ANALOGUES 



5 - j8 -hydroxyethyl - 4 - methyl - 3-[4'-(5'-methyl-imidazolyl)] -thiazolitim 

 chloride, 3-benzyl-5-j8-hydroxyethyl-4-methyl-thiazolium chloride, 4- 

 methyl-thiazole, 4: 5-dimethyl-thiazole, 5-j3-acetoxyethyl-4-methyl- 

 2-thiol-thiazole, 2-amino-4-methyl-thiazole and 4 : 5-dimethyl-2-thiol- 

 thiazole. It is difficult to see how some of these compounds could act 

 as precursors of aneurine, especially those compounds in which the 

 j3-hydroxyethyl group is lacking. It is more consistent with current 

 views concerning the biosynthesis of aneurine to regard these thiazole 

 compounds as having a general stimulating effect, rather than a 

 specific action due to their conversion into aneurine. 



5-j8-Hydroxyethyl-4-methyl-imidazole failed to support the growth 

 of pea-roots or of Phycomyces ^ so that the imidazole ring is apparently 

 not a substitute for the thiazole ring. 



The growth-promoting effects of a mixture of the thiazole and 

 pyrimidine portions of aneurine, observed with such micro-organisms 

 as Staphylococcus aureus, Polytomella caeca and Phycomyces Blakes- 

 leeanus (see page 108), were shown by E. and R. Abderhalden ^^ to 

 occur also with pigeons, vitamin B^-deficient birds showing a similar 

 response to that produced by aneurine ; the effect was more marked 

 after oral administration than after intramuscular injection. No 

 aneurine was synthesised from the two halves of the molecule by 

 pigeon tissues in vitro. 



The physiological activity of other pyrimidines and thiazoles was 

 tested by S. Morii,!^ who found that 4-amino-5-hydroxymethyl-2- 

 methyl-pyrimidine and the corresponding chloro- and bromomethyl 

 compounds produced convulsions in vitamin B^-deficient pigeons, 

 whereas 4-amino-5-aminomethyl-2-methyl-pyrimidine, 4-ethyl-2- 

 amino-pyrimidine, 4-amino-6-ethyl-pyrimidine, uracil, thymine, and 

 adenylic acid were inert. 5-jS-Hydroxyethyl-4-methyl-thiazole exerted 

 a marked curative action on vitamin B^-deficient pigeons, and this was 

 not enhanced by simultaneous administration of various pyrimidine 

 derivatives, a result not necessarily in conflict with that recorded by 

 E. and R. Abderhalden, who do not appear to have tested the com- 

 pounds separately. No curative effect was observed on administra- 

 tion of N-(4'-amino-2'-methyl-5'-pyrimidyl-methyl)-5-hydroxy-3 : 4- 

 bishydroxymethyl-6-methyl-pyridinium bromide hydrobromide or its 

 triacetate, or with acetopropyl alcohol given together with 4-amino- 

 2-methyl-5-thioformamidomethyl-pyrimidine or with methionol given 

 together with 4-amino-5-aminomethyl-2-methyl-pyrimidine hydro- 

 chloride. 



F. Schultz * prepared and tested on vitamin B^-deficient pigeons, 

 thirty-nine compounds closely related to aneurine. Of these, sixteen 

 showed some activity, one actually being more, though perhaps not 

 significantly more, active than aneurine. Assuming aneurine to have 



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