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Cerebral metabolism of oxidized ascorbate
1Department of Physiology and Biophysics, Chicago Medical School, IL 60064.
Brain Research
|November 19, 1993
Summary
Brain tissue regenerates ascorbic acid using a protein component. This process protects against oxidative stress, utilizing reduced glutathione (GSH) and NADPH as key reducing agents.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Ascorbic acid (vitamin C) is crucial for brain health, acting as an antioxidant.
- Maintaining reduced ascorbic acid is vital for protecting central nervous system (CNS) tissues from oxidative stress.
Purpose of the Study:
- To investigate the mechanism of ascorbic acid regeneration in the brain.
- To identify the components responsible for maintaining reduced ascorbic acid levels in the CNS.
Main Methods:
- Homogenization and fractionation of rat or calf cerebrum.
- High-performance liquid chromatography (HPLC) with coulometric electrochemical detection to quantify ascorbic acid, dehydro-L-ascorbic acid (DHAA), and reduced glutathione (GSH).
- Assessing the capacity of tissue fractions to regenerate ascorbic acid from DHAA.
Main Results:
- A cytosolic protein component in brain homogenates regenerates ascorbic acid from DHAA.
- This regeneration activity is heat-stable up to 80°C and sensitive to trypsin digestion.
- Reduced glutathione (GSH) and NADPH were identified as preferential reducing cofactors in this process.
Conclusions:
- The brain possesses a specific enzymatic system, likely a dehydroascorbic acid (DHAA) reductase, for regenerating ascorbic acid.
- This mechanism plays a significant role in maintaining the antioxidant capacity of the brain.