Riboflavin (vitamin B2)
Riboflavin was isolated in a crystalline form from milk by Kuhn and co-workers in 1933. Because of this, the early name of the vitamin was lactoflavin. It was synthesized by two independent groups of scientists working with Kuhn in 1935.
Riboflavin has an isoalloxazine nucleus i.e. a pteridine ring with a benzene ring fused on to it. The side chain is a C5-polyhydroxy group, a derivative of ribitol, a pentahydroxy compound. Riboflavin is chemically known as 6,7-dimethyl-9-D- ri bitylisoalloxazine. The structure of riboflavin is given in Figure 3.3. Once again, do not get intimidated by the chemical names of this compound. As a student of dietetics you liiay not be asked as such to illustrate the structure of these compounds, but surely knowledge of the structure will help you understand the compound and its properties better.