Different Concentrations Of Ascorbate Research Articles

Vitamin C Differentially Impacts the Serum Proteome Profile in Female and Male Mice.

A suboptimal blood vitamin C (ascorbate) level increases the risk of several chronic diseases. However, the detection of hypovitaminosis C is not a simple task, as ascorbate is unstable in blood samples. In this study, we examined the serum proteome of mice lacking the gulonolactone oxidase (Gulo) required for the ascorbate biosynthesis. Gulo-/- mice were supplemented with different concentrations of ascorbate in drinking water, and serum was collected to identify proteins correlating with serum ascorbate levels using an unbiased label-free liquid chromatography-tandem mass spectrometry global quantitative proteomic approach. Parallel reaction monitoring was performed to validate the correlations. We uncovered that the serum proteome profiles differ significantly between male and female mice. Also, unlike Gulo-/- males, a four-week ascorbate treatment did not entirely re-establish the serum proteome profile of ascorbate-deficient Gulo-/- females to the optimal profile exhibited by Gulo-/- females that never experienced an ascorbate deficiency. Finally, the serum proteins involved in retinoid metabolism, cholesterol, and lipid transport were similarly affected by ascorbate levels in males and females. In contrast, the proteins regulating serum peptidases and the protein of the acute phase response were different between males and females. These proteins are potential biomarkers correlating with blood ascorbate levels and require further study in standard clinical settings. The complete proteomics data set generated in this study has been deposited to the public repository ProteomeXchange with the data set identifier: PXD027019.

Vitamin C and Cell Death.

Significance: Persistent oxidative stress is a common feature of cancer cells, giving a specific weapon to selectively eliminate them. Ascorbate in pharmacological concentration can contribute to the suspended formation of hydroxyl radical via the Fenton reaction; thus, it can be an important element of the oxidative stress therapy against cancer cells. Recent Advances: The main components of ascorbate-induced cell death are DNA double-strand breaks via the production of hydroxyl radical and ATP depletion due to the activation of poly (ADP-ribose) polymerase 1. Presumably, DNA damage can be the primary contributor to the anticancer activity of pharmacological ascorbate, as opposed to the rupture of bioenergetics. The caspase independency of high-dose ascorbate-induced cell death proposed the possible involvement of several types of cell death, such as ferroptosis, necroptosis, and autophagy. Critical Issues: Ascorbate can target at least two key molecular features of cancer cells as a part of the anticancer therapy: the intrinsic or acquired resistance to cell death and the dysregulated metabolism of cancer cells. It seems probable that different concentrations of ascorbate alter the nature of induced cell death. Autophagy and necroptosis may play a role at intermediate concentrations, but caspase-independent apoptosis may dominate at higher concentrations. However, ascorbate behaves as an effective inhibitor of ferroptosis that may have crucial importance in its possible clinical application. Future Directions: The elucidation of the details and the links between high-dose ascorbate-induced cancer selective cell death mechanisms may give us a tool to form and apply synergistic cancer therapies. Antioxid. Redox Signal. 34, 831-844.

Ascorbate protects liver from metabolic disorder through inhibition of lipogenesis and suppressor of cytokine signaling 3 (SOCS3)

BackgroundFatty liver is a reversible status, but also an origin stage to develop to other metabolic syndromes, such as diabetes and heart disease that threatens public health worldwide. Ascorbate deficiency is reported to be correlated with increasing risks for metabolic syndromes, but whether ascorbate has a therapeutic effect is unknown. Here, we investigated if ascorbate treatment alone could work on protecting from the development of steatosis and mechanisms beyond.MethodsGuinea pigs were fed with a chow diet or a high palm oil diet (HPD) respectively. HPD induced animals were administered different concentrations of ascorbate in different time intervals through water. Besides, hepatocyte-like cells derived from human embryonic stem cells and HepG2 cells were treated with palmitic acid (PA) to induce lipid accumulation for molecular mechanism study.ResultsWe find that ascorbate rescues HPD and PA induced steatosis and insulin tolerance in vivo and in vitro. We demonstrate that ascorbate changes cellular lipid profiles via inhibits lipogenesis, and inhibits the expression of SOCS3 via STAT3, thus enhances insulin signal transduction. Overexpression of SOCS3 abolishes the ascorbate rescue effects on insulin signal and lipid accumulation in hepatic cells.ConclusionsAscorbate ameliorates hepatic steatosis and improves insulin sensitivity through inhibiting lipogenesis and SOCS3.

