The novel Arabidopsis thaliana svt2 suppressor of the ascorbic acid-deficient mutant vtc1-1 exhibits phenotypic and genotypic instability

For herbivorous insects, dietary sources of low molecular weight non-enzymatic antioxidants, such as ascorbic acid, may influence performance in the presence of phototoxic plant constituents. We examined responses of Trichoplusia ni, a broad generalist, and Depressaria pastinacella, a specialist on furanocoumarin-containing plants, to variation in dietary ascorbic acid availability in the presence and absence of xanthotoxin, a phototoxic furanocoumarin. In T. ni, dietary ascorbic acid significantly increased levels of this compound in body tissues (approximately 7-fold, 5-fold, and 8-fold in hemolymph, gut, and fat body, respectively). In the presence of xanthotoxin, however, the amount of ascorbic acid accumulated significantly decreased. This decrease was not due to antifeedant effects of xanthotoxin and may instead have resulted from depletion of ascorbic acid due to its radical scavenging activity. In contrast, ascorbic acid levels in D. pastinacella were less affected by variation in dietary levels of either xanthotoxin or ascorbic acid, although uric acid, another potential water-soluble nonenzymatic antioxidant, increased in response to dietary ascorbic acid, as it did in T. ni. Thus, for generalists, such as T. ni, that lack specialized detoxification mechanisms against phototoxins such as furanocoumarins, dietary ascorbic acid may play an important role in antioxidant defense, and, for caterpillars in general, uric acid may also contribute to antioxidant defenses. Arch. Copyright 1999 Wiley-Liss, Inc.

BackgroundActinidia eriantha is a precious material to study the metabolism and regulation of ascorbic acid (AsA) because of its high AsA content. Although the pathway of AsA biosynthesis in kiwifruit has been identified, the mechanism of AsA metabolism and regulation is still unclear. The purpose of this experiment is to reveal the AsA metabolic characteristics of A. eriantha ‘Ganmi 6’ from the molecular level, and lay a theoretical foundation for the research on the genetic improvement of kiwifruit quality.ResultsWe found that AsA reached the accumulation peak at S7 (110 DAF) during the process of fruit growth and development. The activity of GalDH, GalLDH, MDHAR and DHAR in fruit was similar to AsA accumulation trend, and both of them were significantly positively correlated with AsA content. It was speculated that GalDH and GalLDH were key enzymes in AsA biosynthesis, while MDHAR and DHAR were key enzymes in AsA regeneration cycle, which together regulated AsA accumulation in fruit. Also, we identified 98,656 unigenes with an average length of 932 bp from the transcriptome libraries using RNA-seq technology after data assembly. There were 50,184 (50.87%) unigenes annotations in four databases. Two thousand nine hundred forty-nine unigenes were enriched into the biosynthesis pathway of secondary metabolites, among which 133 unigenes involved in the AsA and aldehyde metabolism pathways, and 23 candidate genes related to AsA biosynthesis, cycling and degradation were screened out.ConclusionsConsidering gene expression levels and changes of physiological traits and related enzyme activity, we concluded that the accumulation of AsA depends mainly on the L-galactose pathway, and the D-galacturonic acid pathway and AsA recycling pathway as the secondary pathways, which co-maintain the high AsA content in fruit of A. eriantha.

PurposeAscorbic acid has been reported to have an adipogenic effect on 3T3-L1 preadipocytes, while evidence also suggests that ascorbic acid reduces body weight in humans. In this study, we tested the effects of ascorbic acid on adipogenesis and the balance of lipid accumulation in ovariectomized rats, in addition to long-term culture of differentiated 3T3-L1 adipocytes.Materials and MethodsMurine 3T3-L1 fibroblasts and ovariectomized rats were treated with ascorbic acid at various time points. In vitro adipogenesis was analyzed by Oil Red O staining, and in vivo body fat was measured by a body composition analyzer using nuclear magnetic resonance.ResultsWhen ascorbic acid was applied during an early time point in 3T3-L1 preadipocyte differentiation and after bilateral ovariectomy (OVX) in rats, adipogenesis and fat mass gain significantly increased, respectively. However, lipid accumulation in well-differentiated 3T3-L1 adipocytes showed a significant reduction when ascorbic acid was applied after differentiation (10 days after induction). Also, oral ascorbic acid administration 4 weeks after OVX in rats significantly reduced both body weight and subcutaneous fat layer. In comparison to the results of ascorbic acid, which is a well-known cofactor for an enzyme of collagen synthesis, and the antioxidant ramalin, a potent antioxidant but not a cofactor, showed only a lipolytic effect in well-differentiated 3T3-L1 adipocytes, not an adipogenic effect.ConclusionTaking these results into account, we concluded that ascorbic acid has both an adipogenic effect as a cofactor of an enzymatic process and a lipolytic effect as an antioxidant.

