Chloroplastic ascorbate modifies plant metabolism and may act as a metabolite signal regardless of oxidative stress.

Ascorbate is a major plant metabolite that plays crucial roles in various processes, from reactive oxygen scavenging to epigenetic regulation. However, to what extent and how ascorbate modulates metabolism is largely unknown. We investigated the consequences of chloroplastic and total cellular ascorbate-deficiencies by studying chloroplastic ascorbate-transporter mutant lines lacking PHOSPHATE TRANSPORTER 4; 4 (PHT4; 4) , and the ascorbate-deficient vtc2-4 mutant of Arabidopsis (Arabidopsis thaliana). Under regular growth conditions, both ascorbate deficiencies caused minor alterations in photosynthesis, with no apparent signs of oxidative damage. In contrast, metabolomics analysis revealed global and largely overlapping alterations in the metabolome profiles of both ascorbate-deficiency mutants, suggesting that chloroplastic ascorbate modulates plant metabolism. We observed significant alterations in amino acid metabolism, particularly in arginine metabolism, activation of nucleotide salvage pathways, and changes in secondary metabolism. In addition, proteome-wide analysis of thermostability revealed that ascorbate may interact with enzymes involved in arginine metabolism, the Calvin-Benson cycle, and several photosynthetic electron transport components. Overall, our results suggest that, independently of oxidative stress, chloroplastic ascorbate modulates the activity of diverse metabolic pathways in vascular plants and may act as an internal metabolic signal.

Ferrous ascorbate non-effervescent floating mini-caplets as an oral iron supplement.

PURPOSE: This research aimed to develop non-effervescent floating mini-caplets of Ferrous Ascorbate (FA) using low-density polymers to overcome the problems of poor bioavailability associated with immediate-release iron products. Methods: The excipients and method (melt granulation) were selected based on pre-and post-compression parameters in trial batches. The formulation was optimized by a full factorial 32 experimental design. An optimized formulation was evaluated for drug release kinetic, accelerated stability study, and in vivo study in healthy adult New Zealand female rabbits. Results: The optimized formulation F6 mini-caplets (42.5% FA, 45% Glyceryl palmitostearate as Precirol, 10% polyvinyl pyrrolidone K-30, and 2.5% lactose) were found to have instant floating and 12 h floating duration in 0.1N Hydrochloric acid (HCl) dissolution medium. In vitro drug release (diffusion mechanism) at 1 h and 5 h was 30-35% and 65-70%, respectively. It was found stable for three months under an accelerated stability study. In vivo study showed significantly increased serum iron levels and decreased unsaturated iron binding capacity (UIBC) in the test group (optimized formulation) compared to control and standard (immediate-release iron). Conclusion: Based on the in vitro and in vivo results, we conclude that non-effervescent floating FA mini-caplets have higher bioavailability compared to immediate release FA, which may be attributed to prolonged iron release at its absorption site due to their retention in the gastric region. Hence, non-effervescent floating FA mini-caplets may act as a potential approach for iron deficiency.

Fabrication of Abelmoschus manihot gum/pullulan/magnesium L-ascorbate green composite packaging film and its excellent performance in preserving fresh-cut carrots.

Pullulan-based composite film can be a potential alternative packing material to non-environmentally friendly plastic wrap (PE) to preserve fresh-cut carrots. However, many developed pullulan-based composites either have high water vapor permeability (WVP) and high mechanical strength or vice versa, which limits the practicality of the developed packaging materials for potential commercialization. Herein, Abelmoschus manihot gum (AMG)/pullulan/magnesium L-ascorbate (MLA) was created as a green composite film (APL) to preserve fresh-cut carrots. The optimal amount of MLA was found to be 10 % (APL10), demonstrating a balance of lower WVP and greater mechanical strength and antioxidant performance than many pullulan-based films. This effectively solved many problems faced by other pullulan-based packaging films. After the fresh-cut carrots were packed with the composite film for 4 days, it was found that APL10 was effective in preserving the quality of carrots, in terms of freshness, weight loss rate, Vitamin C (VC), and malondialdehyde (MDA) content after 4 days of storage, much better than non-biodegradable PE. Thus, based on these findings, it is concluded that APL films have huge potential as a green packaging material for food to replace PE in the future.

