Flavin and the pellagra-preventing factor as separate constituents of a complex vitamin B2

THE observations to be recorded in this paper arose in quite an indirect manner from enquiries in progress in this Laboratory on certain interrelations between vitamin function and redox systems on one side and cell activity on the other. (This work has since been continued in conjunction with Dr S. N. Ray and Dr P. Gyorgy; and one aspect of it is dealt with in an accompanying paper [Ray et al., 1935].) In the course of these investigations it was observed incidentally that rats fed on certain diets deficient in " vitamin B2 ", modelled on the cataractproducing diet of Langston and Day [1933], developed symptoms of severe and characteristic pellagra in a large proportion of cases. As a necessary preliminary to the further prosecution of this work, and also in order to help to clarify the present position with regard to flavin and vitamin B2, it was thought desirable to examine the nature of the several factors concerned in restoring growth and preventing pellagra on these dietary regimens. As will be shown, the results obtained have confirmed the conclusion of Gyorgy [1934; 1935] that flavin is not the "rat antipellagra factor". It possesses vitamin B2 activity in the sense that it is partly responsible for the growth-promotion observed when the usual natural sources of "heat-stable, growth-promoting vitamin B2" are added to the rat's diet as the supplement to vitamin B1.