KARL FOLKERS 



natural materials which were several hundred to several thousand times 

 the values obtained by different biological or chemical methods. 

 Other experiments showed that the factor responsible for the increased 

 activity was very similar in properties to pyridoxine, and they pro- 

 visionally named the factor "pseudopyridoxine." Subsequent to these 

 studies, Williams stated (65) in his review on the water-soluble vitamins 

 for 1942: "Contrary to the common impression, the chemistry of 

 vitamin Be is in a highly unsatisfactoiy state. There is no question, 

 of course, regarding the fundamental chemistry of pyridoxine, that 

 pyridoxine occurs naturally, or that pyridoxine has vitamin properties. 

 The serious question is whether the vitamin Be activity of tissues is due 

 solely to pyridoxine or whether there are other substances (probably 

 closely related) which serve equally well or better." 



After about two years of further research at the University of 

 Texas on the one or more substances in natural materials tentatively 

 called "pseudopyridoxine," Snell (45) concluded that one of these 

 substances was probably an aldehyde and another was probably an 

 amine. These studies were concerned essentially with the effect of 

 certain selected chemical treatments on the biological activity of pyri- 

 doxine for Streptococcus faecalis R, Lactobacillus casei, and Saccharomyces 

 cerevisiae. After consideration of the functional groups of pyridoxine 

 which might be involved in the reactions, it was believed that the bio- 

 logically active aldehyde would have one of three structures, VIII, 

 IX, or X, and the biologically active amine would have the corre- 

 sponding structure, XI, XII, or XIII. 



CH2OH 

 HO/\cHO 



(VIII) 



CH20H 



H0/\CH2NH2 



CH: 



\N^ 



(XI) 



CHO 

 H0/\CH20H 



CH 



(IX) 



CH2NH2 

 H0/\CH20H 



CH 



(XII) 



CHO 



HO/\cHO 



CHsi^j^^ 

 (X) 



CH2NH2 

 H0/\CH2NH2 



CHi 



(XIII) 



Collaborative studies by Harris, Heyl, and Folkers (15) on the 

 structure and synthesis of the active aldehyde and active amine resulted 



98 