Reactivation of nucleases with peroxidation damages induced by a menadione: ascorbate combination devastates human prostate carcinomas: ultrastructural aspects.

INTRODUCTION: Xenografts of androgen-independent human DU145 prostate metastatic carcinomas implanted in nu/nu male mice have revealed a significant survival after a prooxidant anticancer treatment consisting of a combination of menadione bisulfite and sodium ascorbate (VK3:VC). METHODS: Implanted samples of diaphragm carcinomas from longest survived mice from either oral, intraperitoneal (IP), or both oral and IP treatment groups were assessed with light, scanning, and transmission electron microscopy to analyze morphologic damages. RESULTS: Compared with previous fine structure data of in vitro untreated carcinomas, the changes induced by oral, IP, and oral with IP VK3:VC treatment dismantled those xenografts with autoschizis, and necrotic atrophy was accomplished by cell's oxidative stress whose injuries were consequent to reactivated deoxyribonucleases and ribonucleases. Tumor destructions resulted from irreversible damages of nucleus components, endoplasmic reticulum, and mitochondria there. Other alterations included those of the cytoskeleton that resulted in characteristic self-excisions named " autoschizis." All these injuries lead resilient cancer cells to necrotic cell death. CONCLUSION: The fine structure damages caused by VK3:VC prooxidant combination in the human DU145 prostate xenografts confirmed those shown in vitro and of other cell lines with histochemistry and biomolecular investigations. These devastations incurred without damage to normal tissues; thus, our data brought support for the above combination to assist in the treatment of prostate cancers and other cancers.

L-ascorbate Alleviates Chronic Obstructive Pulmonary Disease through the EGF/PI3K/AKT Signaling Axis.

INTRODUCTION: In this study, the molecular mechanisms through which Lascorbate (Vitamin C) potentially treats Chronic Obstructive Pulmonary Disease (COPD) were identified. A non-targeted metabolomics analysis revealed metabolic disorders and significantly reduced levels of L-ascorbate in COPD patients compared to healthy subjects. METHOD: The COPD rat model was established by exposing them to Cigarette Smoke (CS). The L-ascorbate intervention reduced lung inflammation and histological damage in COPD rat models. Network pharmacology analysis revealed 280 common targets between L-ascorbic acid (drug) and COPD (disease), of which seven core targets were MMP3, MME, PCNA, GCLC, SOD2, EDN1, and EGF. According to molecular docking prediction, L-ascorbate had the highest affinity with EGF. Molecular dynamics simulation indicated relatively stable EGF and L-ascorbate complexes. RESULTS: The PI3K/AKT signaling pathway was significantly enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) functional analysis. CONCLUSION: Finally, the in vivo and in vitro experiments confirmed that L-ascorbate affected COPD by regulating the EGF/PI3K/AKT pathway. In summary, based on network pharmacology and molecular docking analyses, this study revealed that L-ascorbate affects COPD development by regulating the PI3K/AKT signaling pathway through EGF, and thus contributes to the understanding and clinical application of Lascorbate in the treatment of COPD.

The role of ascorbate redox turnover in iron toxicity tolerance.

