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Concept: Ascorbic acid


Limited training, high cost, and low equipment mobility leads to inaccuracies in decision making and is concerning with serious ocular injuries such as suspected ruptured globe or post-operative infections. Here, we present a novel point-of-service (POS) quantitative ascorbic acid (AA) assay with use of the OcuCheck Biosensor. The present work describes the development and clinical testing of the paper-based biosensor that measures the changes in electrical resistance of the enzyme-plated interdigitated electrodes to quantify the level of AA present in ocular fluid. We have demonstrated the proof-of-concept of the biosensor testing 16 clinical samples collected from aqueous humor of patients undergoing therapeutic anterior chamber paracentesis. Comparing with gold standard colorimetric assay for AA concentration, OcuCheck showed accuracy of >80%, sensitivity of >88% and specificity of >71%. At present, there are no FDA-approved POS tests that can directly measures AA concentration levels in ocular fluid. We envisage that the device can be realized as a handheld, battery powered instrument that will have high impact on glaucoma care and point-of-care diagnostics of penetrating ocular globe injuries.

Concepts: Present, Decision making, Acid, Electric current, Electrochemistry, Battery, Aqueous humour, Ascorbic acid


BACKGROUND: An inflammatory component is present in the microenvironment of most neoplastic tissues. Inflammation and elevated C-reactive protein (CRP) are associated with poor prognosis and decreased survival in many types of cancer.Vitamin C has been suggested as having both a preventative and therapeutic role in a number of pathologies when administered at much higher-than-recommended dietary allowance levels.Since in vitro studies demonstrated inhibition of pro-inflammatory pathways by millimolar concentrations of vitamin C, we decided to analyze the effects of high dose IVC therapy in suppression of inflammation in cancer patients. METHODS: 45 patients with prostate cancer, breast cancer, bladder cancer, pancreatic cancer, lung cancer, thyroid cancer, skin cancer and B-cell lymphoma were treated at the Riordan Clinic by high doses of vitamin C (7.5 g -50 g) after standard treatments by conventional methods.CRP and tumor markers were measured in serum or heparin-plasma as a routine analysis. In addition, serum samples were collected before and after the IVCs for the cytokine kit tests. RESULTS: According to our data positive response to treatment, which was demonstrated by measurements of C- reactive protein, was found in 75% of patients and progression of the inflammation in 25% of patients. IVC treatments on all aggressive stage cancer patients showed the poor response of treatment.There was correlation between tumor markers (PSA, CEA, CA27.29 and CA15-3) and changes in the levels of C-reactive protein.Our test of the effect of IVC on pro-inflammatory cytokines demonstrated that inflammation cytokines IL-1alpha, IL-2, IL-8, TNF-alpha, chemokine eotaxin and CRP were reduced significantly after treatments. CONCLUSIONS: The high dose intravenous ascorbic acid therapy affects C-reactive protein levels and pro-inflammation cytokines in cancer patients. In our study, we found that modulation of inflammation by IVC correlated with decreases in tumor marker levels.In summary, our data support the hypothesis that high dose intravenous ascorbate treatments may reduce inflammation in cancer patients. Our results suggest that further investigations into the use of IVC to reduce inflammation in diseases where inflammation is relevant are warranted.

Concepts: Cancer, Metastasis, Oncology, Cancer staging, Types of cancer, Vitamin C, C-reactive protein, Ascorbic acid


Research progress to understand the role of vitamin C (ascorbic acid) in human health has been slow in coming. This is predominantly the result of several flawed approaches to study design, often lacking a full appreciation of the redox chemistry and biology of ascorbic acid. In this review, we summarize our knowledge surrounding the limitations of common approaches used in vitamin C research. In human cell culture, the primary issues are the high oxygen environment, presence of redox-active transition metal ions in culture media, and the use of immortalized cell lines grown in the absence of supplemental ascorbic acid. Studies in animal models are also limited due to the presence of endogenous ascorbic acid synthesis. Despite the use of genetically altered rodent strains lacking synthesis capacity, there are additional concerns that these models do not adequately recapitulate the effects of vitamin C deprivation and supplementation observed in humans. Lastly, several flaws in study design endemic to randomized controlled trials and other human studies greatly limit their conclusions and impact. There also is anecdotal evidence of positive and negative health effects of vitamin C that are widely accepted but have not been substantiated. Only with careful attention to study design and experimental detail can we further our understanding of the possible roles of vitamin C in promoting human health and preventing or treating disease.

