**Abstract**

Antioxidant plays important roles in cellular function and has been implicated in processes associated with aging, vascular and inflammatory damage, and cancer. Ascorbic acid is a water-soluble essential vitamin with antioxidant properties found in both animals and plants but cannot be synthesized by humans and must be obtained from the diet. Ascorbic acid possessed antioxidant property and readily scavenge reactive oxygen and nitrogen species which are associated with lipid peroxidation, damage of DNA, and proteins. Ascorbic acid as an antioxidant contributes to the maintenance of the vascular system, the reduction of atherogenesis through regulation of collagen synthesis, and the production of prostacyclin and nitric oxide. It reacts with compounds like histamine and peroxides to reduce inflammatory responses. Its antioxidant property is also associated with the reduction of cancer incidences. Ascorbic acid plays a role as a redox cofactor and catalyst in a biological system such as in *the conversion of the neurotransmitter dopamine to norepinephrine, in peptide amidation, and in tyrosine metabolism*. In the food industry, ascorbic acid is often added to food treated with nitrite in order to reduce the generation of nitrosamines (a carcinogen), found in sausages and cold cuts.

**Keywords:** ascorbic acid, mechanism, co-antioxidant, electron donation, cofactor, cancer
