"Antioxidant'' (reducing) efficiency of ascorbate in plasma is not affected by concentration

IFF Benzie, WY Chung, JJ Strain

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Ascorbate (vitamin C), an important dietary derived antioxidant, reportedly shows decreasing ``antioxidant efficiency'' with increasing concentrations in indirect radical trapping methods of antioxidant capacity. This study investigated the effect of concentration on antioxidant efficiency of ascorbate using a direct test of antioxidant capacity, the ferric reducing/antioxidant power rest (FRAP assay). Results showed that the antioxidant efficiency factor of ascorbate was 2 and was constant over a wide concentration range in both plasma and pure aqueous solution. However, the absolute amount of ascorbate lost per unit of time increased with concentration. Furthermore, ascorbate was less stable in plasma than in aqueous solutions of similar pH and less stable in ethylenediamine tetraacetic acid (EDTA) than in heparinized plasma. Results indicate that previously reported concentration-dependent changes in antioxidant efficiency of ascorbate may have been caused by loss of ascorbate prior to and during testing, and by methodologic characteristics of indirect peroxyl radical trapping tests of antioxidant capacity. Therefore, it is suggested that the premise that the antioxidant efficiency of ascorbate is concentration-dependent is largely methodologically derived and does not reflect the antioxidant behavior of ascorbate per se. (C) Elsevier Science inc. 1999. All rights reserved.
LanguageEnglish
Pages146-150
JournalJournal of Nutritional Biochemistry
Volume10
Issue number3
Publication statusPublished - Mar 1999

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antioxidants
aqueous solutions
trapping
EDTA (chelating agent)
testing
ascorbic acid
assays

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title = "{"}Antioxidant'' (reducing) efficiency of ascorbate in plasma is not affected by concentration",
abstract = "Ascorbate (vitamin C), an important dietary derived antioxidant, reportedly shows decreasing ``antioxidant efficiency'' with increasing concentrations in indirect radical trapping methods of antioxidant capacity. This study investigated the effect of concentration on antioxidant efficiency of ascorbate using a direct test of antioxidant capacity, the ferric reducing/antioxidant power rest (FRAP assay). Results showed that the antioxidant efficiency factor of ascorbate was 2 and was constant over a wide concentration range in both plasma and pure aqueous solution. However, the absolute amount of ascorbate lost per unit of time increased with concentration. Furthermore, ascorbate was less stable in plasma than in aqueous solutions of similar pH and less stable in ethylenediamine tetraacetic acid (EDTA) than in heparinized plasma. Results indicate that previously reported concentration-dependent changes in antioxidant efficiency of ascorbate may have been caused by loss of ascorbate prior to and during testing, and by methodologic characteristics of indirect peroxyl radical trapping tests of antioxidant capacity. Therefore, it is suggested that the premise that the antioxidant efficiency of ascorbate is concentration-dependent is largely methodologically derived and does not reflect the antioxidant behavior of ascorbate per se. (C) Elsevier Science inc. 1999. All rights reserved.",
author = "IFF Benzie and WY Chung and JJ Strain",
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"Antioxidant'' (reducing) efficiency of ascorbate in plasma is not affected by concentration. / Benzie, IFF; Chung, WY; Strain, JJ.

In: Journal of Nutritional Biochemistry, Vol. 10, No. 3, 03.1999, p. 146-150.

Research output: Contribution to journalArticle

TY - JOUR

T1 - "Antioxidant'' (reducing) efficiency of ascorbate in plasma is not affected by concentration

AU - Benzie, IFF

AU - Chung, WY

AU - Strain, JJ

PY - 1999/3

Y1 - 1999/3

N2 - Ascorbate (vitamin C), an important dietary derived antioxidant, reportedly shows decreasing ``antioxidant efficiency'' with increasing concentrations in indirect radical trapping methods of antioxidant capacity. This study investigated the effect of concentration on antioxidant efficiency of ascorbate using a direct test of antioxidant capacity, the ferric reducing/antioxidant power rest (FRAP assay). Results showed that the antioxidant efficiency factor of ascorbate was 2 and was constant over a wide concentration range in both plasma and pure aqueous solution. However, the absolute amount of ascorbate lost per unit of time increased with concentration. Furthermore, ascorbate was less stable in plasma than in aqueous solutions of similar pH and less stable in ethylenediamine tetraacetic acid (EDTA) than in heparinized plasma. Results indicate that previously reported concentration-dependent changes in antioxidant efficiency of ascorbate may have been caused by loss of ascorbate prior to and during testing, and by methodologic characteristics of indirect peroxyl radical trapping tests of antioxidant capacity. Therefore, it is suggested that the premise that the antioxidant efficiency of ascorbate is concentration-dependent is largely methodologically derived and does not reflect the antioxidant behavior of ascorbate per se. (C) Elsevier Science inc. 1999. All rights reserved.

AB - Ascorbate (vitamin C), an important dietary derived antioxidant, reportedly shows decreasing ``antioxidant efficiency'' with increasing concentrations in indirect radical trapping methods of antioxidant capacity. This study investigated the effect of concentration on antioxidant efficiency of ascorbate using a direct test of antioxidant capacity, the ferric reducing/antioxidant power rest (FRAP assay). Results showed that the antioxidant efficiency factor of ascorbate was 2 and was constant over a wide concentration range in both plasma and pure aqueous solution. However, the absolute amount of ascorbate lost per unit of time increased with concentration. Furthermore, ascorbate was less stable in plasma than in aqueous solutions of similar pH and less stable in ethylenediamine tetraacetic acid (EDTA) than in heparinized plasma. Results indicate that previously reported concentration-dependent changes in antioxidant efficiency of ascorbate may have been caused by loss of ascorbate prior to and during testing, and by methodologic characteristics of indirect peroxyl radical trapping tests of antioxidant capacity. Therefore, it is suggested that the premise that the antioxidant efficiency of ascorbate is concentration-dependent is largely methodologically derived and does not reflect the antioxidant behavior of ascorbate per se. (C) Elsevier Science inc. 1999. All rights reserved.

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