content than their soil-grown counterparts, and hydroponic gardening is a viable option for producing nutritious fruits and vegetables.
文摘The aim of this study was to investigate the effect of storage conditions on the sensory quality, colour and texture of fresh-cut cabbage during the addition of ascorbic acid, citric acid and calcium chloride. Ascorbic acid maintained the overall quality for 14 days at 0℃ and 7 days at 5℃;no difference, however, was observed regarding browning of cut surface compared to the control sample at both storage temperatures. Calcium chloride maintained the overall quality and cut surface browning for 14 days at both storage temperatures. It was also found that citric acid 1% can be used for minimally processed cabbage. Soaking with citric acid helped retain the color and increased the overall acceptance and organoleptic quality of fresh cut cabbage;it reduced browning of the cut surface and protected against formation of black specks. Citric acid treatment combined with low temperature storage (0℃) prolonged the shelf life of minimally processed cabbage for 22 days, time sufficient for acceptable marketing of the product. The lightness of minimally processed cabbage decreased linearly from 70.94 ± 6 to 63.8 ± 8.5 - 61.3 ± 8 units for the chemical treatments during 22 days of storage at 0℃. Hue angle values during storage time were also significantly influenced by chemical treatments mainly at 0℃.
文摘In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrode. Using this technique, the catalytic ability of cobalt hexacyanoferrate(CoHCF) microcrystalline toward AA oxidation was also studied. It was found that the dispersed CoHCF powder in the PEG paste can generate well shaped thin layer cyclic voltammetric waves with the peak height proportional to the scan rate, corresponding to the Fe centered redox reactions. This oxidation step catalyzed the AA oxidation. Also, this pasted CoHCF powder generated well resolved in situ MFTIRs spectra, by which a chemical interaction between CC bond of AA ring and CoHCF lattice was revealed. A corresponding surface docking mechanism for the catalytic reaction has been proposed.
文摘The synergetic cytocidal effect of ascorbic acid and mitomycin C on Ehrlich as-cites tumor cells in culture was studied. The chain scission of DNA by Cu(Ⅱ)mitomycin C/ascorbic acid system,and the chemical kinetics of the Cu(Ⅱ) catalyzed aerobic oxidation of ascorbic acid in the presence of mitomycin C were also discussed. Experimental results showed that ascorbic acid and mitomycin C were synergetic in destroying Ehrlich ascites tumor cells.The effect is related to the breaking action of the Cu(Ⅱ)mitomycin C/ascorbic acid system on the DNA chain, and to the quantity of the system produced ·OH, and the speed of production which are both directly proportional to the concentration of ascorbic aci.These results imply that the ·OH produced in the aerobic oxidation of ascorbic acid,and·OH induced scission of DNA chain, are important factors to he synergetic cytocidal effect of ascorbic acid and mitomycin C on Ehrlich ascites tumor cells.
基金financially supported by National Nature Science Foundation of China (No. 21475053)
文摘In this work,molybdenum disulfide quantum dots（MoS2 QDs） were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors,and applied in ascorbic acid detection.When joining MnO2 nanosheets into MoS2 QDs solution,they produced an obvious fluorescence quenching,which should be due to inner filter effect（IFE）.Meanwhile,the fluorescent probe was formed,Interestingly,we found that this quenching phenomenon disappeared with the addition of ascorbic acid,In other words,the fluorescence gradually restored.This recovery phenomenon is mainly due to the reduction effect of ascorbic acid for MnO2 nanosheets.Under the optimum conditions,the limit of detection（LOD） of 39 nmol/L for ascorbic acid was achieved with a linear range of 0.33-5.00 μmol/L.The repeatability was better than 5.0% for ascorbic acid in both standard and fruit samples（n = 3）.Moreover,the as-fabricated fluorescent sensing system was successfully employed to detect the ascorbic acid levels in hawthorn and jujube with satisfactory results.
