According to Madarcos (2013), Riboflavin is consists of the heterocyclic ring isoalloxacin (flavin) connected through N10 to the alcohol ribitol. There are 2 biologically active forms of Riboflavin namely Flavin Mononucleotide (FMN) and Flavin Adenine Dinucleotide (FAD). FMN is formed by ATP-dependent phosphorylation of riboflavin, whereas FAD is synthesized by further reaction with ATP in which its AMP is transferred to FMN. FMN and FAD are each capable of reversibly accepting two H+ atoms (electron carriers), forming FMN2 and FADH2. They are also tightly bound as coenzymes to flavoenzymes (or flavoproteins) that catalyze redox reactions. The main dietary sources of riboflavin are milk and dairy products. In addition, because of its intense yellow color, riboflavin is widely used as a food additive (Murray et. al. 2009)
As mentioned on the first paragraph, flavin coenzymes can be an electron carrier particularly on some oxidoreduction reactions. These include the mitochondrial respiratory chain, key enzymes in fatty acid and amino acid oxidation, and the citric acid cycle. Reoxidation of the reduced flavin in oxygenases and mixed-function oxidases proceeds by way of formation of the flavin radical and flavin hydroperoxide, with the intermediate generation of superoxide and perhydroxyl radicals and hydrogen peroxide. Because of this, flavin oxidases make a significant contribution to the total oxidant stress in the body (Murray et. al 2009).
As mentioned on the first paragraph, flavin coenzymes can be an electron carrier particularly on some oxidoreduction reactions. These include the mitochondrial respiratory chain, key enzymes in fatty acid and amino acid oxidation, and the citric acid cycle. Reoxidation of the reduced flavin in oxygenases and mixed-function oxidases proceeds by way of formation of the flavin radical and flavin hydroperoxide, with the intermediate generation of superoxide and perhydroxyl radicals and hydrogen peroxide. Because of this, flavin oxidases make a significant contribution to the total oxidant stress in the body (Murray et. al 2009).
According to Murray et. al. (2009), although riboflavin is centrally involved in lipid and carbohydrate metabolism and deficiency occurs in many countries, it is not fatal, because there is very efficient conservation of tissue riboflavin. Riboflavin released by the catabolism of enzymes is rapidly incorporated into newly synthesized enzymes. Deficiency of Vitamin B2 symptoms include dermatitis, cheilosis (fissuring at the corners of the mouth) (Figure8), and glossitis (the tongue appearing smooth and purplish) (Harvey & Ferrier, 2011).
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