392 BACTERIOLOGICAL CHEMISTRY 



latter is the amide of phenazine-1-carboxylic acid, 

 N CONH2 



. On reduction with zinc dust in water 



N 

 it gives the orange -yellow, crystalline dihydrophenazine- 

 1-carboxylamide, m.p. 192-4° C. Chlororaphin is com- 

 posed of one molecule of oxychlororaphin and one molecule 

 of dihydrophenazine-1-carboxylamide and can be pro- 

 duced synthetically by combining the components in 

 acetic acid solution. Chromobacterium iodinum gives the 

 pigment, iodinin, which is the N,N' dioxide of a dihy- 

 droxyphenazine 



O 



II 



N OH 



/ 8 



%. 



OH 



2 I 



3 



4 



N 



The positions of the two hydro xyl groups is not known 

 but they are probably not at positions 2:3 or 2 : 5. 

 Iodinin, like pyocyanin and chlororaphin, is inhibitory to 

 bacteria, 2/xg/ml. being sufficient to inhibit the gro\vth of 

 Streptococcus pyogenes. The effect can be reversed by the 

 action of hydroxy-anthraquinones or by 2 -methyl- 1 : 4- 

 naphthoquinone. It is possible that iodinin and the 

 other phenazine derivatives interfere with the mechanism 

 of hydrogen transfer which involves quinones, by reacting 

 at the same enzyme centres, in virtue of their similarity 

 in structure. 



The human tubercle bacillus produces a yellow 

 crystalline pigment, phthiocol, shown to have the 

 constitution, 3-hydroxy-2-methyl-l:4-naphthoquinone, 



