The Concentration and Probable Chemical Nature of Vitamin G

Attempts to concentrate and isolate or identify vitamin G have disclosed many experimental difficulties which have greatly retarded progress in the investigations of the chemical nature of vitamin G.It would seem that these difficulties are now sufficiently well recognized as not to require further elaboration here.Most investigators active in the study of the chemical nature of vitamin G (Bz) are of the opinion that vitamin G is a nitrogenous compound and certain of these believe that it may also contain sulfur.Very recently Kuhn and his coworkers (1, 2) have reported the isolation of the yellow pigment from egg white which they have named OvoJlavin and which they believe to be one factor of the vitamin G (B,) complex.This pigment was obtained by a method including adsorption and precipitation procedures, in crystalline form; elementary analysis indicated an empirical formula, C&LoNzOa.In their second publication they report that this pigment substance requires a further supplementary fraction obtained from autoclaved yeast in order to promote growth in vitamin G test rats.Previous work (3) in this laboratory has shown that a N-fold concentrate of the vitamin G in skim milk powder may be prepared by a simple extraction with boiling 93 to 94 per cent (by weight) ethyl alcohol.An attempt to concentrate the vitamin further by introduction of an ethyl ether precipitation procedure furnished evidence indicating that a separation of vitamin G factors had occurred at this step.The present study was designed to introduce only the mildest chemical operations, avoiding particularly precipitation proce-39