Iron (Fe) toxicity is a major abiotic stress in lowland rice production. Breeding tolerant varieties has proven challenging due to the complex genetic architecture of Fe toxicity tolerance and the strong genotype-by-environment interactions. Additionally, conventional methods for phenotyping visible stress symptoms are often inaccurate, inconsistent, and lack reproducibility. In our previous work, we identified that ascorbate redox regulation, mediated by the activities of dehydroascorbate reductase (DHAR) and ascorbate oxidase (AO), contributed to high tolerance in an indica rice genotype across various environments. To explore whether this mechanism is common among other rice genotypes, we selected ten genotypes with contrasting stress symptoms under Fe-toxic conditions to examine the roles of DHAR and AO in regulating Fe toxicity tolerance. Additionally, we aimed to develop objective and accurate image-based phenotyping methods to replace the traditional leaf bronzing scoring method. Among the ten genotypes we tested, we found significant positive correlations between DHAR activity and stress symptoms in plants grown under both Fe toxicity and control conditions, suggesting a general link between ascorbate redox regulation and Fe toxicity tolerance. Using RGB signals from leaf images of plants exposed to 1000 mg/L Fe2+, we evaluated 36 different color indices to quantify stress symptoms. We identified the normalized green‒red difference index as most significant in quantifying stress symptoms under Fe toxicity conditions. Our findings suggest that DHAR activity could be potentially employed as a biomarker in the screening of rice germplasms and breeding tolerant cultivars to Fe toxicity.

Investigation of potential ascorbate peroxidase inhibitors for anti-leishmaniasis therapy.

L eishmaniasis is a prevalent disease that impacts 98 countries and territories, mainly in Africa, Asia, and South America. It can cause substantial illness and death, particularly in its visceral manifestation that can be specifically targeted in the development of medications to combat leishmaniasis. This study has found natural compounds with possible inhibitory activity against APX using a reliable and accurate QSAR model. Despite the severe side effects of current treatments and the absence of an effective vaccination, these compounds show promise as a potential treatment for the disease. Nine hit compounds were found, and subsequent molecular docking was performed. Estradiol cypionate showed the lowest binding energy (- 10.5 kcal/mol), thus showing the strongest binding, and also had the strongest binding affinity, with a ΔGTotal of - 26.31 ± 3.01 kcal/mol, second only to the control molecule. Additionally, three hits viz. cloxacillin-sodium (- 16.57 ± 2.89 kcal/mol), cinchonidine (- 16.04 ± 3.27 kcal/mol), and quinine hydrochloride dihydrate (13.38 ± 1.06 kcal/mol) also showed significant binding affinity. Multiple interactions between drugs and active site residues demonstrated a substantial binding affinity with the target protein. The identified compounds exhibited drug-like effects and were orally bioavailable based on their ADME-toxicology features. Overall, estradiol cypionate, cloxacillin sodium, cinchonidine, and quinine hydrochloride dihydrate all exhibited inhibitory effects on the APX enzyme of Leishmania donovani. These results suggest that further investigation is needed to explore the potential of developing novel anti-leishmaniasis drugs using these compounds.

Modulation of microglia activation by the ascorbic acid transporter SVCT2.

Neuroinflammation is a major characteristic of pathology in several neurodegenerative diseases. Microglia, the brain's resident myeloid cells, shift between activation states under neuroinflammatory conditions, both responding to, but also driving damage in the brain. Vitamin C (ascorbate) is an essential antioxidant for central nervous system function that may have a specific role in the neuroinflammatory response. Uptake of ascorbate throughout the central nervous system is facilitated by the sodium-dependent vitamin C transporter 2 (SVCT2). SVCT2 transports the reduced form of ascorbate into neurons and microglia, however the contribution of altered SVCT2 expression to the neuroinflammatory response in microglia is not well understood. In this study we demonstrate that SVCT2 expression modifies microglial response, as shown through changes in cell morphology and mRNA expression, following a mild traumatic brain injury (mTBI) in mice with decreased or increased expression of SVCT2. Results were supported by in vitro studies in an immortalized microglial cell line and in primary microglial cultures derived from SVCT2-heterozygous and transgenic animals. Overall, this work demonstrates the importance of SVCT2 and ascorbate in modulating the microglial response to mTBI and suggests a potential role for both in response to neuroinflammatory challenges.

Reversal of cerebral ischaemia and hypoxia and of sickness behaviour by megadose sodium ascorbate in ovine Gram-negative sepsis.

