riboflavin_fall_2011 - Riboflavin B2 Discovery one of the substances uncovered in the search for the anti beriberi factor isolated and structure

Riboflavin – B2 Discovery • one of the substances uncovered in the search for the anti beriberi factor. • isolated and structure identified in 1933 by Kuhn, Szent-Györgyi and Wagner-Jaunergy • labeled vitamin B2 in England and vitamin G in USA. • has a fluorescent orange-yellow color. • name comes from: ribo – sugar alcohol ribitol in the structure and flavin – flavus – Latin for yellow

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Riboflavin Structure • Riboflavin contains a isoalloxazine ring with ribitol (sugar alcohol) attached. • Seen in the body as two phosphorylated forms: flavin mononucleotide (FMN) flavin adenine dinucleotide (FAD)

Fig. 9-11, p. 329 Riboflavin Structure

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Sources • Present in largest amounts in animal products: milk , eggs, cheese , meat . legumes, mushrooms and green vegetables (spinach) also good sources. • Found different forms in food. Free or protein-bound : milk, eggs and enriched breads and cereals primarily found as FMN and FAD : other foods • Riboflavin is freed from the proteins by action of stomach acid. • FMN and FAD must be converted to free form before absorption • Primarily absorbed in the jejunum, some from the duodnum.