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Okazaki Y, Tanaka H, Hori M, Toyokuni S. -Dehydroascorbic acid recycled by thiols efficiently scavenges non-thermal plasma-induced hydroxyl radicals. Arch Biochem Biophys 2019; 669:87-95. [DOI: 10.1016/j.abb.2019.05.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/19/2019] [Accepted: 05/24/2019] [Indexed: 01/20/2023]
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Molecular structure regulation and enzyme cascade signal amplification strategy for upconversion ratiometric luminescent and colorimetric alkaline phosphatase detection. Anal Chim Acta 2019; 1051:160-168. [DOI: 10.1016/j.aca.2018.11.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/05/2018] [Accepted: 11/13/2018] [Indexed: 12/29/2022]
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Subramani T, Yeap SK, Ho WY, Ho CL, Omar AR, Aziz SA, Rahman NMANA, Alitheen NB. Vitamin C suppresses cell death in MCF-7 human breast cancer cells induced by tamoxifen. J Cell Mol Med 2013; 18:305-13. [PMID: 24266867 PMCID: PMC3930417 DOI: 10.1111/jcmm.12188] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 10/11/2013] [Indexed: 01/28/2023] Open
Abstract
Vitamin C is generally thought to enhance immunity and is widely taken as a supplement especially during cancer treatment. Tamoxifen (TAM) has both cytostatic and cytotoxic properties for breast cancer. TAM engaged mitochondrial oestrogen receptor beta in MCF-7 cells and induces apoptosis by activation of pro-caspase-8 followed by downstream events, including an increase in reactive oxygen species and the release of pro-apoptotic factors from the mitochondria. In addition to that, TAM binds with high affinity to the microsomal anti-oestrogen-binding site and inhibits cholesterol esterification at therapeutic doses. This study aimed to investigate the role of vitamin C in TAM-mediated apoptosis. Cells were loaded with vitamin C by exposure to dehydroascorbic acid, thereby circumventing in vitro artefacts associated with the poor transport and pro-oxidant effects of ascorbic acid. Pre-treatment with vitamin C caused a dose-dependent attenuation of cytotoxicity, as measured by acridine-orange/propidium iodide (AO/PI) and Annexin V assay after treatment with TAM. Vitamin C dose-dependently protected cancer cells against lipid peroxidation caused by TAM treatment. By real-time PCR analysis, an impressive increase in FasL and tumour necrosis factor-α (TNF-α) mRNA was detected after TAM treatment. In addition, a decrease in mitochondrial transmembrane potential was observed. These results support the hypothesis that vitamin C supplementation during cancer treatment may detrimentally affect therapeutic response.
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Affiliation(s)
- Tamilselvan Subramani
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
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Yang Y, Gao M, Nie W, Yuan J, Zhang B, Wang Z, Wu Z. Dietary magnesium sulfate supplementation protects heat stress-induced oxidative damage by restoring the activities of anti-oxidative enzymes in broilers. Biol Trace Elem Res 2012; 146:53-8. [PMID: 21947793 DOI: 10.1007/s12011-011-9210-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Accepted: 09/12/2011] [Indexed: 10/17/2022]
Abstract
The purpose of this study was to investigate the effect of dietary magnesium sulfate supplementation on heat stress-induced oxidative damage in broilers. One hundred twenty 14-day-old broilers were randomly assigned into four treatment groups with three replicates of ten birds each. The broilers were reared under normal ambient temperature (24 ± 1°C) fed with a basal (control) diet or reared under high ambient temperature (35 ± 1°C between 1000 and 1800 h, 8 h each day) fed with a basal diet supplemented with magnesium sulfate (0, 2.5 or 5.0 mg/kg of diet) from 14 to 42 days of age. Growth performance and oxidative damage were evaluated in each treatment group. Our results demonstrated that dietary magnesium sulfate supplementation significantly prevented heat stress-induced oxidative damage and improved growth performance in broilers compared with that of control. Mechanistically, this beneficial effect was mediated, at least partly, by restoring the activity of anti-oxidative enzymes. This finding suggests that magnesium sulfate supplementation might be a potential strategy to attenuate heat stress-induced detrimental effects in broilers raised in summer season or tropical areas.
