Utilization of analogues of riboflavin by the riboflavin-deficient chick embryo.

Detailed studies of the biological activity of several analogues of riboflavin in the riboflavin-deficient chick embryo were undertaken to extend our knowledge of the comparative biochemistry of these flavins. The riboflavin-deficient eggs were produced by hens homozygous for an autosomal recessive gene (rdrd). 7-Ethyl-8-methyl-flavin was found to be an adequate replacement for riboflavin in che chick embryo, a finding which mimics its effect in the riboflavin-deficient rat. 7,8-Diethyl-flavin was found to be an antagonist in the chick embryo as had been found to be true in the rat. 7-Methyl-8-ethyl-flavin can not be used as a replacement for riboflavin in the chick embryo and further, it inhibits the utilization of riboflavin in normal eggs. 7-Methyl-8-ethyl-flavin had been found to be an adequate replacement for riboflavin in the riboflavin-deficient rat. The classes mammalia and aves are clearly different in respect to the utilization of this flavin.