Ascorbic acid concentrations in dimethylnitrosamine-induced hepatic fibrosis in rats

Mercury chloride HgCl2, known scientifically as mercuric chloride, is a potent compound with a long history of use in various fields. It has been used in antiseptics and disinfectants, and even in the production of batteries and electroplating. Despite its utility, HgCl2 is highly toxic, posing significant health risks upon exposure. Chronic exposure can lead to severe neurological damages. Ginkgo biloba extract (EGB 761) is widely used for its neuroprotective properties, which include enhancing cognitive function and memory, particularly in age-related conditions like Alzheimer's disease. Ascorbic acid is vital for the synthesis of collagen, the repair of tissues, and the enzymatic production of certain neurotransmitters. As a powerful antioxidant, ascorbic acid helps protect cells from damage by free radicals. The present study was to evaluate the effects of Ginkgo biloba and L-Ascorbic Acid on Mercury Chloride (HgCl2)-Induced Oxidative stress and Neuroinflammation in Adult Male Wistar Rats for the period of 21 days. A total of 48 adult male Wistar rats were randomly divided into 6 groups of 8 rats each. The control group received distilled water only all through the period of the experiment serving as the positive control. HgCl2 Only Group received (5 mg/kg HgCl2 Only), Group HgCl2 + A. A (LD) received (5 mg/kg HgCl2 + 100 mg/kg A. A (LD), Group HgCl2 + A. A (HD) received (5 mg/kg HgCl2 + 500 mg/kg A. A (HD), Group HgCl2 + EGB 761 (LD) received (5 mg/kg HgCl2 + 100 mg/kg EGB 761 (HD) and Group HgCl2+ EGB 761 (HD) received (5 mg/kg HgCl2 + 500 mg/kg EGB 761 (HD). At the end of the administration, the animals were then subjected to Y maze test and were humanely sacrificed on day 22 of the experiment and brain were excised. 1 g of tissues immediately homogenized, the homogenates were centrifuged and the supernatant was utilized to assay for antioxidants enzymes (MDA, SOD, CAT and GSH) using spectrophotometric and some inflammatory cytokines (TNF- α and IL-6) activity in brain tissue. The result showed significant (P<0.05) impairment in spatial learning in HgCl2 Only Group, Ascorbic acid (500 mg) treated animals showed significant (p < 0.05) improvement in the spatial learning deficits and the Ginkgo biloba (100 mg and 500 mg) treated group of animals showed more alternations. The result also showed a significant (p < 0.05) decrease of superoxide dismutase (SOD) in HgCl2 group when compared to controls. Tissue catalase (CAT) and GSH activity decreased significantly (P < 0.05) in HgCl2 group when compared with control rats. Malondialdehyde concentrations increased significantly (P < 0.05) in HgCl2 treated group when compared to controls. Ascorbic acid (500 mg/kg), being a potent antioxidant caused significant (P < 0.05) decrease in MDA level, significant (P < 0.05) increase in CAT, SOD level thereby mitigating mercury-induced oxidative stress. The administration of Ginkgo Biloba Extract markedly ameliorated the toxic effects of HgCl2 on the previous parameters indicating also that Ascorbic acid and Ginkgo Biloba Extract has neuro protective property.

