488 



VITAMIN Bi-i 



the first time. The antimetabolite properties of thirty-five of these com- 

 pounds were tested against bacteria, chiefly Staphylococcus aureus. Conver- 

 sion of one amino group to alkylamino or to acylamino resulted in elimina- 

 tion of the toxic properties. The replacement of an amino group by nitro 

 or hydroxyl gave active growth inhibitors. As the structure of the anti- 

 metabolite became further removed from dimethyldiaminobenzene the 



TABLE XVIII 



This was the largest concentration which could be dissolved in test media. 



toxic properties became irreversible by dimethyldiaminobenzene. How- 

 ever, these compounds still showed a marked reduction in the synthesis 

 of vitamin B12 in growing cultures of B. megatherium just as dichloro- 

 diaminobenzene has been found to do.^* 



Beiler et al.^^ report that treatment of a dilute solution of vitamin B12 

 with hydrogen peroxide formed an antagonist of vitamin B12. The inhibi- 

 tory properties of the reaction mixture were qualitatively competitively 



31 J. M. Beiler, J. N. Moss, and G. J. Martin, Science 114, 122 (1951). 



