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|Section2= |Section6= |Section7= }} Ascorbic acid is a naturally occurring organic compound with antioxidant properties. It is a white solid, but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. Ascorbic acid is one form ("vitamer") of vitamin C. It was originally called L-hexuronic acid, but, when it was found to have vitamin C activity in animals ("vitamin C" being defined as a vitamin activity, not then a specific substance), the suggestion was made to rename it. The new name, ascorbic acid, is derived from ''a-'' (meaning "no") and ''scorbutus'' (scurvy), the disease caused by a deficiency of vitamin C. Because it is derived from glucose, many non-human animals are able to produce it, but humans require it as part of their nutrition. Other vertebrates which lack the ability to produce ascorbic acid include some primates, guinea pigs, teleost fishes, bats, and some birds, all of which require it as a dietary micronutrient (that is, in vitamin form). ==History== From the middle of the 18th century, it was noted that lemon and lime juice could help prevent sailors from getting scurvy. At first, it was supposed that the acid properties were responsible for this benefit; however, it soon became clear that other dietary acids, such as vinegar, had no such benefits. In 1907, two Norwegian physicians reported an essential disease-preventing compound in foods that was distinct from the one that prevented beriberi. These physicians were investigating dietary-deficiency diseases using the new animal model of guinea pigs, which are susceptible to scurvy. The newly discovered food-factor was eventually called vitamin C. From 1928 to 1932, the Hungarian research team led by Albert Szent-Györgyi, as well as that of the American researcher Charles Glen King, identified the antiscorbutic factor as a particular single chemical substance. At the Mayo clinic, Szent-Györgyi had isolated the chemical hexuronic acid from animal adrenal glands. He suspected it to be the antiscorbutic factor but could not prove it without a biological assay. This assay was finally conducted at the University of Pittsburgh in the laboratory of King, which had been working on the problem for years, using guinea pigs. In late 1931, King's lab obtained adrenal hexuronic acid indirectly from Szent-Györgyi and, using their animal model, proved that it is vitamin C, by early 1932. This was the last of the compound from animal sources, but, later that year, Szent-Györgyi's group discovered that paprika pepper, a common spice in the Hungarian diet, is a rich source of hexuronic acid. He sent some of the now-more-available chemical to Walter Norman Haworth, a British sugar chemist.〔(Story of Vitamin C's chemical discovery ). Profiles.nlm.nih.gov. Retrieved on 2012-12-04.〕 In 1933, working with the then-Assistant Director of Research (later Sir) Edmund Hirst and their research teams, Haworth deduced the correct structure and optical-isomeric nature of vitamin C, and in 1934 reported the first synthesis of the vitamin.〔 〕 In honor of the compound's antiscorbutic properties, Haworth and Szent-Györgyi now proposed the new name of "a-scorbic acid" for the compound. It was named L-ascorbic acid by Haworth and Szent-Györgyi when its structure was finally proven by synthesis.〔. Part of the National Library of Medicine collection. Accessed January 2007〕 In 1937, the Nobel Prize for chemistry was awarded to Haworth for his work in determining the structure of ascorbic acid — shared with Paul Karrer, who received his award for work on vitamins — and the prize for Physiology or Medicine that year went to Albert Szent-Györgyi for his studies of the biological functions of L-ascorbic acid. The American physician Fred R. Klenner, M.D. promoted vitamin C as a cure for many diseases in the 1950s by elevating the dosages greatly to as much as tens of grams vitamin C daily orally and by injection. From 1967 on, Nobel prize winner Linus Pauling recommended high doses of ascorbic acid as a prevention against cold and cancer. However, modern evidence does not support a role for high dose vitamin C in the treatment of cancer or the prevention of the common cold in the general population. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ascorbic acid」の詳細全文を読む スポンサード リンク
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