654 THE BIOCHEMISTRY OF B VITAMINS 



to tomato roots. Desoxypyridoxine (2,4-dimethyl-3-hydroxy-5-hydroxy- 

 methylpyridine) possesses growth-promoting activity for several micro- 

 organisms, but is an antagonist of pyridoxine for the rat and certain other 

 animals (p. 601). 2-Methyl-3-hydroxy-4-methoxymethyl-5-hydroxy- 

 methylpyricline and 2-methyl-3-hydroxy-4,5-epoxydimethylpyridine are 

 utilized effectively by Lactobacillus casei, but are inactive for Sac- 

 charomyces carlsbergensis. The relatively high activity of 2-methyl-3- 

 hydroxy-4,5-bis(bromomethyl) pyridine for both Lactobacillus casei and 

 Saccharomyces carlsbergensis is interesting. 



For many organisms, the triacetate of pyridoxine is as active as 

 pyridoxine, but this compound is not utilized by Lactobacillus casei. On 

 the other hand, both pyridoxine triacetate and tribenzoate are more 

 effective for Streptococcus faecalis R than is pyridoxine. Pyridoxine 

 diacetate is almost ten times as effective as pyridoxine for Streptococcus 

 faecalis R. These as well as some prior results indicated that compounds 

 exist which are considerably more active than pyridoxine for Streptococ- 

 cus faecalis R. 



Pyridoxamine and Pyridoxal. A naturally occurring form of vitamin 

 B 6 which was more active than pyridoxine was discovered by Snell, 

 Guirard and Williams, 33 who found that assays for the pyridoxine content 

 of natural extracts with Streptococcus faecalis R gave values for the 

 pyridoxine content several hundred to several thousand times as great as 

 could be accounted for on the basis of pyridoxine actually present. This 

 "pseudopyridoxine" was found to have properties similar to pyridoxine, 

 and tissues of animals deficient in vitamin B 6 also contained less "pseudo- 

 pyridoxine." 



It was demonstrated by Snell 34 that pyridoxine was almost inactive 

 unless autoclaved with the medium or with certain amino acids. Carpenter 

 and Strong ~ >6 independently found that mild oxidation of pyridoxine 

 yielded a substance with increased activity for Lactobacillus casei. 

 Snell 27, 35 had indicated that mixtures resulting from the reaction of 

 pyridoxine with animating agents or mild oxidizing agents were more 

 active for Streptococcus faecalis R than the original vitamin. The proper- 

 ties of the active substance indicated that both an amine and an aldehyde 

 derived chemically from pyridoxine were the active principles. With this 

 and additional evidence, the structures of the two substances were limited 

 essentially to four possibilities, which were synthesized in pure form by 

 Harris, Heyl and Folkers 36 by methods analogous to those used by Snell. 

 Biological tests of the synthetic compounds revealed that 2-methyl-3- 

 hydroxy-4-aminomethyl-5-hydroxymethylpyridine and 2-methyl-3-hy- 

 droxy-4-formyl-5-hydroxymethylpyridine were the active amine and 