Concepts: Cell, Epidemiology, Nutrition, Cell culture, Zinc, Vitamin C, Transition metal, Ascorbic acid


Topical application of nitric oxide (NO) has been shown to exert beneficial effects in the therapy of chronic wounds, impaired microcirculation, and skin infections. Nitrite acidified by ascorbic acid has been widely used in many studies as NO-donor system, unfortunately with inflammatory and toxic effects on the treated skin due to unregulated excessive NO generation, low pH and possible toxic side products. Here we describe an essentially modified nitrite based NO generating system that avoid the mentioned unwanted side effects on human skin by using a pH-stable acetate/acetic acid buffer with a skin neutral pH of 5.5 and sodium ascorbate. In order to overcome the shortcoming of lower NO yields due to the higher pH-value and low nitrite concentrations, we have determined additionally the influence of copper ions. To investigate the influence of different NO release and penetration kinetics on NO-induced toxicity, we have developed a fibroblast assay using cell culture plates with gas permeable bottoms. The results show clearly that the donor system can achieve a sustained NO generation without generating high peaks. Furthermore, the presence of Cu(2+) ions enhances manifold NO generation of pH/ascorbate-induced nitrite decomposition, a mechanism comprising the reduction of Cu(2+) ions to Cu(1+) by ascorbate. Finally, we have found that apart from the NO dose the NO release kinetics had a significant influence of cell toxicity. Thus, application of comparable NO amounts within a time interval of 600s led to the development of variable cell toxicities, which predominantly depended on the NO concentration values generated in the first 200s. In summary, we here describe a novel nitrite-based NO-donor system that can provide well defined NO concentrations at skin neutral pH-values for side effect poor topical dermal application, i.e. in the therapy of chronic wounds and impaired microcirculation.

Concepts: Acid, Ammonia, Skin, PH, Vitamin C, Toxicity, Ascorbic acid, Sodium ascorbate


Since the discovery of vitamin C, the number of its known biological functions is continually expanding. Both the names ascorbic acid and vitamin C reflect its antiscorbutic properties due to its role in the synthesis of collagen in connective tissues. Ascorbate acts as an electron-donor keeping iron in the ferrous state thereby maintaining the full activity of collagen hydroxylases; parallel reactions with a variety of dioxygenases affect the expression of a wide array of genes, for example via the HIF system, as well as via the epigenetic landscape of cells and tissues. In fact, all known physiological and biochemical functions of ascorbate are due to its action as an electron donor. The ability to donate one or two electrons makes AscH(-) an excellent reducing agent and antioxidant. Ascorbate readily undergoes pH-dependent autoxidation producing hydrogen peroxide (H(2)O(2)). In the presence of catalytic metals this oxidation is accelerated. In this review, we show that the chemical and biochemical nature of ascorbate contribute to its antioxidant as well as its prooxidant properties. Recent pharmacokinetic data indicate that intravenous (i.v.) administration of ascorbate bypasses the tight control of the gut producing highly elevated plasma levels; ascorbate at very high levels can act as prodrug to deliver a significant flux of H(2)O(2) to tumors. This new knowledge has rekindled interest and spurred new research into the clinical potential of pharmacological ascorbate. Knowledge and understanding of the mechanisms of action of pharmacological ascorbate bring a rationale to its use to treat disease especially the use of i.v. delivery of pharmacological ascorbate as an adjuvant in the treatment of cancer.

Concepts: Collagen, Antioxidant, Hydrogen, Redox, Vitamin, Vitamin C, Ascorbic acid, Scurvy


Quercetin, a flavonol in fruits and vegetables, has been demonstrated to have antioxidant, anti-inflammatory and immunomodulating influences. The purpose of the present study was to determine if quercetin, vitamin C and niacin supplements (Q-500 = 500 mg/d of quercetin, 125 mg/d of vitamin C and 5 mg/d of niacin; Q-1000 = 1000 mg/d of quercetin, 250 mg/d of vitamin C and 10 mg/d of niacin) would alter small-molecule metabolite profiles and serum quercetin conjugate levels in adults. Healthy adults (fifty-eight women and forty-two men; aged 40-83 years) were assigned using a randomised double-blinded placebo-controlled trial to one of three supplement groups (Q-1000, Q-500 or placebo). Overnight fasted blood samples were collected at 0, 1 and 3 months. Quercetin conjugate concentrations were measured using ultra-performance liquid chromatography (UPLC)-MS/MS, and metabolite profiles were measured using two MS platforms (UPLC-quadrupole time-of-flight MS (TOFMS) and GC-TOFMS). Statistical procedures included partial least square discriminant analysis (PLS-DA) and linear mixed model analysis with repeated measures. After accounting for age, sex and BMI, quercetin supplementation was associated with significant shifts in 163 metabolites/quercetin conjugates (false discovery rate, P < 0·05). The top five metabolite shifts were an increase in serum guaiacol, 2-oxo-4-methylthiobutanoic acid, allocystathionine and two bile acids. Inflammatory and oxidative stress metabolites were not affected. PLS-DA revealed a clear separation only between the 1000 mg/d and placebo groups (Q 2 Y = 0·763). The quercetin conjugate, isorhamnetin-3-glucuronide, had the highest concentration at 3 months followed by quercetin-3-glucuronide, quercetin-3-sulphate and quercetin diglucuronide. In human subjects, long-term quercetin supplementation exerts disparate and wide-ranging metabolic effects and changes in quercetin conjugate concentrations. Metabolic shifts were apparent at the 1000 mg/d dose; further research is required to understand the health implications of these shifts.

