ANALOGUES 



aneurine, one part of which counteracted the effect of about forty 

 parts of the homologue. The homologue also decreased the survival 

 period of rats maintained on a diet low in aneurine. 



The isomer of aneurine in which the positions of the amino and 

 methyl groups in the pyrimidine ring were reversed had no vitamin 

 Bi activity.19 



Hetero-vitaxnins Bi 



A particularly interesting substance would be obtained by replacing 

 the thiazole ring with a pyridine ring. J. Finkelstein and R. C. 

 Elderfield ^^ synthesised two pyridine analogues, both of which were 

 stated to be inactive for rats at a dose of loo fig. per rat, whilst P. 

 Baumgarten and A. Dornow ^^ claimed to have prepared " hetero- 

 vitamin B^ ", i - (4'- amino- 2'-methyl- 5'-pyrimidyl-methyl)-3-^- 

 hydroxyethyl-2-methyl-py^idinium bromide hydrobromide : 



N=C . mi, 9^» 9^2 • C^^OH 



I I \ / 



CH3 . C C— CHa— N^ ^ 



N— CH Br • "^^ 



and its lower homologue, in which the methyl group was absent from 

 the pyridine ring ; these compounds were said to possess i/26th and 

 i/240th the activity of aneurine respectively. Subsequently, however, 

 they showed 22 that the compound was the a- and not the ^-hydroxy- 

 ethyl-pyridine analogue. A. H. Tracy and R. C. Elderfield ^3 then 

 announced the synthesis of a substance which they believed to be the 

 true pyridine analogue of aneurine, noting that the compound was 

 different in chemical properties from that of P. Baumgarten and 

 A. Dornow ^i and from that prepared by F. C. Smelkes,^* which had 

 been stated to possess some activity. The activity of this new com- 

 pound, called by them pyrithiamine, was tested by W. J. Robbins ^^ 

 on three different fungi. The growth of Phy corny ces Blakesleeanus 

 was not stimulated unless the thiazole half of aneurine was also present, 

 indicating that this fungus could .split the pyridine analogue and 

 utilise the pyrimidine half for synthesising aneurine from the added 

 thiazole compound. Pythiomorpha gonapodioides, which grows in the 

 absence of the thiazole half of the aneurine molecule if the pyrimidine 

 portion is present, was able to grow in presence of the pyridine analogue 

 only, presumably degrading it and then utilising the pyrimidine 

 portion. Phytophthora cinnamomi, which normally requires intact 

 aneurine, would not grow when this was replaced by the pyridine 

 analogue, even in presence of the pyrimidine or the thiazole portion. 



123 