Antioxidant effect of ascorbic acid against cisplatin-induced nephrotoxicity and P-glycoprotein expression in rats

Antioxidant and hepatoprotective potentials of active fractions of Lannea barteri Oliv. (Anarcadiaceae) in rats

Antioxidants can scavenge free radicals in the human body and have been associated with a protective effect on the human body against a variety of diseases. As a part of normal cellular function, free radical production occurs continuously within the body at a cellular level. Excess-free radical production from endogenous or exogenous sources may result in a variety of diseases. Vitamins (A, C, and E), carotenoids, polyphenols, and flavonoids are some examples of common natural antioxidants. Among the different antioxidants quercetin, curcumin, and ascorbic acids have been extensively studied, and numerous reports on their antioxidant activity are available in the literature. Antioxidants are regarded as a key player in the current pandemic situation, and they play a key role as a preventive and controlling tool. There are a variety of herbal formulations and immune booster therapies available, many of which claim to contain various antioxidants and are effective against covid-19. Numerous herbal formulations and immune booster therapies are available and claimed to have different antioxidants and other constituents. In the present study simple, rapid, accurate, precise, and sensitive high-performance thin-layer chromatographic analytical method was developed for simultaneous estimation of quercetin, curcumin, and ascorbic acid. The developed method can effectively employ for different polyherbal formulations. The developed method was validated according to ICH guidelines. In the present study, an aluminum plate precoated with 60F 254 silica gel was used as a stationary phase whereas chloroform: ethyl acetate: formic acid (6:6:2.5 v/v/v) was used as a mobile phase. Chromatographic detection was performed with a Camag TLC scanner at 265 nm. The linearity range for the proposed method was found to be 500–1000 ng/band for all three analytes. The antioxidant potentiality of selected antioxidants was evaluated by an optimized UV visible spectroscopic-reducing power method. The reducing power method was optimized for the concentration and volume of reagent, incubation temperature, and time. The results of the study revealed that quercetin is having the best antioxidant potential compared to curcumin and ascorbic acid.

Ascorbic acid (AsA) is the most abundant water-soluble antioxidant in plants, and it plays a crucial role in plant growth, development and abiotic stress tolerance. In the present study, six key Arabidopsis or rapeseed genes involved in AsA biosynthesis were constitutively overexpressed in an elite Japonica rice cultivar. These genes encoded the GDP-mannose pyrophosphorylase (GMP), GDP-mannose-3',5'-epimerase (GME), GDP-L-galactose phosphorylase (GGP), L-galactose-1-phosphate phosphatase (GPP), L-galactose dehydrogenase (GDH), and L-galactono-1,4-lactone dehydrogenase (GalLDH). The effects of transgene expression on rice leaf AsA accumulation were carefully evaluated. In homozygous transgenic seedlings, AtGGP transgenic lines had the highest AsA contents (2.55-fold greater than the empty vector transgenic control), followed by the AtGME and AtGDH transgenic lines. Moreover, with the exception of the AtGPP lines, the increased AsA content also provoked an increase in the redox state (AsA/DHA ratio). To evaluate salt tolerance, AtGGP and AtGME transgenic seedlings were exposed to salt stress for one week. The relative plant height, root length and fresh weight growth rates were significantly higher for the transgenic lines compared with the control plants. Altogether, our results suggest that GGP may be a key rate-limiting step in rice AsA biosynthesis, and the plants with elevated AsA contents demonstrated enhanced tolerance for salt stress.