基金financial support by the Natural Science Foundation of Shanghai City(No.18ZR1416400)the National Natural Science Foundation of China(No.21305086)Science and Technology Development Fund of Shanghai Municipal Public Security Bureau(No.2018003)。
文摘The exploitation of multifunctional nanocomposites is highly desired in environmental monitoring,biosensors,and medical diagnosis.In this paper,a simple approach has been proposed to fabricate MoS2 decorated N-doped carbon nanotubes(NCNTs@MoS2)hybrid composites as efficient peroxidase-like mimics.The combination of the MoS2 and N-doped carbon nanotubes(NCNTs)brings about an enhanced synergistic effect,leading to remarkably decent intrinsic peroxidase-mimic activities than that of the single components.Due to the high catalytic efficiency of the resultant NCNTs@MoS2 hybrid nanotubes as peroxidase-like mimics,a co nvenient colorimetric approach for the sensitive determination of H2 O2 and ascorbic acid have been developed with a detection limit of about 0.14μmol/L and 0.12μmol/L,respectively.The work offers a new strategy for the fabrication of peroxidase-like nanomaterials with excellent catalytic activity,which indicates great promising applications in sensitive detections in real samples.
文摘To counteract the effects of drought stress,scientists have adopted several approaches including the use of different chemicals both inorganic and organic,which is contemplated as a highly efficient and cost-effective shot-gun approach.Ascorbic acid(AsA)is a potential organic substance,which widely occurs in plants,and is considered to be an effective antioxidant to counteract reactive oxygen species(ROS).Thus,a pot experiment was performed to assess the relative mitigating impacts of synthetic AsA and naturally occurring AsA in the form of lemon juice(LJ)and orange juice(OJ)on two cultivars of okra(Abelmoschus esculentus L.)namely Sabz Pari and Bhindi Sanwali under varying water deficit conditions.After 30 days of seed germination,okra seedlings were subjected to different irrigation regimes,i.e.,water deficit stress[(65%and 50%F.C.)and control conditions(100%F.C.)].Different levels of AsA[control(no spray),14 mg L^(−1)LJ,24 mg L^(−1)OJ and 150 mg L^(−1)AsA]obtained from different sources were applied as a foliar spray to control and water-stressed plants.Drought stress prominently reduced plant growth and yield attributes of the okra cultivars.Water-deficit conditions(65%and 50%F.C.)substantially decreased the fruit chlorophyll(a,b)pigments and the activity of superoxide dismutase(SOD)enzyme,while an increase was observed in the contents of fruit’s hydrogen peroxide(H_(2)O_(2)),malondialdehyde(MDA),total phenolics,total soluble sugars,AsA,and total soluble proteins.Drought stress also increased the activities of antioxidant enzymes like peroxidase(POD)and catalase(CAT).However,plant growth and yield attributes,fruit chlorophyll pigments,total phenolics,total soluble sugars,total free amino acids,total soluble proteins,AsA,GB,H_(2)O_(2),and the activities of antioxidant enzymes(POD and CAT)were increased by the AsA exogenous treatment in both okra cultivars under water deficit and control conditions.Overall,LJ and OJ were more effective than the synthetic AsA in upregulating the physiological and metabolic processes of okra plants.So,cost-effective as well as multi-nutrient natural sources of AsA could be suggested for alleviating the harmful effects of water deficit stress on plants.
基金Supported by the National Natural Science Foundation of China(21476086)Guangdong Natural Science Foundation(2014A030312007)
文摘Edible zein-based films containing lysozyme(LY) and ascorbic acid(AA) were developed in the presence of polyethylene glycol 400(PEG 400), the combined effects of LY and AA on the microstructure, mechanical properties and release properties of developed zein films were investigated in detail. The results of microstructure characterization indicated that zein-based films became compact and smooth, and LY aggregates were well distributed in the zein matrix because of the simultaneous addition of LY and AA. The results of mechanical tests showed that because of the synergistic effects of LY and AA on zein film, elongation at break of zein-based film could be up to 138%, which was 34.5 times higher than that of zein control film. LY release tests showed that when the concentration of AA was less than 3.1 mg·cm^(-2), the release rate of LY significantly decreased by 33.7%, and the total release increased by 80.6%. While the release profiles of AA showed that the release rate and total release of AA from the films containing LY increased by approximately 68.9% and 61.7% than the films without LY. Good antioxidant and sustained antimicrobial activities were found for the developed zein films.
文摘The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fluorescence intensity of SC4Bu quenched regularly upon the addition of AA. A 1:1 stoichiometry for the complexation was established and was verified by Job’s plot. The temperature-dependent inclusion constants were calculated, form which Δ H and ΔS values were calculated. Meanwhile the proposed interaction mechanism of the inclusion complex was discussed based on 1H NMR results. The various factors (ionic strength, and surfactants) effecting the inclusion process were examined in detail.
