182 CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 



CH3O.C C=CHp H 



HC CH3 



I 



I I 



c 



ZC C=CH\ HOC CH 



ri2C CH.CO 

 O 



/ 



COOH 

 PENICILLIC ACID CLAVACIN 



HC C.CH2OH 



KOJIC ACID 



PHENAZINE 



FUMIGATIN 



CONH2 



CHLORORAPHIN 



Figure 18. Structural formulae of some antibiotic substances. 



lodinin is a deep purple-bronze pigment, m.p. 236° C. (Figure 18). 

 It is produced by Ch. iodinum {S9l) and is excreted into the medium. 

 It is insoluble in water and in acids but soluble in alkali, and is phenolic 

 in character. It is dissolved in chloroform. It is active against S. hemo- 

 lyticus, less so against S. aureus and other bacteria. 



Violacein, a purple pigment, is produced by Ch. violaceum. This 

 pigment is active against gram-positive bacteria, except CI. welchii; it 