BACKGROUND: The mechanisms by which megadose sodium ascorbate improves clinical status in experimental sepsis is unclear. We determined its effects on cerebral perfusion, oxygenation, and temperature, and plasma levels of inflammatory biomarkers, nitrates, nitrites, and ascorbate in ovine Gram-negative sepsis. METHODS: Sepsis was induced by i.v. infusion of live Escherichia coli for 31 h in unanaesthetised Merino ewes instrumented with a combination sensor in the frontal cerebral cortex to measure tissue perfusion, oxygenation, and temperature. Fluid resuscitation at 23 h was followed by i.v. megadose sodium ascorbate (0.5 g kg-1 over 30 min+0.5 g kg-1 h-1 for 6.5 h) or vehicle (n=6 per group). Norepinephrine was titrated to restore mean arterial pressure (MAP) to 70-80 mm Hg. RESULTS: At 23 h of sepsis, MAP (mean [sem]: 85 [2] to 64 [2] mm Hg) and plasma ascorbate (27 [2] to 15 [1] µM) decreased (both P<0.001). Cerebral ischaemia (901 [58] to 396 [40] units), hypoxia (34 [1] to 19 [3] mm Hg), and hyperthermia (39.5 [0.1]°C to 40.8 [0.1]°C) (all P<0.001) developed, accompanied by malaise and lethargy. Sodium ascorbate restored cerebral perfusion (703 [121] units], oxygenation (30 [2] mm Hg), temperature (39.2 [0.1]°C) (all PTreatment<0.05), and the behavioural state to normal. Sodium ascorbate slightly reduced the sepsis-induced increase in interleukin-6, returned VEGF-A to normal (both PGroupxTime<0.01), and increased plasma ascorbate (20 000 [300] µM; PGroup<0.001). The effects of sodium ascorbate were not reproduced by equimolar sodium bicarbonate. CONCLUSIONS: Megadose sodium ascorbate rapidly reversed sepsis-induced cerebral ischaemia, hypoxia, hyperthermia, and sickness behaviour. These effects were not reproduced by an equimolar sodium load.

The role of vitamin C in the prevention of pancreatic cancer: a systematic-review.

Introduction and aim: The aim of this systematic review was to assess the role of vitamin C in the prevention of pancreatic cancer (PC). Methods: A comprehensive literature search was performed in PubMed, Embase and Web of Science up to August 2023, to identify randomized controlled trials (RCT), cohort studies and mendelian randomization studies based on prospective databases assessing the role of vitamin C in PC prevention. Results: A total of twelve studies including European and North-American participants were included: two RCT, three mendelian randomization (MR) studies and seven cohort studies. Both RCT showed high quality in Cochrane risk of bias tool. Only one cohort study had <7 points in Newcastle Ottawa Scale. Both RCT found no association between the intake of 500 mg/day of vitamin C and the incidence of PC. Only one prospective cohort study found an association between vitamin C serum levels and a lower incidence of PC. The remaining cohort studies and MR studies found no association between dietary/supplements intake of vitamin C or circulating vitamin C levels and the incidence of PC. Conclusion: There is no supporting evidence that vitamin C prevents PC development. Future prospective quality studies including high-risk populations are needed.

Exogenous Sodium Nitroprusside Affects the Redox System of Wheat Roots Differentially Regulating the Activity of Antioxidant Enzymes under Short-Time Osmotic Stress.