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Affiliation(s)
- Ying Yang
- State key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, People's Republic of China
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Pundir S, Gera A, Pundir CS. Photochemical Immobilization of Cucurbita Fruit Ascorbate Oxidase onto Polyethylene Disc for Determination of Ascorbate in Serum and Foodstuffs. ACTA ACUST UNITED AC 2011; 39:324-9. [DOI: 10.3109/10731199.2011.573481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Chauhan N, Narang J, Pundir CS. Fabrication of multiwalled carbon nanotubes/polyaniline modified Au electrode for ascorbic acid determination. Analyst 2011; 136:1938-45. [DOI: 10.1039/c0an00218f] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Pundir CS, Chauhan N, Jyoti. Construction of an Amperometric Ascorbate Biosensor Using Epoxy Resin Membrane BoundLagenaria sicerariaFruit Ascorbate Oxidase. ACTA ACUST UNITED AC 2010; 39:177-84. [DOI: 10.3109/10731199.2010.525711] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Fabrication of an amperometric ascorbate biosensor using egg shell membrane bound Lagenaria siceraria fruit ascorbate oxidase. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.molcatb.2010.07.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Kubota Y, Moriyama Y, Yamagishi K, Tanigawa T, Noda H, Yokota K, Harada M, Inagawa M, Oshima M, Sato S, Iso H. Serum vitamin C concentration and hs-CRP level in middle-aged Japanese men and women. Atherosclerosis 2009; 208:496-500. [PMID: 19717151 DOI: 10.1016/j.atherosclerosis.2009.07.052] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 07/24/2009] [Accepted: 07/27/2009] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To examine the association between concentrations of serum vitamin C, a contributive factor to prevention of cardiovascular disease and levels of hs-CRP, a risk factor for cardiovascular disease, in population-based samples of middle-aged men and women. DESIGN A cross-sectional study. METHODS AND RESULTS The subjects were 778 men and 1404 women, aged 40-69 years, who participated in a cardiovascular risk survey in Kyowa, Ibaraki prefecture in 2002 as part of the Circulatory Risk in Communities Study (CIRCS). Inverse associations between serum vitamin C concentrations and hs-CRP levels were established for both men and women. Multivariable-adjusted mean values of hs-CRP for the lowest to highest quintiles of vitamin C levels were 0.75, 0.65, 0.61, 0.61 and 0.47 mg/L (P for trend <0.001) for men, and 0.56, 0.51, 0.49, 0.41 and 0.41 mg/L (P for trend <0.001) for women. The inverse association between vitamin C and hs-CRP was stronger for non-smoking men and women, non-overweight women and postmenopausal women. CONCLUSIONS Serum vitamin C concentrations were found to be inversely associated with hs-CRP levels in both men and women, primarily among non-smokers, non-overweight women and postmenopausal women. The respective roles of serum vitamin C and hs-CRP levels in the development of cardiovascular disease thus warrant further investigation.
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Affiliation(s)
- Yoshimi Kubota
- Public Health, Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita-shi, Osaka 565-0871, Japan
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Jansson PJ, Jung HR, Lindqvist C, Nordström T. Oxidative Decomposition of Vitamin C in Drinking Water. Free Radic Res 2009; 38:855-60. [PMID: 15493459 DOI: 10.1080/10715760410001700497] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have previously shown that vitamin C (ascorbic acid) can initiate hydroxyl radical formation in copper contaminated household drinking water. In the present study, we have examined the stability of vitamin C in copper and bicarbonate containing household drinking water. In drinking water samples, contaminated with copper from the pipes and buffered with bicarbonate, 35% of the added vitamin C was oxidized to dehydroascorbic acid within 15 min. After 3h incubation at room temperature, 93% of the added (2 mM) ascorbic acid had been oxidized. The dehydroascorbic acid formed was further decomposed to oxalic acid and threonic acid by the hydrogen peroxide generated from the copper (I) autooxidation in the presence of oxygen. A very modest oxidation of vitamin C occurred in Milli-Q water and in household water samples not contaminated by copper ions. Moreover, addition of vitamin C to commercially sold domestic bottled water samples did not result in vitamin C oxidation. Our results demonstrate that ascorbic acid is rapidly oxidized to dehydroascorbic acid and further decomposed to oxalic- and threonic acid in copper contaminated household tap water that is buffered with bicarbonate. The impact of consuming ascorbic acid together with copper and bicarbonate containing drinking water on human health is discussed.