EFFECT OF ASCORBATE, SALICYLATE AND SILICATE ON POTATO PLANT UNDER WATER DEFICIT STRESS CONDITIONS

The effect of different concentrations of ascorbate (As) at 0, 0.25, 0.5 and 1.0 mM, salicylate (Sa) at 0, 0.25, 0.5 and 1.0 mM , in addition to silicate (Si) at 0, 100, 250, and 500 ppm on potato plant subjected to different water regimes; three days interval (control), four days interval (4DI) and five days interval (5DI). Photosynthetic pigments, free proline and malonyldialdehyde (MDA) concentrations, and plant dry matter percentage were determined. Also, tuber yield was recorded and the percentage of tuber dry matter was determined. Water deficit resulted in significant reduction in tuber yield, plant dry matter percentage beside significant increase in free proline and MDA contents. Meanwhile, effects on photosynthetic pigments content and tuber dry matter were inconsistent. The effects of using different concentrations of ascorbate (As) under water deficit provide a superior effect of As at 0.25 mM. Data revealed that ascorbate treatment enhanced tuber yield by improved Chl (a and b) and carotenoids content, with a promoted reduction in free proline content and MDA. Salicylate (Sa) treatment under water deficit exhibited partial enhancement in photosynthetic pigments; where, Sa (1.0 mM) increased Chl a under all water regimes and Chl b at control and 4DI water regimes. While Sa (0.5 mM) improved carotenoids content at 5DI water regimes. The positive effect of salicylate on tuber yield was obvious only at 5DI water regime; as salicylate concentrations (0.25, 0.5 and 1.0 mM) enhanced tuber yield by 65.61, 21.8 and 33.33%. Data exhibited that these increments were concomitant with a reduction in free proline content and a slight increase in tuber dry matter. Interactive effects of Silicate (Si)/water deficit were variable with the concentration under the used water deficit regimes, where, Si (100 ppm), showed higher means of Chl (a and b) with a reduction in free proline contents, at both 4DI and 5DI. The higher tuber yield resulted only at 5DI. More pronounced effect, Si (250 ppm) exhibited increment of photosynthetic pigments, plant dry matter, tuber yield, along with slight reduction in MDA, particularly at 5DI. It could be concluded that silicate treatment alleviated water stress by improving carotenoids content, plant dry matter and reducing both free proline and MDA contents, which attributes enhancement in tuber yield under water deficit. Generally, lower concentrations of As, Sa and Si showed their benefits under higher water stress regimes.

Variation in Extracellular Detoxification Is a Link to Different Carcinogenicity among Chromates in Rodent and Human Lungs.

Inhalation of soluble chromium(VI) is firmly linked with higher risks of lung cancer in humans. However, comparative studies in rats have found a high lung tumorigenicity for moderately soluble chromates but no tumors for highly soluble chromates. These major species differences remain unexplained. We investigated the impact of extracellular reducers on responses of human and rat lung epithelial cells to different Cr(VI) forms. Extracellular reduction of Cr(VI) is a detoxification process, and rat and human lung lining fluids contain different concentrations of ascorbate and glutathione. We found that reduction of chromate anions in simulated lung fluids was principally driven by ascorbate with only minimal contribution from glutathione. The addition of 500 μM ascorbate (∼rat lung fluid concentration) to culture media strongly inhibited cellular uptake of chromate anions and completely prevented their cytotoxicity even at otherwise lethal doses. While proportionally less effective, 50 μM extracellular ascorbate (∼human lung fluid concentration) also decreased uptake of chromate anions and their cytotoxicity. In comparison to chromate anions, uptake and cytotoxicity of respirable particles of moderately soluble CaCrO4 and SrCrO4 were much less sensitive to suppression by extracellular ascorbate, especially during early exposure times and in primary bronchial cells. In the absence of extracellular ascorbate, chromate anions and CaCrO4/SrCrO4 particles produced overall similar levels of DNA double-stranded breaks, with less soluble particles exhibiting a slower rate of breakage. Our results indicate that a gradual extracellular dissolution and a rapid internalization of calcium chromate and strontium chromate particles makes them resistant to detoxification outside the cells, which is extremely effective for chromate anions in the rat lung fluid. The detoxification potential of the human lung fluid is significant but much lower and insufficient to provide a threshold-type dose dependence for soluble chromates.

