Vitamin C (Ascorbic Acid)

Ascorbic acid was recognized as early as 1734 as the factor in fresh fruit and vegetables that prevents the development of scurvy. Despite this early recognition, it was not until 1932 that two different research groups isolated and identified this compound from mammalian adrenal glands and citrus fruits. Ascorbic acid is a white crystalline compound, classified as a carbohydrate, with a molecular weight of 176 and a melting point of 190 to 192ºC. It is readily soluble in water, slightly soluble in alcohol and glycerol, and virtually insoluble in ether and chloroform. Ascorbic acid is relatively stable in air. In aqueous solutions, however, ascorbic acid is attacked by oxygen and other oxidizing agents that convert the reduced form of the vitamin first to dehydroascorbic acid and then on to further oxidation products in irreversible reactions.
Ascorbic acid can be synthesized from glucose through the intermediate formation of glucuronic acid and gulonic acid. Ascorbic acid appears to be ubiquitous in all plants. It is synthesized in all animal species studied with the exception of humans, several primates, the Indian fruit bat, the guinea pig, a few birds, fish, and invertebrates. Therefore, ascorbic acid is not considered to be an essential dietary nutrient for most domestic animals and laboratory animals; however, it is physiologically essential for all of them.