Nitric oxide (NO) is a multifunctional signalling molecule involved in the regulation of plant ontogenesis and adaptation to different adverse environmental factors, in particular to osmotic stress. Understanding NO-induced plant protection is important for the improvement of plant stress tolerance and crop productivity under global climate changes. The root system is crucial for plant survival in a changeable environment. Damages that it experiences under water deficit conditions during the initial developmental periods seriously affect the viability of the plants. This work was devoted to the comparative analysis of the pretreatment of wheat seedlings through the root system with NO donor sodium nitroprusside (SNP) for 24 h on various parameters of redox homeostasis under exposure to osmotic stress (PEG 6000, 12%) over 0.5-24 h. The active and exhausted solutions of SNP, termed as (SNP/+NO) and (SNP/-NO), respectively, were used in this work at a concentration of 2 × 10-4 M. Using biochemistry and light microscopy methods, it has been revealed that osmotic stress caused oxidative damages and the disruption of membrane cell structures in wheat roots. PEG exposure increased the production of superoxide (O2•-), hydrogen peroxide (H2O2), malondialdehyde (MDA), and the levels of electrolyte leakage (EL) and lipid peroxidation (LPO). Stress treatment enhanced the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), the excretion of proline, and the rate of cell death and inhibited their division. Pretreatment with (SNP/+NO) decreased PEG-induced root damages by differently regulating the antioxidant enzymes under stress conditions. Thus, (SNP/+NO) pretreatment led to SOD, APX, and CAT inhibition during the first 4 h of stress and stimulated their activity after 24 h of PEG exposure when compared to SNP-untreated or (SNP/-NO)-pretreated and stress-subjected plants. Osmotic stress triggered the intense excretion of proline by roots into the external medium. Pretreatment with (SNP/+NO) in contrast with (SNP/-NO) additionally increased stress-induced proline excretion. Our results indicate that NO is able to mitigate the destructive effects of osmotic stress on the roots of wheat seedlings. However, the mechanisms of NO protective action may be different at certain periods of stress exposure.

Study on a Mechanism of Improving MaAPX1 Protein Activity by Mutating Methionine to Lysine.

Ascorbate peroxidases (APXs) are key components of the ascorbate-glytathione cycle, which plays an important role in removing excess reactive oxygen species (ROS) in plants. Herein, MaAPX1 was verified as being involved in the ripening and senescence of banana fruit, exhibiting responsiveness to the accumulation of ROS and the oxidation of proteins. Site-directed mutation was applied to explore the mechanism of MaAPX1 activity changes. We found that the 32-site cysteine (Cys, C) served as a potential S-nitrosylation site. The mutant MaAPX1C32S activity was decreased significantly when Cys32 was mutated to serine (Ser, S). Intriguingly, the neighboring conserved 36-site methionine (Met, M), which is adjacent to Cys32, displayed an enzyme activity that was approximately five times higher than that of the wild-type MaAPX1 when mutated to lysine (Lys, K). Utilizing LC-MS/MS spectroscopy coupled with stopped-flow analysis showed that the enhanced MaAPX1M36K activity might be due to the increased S-nitrosylation level of Cys32 and the promotion of intermediate (compound I, the first intermediate product of the reaction of APX with H2O2) production. Molecular docking simulations showed that the S-N bond between Cys32 and Lys36 in MaAPX1M36K might have a function in protecting the thiol of Cys32 from oxidation. MaAPX1M36K, a promising mutant, possesses immense potential for improving the antioxidant capabilities of APX in the realm of bioengineering technology research.

Molecular Pharmacology of Vitamin C and Relevance to Health and Obesity-A Narrative Review.

The role of food constituents as pharmacological agents is an important consideration in health and obesity. Vitamin C acts as a small molecule antioxidant but is also a co-factor for numerous transition metal-dependent enzymes involved in healthy weight and energy metabolism. Vitamin C cannot be manufactured by humans and is mainly obtained from the dietary intake of fresh fruit and vegetables. There is great variability between different nutritional guidelines in the recommended daily allowance of vitamin C. Vitamin C deficiency results from an inadequate intake of vitamin C-containing foods and also increased utilization by oxidative and carbonyl stress. Risk factors for vitamin C deficiency include cigarette smoking, malnutrition, obesity, type 2 diabetes mellitus, age, race, sex, social isolation, major surgery, and Western-type diets. Despite the common belief that vitamin C deficiency is rare in affluent countries, surveys of large populations and specific patient groups suggest otherwise. Patients with obesity typically consume highly processed, energy-dense foods which contain inadequate micronutrients. As obesity increases, larger amounts of oral vitamin C are required to achieve adequate plasma and tissue concentrations, as compared to persons with a healthy weight. This is important in the control of oxidative stress and the maintenance of homeostasis and organ function. In this narrative review, the dosage, absorption, distribution, excretion, and catabolism of vitamin C are reviewed, together with the latest findings on vitamin C pharmacology in patients with obesity.

