CHEMICAL NATURE OF ANTIBIOTICS 



49 



copper in addition to the four most common 

 elements. One will note that there are no 

 known antibiotics of actinomycetes with a 

 molecule composed of only carbon and hy- 

 drogen. 



In the following review of the chemical 

 structure of the antibiotics of actinomycetes, 

 an effort has been made to group together 

 the antibiotics with similar structure. In 

 some cases the antibiotics are grouped to- 

 gether because they have an outstanding 

 functional group in common. For example, 

 chloramphenicol is discussed with bovinoci- 

 din because they both have a nitro group. 



In the chemical formulas used throughout 

 this book no pretention is made to show the 

 spacial arrangement of the atoms. 



Nitro Compounds 



BovinocidiN (/5-nitropropionic acid) has the 

 following structure: 



NOo 



I 

 CH2— CHo— COOH 



This substance, which is also produced by 

 higher plants and fungi, has weak anti- 

 my cobacterial activity . 



Somewhat more complicated chemically is 

 chloramphenicol, 



NO2 



> CHoOH 



I 

 CH(OH)— CH— XHCOCHCI, 



Its molecule, which contains nitrobenzene 

 and two atoms of nonionic chlorine, is very 

 active biologically. Chloramphenicol is ac- 

 tive against both gram-positive and gram- 

 negative bacteria, rickettsiae, and members 

 of the lymphogranuloma group of intracellu- 

 lar parasites. It can he synthesized chem- 

 ically in commercial (luantities. 



Azomi/cin, which is discussed under 

 miscellaneous monocyclic compounds, is also 

 a nitro compound. 



Straight -chained Diazo Compounds 



Azascrinc and DON are diazo derivatives 

 of amino acids. DON is G-diazo-o-oxo-L- 

 norleucine, 



N.— CH— CO— (CH,).,— CH— COOH 



NH2 



and azaserine is o-diazoacetyl-L-serine, 



N2— CH— CO— ()— CHo— CH— COOH 



i 

 NHo 



The antitumor activities of these two 

 similar compounds have aroused interest. 

 Both compounds also have modest anti- 

 microbial activity. Three compounds of 

 undetermined structure, diazomijcins A, B, 

 and C, are also aliphatic diazo compounds 

 with a similar type of biological activity. 

 Alazopcptin, a more complex substance, is a 

 peptide containing a-alanine and a diazo- 

 ketoamino acid. It has modest antitumor 

 activity. 



Elaiom>jcin is one of the few natural 

 products with an alipiialic azoxy linkage: 



CH0OCH3 



T I 



CH;,(CH,),,CH=CH— X=X— CH— CHOH— CH:, 



It is actix'c almost exclusively against myco- 

 bacteria. 



Miscclhmeous Monocyclic Compounds 



Qticstiomtjcin B is o-aminophenol, 

 OH 



XHo 



It has some antimycobacterial activity and 

 is believed to be the })uilding stone of another 

 antibiotic, questiomyciu A (O-aminophen- 

 oxazone), which will l)e discussed with the 

 actinomycins. 



Sarkomijcin is a simple cyclopentane 

 derivative, 



H2C=| ,— COOH 



o=L J 



