VITAMIN RESEARCH 



in the synthesis of aldehydes VIII and IX and amines XI and XII. 

 Biological tests on these synthetic compounds by Snell (46) showed that 

 the biologically active aldehyde was 2-mcthyl-3-hydroxy-4-formyl-5- 

 hydroxymethylpyridine (IX), and that the biologically active amine 

 was 2-methyl-3-hydroxy-4-aminomethyl-5-hydroxymethylpyridine (see 

 XII). The active aldehyde and amine were given the trivial names 

 "pyridoxal" and "pyridoxaminc," respectively. The microbiological 

 assays showed that pyridoxal was about 1400 times more active, and 

 pyridoxamine about 10 times more active, than pyridoxine hydro- 

 chloride for promoting the growth of L. casei. Pyridoxamine was 

 about 8000 times more active, pyridoxal was about 5500 times more 

 active, in promoting the growth of S. Jaecalis R, than was pyridoxine 

 hydrochloride. The comparative activity of pyridoxal, pyridoxamine, 

 and pyridoxine for Saccharomyces carlsbergensis was of the same order of 

 magnitude. 



Evidence for the occurrence of pyridoxal and pyridoxamine in 

 natural extracts was secured by Snell (47) by development of a differen- 

 tial microbiological assay technique with the three organisms mentioned 

 above and application of the assay to extracts of natural materials. 

 Further evidence for the existence of pyridoxal and pyridoxamine in 

 nature was secured by studying the effect of certain chemical treat- 

 ments upon the "pyridoxine, pyridoxal, and pyridoxamine fractions" 

 in comparison with the effect of these treatments upon the synthetic 

 vitamins. 



Vitamin Be was originally considered to be a single pyridine 

 derivative, pyridoxine. It may now be considered, as a result of 

 these combined microbiological and organic chemical studies, as a 

 name which designates a group of vitamins, i. e., the "vitamin Be 

 group." Pyridoxal and pyridoxamine may occupy a place of equal 

 or greater importance in this group as compared with that of pyri- 

 doxine. 



In retrospect, it is interesting to note that, in the original 

 isolation work, Keresztesy and Stevens (25) and Lcpkovsky (29) used 

 rice bran as the source of their vitamin Be, while Kuhn and Wcndt 

 (28) and Gyorgy (11) used yeast as their source of the crystalline 

 vitamin Be (pyridoxine). Snell's microbiological differential assays 

 showed (47) that a rice-bran concentrate contained far more pyri- 

 doxine fraction than pyridoxal or pyridoxamine fractions, whereas 



99 



