RIBOFLAVINE 



1935. 111. 119 ; ,S. Ansbacher, G. C. Supplee and R. C. Bender, 

 /. Nutrition, 1936, 11, 529. 



12. C. A. Elvehjem^nd C. J. Koehn, /. Biol. Chem., 1935, 108, 709. 



13. C. J. Koehn and C. A. Elvehjem, /. Nutrition, 1936, 11, 67. 



14. W. J. Dann and Y. SubbaRow, ibid., 1938, 16, 183. 



2. ISOLATION OF RIBOFLAVINE 



The first step towards an understanding of the nature of vitamin B2 

 was taken by R. Kuhn, P. Gyorgy and T. Wagner- Jauregg/ who 

 isolated from egg-white a compound with a strong yellowish-green 

 fluorescence. They called this substance " ovofiavine ", and showed 

 that it stimulated the growth of rats, 100 fig. a day producing an 

 increase in weight of about 10 g. per week. In the issue of the Berichte 

 containing the paper by Kuhn et al., P. Ellinger and W. Koschara ^ 

 reported the presence of similar fluorescent substances in milk, liver, 

 kidney, urine, muscle, yeast and certain plant materials, and described 

 the isolation of a crystalline fluorescent substance from whey. They 

 proposed the name " lyochrome " for the group to which all these 

 substances belonged, and both Kuhn and Koschara suggested that the 

 pigments might be related to the " yellow enzyme " discovered in 

 yeast by O. Warburg and W. Christian ^ in the preceding year. Kuhn 

 showed, in fact, that one and the same substance, lumiflavine, was 

 produced by irradiation of the yellow enz5ane and of ovoflavine. 

 Shortly after the publication of these papers, L. E. Booher * reported 

 the preparation of a concentrate from whey powder that showed a 

 strong yellow fluorescence and had growth-promoting properties for 

 the rat. 



The isolation of fluorescent pigments from milk, liver, kidney, 

 urine, malt, dandelion flowers, lucerne, egg-yolk and the retinae of 

 fishes was reported by Kuhn et al.,^ by Karrer et al.,^ by W. Koschara,^ 

 and by H. von Euler and E. Adler,^ and by Itter et al.^ 



At first these pigments were given specific names according to their 

 origin, e.g. ovoflavine, lactoflavine, uroflavine and hepatoflavine, 

 until it was realised that they were probably identical with one 

 another. This was confirmed by a direct comparison of some of the 

 compounds, but several were isolated in such small amounts that a 

 rigid proof of identity was not possible. The substance was generally 

 referred to as lactoflavine, until its constitution had been determined, 

 when the name was altered to riboflavine. Shortly afterwards, the 

 terminal " e " was dropped to avoid confusion with acriflavine and 

 its analogues, which have an entirely different type of structure. 

 Recently, however, there has been a tendency to revert to the original 



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