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Plasmatic antioxidant capacity due to ascorbate using TEMPO scavenging and electron spin resonance
Lidia L Piehl1, Graciela B Facorro, Mónica G Huarte
1Cátedra de Física, Facultad de Farmacia y Bioquímica and Laboratorio Nacional de Investigación y Servicios en Radicales Libres en Biología y Medicina, Universidad de Buenos Aires, Junín 956. 1113 Buenos Aires, Argentina. lpiehl@ffyb.uba.ar
Summary
A new method, Plasma Reactivity with TEMPO (PR-T), accurately measures plasma ascorbate levels. This technique offers a simpler way to assess antioxidant status and can track changes during ascorbic acid supplementation.
Area of Science:
- Biochemistry
- Analytical Chemistry
Background:
- Ascorbate (vitamin C) is a key water-soluble antioxidant.
- Current methods for measuring plasma ascorbate include HPLC and capillary electrophoresis.
- Assessing plasma antioxidant capacity involves various indexes like ORAC and TRAP.
Purpose of the Study:
- To develop and validate an alternative method for evaluating plasma antioxidant status specifically related to ascorbate.
- To assess the correlation between the new method and established techniques for measuring plasma ascorbate concentration.
Main Methods:
- Electron Spin Resonance (ESR) spectroscopy was used to analyze TEMPO (2,2,6,6-Tetramethylpiperidine-1-oxyl) radical scavenging kinetics in plasma.
- Plasma ascorbate concentrations were determined using capillary electrophoresis.
- Ascorbyl radical levels were quantified via ESR spectroscopy.
Main Results:
- Plasma Reactivity with TEMPO (PR-T) demonstrated a strong correlation (r=0.92) with plasma ascorbate levels measured by capillary electrophoresis.
- PR-T values increased significantly after ascorbic acid intake (from 85±27 to 130±20 µmol/L).
- The PR-T method avoids the need for a deproteination step, simplifying the assay.
Conclusions:
- PR-T serves as a reliable indicator of plasma antioxidant capacity attributed to ascorbate.
- This method is valuable for investigating diverse physiological and pathological antioxidant states.
- PR-T offers a practical alternative for monitoring plasma ascorbate levels and antioxidant status.