Resumo

TAVARES, Nélson. Putative role of riboflavin in disease prevention. Arq Med [online]. 2005, vol.19, n.1-2, pp.55-65. ISSN 2183-2447.

In the early part of the twentieth century, pioneering studies on the deficiency state of pellagra in experimental animals showed that water-soluble tissue extracts could be effective in treating diseases. Further studies showed that one part of the heat-stable fraction from the mentioned extract, called yellow growth factor, had fluorescent properties. This was later purified and named riboflavin. Until 1932, when the landmark discovery of the ‘’yellow enzyme’’ containing an isoalloxazine ring and a phosphate group was made, the physiological role of the yellow growth factor remained obscure. The synthesis of riboflavin, accomplished in 1935, was followed by the identification of the two active coenzyme forms, flavin mononucleotide (FMN) in 1937 and the clarification of the structure of flavin adenine dinucleotide in 1938, this formed from FMN. As a water-soluble vitamin, riboflavin plays a part in a variety of oxidation-reduction reactions. Flavin mononucleotide and flavin dinucleotide act as active coenzyme forms of riboflavin that participate in a variety of reactions in the human body. Riboflavin has an important role in the fat metabolism disturbances. Through deficiency and supplementation studies and effects on the structure and function of the small intestine, riboflavin has a role in iron handling. Riboflavin is associated with compromised oxidant defense. Flavin adenine dinucleotide acts as the co-factor for 5,10 Methylenetetrahydrofolate reductase, an important enzyme, which participates in the remethylation pathway for homocysteine metabolism. Homocysteine is located at a critical metabolic crossroad and therefore both pathways, remethylation and transsulfuration; and directly and indirectly impacts all methyl and sulphur group metabolism occurring in the body. Poor vitamin status could promote higher homocysteine levels. In addition, high levels of homocysteine could be considered conditional risk factors for cardiovascular diseases. Riboflavin has also been ascribed a role in the protection against certain cancers and cataracts.

Palavras-chave : Riboflavin; homocysteine; iron handling.

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