Large Amounts Of Ascorbic Acid Research Articles

Photoelectrochemical immunoassay of carcinoembryonic antigen based on hollow In2O3/In2S3 nanocolumn

AbstractThis work presents a split‐type photoelectrochemical (PEC) immunoassay platform for ultrasensitive determination carcinoembryonic antigen (CEA) using In2O3/In2S3 nanocolumn as the photoactive matrix. Initially, In2O3/In2S3 nanocolumn with high photocurrent response was obtained by vulcanizing metal‐organic framework‐derived hollow In2O3 nanomaterials for surface modification. Subsequently, sandwich immunoreactions were conducted utilizing an alkaline phosphatase‐labeled secondary antibody that served as a signal pointer. A large amount of ascorbic acid was produced by the biocatalytic reaction, which enhanced the anodic photocurrent of the In2O3/In2S3 nanocolumn‐modified electrode. Under optimized conditions, the In2O3/In2S3 nanocolumn‐based PEC immunoassay exhibited a promising photocurrent response to the target CEA in the operational scope of 0.02 ng/mL to 10 ng/mL, with a limit of detection of 8.4 pg/mL. Benefiting from the excellent photoelectrochemical response of In2O3/In2S3 nanocolumn to ascorbic acid and the separated detection operation, the constructed PEC immunosensing platform has the advantages of great precision and strong anti‐jamming capability, and the detection results are comparable to those of commercial ELISA kits. Collectively, this study not only offered an efficacious semiconducting surface modification strategy to enhance photocurrent response activity, but also offered a novel thought for the sensitive measurement of a marker of cancer.

Determination of the content of organic acids in the chemical composition of buckbuckthorn oil, obtained from regional raw materials

The purpose of the work is to determine the content of organic acids in the chemical composition of sea buckthorn oil obtained from regional raw materials and to establish the influence of sea buckthorn oil production technology on the content of biologically active substances. Sea buckthorn is a unique source product for enriching food products with biologically active substances that play a diverse, important role in the vital activity of the body. It has been proven that the content of organic acids and vitamin C is the main variable in the chemical components of sea buckthorn, the phytochemical and nutritional composition of whose berries differs significantly depending on the species, climatic and growing conditions, and the technology of obtaining sea buckthorn oil. This attracts attention from the standpoint of the need to study sea buckthorn, which grows in regional territories. It was established that sea buckthorn oil obtained from the juice contains: organic acids 154.1–167.5 mg%, vitamin C 168-214 mg%. Sea buckthorn oil extracted with refined sunflower oil contains: organic acids 234.5–388.6 mg%, vitamin C 189–243 mg%. The effect of the technology of obtaining sea buckthorn oil from regional raw materials on the content of biologically active substances, such as organic acids, vitamin C, was determined. Based on the results of research, the advantages of oil obtained by the technology of extraction with refined sunflower oil were determined. Such oil contains a larger amount of ascorbic acid and free organic acids. When analyzing the results of research on oil and dry raw materials collected in the Kherson region, it was established that in the case of organic acids, in particular vitamin C, the indicator of quantitative content is affected not only by the production technology, but also by the biological variety of sea buckthorn. It is advisable to intensively continue scientific work on the research of substances that are responsible for the specific biological activity of sea buckthorn oil.

Sugar content, acidity and antioxidant activity in dehydrated blackcurrant

The main reason for spoilage of berry raw materials is the high water content in it. And in order to increase the shelf life of such raw materials and products based on it, various dehydration methods are used. Osmotic dehydration, considered in this article, is one of the best and suitable methods for increasing the shelf life of berry products, as well as increasing the biological value of the product. This method is preferred relative to other methods of dehydration due to the fact that when it is used in raw materials, more vitamins and minerals are preserved, and the color, aroma and taste of berries are also better preserved. Osmotic dehydration is a process due to the presence of semi-permeable membranes, during which the concentration is balanced. Osmosis takes place during the immersion of fruits in concentrated solutions of osmotically active substances. In such a system, two opposite processes occur: water diffuses from the product into the solution, and the dissolved substance diffuses from the solution into the product. This article discusses the features of the process of osmotic dehydration of blackcurrant berries. Blackcurrant is a promising raw material for processing enterprises. The berry contains a large amount of ascorbic acid, anthocyanins and has a high antioxidant activity. Methods were studied for samples of dried blackcurrant berries (by convection), with preliminary osmotic dehydration with various osmotic agents (sucrose, flower honey), using the following methods: ascorbic acid and antioxidant activity were determined titrimetrically using the Folin-Ciocalteu reagent polyphenols, spectrophotometrically anthocyanins.

