Explain about the water-soluble vitamin - Riboflavin?

Riboflavin (vitamin B₂), a water-soluble vitamin, was discovered in milk as a pigment possessing a yellow green fluorescence as early as in 1879. However, its role in our body was identified much later. The name 'riboflavin' was given to this vitamin in view of the similarity of a part of its structure to that of the sugar ribose and because of its relation to the general group of flavins.

Riboflavin and its coenzyme derivatives are isoalloxazines i.e. they contain a pteridine ring with a benzene ring fused on to it. The side chain is a C5 polyhydroxy group,  a derivative of ribitol, a pentaliydroxy compound. You would recall studying in the Nutritional Biochemistry Course that riboflavin has two major coenzyme derivatives, namely flavin mononzicleotide (FMN ) and flavin  adenine dinucleotide (FAD ) which is formed by the combination of FMN with one  molecule of adenosine triphosphate (ATP).