The photolysis mechanism of riboflavin in milk serum: The correlation between the superoxide and riboflavin decomposition.

作者：Toshiyuki Toyosaki, Akemi YAMAMOTO, Takeshi Mineshita · 发表于：Agricultural and Biological Chemistry · 年份：1984 · DOI：10.1271/bbb1961.48.2919 · 被引用次数：10 · 研究领域：Metabolism and Genetic Disorders、Photoreceptor and optogenetics research、Chemical Analysis and Environmental Impact

The photolysis mechanism of riboflavin (RF) in milk serum was studied.Whenmilk serum was light-illuminated, the decomposition of RFin the serum was accelerated.Superoxide anion (O2T) and hydrogen peroxide (H2O2) were found to form during the illumination, while superoxide dismutase (SOD) activity could not be detected in the milk serum.The decomposition of RF was significantly inhibited by the addition of tryptophan or mannitol which are scavengers of the hydroxyl radical.Conversely, addition of Fe3+ or lactoferrin promoted the decomposition.These results strongly suggest the direct participation of the hydroxyl radical in the RF decomposition in milk serum during light-illumination.It was also suggested that the hydroxyl radical was formed via the iron catalyzed Haver-Weiss reaction in which iron reacts with O2 T and H2O2, although it is still unknown how O2T and H2O2were generated by illumination.Milk, available on the market, is an excellent source of Vitamin B2 (RF).RF is unstable to light,1} hence, it is considered that a fairly large amount of RF is decomposed under various conditions during distribution and storage processes.2)Since it is an extremely important problem from a food nutritional standpoint to prevent the decomposition of RF in milk, the decomposition mechanism of RF is worth studying.When the milk serum was illuminated with fluorescent light O2 T was formed, and the formation was observed only under weak light.1}In the case of a multi-