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Oxygen-radical absorbance capacity assay for antioxidants
G Cao1, H M Alessio, R G Cutler
1Gerontology Research Center, National Institute on Aging, NIH, Baltimore, MD 21224.
Free Radical Biology & Medicine
|March 1, 1993
Summary
A new method quantifies antioxidant capacity in serum using oxygen-radical absorbing capacity (ORAC) assays. This reliable technique measures total antioxidant potential by completing oxidation, offering accurate results for various antioxidants.
Area of Science:
- Biochemistry
- Analytical Chemistry
Background:
- Assessing antioxidant capacity is crucial for understanding oxidative stress.
- Existing methods for measuring antioxidant capacity can be complex and time-consuming.
Purpose of the Study:
- To describe a simple, sensitive, and reliable method for quantifying the oxygen-radical absorbing capacity (ORAC) of antioxidants in serum.
- To establish a standardized assay for measuring total antioxidant capacity in biological samples.
Main Methods:
- Utilized beta-phycoerythrin (beta-PE) as an indicator protein and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) as a peroxyl radical generator.
- Employed Trolox (a vitamin E analogue) as a control standard, expressing results in ORAC units.
- Quantified antioxidant capacity by measuring the protection of beta-PE from oxidation after the reaction is complete.
Main Results:
- Demonstrated a linear correlation between ORAC values and the concentration of serum, Trolox, vitamin C, uric acid, and bovine albumin.
- Achieved a coefficient of variation of approximately 2% within runs and 5% between runs, indicating high reliability.
- Determined the relative peroxyl radical absorbance capacity of various antioxidants, with Trolox and alpha-tocopherol showing the highest capacity.
Conclusions:
- The described ORAC assay provides a robust and efficient method for assessing total antioxidant capacity in serum.
- This assay simplifies the measurement of antioxidant potential, overcoming limitations of kinetic or lag-time based methods.
- The findings support the utility of ORAC assays in various research applications, including nutritional and clinical studies.