A novel MYB transcription factor regulates ascorbic acid synthesis and affects cold tolerance.

Dehydroascorbate reductase (DHAR) plays an important role in stress responses, but the transcriptional regulation of DHAR in response to abiotic stress is still poorly understood. In this study, we isolated a novel R2R3-type MYB transcription factor from Pyrus betulaefolia by yeast one-hybrid screening, designated as PbrMYB5. PbrMYB5 was localized in the nucleus and could bind specifically to the promoter of PbrDHAR2. PbrMYB5 was greatly induced by cold and salt but slightly by dehydration. Overexpression of PbrMYB5 in tobacco conferred enhanced tolerance to chilling stresses, whereas down-regulation of PbrMYB5 in P.betulaefolia by virus-induced gene silencing resulted in elevated chilling sensitivity. Transgenic tobacco exhibited higher expression levels of NtDHAR2 and accumulated larger amount of ascorbic acid (AsA) than the wild-type plants. Virus-induced gene silencing of PbrMYB5 in P.betulaefolia down-regulated PbrDHAR2 abundance and decreased AsA level, accompanied by an increased sensitivity to the chilling stress. Taken together, these results demonstrated that PbrMYB5 was an activator of AsA biosynthesis and may play a positive role in chilling tolerance, at least in part, due to the modulation of AsA synthesis by regulating the PbrDHAR2 expression.

Gold nanocages decorated biocompatible amine functionalized graphene as an efficient dopamine sensor platform

Nanocomposite of gold nanocages and chemically modified graphene oxide (GNCs/CMG) was synthesized in N,N-dimethylformamide (DMF) for sensitive detection of dopamine (DA). DA is widely spread in central nervous system which can regulates essential body functions like movement and emotional behaviour. In this regard sensitive and fast detection of DA level in human body is still challenging considering its interference with other biomolecules in biological samples. CMG was synthesized through amine modification of graphene oxide (GO) with DMF at relatively high temperature followed by attachment of GNCs, fabricated using a galvanic replacement between silver nanocubes and HAuCl4 solution in the DMF. X-ray diffraction (XRD) pattern of GNCs/CMG nanocomposite revealed high crystallization of GNCs attached to the graphene nanosheets and microscopic images revealed relatively uniform decoration of GNCs on the surface of CMG. Nanocomposite modified glassy carbon electrode (GNCs/CMG/GCE) was used to investigate the electrochemical behaviour of DA with cyclic voltammetry and amperometry techniques. The linear range for dopamine was between 0.1 and 80μM with a low detection limit of 0.02μM. Furthermore, GNCs/CMG/GCE exhibited satisfying reproducibility, long-term stability and high selectivity for DA detection in large amount of ascorbic acid with good results for determination in human serum samples.

Sensitive and selective dopamine sensor based on novel conjugated polymer decorated with gold nanoparticles

Abstract A novel surface material was fabricated for the first time at a glassy carbon electrode based on electrochemical polymerization of poly(2,4,6-triaminopyrmidine) (PTAP) decorated with gold nanoparticles (AuNPs). A schematic reaction mechanism was proposed to account for the aggregation of the polymer. The electrochemical performance and surface characterization were achieved employing cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), atomic force microspectroscopy (AFM) and energy dispersive system (EDS). Synergistic effects of the composite hybrid of PTAP and AuNPs promote the catalytic efficiency of the developed (AuNPs-PTAP/GCE) sensor for the electrochemical detection of dopamine (DA). The sensor showed an excellent selectivity for DA quantification with a detection limit of 0.017 μM in electrolytic medium composed of large amounts of ascorbic acid (AA) and uric acid (UA). The sensor was also applied for DA detection in real samples with satisfactory coverage.

