リボフラビン

解説7,8-dimethyl-10-D-ribitylisoalloxazine．C17H20N4O6(376.37)．ビタミン B2 ともいう．動物の成長促進因子．現在は2-アミノ-4,5-ジメチル-1-リビチルアミノベンゼンとアロキサンとの縮合により生産されている．黄色の結晶性粉末．分解点280 ℃．[α]25D－112°(0.1 mol L－1 水酸化ナトリウム)，－122°(水)．λmax 220～225，267，374，475 nm(0.1 mol L－1 塩酸)．pK1 3.57，pK2 9.50(35 ℃)．熱に対して安定であるが，紫外線により強い緑色の蛍光を発して不可逆的に分解し，アルカリ性ではルミフラビンに，中性や酸性ではルミクロムになる．水溶液は黄緑色の蛍光を発し，還元すると無色のロイコフラビンになり，空気にさらして酸化するとふたたびフラビンに戻る．リボフラビンは，アミノ酸オキシダーゼ，NADHデヒドロゲナーゼ，キサンチンオキシダーゼなどでFADまたはFMNの形で補酵素として機能し，細胞呼吸，水素および電子伝達に重要な作用をしている．この欠乏症としては，口唇の障害，口角炎，顔面の局所性脂漏性皮膚炎，特殊な舌炎，眼球機能障害などがある．[CAS 83-88-5]森北出版「化学辞典（第2版）

用途光学分割剤。

説明A water-soluble B fraction was found in the 1920s to contain a yellow, fluorescent growth factor called riboflavin in England and vitamin G in the United States. In the early 1930s, several groups found the coenzyme forms of riboflavin 50-phosphate (flavin mononucleotide) and the further conjugate with adenylic acid (flavin adenine dinucleotide).

使用riboflavin (Vitamin B2) is used in skin care preparations as an emollient. It can be found in sun care products as a suntan enhancer. Medicinally, it is used for the treatment of skin lesions.

一般的な説明The conflicting results were eventually found to be due,in part, to deficiencies in study animals not just of vitamin B2,but also vitamin B3 (niacin), the cause of human forms of pellagra,and/or vitamin B6 (pyridoxine), another cause of dermatitis.Likewise, treatments with vitamin B2 were inconsistentbecause the early sources of this vitamin contained otherB vitamins. Vitamin B2 was eventually isolated from eggwhites in 1933 and produced synthetically in 1935. Thename riboflavine was officially accepted in 1960; althoughthe term was in common use before then. In 1966, IUPACchanged it to riboflavin, which is in common use today.Riboflavin is synthesized by all green plants and by mostbacteria and fungi. Therefore, riboflavin is found, at least insmall amounts, in most foods. Foods that are naturally highin riboflavin include milk and other dairy products, meat,eggs, fatty fish, and dark green vegetables. Chemically, riboflavin is an N-glycoside of flavin, alsoknown as lumichrome, and the sugar, ribitol .Flavin is derived from the Latin word flavus for “yellow”because of the yellow color of its crystals and yellow fluorescenceunder UV light. Riboflavin is heat stable but easilydegraded by light. Its systematic names are 7,8-dimethyl-10-ribitylisoalloxazine and 7,8-dimethyl-10-(D-ribo-2,3,4,5-tetrahydroxypentyl)isoalloxazine.