基金Project supported by the National Natural Science Foundation of China (No. 20176052) and the Scientific Research Foundation for Returned Overseas Chinese Scholars, Ministry of Education, China
文摘Study on NO2 absorption aimed at seeking a better NO2 absorption chemical at pH 4.5-7.0 for application to existing wet flue gas desulfurization （FGD）. The results from the double-stirred reactor indicated that ascorbic acid has very high absorption rate at this pH range. The rate constant of ascorbic acid reaction with NO2 （0～ 1000× 10^-6 mol/mol） is about 3.54× 10^6 mol/（L.s） at pH 5.4～6.5 at 55 ℃.
文摘Objective: To determine the effect of ascorbic acid (AA) on DNA synthesis, intracellular accumulation of ADM and ADM resistance of tumor cell lines. Methods: K562, K562/ADM and KB cell lines were used to study the effect of ascorbic acid on DNA synthesis, intracellular accumulation of ADM and ADM resistance by fluid scintillometry, MTT method, spectrofluorophotometry and immunocytochemistry. Results: Results showed that AA was capable of inhibiting DNA synthesis of K562 and K562/ADM in a dosedependence fashion, but not KB cell line, and significantly reducing ADM sensitivity in K562 and KB cell lines, as well as potentiating obviously ADM resistance in K562/ADM cell line. Conclusion: These effects of AA may be closely correlated with significant elevation of intracellular accumulation of ADM in KB cell line, and significant reduction of that in K562 and K562/ADM cell lines but possibly not correlated with the expression of Pglycoprotein.
文摘Dimethoate,an organophosphorus insecticidewas found to be mutagenic in various testsystems.Ascorbic acid showed antimutageniceffects in micro organisms,mouse,etc.Inthe present study the antimutagenic effectof ascorbic acid was tested for dimethoateinduced cytogenetic damage in
文摘In this study, the effect of ascorbic acid 2-phosphate (Asc2P) was tested on porcine and rat mature hepatocytes in vitro. a). Asc2P increased the porcine, but not rat, albumin secretion and mRNA expression. The enhancing effect of Asc2P on porcine C/EBP alpha mRNA was observed in porcine mature hepatocytes. These data suggested that Asc2P played an important role in the regulation of porcine albumin mRNA level. b). The enhancing effect of Asc2P on ammonium metabolic activity was also observed in porcine, but not rat, mature hepatocytes. The porcine ornithine transcarbamylase (OTC) and arginase mRNAs were augmented by Asc2P, indicating that Asc2P had a direct effect on the urea cycle. c). The porcine collagen type I and type III mRNA, but not type XII mRNA, were detected as well, sugessting that Asc2P did not have the effect on the non-parenchymal hepatocytes to induce collagen type I and III mRNA expression. d). Our RT-PCR analysis demonstrated that the porcine hepatocytes expressed the sodium-ascorbate co-transporters SVCT1 and SVCT2, however, the intensities of porcine sodium-ascorbate co-transporters SVCT1 and SVCT2 bands were not changed markedly. These findings indicated that the Asc2P had no effect on SVCT1 and SVCT2 mRNA expression. e). The enhancing effect of Asc2P on porcine albumin mRNA was inhibited by staurosporine, a portein kinase inhibitor. We conclude that the enhanced albumin mRNA by Asc2P might be due to activation of tyrosine protein kinase and/or PKC and the Asc2P enhanced porcine albumin mRNA mainly at the transcriptional step.
基金Funded by the National Natural Science Foundation of China(No.51273155)the Fundamental Research Funds for the Central Universities(No.2012-Ia-022)
文摘A sensitive and selective method for the determination of ascorbic acid（AA） using [Cu（phen）2]2＋/multiwalled carbon nanotubes modified glassy carbon electrode was developed. Electrochemical behavior and surface characteristics of the modified electrode were studied using scanning electrode microscopy（SEM）, electrochemical impedance spectroscopy（EIS） and cyclic voltammetry（CV）. The experimental results showed that the modified electrode enhanced the electrochemical response of AA and exhibited good analytical performance for AA determination from 10 to 1 042 ？mol/L with a low detection limit of 9.67μmol/L（S/N=3）. The modified electrode was also applied to the determination of AA in the Vitamin tablets and showed good recovery.