Cis-regulatory elements involved in species-specific transcriptional regulation of the SVCT1 gene in rat and human hepatoma cells

Ascorbic acid is transported into cells by the sodium-coupled vitamin C transporters (SVCTs). Recently, we obtained evidence of differential regulation of SVCT expression in response to acute oxidative stress in cells from species that differ in their capacity to synthesize vitamin C, with a marked decrease in SVCT1 mRNA and protein levels in rat hepatoma cells that was not observed in human hepatoma cells. To better understand the regulatory aspects involved, we performed a structural and functional analysis of the proximal promoter of the SVCT1 rat gene. We cloned a 1476-bp segment containing the proximal promoter of the rat SVCT1 gene and generated deletion-derived truncated promoters of decreasing sizes and mutant promoters by modification of consensus binding sites for transcription factors by site-directed mutagenesis. We next analyzed their capacity to direct the transcription of a reporter gene after transfection into rat H4IIE and human HepG2 hepatoma cells, in experiments involving the coexpression of transcription factors whose consensus binding sequences are present in the SVCT1 promoter. This analysis revealed the presence of two critical cis-regulatory elements of the transcriptional activity of the rat SVCT1 gene promoter, sites containing consensus sequences for the binding of the transcription factors Bach1 and HNF4 that are not present in equivalent locations in the human SVCT1 gene promoter. Moreover, a consensus site for HNF1 that is crucial for the regulation of the human SVCT1 promoter is present in the SVCT1 rat promoter but has no effect on its transcriptional activity. These findings imply that regulation of vitamin C metabolism in the rat, a species with the capacity to synthesize large amounts of ascorbic acid, may differ from that of humans, a species that must obtain ascorbic acid from the diet through a transport mechanism that depends on proper SVCT1 expression.

Metabolomic pattern of childhood neuroblastoma obtained by 1H‐high‐resolution magic angle spinning (HRMAS) NMR spectroscopy

The aim of this preliminary study is to characterize by ¹H high-resolution magic angle spinning NMR spectroscopy (HRMAS) the metabolic content of intact biopsy samples obtained from 12 patients suffering from neuroblastoma (NB). The biochemical NB profile was first compared to normal adrenal medulla. In a second step, the relationship between the tumor metabolic profile and the patients' clinical data was investigated. A higher level of creatine, glutamine/glutamate, acetate and glycine characterized NB biopsies while healthy adrenal medulla tissue contained adrenaline and a larger amount of ascorbic acid. Adrenaline, which was undetectable in NB spectra, represented the metabolic signature of normal adrenal medulla. NB from patients younger than 12 months contained a higher level of acetate and lysine. Conversely, higher amounts of glutathione, glutamate, myo-inositol, glycine, serine and ascorbic acid were detected in NB samples belonging to younger children. Glutamine/glutamate, aspartate, creatine, glycine were characteristic of stage I-II NB. Acetate and creatine were characteristic of stage IV NB. Finally, a relatively higher amount of aspartate, succinate, and glutathione was detected in patients alive without active disease after a mean follow-up of 7 years whereas a higher concentration of acetate and taurine was characteristic of patients with worse prognosis. Our preliminary results suggest the existence of a complex metabolic reality in NB, probably representative of tumor behavior. However, the real impact of these promising results should be assessed by long-term prospective studies on a larger cohort of patients.

An Electron Spin Resonance Study for Real-time Detection of Ascorbyl Free Radicals After Addition of Dimethyl Sulfoxide in Murine Hippocampus or Plasma During Kainic Acid-Induced Seizures

Electron spin resonance (ESR)-silent ascorbate solutions generate a detectable, likely concentration-dependent signal of ascorbyl free radicals (AFR) immediately upon addition of a molar excess of dimethyl sulfoxide (DMSO). We aimed to perform quantitative ESR analysis of AFR in real time after addition of DMSO (AFR/DMSO) to evaluate ascorbate concentrations in fresh hippocampus or plasma following systemic administration of kainate in mice. Use of a special tissue-type quartz cell allowed immediate detection of AFR/DMSO ESR spectra in fresh tissues from mice. AFR/DMSO content was increased significantly in fresh hippocampus or plasma obtained during kainate-induced seizures of mice, reaching maximum levels at 90 min after intraperitoneal administration of 50 mg/kg kainic acid. This suggests that oxidative injury of the hippocampus resulted from the accumulation of large amounts of ascorbic acid in the brain after kainic acid administration. AFR/DMSO content measured on an ESR spectrometer can be used for real-time evaluation of ascorbate content in fresh tissue. Due to the simplicity, good performance, low cost and real-time monitoring of ascorbate, this method may be applied to clinical research and treatment in the future.