Hydroxyl radical-mediated synthesis of carbonyl functionalized graphene quantum dots-like as enzyme mimics with tunable fluorescence emission.

The synthesis of graphene quantum dots-like enriched with specific oxygenated groups (o-GQDs) exhibiting great catalytic performance offers a promising tool for diagnosis and biomedicine, but introducing specific oxygen groups remains a challenge. Here, we propose a mild synthetic protocol for producing regulated fluorescence emission (from blue to yellow) carbonyl functionalized GQDs with double catalytic function through Fe3O4-catalyzed hydroxyl radical (·OH) oxidation the precursors like graphene oxide, polyaniline (PANI) and polydopamine (PDA). The method can be carried out at room temperature than the traditional high-temperature oxidation in concentrated acid. Interestingly, o-GQDs exhibit excellent peroxidase (POD)- and ascorbate oxidase-like activity. XPS characterization showed a significant increase in carbonyl content in o-GQDs compared to the precursor, even a 14-fold increase in blue-emitting iron-doped GQDs (b-Fe-GQDs). The introduction of Fe3O4 during the synthesis process results in a minor degree of Fe doping, which enhances the catalytic activity of b-Fe-GQDs through coordination with N. Based on this feature, highly sensitive single-signal and ultra-selective dual-signal methods for alkaline phosphatase detection were developed. This low cost and safe synthesis strategy paves the way for practical usage of o-GQDs.

Ascorbate insufficiency disrupts glutamatergic signaling and alters electroencephalogram phenotypes in a mouse model of Alzheimer's disease.

Clinical studies have reported that increased epileptiform and subclinical epileptiform activity can be detected in many patients with an Alzheimer's disease (AD) diagnosis using electroencephalogram (EEG) and this may correlate with poorer cognition. Ascorbate may have a specific role as a neuromodulator in AD as it is released concomitantly with glutamate reuptake following excitatory neurotransmission. Insufficiency may therefore result in an exacerbated excitatory/inhibitory imbalance in neuronal signaling. Using a mouse model of AD that requires dietary ascorbate (Gulo-/-APPswe/PSEN1dE9), EEG was recorded at baseline and during 4 weeks of ascorbate depletion in young (5-month-old) and aged (20-month-old) animals. Data were scored for changes in quantity of spike trains, individual spikes, sleep-wake rhythms, sleep fragmentation, and brainwave power bands during light periods each week. We found an early increase in neuronal spike discharges with age and following ascorbate depletion in AD model mice and not controls, which did not correlate with brain amyloid load. Our data also show more sleep fragmentation with age and with ascorbate depletion. Additionally, changes in brain wave activity were observed within different vigilance states in both young and aged mice, where Gulo-/-APPswe/PSEN1dE9 mice had shifts towards higher frequency bands (alpha, beta, and gamma) and ascorbate depletion resulted in shifts towards lower frequency bands (delta and theta). Microarray data supported ascorbate insufficiency altering glutamatergic transmission through the decreased expression of glutamate related genes, however no changes in protein expression of glutamate reuptake transporters were observed. These data suggest that maintaining optimal brain ascorbate levels may support normal brain electrical activity and sleep patterns, particularly in AD patient populations where disruptions are observed.

The Antioxidant Defense System of Tomato (Solanum lycopersicum L.) Varieties under Drought Stress and upon Post-Drought Rewatering.