Study question Does every antioxidant compounds perform similarly in reducing the excessive levels of Oxidation Reduction Potential (ORP) in IVF culture media? Summary answer Not all antioxidant compounds perform similarly in maintaining physiological ORP levels in IVF culture media. What is known already During assisted reproduction technologies (ART), several external factors are responsible for disturbing the ORP equilibrium in gametes and embryos. Therefore, antioxidant supplementation of culture media has been evaluated and reported. However, there is lack of consensus on the efficiency of antioxidant action in embryo culture media. Antioxidants are known to lower the levels of free radical concentration to physiological levels, preventing cellular damage caused by oxidative stress. Therefore, it is important to determine which antioxidant compound are the most effective in reducing ORP levels in embryo culture media. Study design, size, duration In this prospective study was performed at CITMER Reproductive Medicine, Mexico city. ORP levels were measured by MiOXSYS System (UAB Caerus Biotechnologies, Vilnius, Lithuania) in embryo-free culture medium (Global® Total®, LifeGlobal®, Connecticut, US). Embryo-free culture medium was supplemented with cumene hydroperoxide and seven different antioxidants were tested each day for 5 continuous days (n = 40). Follicular fluid ORP levels from dominant follicles of 40 oocyte donors were used as control and considered as a physiological target. Participants/materials, setting, methods Cumene hydroperoxide (CH) 1mM, was utilized to increase ORP values in culture media from 224 mV to 415 mV. The following compounds considered as antioxidants according to literature were supplemented at 2 mM to the CH culture media: Ascorbic acid (ASC), L-Carnitine (CAR), L-Cysteine (CYS), Glutathione (GLT), Curcumin (CU), Resveratrol (RSV) and b-Mercaptoethanol (BME). ORP levels were quickly evaluated each time. Main results and the role of chance In this study, CH was used as a culture media oxidant to measure the antioxidants capacity in lowering the excessive ORP values of CH culture media. ORP in CH solution was 415 mV ± 4.3. All antioxidants showed a statistically different capacity (p < 0.05) to lower the ORP values when added to CH solution: RSV decreased the ORP to 348.3 mV ± 3.6 p = 0.0449, CAR to 316.32 mV ± 4.7 (p < 0.0001), CU to 315.7 mV ± 4.4 (p < 0.0001) and GLT to 258.4 mV ± 15.1 (p = 0.00002). The compounds that showed higher antioxidant capacity were CYS 158.4 mV ± 4.7 (p < 0.00001), ASC 154.1 mV ± 3.1 (p < 0.00001) and BME 136.1 mV ± 9.6 (p < 0.00001). CYS, ASC and BME ORP values reached the physiological ORP values found in follicular fluid from donors, which are 89 mV±23.6 mV. Limitations, reasons for caution Further studies should focus on the comparison between physiological dynamics of antioxidant supplementation on culture media and molecular and biochemical effect of antioxidants on embryos and gametes. Wider implications of the findings According to our results, CYS, ASC and BME were significantly more potent antioxidants in lowering the ORP in culture medium to physiological levels. The measurement of antioxidant capacity in lowering excess of ROS in culture media may assist in developing the most effective antioxidant supplements, thus improving ART outcomes. Trial registration number none

We tested the hypothesis that infusion of ascorbic acid (AA), a potent antioxidant, would alter vasodilator responses to exercise in human obesity and metabolic syndrome (MetSyn). Forearm blood flow (FBF, Doppler ultrasound) was measured in lean, obese, and MetSyn adults (n = 39, 32 ± 2 yr). A brachial artery catheter was inserted for blood pressure monitoring and local infusion of AA. FBF was measured during dynamic handgrip exercise (15% maximal effort) with and without AA infusion. To account for group differences in blood pressure and forearm size, and to assess vasodilation, forearm vascular conductance (FVC = FBF/mean arterial blood pressure/lean forearm mass) was calculated. We examined the time to achieve steady-state FVC (mean response time, MRT) and the rise in FVC from rest to steady-state exercise (Δ, exercise - rest) before and during acute AA infusion. The MRT (P = 0.26) and steady-state vasodilator responses to exercise (ΔFVC, P = 0.31) were not different between groups. Intra-arterial infusion of AA resulted in a significant increase in plasma total antioxidant capacity (174 ± 37%). AA infusion did not alter MRT or steady-state FVC in any group (P = 0.90 and P = 0.85, respectively). Interestingly, higher levels of C-reactive protein predicted longer MRT (r = 0.52, P < 0.01) and a greater reduction in MRT with AA infusion (r = -0.43, P = 0.02). We concluded that AA infusion during moderate-intensity, rhythmic forearm exercise does not alter the time course or magnitude of exercise-mediated vasodilation in groups of young lean, obese, or MetSyn adults. However, systemic inflammation may limit the MRT to exercise, which can be improved with AA.