A highly selective and sensitive dopamine and uric acid biosensor fabricated with functionalized ordered mesoporous carbon and hydrophobic ionic liquid

An ordered mesoporous carbon material functionalized with carboxylic acid groups was synthesized. It was characterized by powder X-ray diffraction, transmission electron microscopy, Fourier transform IR spectroscopy and N(2) adsorption/desorption. Furthermore, this material was used to modify an electrode surface combined with a hydrophobic ionic liquid. The functionalized ordered mesoporous carbon/ionic liquid gel modified electrode shows excellent electrocatalytic performances for the oxidation of dopamine, uric acid and ascorbic acid. The presence of the ionic liquid promotes the electron transfer. Linear responses for dopamine and uric acid were obtained in the ranges of 0.1 to 500 μM and from 0.1 to 100 μM with detection limits of 4.1 and 2.5 nM (signal-to-noise ratio of 3), respectively, under optimum conditions. A quick and sensitive biosensor based on functionalized ordered mesoporous carbon and an ionic liquid has been developed for the first time for the detection of dopamine and uric acid in the presence of a large amount of ascorbic acid.

Selective determination of uric acid with DNA doped polymers modified carbon fiber microelectrode

New biocomposite materials, based on the incorporation of DNA doped p-aminobenzensulfonic acid, was fabricated by electrochemical method. A carbon fiber microelectrode modified by this thin film was fabricated for selective determination of uric acid (UA) in the presence of a larger amount of ascorbic acid (AA). It was found that the voltammetric oxidation peak separation between UA and AA is about 260 mV at the modified electrode. A linear response of the peak current versus the concentration was found in the range of 8 × 10 −7–6 × 10 −4 M with correlation coefficient of 0.9991 and the detection limit was 5 × 10 −7 M ( s/ n = 3) at the 5 × 10 −4 M AA. The presence of high concentration AA did not interference the determination. The electropolymerized film was characterized by SEM techniques. The modified electrode shows good sensitivity, selectivity and stability.

Glassy carbon electrode modified with gold nanoparticles and DNA for the simultaneous determination of uric acid and norepinephrine under coexistence of ascorbic acid.

A novel biochemical sensor was assembled on a glass carbon electrode by a electrodeposition process. Gold nanoparticles were deposited by potential +1.5 V on the glass carbon electrode. CT-DNA was deposited by potential +1.5 V on the gold nanoparticles array electrode. The properties of the modified electrode were characterized by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Our results showed that gold nanoparticles increase the DNA membrane capacitance and reduce the membrane resistance. This modified electrode can selectively determine uric acid and norepinephrine in the presence of a larger amount of ascorbic acid. The fabricated electrode showed good sensitivity, reproducibility, and stability.

Quality of Lettuce Stored in a Low Oxygen Closed System.

For the low cost vegetable transportation, the applicability of a low O2 closed system was examined under ambient temperature. Heads of leaf lettuce grown under the controlled climate of a commercially operated plant factory individually placed in airtight containers filled with normal air or with low O2 mixed gas (5% 02+95% N2) were stored for 11 d and 13 d at 15°C and for 7 d at 20°C. Populations of mesophilic aerobic bacteria from levels of 107 to 109 CFU/g were detected at the end of storage on lettuce heads in control treatment (normal air). Contrary to this, final populations on lettuce heads in low O2 treatment were 102- to 105-fold less than those in control treatment. As the final populations were less than 1 x 107 CFU/g, leaves of lettuce heads in low O2 treatment were not spoiled for all storage experiments. Supplementary examinations indicated that low O2 treatment was not effective to suppress bacterial populations on lettuce heads having large populations as about the level of 105 CFU/g or more at the beginning of storage. Hence, the low O2 closed system can be applied exclusively to the leaf lettuce grown in plant factory that can normally assure small populations of bacteria. Adding to this bacterial point of view, cumulative quantity of CO2 showed a reduction in respiration of lettuce head in low O2 treatment. Moreover, large amount of ascorbic acid was lost in control treatment as compared to that in low O2 treatment. However, no significant difference was observed in weight loss regardless of treatment.