Water shortage induces physiological, biochemical, and molecular alterations in plant leaves that play an essential role in plant adaptive response. The effects of drought and post-drought rewatering on the activity of antioxidant enzymes and levels of H2O2, phenolic compounds, ascorbic acid, and proline were studied in six local tomato (Solanum lycopersicum L.) varieties. The contents of H2O2 and ascorbic acid increased in all drought-exposed tomato plants and then decreased upon rewatering. The level of phenolic compounds also decreased in response to water shortage and then recovered upon rehydration, although the extent of this response was different in different varieties. The activities of ascorbate peroxidase (APX) and guaiacol peroxidase (POX) and the content of proline significantly increased in the drought-stressed plants and then decreased when the plants were rewatered. The activities of 8 constitutive APX isoforms and 2 constitutive POX isoforms varied upon exposure to drought and were observed after rewatering in all studied varieties. The information on the response of tomato plants to drought and subsequent rewatering is of great importance for screening and selection of drought-tolerant varieties, as well as for development of strategies for increasing plant productivity under adverse environmental conditions.

A Metastable Semiquinone Molecular Switch Modulated by Ascorbate/O2: a Study from a System Far-From-Equilibrium to Biological Assays in Mitochondria.

A molecular switch based on the metastable radical anion derived from a substituted heteroaryl quinone is described. Pyrrolil quinone thiocyanate (PQ 5) showed an interaction with the fluoride anion that was visible to the naked eye and quantified by UV/vis and 1H and 13C NMR. The metastable quinoid species formed by the interaction with F- ("ON" state) showed a molecular switching effect autocontrolled by the presence of ascorbate ("OFF" state) and back to the "ON" state by an autooxidation process, measured by visible and UV/vis spectroscopy. Due to its out-of-equilibrium properties and the exchange of matter and energy, a dissipative structural behaviour is proposed. Considering its similarity to the mechanism of coenzyme Q in oxidative phosphophorylation, PQ 5 was evaluated on Saccharomyces cerevisiae mitochondrial function for inhibition of complexes II, III and IV, reactive oxygen species (ROS) production, catalase activity and lipid peroxidation. The results showed that PQ 5 inhibited complex III activity as well as the activity of all electron transport chain (ETC) complexes. In addition, PQ 5 reduced ROS production and catalase activity in yeast. The results suggest that PQ 5 may have potential applications as a new microbicidal compound by inducing ETC dysfunction.

The Use of High-Dose Intravenous L-Ascorbate in Pain Therapy: Current Evidence from the Literature.

INTRODUCTION: Pain is the most common reason for seeking medical treatment. Despite extensive research efforts and effective analgesics modulating pain, there is still a major therapeutic gap in addressing the root causes of pain. Pain is associated with tissue damage induced by oxidative stress and induction of inflammatory mediators following high consumption of antioxidants. The role of antioxidants in general, and the administration of L-ascorbate in particular, is still controversially discussed and underestimated in the daily clinical practice. METHODS: The current literature on the therapeutic effect of L-ascorbate, ascorbic acid, and vitamin C on various pain conditions was evaluated against the background of evidence-based medicine. Those articles, obtained from systematic search in PubMed, were critically assessed and rated in terms of evidence level and methodological quality by two independent experts. The primary purpose of this work was to establish specific pain therapy guidance for intravenous L-ascorbate. RESULTS: A PubMed search revealed 14 suitable articles comprising controlled clinical trials and meta-analyses. An additional ten publications could be identified via secondary literature. There is supporting evidence for the efficacy of ascorbate treatment in inflammatory pain conditions, in the complex regional pain syndrome, in post zoster neuralgia, in neuropathic pain, in post-operative pain conditions, and in tumor-related pain. However, the considered studies differ in the type of administration, in dosage, in duration of treatment, as well as in quality of research. Despite all study heterogeneity, it became evident that research of high scientific quality is in support of the efficacy of L-ascorbate in pain treatment. DISCUSSION: Oxidative stress is present in almost all pain conditions. Because oral administration of most magistral formulas of vitamin C does not provide biological availability, parenteral administration should be preferred and can be supported by an oral dose with high bioavailability on days without intravenous treatment. L-ascorbate should be preferred for parenteral high dosage, rather than ascorbic acid, as it does not release acid valences under physiological conditions. CONCLUSIONS: L-ascorbate is an effective, safe, and economically favorable integrative treatment option for various pain conditions, addressing the root cause of tissue damage and inflammatory mediator burst.