Concepts: Protein, Metabolism, Nutrition, Antioxidant, Oxidative phosphorylation, Dietary supplement, Vitamin C, Ascorbic acid


The effect of harvest date on nutritional compounds and antioxidant activity (AOC) in avocado (Persea americana Mill. cv Hass) fruit during storage was determined. The fruits were harvested at seven different dates and ripened at 25 °C following 21 or 35 days of cold storage. The results indicated that the phenolic and glutathione contents were increased and the ascorbic acid content was not significantly different in early harvested fruit (January to March), and the phenolic, ascorbic acid and glutathione contents were increased slightly and then decreased on late harvested fruit (April to June). Similar trends were observed in the changes of AOC. Furthermore, AOC in early harvested fruit after storage for 35 days was much higher than that in late harvested fruit after storage for 21 days. Therefore, avocado can be harvested earlier for economic benefits according to the market and can keep high nutritional value for human health benefits.

Concepts: Nutrition, Antioxidant, Reactive oxygen species, Vitamin C, Avocado, Ascorbic acid, Persea, Acids in wine


Mature-green and ripe fleshes from twelve samples of Mangifera were selected for this study. The mature-green fleshes were found having higher vitamin C contents than the ripe fleshes. However, not all higher total or individual phenolic contents were measured from the mature-green fleshes. The highest contents of vitamin C and total phenolic were respectively measured from the aqueous extracts of mature-green (255.86 ± 12.98 microg AAE/g sample) and ripe (142.57 ± 0.38 microg GAE/g sample) fleshes of M. petandra cv. Pauh. Gallic acid and mangiferin were detected in all aqueous extracts. The extracts of mature-green flesh of M. indica cv. Chokanan and ripe flesh of M. indica cv. Siku Raja respectively exhibited the greatest 1,1- diphenyl-2-picryhydrazyl radical (DPPH)-scavenging activity (408.21 ± 5.37 microg TE/g sample) and metal chelating activity (93.68 ± 0.74%). The combined or potentiation effects of the moderate vitamin C, gallic acid and mangiferin contents in both extracts may be responsible for the activities. The highest mangiferin content (31.72 ± 2.57 microg/g sample) in the mature-green M. caesia (Binjai) could be the major contributor of its highest FRAP activity (868.29 ± 2.71 microg TE/g sample). This study is apparently the first comparative report highlighting the antioxidant activities of these fruit fleshes.

Concepts: Nutrition, Antioxidant, Vitamin C, Tannin, Mango, Ascorbic acid, Raspberry, BlackBerry


In continuation with the screening of biological properties of seagrasses, we isolated sulphated polysaccharides from Halodule pinifolia. This is the first report that indicates the presence of fucoidan-like Halodule pinifolia crude sulphated polysaccharide (HPCSP) that are commonly found in brown algae being present in marine angiosperms. Fucoidan-like structures such as ß-mannuronic acid residues and sulphate groups were confirmed by Fourier Transform Infrared (FTIR) spectral analysis. There was a high content of uronic acid. The isolated HPCSP consisted mainly of total sugar (54.17%), protein (11.06%), carbon (18.25%), nitrogen (1.77%), hydrogen (3.62%), C/N ratio (2.04%) and uronic acid (2.61%). This isolated HPCSP was further investigated to determine anticoagulant and antioxidant activity. The HPCSP had high activity in the total antioxidant assay (125.86mg ascorbic acid equivalents/g), DPPH radical scavenging rate (IC50 value 2.045±0.12μg/mL), deoxyribose radical scavenging rate (51.82% at 1000μg/mL) and H2O2 radical scavenging rate (IC50 value 6.904±0.34μg/mL). In the anticoagulant assay, prolonged clotting time was observed with application of HPCSP with increasing concentrations. Further purification and characterization process is underway to confirm the structures of this fucoidan from H. pinifolia. From the observed results, this fucoidan-like HPCSP could be developed as a new natural source of potential antioxidants in the functional food industry.

Concepts: Protein, Acid, Nutrition, Antioxidant, Vitamin C, Fourier transform, Fourier analysis, Ascorbic acid


Ferulic acid esterified with poly(ethylene glycol) with three different average molecular weights (200, 400 and 1000 g mol(-1)) was studied in bread-making. The effects of these antioxidants on the properties of wheat flour dough and bread were analysed and compared with those obtained with ferulic acid and two commercial surfactants, the diacetyl tartaric acid ester of mono- and diglycerides and sodium stearoyl lactylate. Farinographic and alveographic methods as well as weight, volume and bread firmness measurements were used for this purpose.

Concepts: Wheat, Acetic acid, Ester, Bread, Flour, Ascorbic acid, Dough, Sodium stearoyl lactylate