Regulation of cigarette smoke-induced cytochrome P4501A1 gene expression in osteogenic disorder Shionogi rat liver and in lung by large ascorbic acid dose.

The effects of a large ascorbic acid dose on cytochrome P4501A1 gene expression induced by cigarette smoke exposure was studied in Osteogenic Disorder Shionogi rats, which lack ascorbic acid biosynthesis. The rats were divided into four groups and were administered either a minimal amount (4 mg/day, 4S and 4C) or a large amount (40 mg/day, 40S and 40C) of ascorbic acid. The 4S group and 40S group were daily exposed to cigarette smoke for 2 hours, while the 4C group and 40C group were not. At the end of the 25-day experiment, the rats were killed. The cytochrome P4501A1 mRNA level both in the liver and lung was measured by a competitive reverse transcription-polymerase chain reaction method. When a minimal amount of ascorbic acid was administered, the cytochrome P4501A1 mRNA increased in the liver of the cigarette smoke-exposed group (4S) compared with the control group (4C). On the other hand, when a large amount of ascorbic acid was administered, this increase was not observed in the cigarette smoke-induced group (40S) in liver. On the other hand, in lung, an increased mRNA level in 4S group was not decreased by large ascorbic acid administration (40S). This is the first direct mRNA-level evidence of the effects of a large ascorbic acid dose on the gene expression stimulated by cigarette smoke.

The ascorbate system in recalcitrant and orthodox seeds

Recalcitrant seeds of Ginkgo biloba L., Quercus cerris L., Aesculus hippocastanum L. and Cycasrevoluta Thunb. are shed by the plant at a high moisture content, contain a large amount of ascorbic acid (ASA) and maintain high ascorbate (ASC) peroxidase (EC 1.11.1.11) activity. Three proteins showing ASC peroxidase activity are present in G. biloba seeds. Conversely, dry orthodox seeds (Vicia faba L., Avena sativa L., Pinus pinea L.) are completely devoid of ASA and ASC peroxidase. Experimentally induced rapid variations of the water level in both recalcitrant and orthodox seeds do not affect the ASC peroxidase; slow dehydration affects the ASC peroxidase activity moderately in recalcitrant seeds, but provokes a complete loss of germinability. Another peculiar difference between orthodox and recalcitrant seeds concerns the ascorbate recycling enzymes, ascorbate free radical (AFR) reductase (EC 1.6.5.4) and dehydroascorbate (DHA) reductase (EC 1.8.5.1). The DHA reduction capability is low in recalcitrant seeds, but is high in the orthodox ones. In contrast, AFR reductase activity is high in recalcitrant seeds and low in the orthodox ones. Data reported here concerning the ASC system appear to contribute to better understanding the recalcitrance. The presence of three different proteins showing ASC peroxidase activity in the archaic seed‐bearing plant G. biloba and its involvement in the spermatophyte evolution is discussed.

Vitamin C Supplementation Does Not Modify Bone Mineral Content or Mineral Absorption in Growing Pigs ,

We have demonstrated that alkaline phosphatase activity and collagen synthesis are dose-dependently stimulated by ascorbic acid in differentiated pig osteoblasts. In this study we further examined the relationship between ascorbic acid and bone metabolism by feeding young pigs large amounts of ascorbic acid. Three groups of seven 47-d-old pigs were given no ascorbic acid supplement (control), 500 (500 AA) or 1000 (1000 AA) mg ascorbic acid/kg diet for 4 mo. Calcium and P absorption and retention were evaluated by a 14-d balance trial immediately before killing in control and 1000 AA groups only (n = 6). Bones were collected at death and the bone ash and bending moment (three-point bending test) determined. Various plasma and urine indices of bone metabolism, especially those reflecting collagen degradation (hydroxyproline, deoxypyridinoline) and synthesis (carboxyterminal propeptide of type I collagen) were monitored. The plasma ascorbic acid concentrations increased with time and paralleled the dietary concentrations (P < 0.01). The Ca and P balances and the bone ash and bending moments in the ascorbic acid–supplemented pigs did not differ from those of the controls. Plasma osteocalcin was elevated (P < 0.05), whereas the other bone formation markers, alkaline phosphatase and carboxy terminal propeptide of type I collagen, were not affected by ascorbic acid. The plasma concentrations of Ca, P and 1,25-dihydroxycholecalciferol did not differ among the three groups. The unaffected urinary excretion of deoxypyridinoline and hydroxyproline in the ascorbic acid–supplemented pigs indicates that ascorbic acid does not alter bone resorption. Thus, high intakes of ascorbic acid have no positive influence on bone metabolism and bone characteristics in pigs. The in vivo long-term effects do not correlate with the short-term in vitro effects previously reported.

