152 OXIDATION-REDUCTION POTENTIALS 



CHLOROMYCETIN, CHLORAMPHENICOL 



Chloromycetin has several special claims to interest. It is the first useful anti- 

 biotic to be synthesised so that we shall not be dependent upon very costly fermenta- 

 tion methods of production. Fermentation methods are not necessarily expensive, 

 but the very small yields and delicate nature of many antibiotics have made their 

 bulk production difl&cult. The distinction between chemotherapeutic agents and 

 antibiotics is rapidly disappearing and " chloramphenicol," the name given to the 

 synthetic product, has made the distinction between them even more narrow. 

 Chloromycetin is remarkable in being a nitro-benzene derivative, hitherto not described 

 in a natural product. It also contains dichloracetic acid in a side chain, an unusual 

 but not unique occurrence. The structural formula of this relatively simple com- 

 pound is • — 



NO2 



CHOH 



(!:h.nh.co.chci2 



Chloromycetin 



Its full name is (l)-,//-l-p-nitrophenyl-2-dichloroacetamidopropane-l : 3-diol. 



The chief value of Chloromycetin at present is in the treatment of louse-borne 

 typhus (due to infection with Rickettsia -proivazeki) and scrub-typhus. A team of 

 workers in Parke-Davis laboratories have been responsible for this interesting work 

 (Ehrhch, Bartz, Smith, Joslyn and Burkholder, 1947 ; Smadel and Jackson, 1949). 

 The drug may also be of value in typhoid fever. 



OTHER ANTIBIOTICS 



In view of its interest and importance frequent further developments in this 

 field may be anticipated, but a few of the many products described to date may be 

 briefly mentioned. 



GRAMICIDIN AND TYEOCIDINE 



Isolated from Bacillus brevis with the idea of finding an agent active against the 

 Gram-positive complex (Dubos and Cattaneo. 1939), these polypeptides contain 

 many d-(unnatural) amino acids (Hotchkiss, 1944). Their composition has been 

 determined by differential hydrolysis and the order in which they occur determined 

 with the aid of chromatographic analysis. The polypeptides are too toxic for 

 parenteral use. 



LICHENIFORMIN 

 Callow and Hart (1946) isolated this group of polypeptides from B. licheniformis. 

 Licheniformin is very active against C. diphtherim and other bacteria in vitro, but is 

 rather toxic to guinea-pigs (Hewitt, 1948). 



