riboflavin

/ruy'boh flay"vin, ruy"boh flay'-, -beuh-/, n. Biochem.

a vitamin B complex factor appearing as an orange-yellow, crystalline compound, C₁₇H₂₀N₄O₆, derived from ribose, essential for growth, found in milk, fresh meat, eggs, leafy vegetables, etc., or made synthetically, and used in enriching flour, in vitamin preparations, and in treating facial lesions.

Also, riboflavine /ruy'boh flay"vin, -veen/. Also called lactoflavin, vitamin B₂, vitamin G.

[1930-35; RIBO(SE) + FLAVIN]

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or vitamin B₂

Yellow, water-soluble organic compound, abundant in whey and egg white.

It has a complex structure incorporating three rings. Green plants and most microorganisms can synthesize it; animals need to acquire it in their diet. It exists in combined forms as coenzymes and functions in the metabolism of carbohydrates and amino acids. A syndrome resembling pellagra is thought to result from riboflavin deficiency. See also flavin.

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▪ chemical compound

also called  vitamin B₂ 

      a yellow, water-soluble organic compound that occurs abundantly in whey (the watery part of milk) and in egg white. An essential nutrient for animals, it can be synthesized by green plants and by most bacteria and fungi. The greenish yellow fluorescence of whey and egg white is caused by the presence of riboflavin, which was isolated in pure form in 1933 and was first synthesized in 1935. It has the following chemical structure:

      Riboflavin functions as part of metabolic systems concerned with the oxidation of carbohydrates and amino acids, the constituents of proteins. Like thiamin (vitamin B₁), it is active not in the free form but in more complex compounds known as coenzymes, such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), or flavoprotein. Riboflavin is widely distributed in both plants and animals, but its abundance varies considerably. Milk, eggs, leafy vegetables, kidney, and liver are good dietary sources. An adult human needs 1.0 to 1.3 mg (1 mg = 0.001 gram) of the vitamin per day.

      A dietary lack of riboflavin is characterized by variable symptoms that may include reddening of the lips with cracks at the corners of the mouth (cheilosis); inflammation of the tongue ( glossitis); ocular disturbances, such as vascularization of the eyeball with eyestrain and abnormal intolerance of light; and a greasy, scaly inflammation of the skin. Some disagreement persists as to the characteristic syndrome of riboflavin deficiency in humans because it tends to be associated with a deficiency of other vitamins, notably niacin (see pellagra).

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