Hemoglobin-mediated oxidant damage to the central nervous system requires endogenous ascorbate.

Hemorrhage within the central nervous system (CNS) may be associated with subsequent development of seizure states or paralysis. Prior investigations indicate that hemoglobin, released from extravasated erythrocytes, may be toxic to the CNS by promoting peroxidation of lipids and inhibition of Na,K-ATPase. These deleterious effects are blocked both in vitro and in vivo by the Fe3+ chelator, desferrioxamine, indicating the involvement of free iron derived from hemoglobin. We now report that the Fe2+ chelator, ferene, also inhibits methemoglobin- and ferric iron-mediated CNS lipid oxidation, reflecting the reduction of Fe3+ by some component of the CNS. This reduction is apparent in the accumulation of the highly chromophoric ferene: Fe2+ chelate after the addition of Fe3+ salts to supernatants of murine brain homogenates. Because large amounts of ascorbic acid occur in mammalian CNS, we suspected that this reducing substance might be responsible. Indeed, the peroxidative effects of hemoglobin and iron on murine brain are blocked by washing of CNS membranes or by preincubation of crude homogenates with ascorbate oxidase. Furthermore, the addition of ascorbate to washed CNS membranes fully restores hemoglobin/iron-driven peroxidation. We conclude that posthemorrhagic CNS dysfunction may stem from damaging redox reactions between hemoglobin iron, ascorbic acid, and oxidizable components of the nervous system.

Evidence of rebound effect with ascorbic acid

The urinary excretion pattern of ascorbic acid in two subjects who had been taking a large amount of ascorbic acid (10 g per day) and later reverted to a small intake (125 mg per day) is described. The ascorbic acid concentration in the 24-hour urine samples was measured over a 40-day collection of this period. The mean urinary ascorbic acid excretion during the loading period of the two subjects was about 2 g per day. Upon termination of the high intake of ascorbic acid, urinary ascorbic acid excretion dropped to presupplementation levels within 6 days. Urinary ascorbic acid of the two subjects continued to decrease to below basal level, and remained at abnormally low levels for 10 and 12 days respectively. We hypothesize that the high intake of ascorbic acid has induced the formation of increased amounts of enzymes that help convert the ascorbic acid into other substances and that these substances are valuable. Some possible physiological actions of these ascorbic acid metabolites are discussed.

Relationship between ascorbic acid and cell division

Proliferating cells require large amounts of ascorbic acid to reach cell division. The decrease in ascorbic acid caused by adding lycorine, an inhibitor of ascorbic acid biosynthesis, induces profound inhibition of cell division: the cell cycle is arrested in G1 and G2 phase, more than 90% of the cells being accumulated in G1 after some time. The effect of lycorine on mitotic index (MI) has been reversed by increasing experimentally the concentration of ascorbic acid in tissues. Ascorbic acid control on cell division is found to be specific, since isoascorbic acid is wholly ineffective. It is suggested that the principal role of ascorbic acid in the cell cycle may be related to its action in controlling the synthesis of hydroxyproline-containing proteins, which can be essential requirements for development of G1 and G2.

Ascorbic acid in neural tissues.

Large amounts of ascorbic acid were readily removed from neural tissue by washing with warmed saline solutions. In areas where the original level was highest, such as cortex and cerebellum, a higher percentage was removed than from areas of lower concentration, such as pons-medulla. The residual level in both types of tissue was similar. During scurvy, the ascorbic acid retained in the guinea pig brain is more readily removed by washing than is that of the normal brain.