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Affiliation(s)
- Patric J Jansson
- Department of Biochemistry and Pharmacy, Abo Akademi University, BioCity, 20521 Turku, Finland
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KURIHARA H, SHIBATA H, TSURUOKA N, KISO Y, ABE K, NAGAI H, FUKAMI H. Carnosine Modulates Stress-Attenuated Plasma Antioxidative Capacity. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2009. [DOI: 10.3136/fstr.15.179] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Frank J, Flaccus A, Schwarz C, Lambert C, Biesalski HK. Ascorbic acid suppresses cell death in rat DS-sarcoma cancer cells induced by 5-aminolevulinic acid-based photodynamic therapy. Free Radic Biol Med 2006; 40:827-36. [PMID: 16520235 DOI: 10.1016/j.freeradbiomed.2005.10.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Revised: 10/05/2005] [Accepted: 10/08/2005] [Indexed: 11/22/2022]
Abstract
Especially in the public, vitamin C is considered supportive for the treatment of cancer and supplementation is common. However, the underlying mechanism that most chemotherapeutic agents, ionizing radiation, and photodynamic therapy exert on tumor cell kill is an increased production of reactive oxygen species (ROS) leading to irreversible tissue injury. Therefore, antioxidants like ascorbic acid (AA) may prevent cancer cells of cellular free radical damage and may therefore be contraindicated in patients undergoing tumor treatment. We report on the effects of AA on markers of oxidative stress and apoptosis in rat DS-sarcoma cells on 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT). AA dose-dependently protected cancer cells against lipid and protein oxidation caused by ALA-PDT treatment. By real-time RT-PCR analysis an impressive increase of FasL (124-fold) and TNF-alpha (121-fold) mRNA was detected after PDT treatment. In addition, a decrease in mitochondrial transmembrane potential followed by the mitochondrial release of apoptosis-inducing factor (AIF) was observed. All these early signs of apoptosis were significantly reduced by AA, resulting in a 2.1-fold increased cell survival rate on ALA-PDT treatment. In conclusion, AA functions as a potent antioxidant, protecting mitochondria and other cell structures of oxidative cell injury induced by ALA-PDT and may therefore be contraindicated in patients undergoing tumor treatment.
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Affiliation(s)
- Juergen Frank
- Institute of Biological Chemistry and Nutrition, University of Hohenheim, Stuttgart, Germany.
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Back EI, Frindt C, Oćenásková E, Nohr D, Stern M, Biesalski HK. Can changes in hydrophobicity increase the bioavailability of α–tocopherol? Eur J Nutr 2005; 45:1-6. [PMID: 15765200 DOI: 10.1007/s00394-005-0556-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Accepted: 01/12/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Bioavailability of fat-soluble vitamins from conventional oral supplements is insufficient in some conditions in which fat digestion and absorption are chronically impaired (e. g. cystic fibrosis). AIM OF THE STUDY We used a water-soluble form of fatsoluble vitamin E (AQUANOVA solubilisate) to create a nutritional supplement (NS) in the form of vitaminized gummi bears (with micellised water-soluble alpha-tocopheryl acetate (100 IU) and 400 mg crystalline vitamin C). We assessed the bioavailability of the NS in comparison to conventional preparations. METHODS The trial consisted of three study days (d0: NS sucked; d10: NS swallowed; d20: reference products swallowed). A total of 14 subjects (6 male/8 female), aged 25.3 (22.7-35.3) years, BMI 24.3 (19.0-31.7) kg/m(2) participated in the study. They had blood samples drawn after fasting for >or=12 hours and then 1, 5, 15, 30, 60, 120, 180, 240, 300 and 320 minutes after ingesting the vitamins. HPLC and a colorimetric method were used to determine vitamin E and vitamin C, respectively. Areas under the curve (AUC(0-320min)) and maximum increases in plasma concentrations (Delta concentration) were calculated to assess bioavailability. RESULTS The AUCs(0-320min) of alpha-tocopherol from d0 were significantly larger (p = 0.016) when compared to d20. Moreover, the maximum increase in alpha-tocopherol plasma concentrations was significantly higher for d0 (p = 0.023) and d10 (p = 0.002) when compared to d20. CONCLUSIONS Short-term bioavailability of AQUANOVA micellised fat-soluble vitamin E from our NS was significantly higher than from regular supplements. The NS will now be tested for its clinical efficacy in a randomized double-blind controlled intervention trial with CF patients.