Reactive oxygen species and antioxidant levels as the factors of autumn senescence in phenological forms of beech (Fagus sylvatica L.)

This study examines changes in the reactive oxygen species (ROS) content and in the level and degree of ascorbate and glutathione oxidation during leaf senescence in phenological forms of beech (Fagus sylvatica L.). Leaves were collected between August and October in 2009 and 2012. Chlorophyll degradation depended significantly on the phenological characteristics of the specimens. Chlorophyll, proteins, superoxide ion and hydrogen peroxide contents and lipid peroxidation dynamics exhibited greater dependence on temperature changes in the early form than in the late form. In the early stage of senescence, the late beech form presented a greater increase in ascorbate and glutathione synthesis than did the early form (ascorbate and glutathione synthesis was the main characteristic of the phenological forms’ defence mechanism against increasing ROS concentration). The early form was characterized by a stronger correlation between increasing ROS and the concentrations of oxidized forms of ascorbate and glutathione. We conclude that the earlier onset and greater rate of autumn senescence in the early phenological form relative to the late form were associated with significantly quicker chlorophyll degradation and greater production of ROS, which was better balanced by the antioxidant system in the late phenological form. The different concentrations of ascorbate and glutathione and the degree of their oxidation influenced the oxidative stress tolerance in the senescing leaves of the different phenological forms of beech.

Ascorbate uptake is decreased in the hippocampus of ageing rats

Ascorbate, an intracellular antioxidant, has been considered critical for neuronal protection against oxidant stress, which is supported especially by in vitro studies. Besides, it has been demonstrated an age-related decrease in brain ascorbate levels. The aims of the present study were to investigate ascorbate uptake in hippocampal slices from old Wistar rats, as well as its neuroprotective effects in in vitro and in vivo assays. Hippocampal slices from male Wistar rats aged 4, 11 and 24 months were incubated with radiolabeled ascorbate and incorporated radioactivity was measured. Hippocampal slices from rats were incubated with different concentrations of ascorbate and submitted to H 2O 2-induced injury, cellular damage and S100B protein levels were evaluated. The effect of chronic administration of ascorbate on cellular oxidative state and astrocyte biochemical parameters in the hippocampus from 18-months-old Wistar rats was also studied. The ascorbate uptake was decreased in hippocampal slices from old-aged rats, while supplementation with ascorbate (2 weeks) did not modify any tested oxidative status in the hippocampus and the incubation was unable to protect hippocampal slices submitted to oxidative damage (H 2O 2) from old rats. Our data suggest that the decline of ascorbate uptake might be involved in the brain greater susceptibility to oxidative damage with advancing age and both in vitro and vivo assays suggest that ascorbate supplementation did not protect hippocampal cells.

Generation of reactive oxygen species by a novel anthraquinone derivative in the cyanobacterium Planktothrix perornata (Skuja)

A water-soluble anthraquinone derivative (2-[methylamino- N-(1′-methylethyl)]-9,10-anthraquinone monophosphate), previously found to be selectively toxic towards Planktothrix perornata at submicromolar concentrations, was studied to determine its toxic mode of action towards this cyanobacterium. Chlorophyll fluorescence was monitored as an indicator of photosynthetic efficiency, and measurement of reactive oxygen species (ROS) was performed using the ROS-sensitive probe 2′,7′-dichlorodihydrofluorescein diacetate. The effects of the herbicide paraquat (a ROS generator) as well as ascorbate and α-tocopherol (ROS scavengers) on ROS formation by P. perornata were studied. Also, the effects of different concentrations of ascorbate, α-tocopherol, and the herbicide diuron on reducing the toxicity of the water-soluble anthraquinone derivative towards P. perornata were determined. Our results indicate that the water-soluble anthraquinone derivative does not inhibit photosynthetic electron transport directly, but does generate ROS at levels that may cause toxicity towards P. perornata.