BackgroundTo gain insight into the regulation of fruit ascorbic acid (AsA) pool in tomatoes, a combination of metabolite analyses, non-labelled and radiolabelled substrate feeding experiments, enzyme activity measurements and gene expression studies were carried out in fruits of the ‘low-’ and ‘high-AsA’ tomato cultivars ‘Ailsa Craig’ and ‘Santorini’ respectively.ResultsThe two cultivars exhibited different profiles of total AsA (totAsA, AsA + dehydroascorbate) and AsA accumulation during ripening, but both displayed a characteristic peak in concentrations at the breaker stage. Substrate feeding experiments demonstrated that the L-galactose pathway is the main AsA biosynthetic route in tomato fruits, but that substrates from alternative pathways can increase the AsA pool at specific developmental stages. In addition, we show that young fruits display a higher AsA biosynthetic capacity than mature ones, but this does not lead to higher AsA concentrations due to either enhanced rates of AsA breakdown (‘Ailsa Craig’) or decreased rates of AsA recycling (‘Santorini’), depending on the cultivar. In the later stages of ripening, differences in fruit totAsA-AsA concentrations of the two cultivars can be explained by differences in the rate of AsA recycling activities. Analysis of the expression of AsA metabolic genes showed that only the expression of one orthologue of GDP-L-galactose phosphorylase (SlGGP1), and of two monodehydroascorbate reductases (SlMDHAR1 and SlMDHAR3) correlated with the changes in fruit totAsA-AsA concentrations during fruit ripening in ‘Ailsa Craig’, and that only the expression of SlGGP1 was linked to the high AsA concentrations found in red ripe ‘Santorini’ fruits.ConclusionsResults indicate that ‘Ailsa Craig’ and ‘Santorini’ use complementary mechanisms to maintain the fruit AsA pool. In the low-AsA cultivar (‘Ailsa Craig’), alternative routes of AsA biosynthesis may supplement biosynthesis via L-galactose, while in the high-AsA cultivar (‘Santorini’), enhanced AsA recycling activities appear to be responsible for AsA accumulation in the later stages of ripening. Gene expression studies indicate that expression of SlGGP1 and two orthologues of SlMDHAR are closely correlated with totAsA-AsA concentrations during ripening and are potentially good candidates for marker development for breeding and selection.

Phosphomannose isomerase (PMI) is an enzyme that catalyses the first step of the L-galactose pathway for ascorbic acid (AsA) biosynthesis in plants. To clarify the physiological roles of PMI in AsA biosynthesis, the cDNA sequence of PMI was cloned from non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) and overexpressed in tobacco transformed with Agrobacterium tumefaciens. The AsA and soluble sugar contents were lower in 35S::BcPMI2 tobacco than in wild-type tobacco. However, the AsA level in BcPMI2-overexpressing plants under stress was significantly increased. The T1 seed germination rate of transgenic plants was higher than that of wild-type plants under NaCl or H2O2 treatment. Meanwhile, transgenic plants showed higher tolerance than wild-type plants. This finding implied that BcPMI2 overexpression improved AsA biosynthetic capability and accumulation, and evidently enhanced tolerance to oxidative and salt stress, although the AsA level was lower in transgenic tobacco than in wild-type tobacco under normal condition.

Higher transcription levels in ascorbic acid biosynthetic and recycling genes were associated with higher ascorbic acid accumulation in blueberry

This report highlights the phytochemical analysis, antioxidant potential and anticancer activity against breast carcinoma of 70% methanolic extract of lichen, Parmotrema reticulatum (PRME). Phytochemical analysis of PRME confirms the presence of various phytoconstituents like alkaloids, carbohydrates, flavonoids, glycosides, phenols, saponins, tannins, anthraquinones, and ascorbic acid; among which alkaloids, phenols and flavonoids are found in abundant amount. High performance liquid chromatography (HPLC) analysis of PRME revealed the presence of catechin, purpurin, tannic acid and reserpine. Antioxidant activity was evaluated by nine separate methods. PRME showed excellent hydroxyl and hypochlorous radical scavenging as well as moderate DPPH, superoxide, singlet oxygen, nitric oxide and peroxynitrite scavenging activity. Cytotoxicity of PRME was tested against breast carcinoma (MCF-7), lung carcinoma (A549) and normal lung fibroblast (WI-38) using WST-1 method. PRME was found cytotoxic against MCF-7 cells with an IC50 value 130.03±3.11 µg/ml while negligible cytotoxicity was observed on A549 and WI-38 cells. Further flow cytometric study showed that PRME halted the MCF-7 cells in S and G2/M phases and induces apoptosis in dose as well as time dependent manner. Cell cycle arrest was associated with downregulation of cyclin B1, Cdk-2 and Cdc25C as well as slight decrease in the expression of Cdk-1 and cyclin A1 with subsequent upregulation of p53 and p21. Moreover PRME induced Bax and inhibited Bcl-2 expression, which results in increasing Bax/Bcl-2 ratio and activation of caspase cascade. This ultimately leads to PARP degradation and induces apoptosis in MCF-7 cells. It can be hypothesised from the current study that the antioxidant and anticancer potential of the PRME may reside in the phytoconstitutents present in it and therefore, PRME may be used as a possible source of natural antioxidant that may be developed to an anticancer agent.