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Affiliation(s)
- Evelyn I Back
- University of Hohenheim, Institute of Biological Chemistry and Nutrition, Garbenstr. 30, 70593 Stuttgart, Germany
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Ihara H, Shino Y, Hashizume N. Recommended dietary allowance for vitamin C in the United States is also applicable to a population of young Japanese women. J Clin Lab Anal 2004; 18:305-8. [PMID: 15543561 PMCID: PMC6808108 DOI: 10.1002/jcla.20043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The recommended dietary allowance (RDA) for ascorbic acid (AA) in Canada and the United States has been set for several years at 75 mg/day for women 19-30 years old. Recently this level was questioned, and an increase to 90 mg/day was suggested. For Japanese women in the same age group, we found that the RDA for AA is currently 100 mg/day. Our goal was to determine which RDA is sufficient for maintaining a serum concentration of AA in young Japanese women above the lower reference limit of 7.0 mg/L. We measured serum AA concentrations by an ascorbate oxidase method in 176 healthy Japanese women (19-26 years old). We also performed an ROC analysis to estimate the optimal cutoff value for oral dosage to distinguish individuals with hypovitaminosis-C (<7.0 mg/L) from those with a normal serum AA. We evaluated the Japanese RDA using the 75 or 90 mg/day U.S. RDA and the weight ratio between Japanese and U.S. women, and discovered that the RDA value ranged between 66 and 79 mg/day. From the ROC analysis, we found that the optimal daily dosage of AA is approximately 75 mg/day. This value gave the highest efficiency, sensitivity, negative predictive value, and positive likelihood ratio, and the lowest negative likelihood ratio. Therefore, an RDA of 100 mg/day may be unnecessarily high for young Japanese women.
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Affiliation(s)
- Hiroshi Ihara
- Department of Laboratory Medicine, Ohashi Hospital, School of Medicine, Toho University, 2-17-6 Ohashi, Meguro, Tokyo 153-8515, Japan.
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Back EI, Frindt C, Nohr D, Frank J, Ziebach R, Stern M, Ranke M, Biesalski HK. Antioxidant deficiency in cystic fibrosis: when is the right time to take action? Am J Clin Nutr 2004; 80:374-84. [PMID: 15277158 DOI: 10.1093/ajcn/80.2.374] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Little is known about age- and disease-related changes in prooxidant and antioxidant systems in patients with cystic fibrosis (CF). OBJECTIVE We investigated changes in antioxidant concentrations and oxidative stress in plasma, buccal mucosal cells (BMCs), and breath condensate in patients with CF in relation to age and disease progression. DESIGN We recruited 22 patients with CF as well as 35 healthy control subjects and conducted a cross-sectional study by dividing the participants into 4 age groups (<6 y, 6-11 y, 12-17 y, > or =18 y). We collected fasting blood samples, BMCs, and breath condensate. Carotenoids, alpha-tocopherol, vitamin C, protein carbonyls, thiobarbituric acid-reactive substances, and F(2)alpha-isoprostane were assessed. RESULTS In patients with CF, plasma vitamin C concentrations, plasma and BMC alpha-tocopherol concentrations, and forced expiratory volume in 1 s (percentage predicted) decreased significantly with age. Plasma beta-carotene, beta-cryptoxanthin, and total lycopene were significantly lower in patients than in control subjects in all age groups. Furthermore, alpha-tocopherol and vitamin C plasma concentrations as well as alpha-tocopherol concentrations in BMCs were significantly lower in CF patients > or =18 y old, whereas all indicators of oxidative stress assessed were significantly higher than those same indicators in control subjects. CONCLUSIONS Adult patients with CF in particular showed distinct vitamin deficits and elevated indicators of oxidative stress in plasma, BMCs, and breath condensate along with a progression of clinical status. We suggest that early in life dietary habits should be improved and that innovative supplementation strategies should be applied to optimize the antioxidant status of patients with CF.
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Affiliation(s)
- Evelyn I Back
- Institute of Biological Chemistry and Nutrition, University of Hohenheim, Garbenstrasse 30, 70593 Stuttgart, Germany
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Kurihara H, Fukami H, Asami S, Toyoda Y, Nakai M, Shibata H, Yao XS. Effects of Oolong Tea on Plasma Antioxidative Capacity in Mice Loaded with Restraint Stress Assessed Using the Oxygen Radical Absorbance Capacity (ORAC) Assay. Biol Pharm Bull 2004; 27:1093-8. [PMID: 15256746 DOI: 10.1248/bpb.27.1093] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present study, we investigated the antioxidative effect of oolong tea in vitro and in vivo using the oxygen radical absorbance capacity (ORAC) assay. An oolong tea extract, catechin and related compounds suppressed the oxidation of fluorescence induced by AAPH in a dose-dependent manner, that is, they prolonged the antioxidant time in vitro. Oral administration of the oolong tea extract to mice treated with restraint stress increased ORAC activity in plasma as compared with a stress control group. The extract also increased plasma vitamin C levels, and there was a good relationship between ORAC activity and the vitamin C level in plasma. The elevation of plasma ORAC and vitamin C level may have been related to the stress-relieving effect of oolong tea. These effects are probably due to the antioxidative properties of the tea. Thus, these findings suggested that oolong tea has beneficial effects on health related to its antioxidative action.