Inactivation of HSV-2 by ascorbate–Cu(II) and its protecting evaluation in CF-1 mice against encephalitis

Ascorbate is an important antioxidant. However, in the presence of transition metals such as Cu(II) or Fe(III), it also has pro-oxidant capabilities. The effect of ascorbate–Cu(II) in the in vitro infection of herpes simplex virus type 2 (HSV-2) and its protecting effect in a murine model was investigated. HSV-2 was treated with different concentrations of ascorbate in the presence of Cu(II). A group of CF-1 mice were treated with the inactivated virus and other treated with maintenance medium containing only ascorbate–Cu(II). Weeks later, mice were challenged intranasally with infectious viruses. HSV-2 was completely inactivated by 2 mM ascorbate plus 1 mM Cu(II). Ascorbate or Cu(II) alone did not inactivate the virus. Compared with the control group, 60% of the immunized animals did not show any sign of encephalitis and survived the herpes virus infection, while a 7% survival rate was observed in the control group ( P=0.056). We concluded that the in vitro treatment of HSV-2 with ascorbate–Cu(II) is not only able to inactivate the virus, but also suggested that the viral particles induced a protective response against herpes encephalitis. This inactivation may provide an alternative method to develop new agents therapeutics.

Lecithin-cholesterol acyltransferase activity during maturation of human preovulatory follicles with different concentrations of ascorbate, alpha-tocopherol and nitrotyrosine.

The enzyme lecithin-cholesterol acyltransferase (LCAT) transfers an acyl chain from lecithin to cholesterol or oestradiol, thus playing a crucial role in reverse cholesterol transport and follicular synthesis of potent long-lived oestrogens. The mechanism of catalysis is biphasic, as it is based on a phospholipase and an esterifying activity. Sulfhydryl groups were previously reported to be required for the esterification step. Lecithin-cholesterol acyltransferase has previously been shown to be inhibited by thiol oxidants such as peroxynitrite. Peroxynitrite also converts tyrosine to nitrotyrosines. In the present study, high levels of nitrotyrosine associated with low LCAT activity, and vice versa, were found in human preovulatory follicular fluids. Follicular fluids were also analysed for oestradiol (E) and progesterone (P) concentrations. The E/P ratio, which decreases as ovulation approaches, was used to evaluate the maturation status of each follicle. Enzyme activity was negatively correlated with the E/P ratio. Ascorbate (Asc) and alpha-tocopherol (Toc) were titrated in follicular fluid and plasma to evaluate their accumulation or consumption in the follicle. High LCAT activity was found in follicular fluids where Asc and Toc had accumulated, whereas lower activity was associated with Asc and Toc consumption. The consumption of both antioxidants was positively correlated with the E/P ratio. The results suggest that as follicle maturation progresses, Toc and Asc concentrations increase in follicular fluid, thus protecting LCAT from oxidative damage and loss of activity.

In vivo determination of extracellular brain ascorbate

A quantitative method consisting of the modification of the zero net flux technique was used to determine the extracellular concentration of ascorbate. A carbon paste electrode (CPE) held at constant potential was combined with a microdialysis probe through which various concentrations of ascorbate were locally infused. In experiments with bilateral CPEs, one of which was combined with a dialysis probe, no difference was observed in either basal or stimulated ascorbate currents. Addition of different concentrations of ascorbate to the perfusion fluid produced rapid changes in the voltammetric current due to ascorbate oxidation. Irrespective of the concentration of ascorbate infused, the current returned to basal level when the perfusion was stopped. The return was found to be more rapid after infusion of concentrations of ascorbate higher than the exracellular concentration than after perfusion with ascorbate-free solutions. This demonstrates that homeostatsis of ascorbate occurs in vivo. The calculated point of zero net flux was 416 ± 66 μM ( n = 6). This represents the extracellular concentration of ascorbate.

Effect of ascorbic acid, sodium citrate, sodium bicarbonate, and their combination effect on the binding of 59Fe 2+ and 59Fe 3+ to plasma membrane of lactating mouse mammary gland

Isolated plasma membranes of lactating mouse mammary gland were treated with different concentrations of ascorbate, sodium citrate, sodium bicarbonate, combinations of them (from 16 x 10 −10 to 4 x 10 −6 moles/L) and studied for the binding of 59Fe 2+ and 59Fe 3+ at pH 7.4. The results show that the Fe 3+ form of iron is under a greater influence of anions used in these experiments. The Fe 2+ form of iron is weakly bounded and affected. It is suggested that the form with a greater positive electric charge is more effectively bound to the receptors in plasma membranes.