Ex vivo Evaluation of a Liposome-Mediated Antioxidant Delivery System on Markers of Skin Photoaging and Skin Penetration.

Purpose: The topical application of antioxidants has been shown to augment the skin's innate antioxidant system and enhance photoprotection. A challenge of topical antioxidant formulation is stability and penetrability. The use of a targeted drug delivery system may improve the bioavailability and delivery of antioxidants. In this ex vivo study, we assessed the effects of the topical application of a liposome-encapsulated antioxidant complex versus a free antioxidant complex alone on skin photoaging parameters and penetrability in human skin explants. Patients and Methods: Human organotypic skin explant cultures (hOSEC) were irradiated to mimic photoaging. The encapsulated antioxidant complex and free antioxidant complex were applied topically onto the irradiated hOSEC daily for 7 days. The two control groups were healthy untreated hOSEC and irradiated hOSEC. Photoprotective efficacy was measured with pro-inflammatory cytokine (IL-6 and IL-8) and matrix metalloproteinase 9 (MMP-9) secretion. Cell viability and metabolic activity were measured via resazurin assay. Tissue damage was evaluated via lactate dehydrogenase (LDH) cytotoxicity assay. Skin penetration of the encapsulated antioxidant complex was assessed via fluorescent dye and confocal microscopy. Results: Compared to healthy skin, irradiated skin experienced increases in IL-6, IL-8 (p < 0.05), and MMP-9 (p < 0.05) secretion. After treatment with the encapsulated antioxidant complex, there was a 39.3% reduction in IL-6 secretion, 49.8% reduction in IL-8 (p < 0.05), and 38.5% reduction in MMP-9 (p < 0.05). After treatment with the free antioxidant complex, there were no significant differences in IL-6, IL-8, or MMP-9 secretion. Neither treatment group experienced significant LDH leakage or reductions in metabolic activity. Liposomes passed through the stratum corneum and into the epidermis. Conclusion: The topical application of a liposome-encapsulated antioxidant complex containing ectoin, astaxanthin-rich microalgae Haematococcus pluvialis extract, and THDA improves penetrability and restored IL-6, IL-8, and MMP-9 levels in irradiated human skin explants, which was not seen in the comparator free antioxidant complex group.

RIP5 Interacts with REL1 and Negatively Regulates Drought Tolerance in Rice.

Improving the drought resistance of rice is of great significance for expanding the planting area and improving the stable yield of rice. In our previous work, we found that ROLLED AND ERECT LEAF1 (REL1) protein promoted enhanced tolerance to drought stress by eliminating reactive oxygen species (ROS) levels and triggering the abscisic acid (ABA) response. However, the mechanism through which REL1 regulates drought tolerance by removing ROS is unclear. In this study, we identified REL1 interacting protein 5 (RIP5) and found that it directly combines with REL1 in the chloroplast. We found that RIP5 was strongly expressed in ZH11 under drought-stress conditions, and that the rip5-ko mutants significantly improved the tolerance of rice plants to drought, whereas overexpression of RIP5 resulted in greater susceptibility to drought. Further investigation suggested that RIP5 negatively regulated drought tolerance in rice by decreasing the content of ascorbic acid (AsA), thereby reducing ROS clearance. RNA sequencing showed that the knockout of RIP5 caused differential gene expression that is chiefly associated with ascorbate and aldarate metabolism. Furthermore, multiple experimental results suggest that REL1 is involved in regulating drought tolerance by inhibiting RIP5. Collectively, our findings reveal the importance of the inhibition of RIP5 by REL1 in affecting the rice's response to drought stress. This work not only explains the drought tolerance mechanism of rice, but will also help to improve the drought tolerance of rice.