Ascorbate: the most effective antioxidant in human blood plasma.

Area of Science:

• Biochemistry
• Oxidative Stress Research
• Nutritional Science

Background:

• Plasma lipoproteins are susceptible to peroxidative damage from various oxidants.
• Polymorphonuclear neutrophils (PMNs) release oxidants upon activation, contributing to oxidative stress.
• Ascorbate (vitamin C) is the primary endogenous antioxidant in human plasma.

Purpose of the Study:

• To investigate the protective role of ascorbate against peroxidative damage to plasma lipoproteins.
• To determine ascorbate's efficacy against both aqueous and lipid-soluble oxidants.
• To assess the potential of ascorbate supplementation in preventing diseases associated with oxidative stress.

Main Methods:

• Assessing the protection of lipoproteins from peroxidative damage induced by aqueous peroxyl radicals.
• Evaluating damage caused by lipid-soluble peroxyl radicals.
• Investigating the role of ascorbate in preventing lipid hydroperoxide formation following leukocyte activation.

Main Results:

• Ascorbate completely protected lipoproteins from damage by aqueous peroxyl radicals and oxidants from activated PMNs.
• Lipid-soluble peroxyl radicals caused significant peroxidative damage to plasma lipids, but ascorbate remained a primary antioxidant defense.
• Ascorbate supplementation prevented pathological lipid hydroperoxide formation linked to leukocyte activation, in the absence of free metal catalysts.

Conclusions:

• Ascorbate is a crucial endogenous antioxidant defending plasma lipoproteins against oxidative damage.
• Ascorbate supplementation shows promise for preventing and treating diseases and degenerative conditions driven by oxidative stress.
• The efficacy of ascorbate in preventing oxidative damage is dependent on the absence of free metal catalysts.