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Affiliation(s)
- Hiroshi Kurihara
- Institute of Traditional Chinese Medicine and Natural Products, Jinan University, Guangzhou, China.
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Je HD, Shin CY, Park SY, Yim SH, Kum C, Huh IH, Kim JH, Sohn UD. Combination of vitamin C and rutin on neuropathy and lung damage of diabetes mellitus rats. Arch Pharm Res 2002; 25:184-90. [PMID: 12009033 DOI: 10.1007/bf02976561] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We investigated the role of vitamin C or rutin on neuropathy and lung damage of diabetic mellitus (DM) rats. Norepinephrine content was significantly decreased in sciatic nerves'of DM rats compared with non-DM controls but vitamin C had no effect on decreases of norepinephrine. 2,4-dinitrophenylhydrazine (DNPH) incorporation, which is biomarker of protein oxidation, was increased in sciatic nerve of DM rats as compared with normal control. However, vitamin C had no effects on increases of DNPH incorporation. We measured the content of conjugated dienes (CD) as a biomarker of lipid oxidation in sciatic nerve. CD was increased in DM as compared with normal control. Vitamin C or rutin had no effects on increases of CD. However, Rutin plus vitamin C significantly decreased the content of CD as compared with DM rats. In lung of DM rats, DNPH incorporation or CD was increased as compared with normal control. Vitamin C or Rutin had no effects on increases of CD. However, Rutin plus vitamin C significantly decreased the content of DNPH incorporation or CD in lung tissue. Vitamin C caused marked pathological changes such as the increases of parenchyma and the thickening of alveolar septa in the lung of DM. Rutin had protective effects on the pathological changes in the lung of DM rats. In conclusion, Vitamin C had no effects on oxidative parameter, such as DNPH incorporation or CD, and on the decreases of norepinephrine content in DM rats. Vitamin C caused the marked pathological changes in the lung of DM rats but rutin had protective effects against the pathological changes.
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Affiliation(s)
- Hyun Dong Je
- Department of Pharmacology, College of Pharmacy, Chung Ang University, Seoul, Korea
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Ihara H, Matsumoto N, Shino Y, Aoki Y, Hashizume N, Nanba S, Urayama T. An automated assay for measuring serum ascorbic acid with use of 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy, free radical and o-phenylenediamine. Clin Chim Acta 2000; 301:193-204. [PMID: 11020473 DOI: 10.1016/s0009-8981(00)00356-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We developed a novel, cost-effective, and automated assay for ascorbic acid (AsA) in serum using a COBAS MIRA S analyzer (Roche Diagnostic System). Our method has a wide dynamic range and covers AsA concentrations from well below the lower reference interval to well above it. AsA is oxidized by 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy, free radical (TEMPO) to dehydroascorbic acid (DAsA). The latter condenses with o-phenylenediamine (OPDA) to form a quinoxaline derivative that absorbs light at 340 nm. The change in absorbance at 340 nm is proportional to the concentration of AsA in the specimen. The automated system permitted the assay of 65 specimens per hour at a cost of approximately US$ 0.01 per specimen for reagents. The assay can be applied directly to serum specimens (direct method) and also to sera with a prior deproteinization step with metaphosphoric acid. The detection limit for the direct serum assays is 0.8 vs. 0.4 mg/l with the deproteinization method. The recovery of AsA from a supplemented serum pool was of >95% for both procedures. We used four distinct methods on 66 patients sera. The direct method for AsA correlated well with an HPLC method (r=0.964, P<0.001); the direct method also correlated well with a method that uses AsA oxidase (r=0.975, P<0. 001). The deproteinization method correlated well with HPLC (r=0.981, P<0.001), and with the AsA oxidase procedure (r=0.994, P<0.001). Ten within-day determinations on a serum pool gave a C.V. <4.3% for both the direct and deproteinization procedures. The between-day assays of the same serum pool over 10 days gave a C.V. of <6.7% by both methods.
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Affiliation(s)
- H Ihara
- Department of Laboratory Medicine, Ohashi Hospital, School of Medicine, Toho University, 2-17-6 Ohashi, Meguro, Tokyo 1538515, Japan.
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