Chapter VIM D 



THE VITAMIN B 6 GROUP 



Although a dermatitis, termed acrodynia, which is characteristic of 

 vitamin B 6 deficiency, was observed as early as 1926 in rats fed a deficient 

 diet, 1 it was not until 1934 that Gyorgy 2 established that the "rat pel- 

 lagra preventitive" factor was a new B vitamin (vitamin B 6 ) ; it was 

 subsequently isolated in crystalline form independently in five different 

 laboratories. 3-7 However, in 1932 Ohdake 8 isolated from rice polishings 

 a compound apparently identical with vitamin B 6 , but did not recognize 

 it as a vitamin. 



The structure of vitamin B 6 indicated below was first elucidated by 

 Kuhn and co-workers 9 < 10, 11 and subsequently was confirmed by inde- 

 pendent work of other laboratories. 12-15 



CH 2 OH 



CH 2 OH 



vitamin B 6 (pyridoxine, adermin) 



The synthesis of vitamin B 6 was accomplished shortly afterward by 

 Harris and Folkers, 16 by Kuhn and co-workers, 17 and by Morii and 

 Makino. 18 



Specificity 



During the proof of structure and synthesis of vitamin B 6 , a number of 

 structurally related compounds were prepared and tested for vitamin B 6 

 activity. The activities of these compounds in replacing vitamin B 6 for 

 various organisms are indicated in Table 35. 



Although many of the organisms respond similarly to the various ana- 

 logues of pyridoxine, there are a few instances which contrast markedly. 

 Thus, 2-ethyl-3-hydroxy-4,5-bis(hydroxymethyl) pyridine, which is as 

 active as pyridoxine for stimulation of growth of excised tomato roots, in- 

 hibits the utilization of pyridoxine by Ceratostomella ulmi; but 2-methyl- 

 3-hydroxy-4-ethoxymethyl-5-hydroxymethylpyridine, which is 1 to 5 per 

 cent as active as pyridoxine for Ceratostomella ulmi, is quite injurious 



