CHEMICAL NATURE OF ANTIBIOTICS 



55 



the data pul)lished on the various polyenes 

 can he found in Part 1^ of this book. One 

 should keep in mind that many of the poly- 

 enes described may be synonyms. This will 

 be clarified l)y further studies in tlie chem- 

 istry of these interesting compounds. 



Macrolides 



Certain antibiotics, which are active 

 mainly against gram-positive Ixicteria, are 

 called macrolides because each has a large 

 macrocychc lactone ring. One will note that 

 the polyenic macrocyclic lactones also ha\'e 

 this structtiral feature. Since the nonpolyenic 

 macrocyclic lactones were described first, the 



Table 17 

 List of niacrolide antibiotics 



Antibiotic 



Amaromycin 



Angolamycin 



Antibiotic PA 108. . 

 Antibiotic PA 133A 

 Antibiotic PA 133B. 

 Antibiotic PA 148.. 



Carbomvcin 



Carbomycin B 



Erythromycin 



Erythromycin B . . . 

 Erythromycin C . . . 



Foromacidin 1) 



(rri.seomycin 



Leucomycin 



Leucomycin B 



Methymycin 



Miamycin 



Narbomycin 



Neomethym\cin. . . . 



Oleandomycin 



IMcromycin 



Proactinomycin A.. 

 Proactinomycin B.. 

 Proactinomycin C. 



Spiramycin I 



Spiramycin II 



Spiramycin III 



Tylosin 



Tertiomycin A 



Tertiomycin B 



Tenichiomvcin 



Empirical formula 



C25H39O7N 



C4 9-6irl>j7-ill' )l8-^ 



CssHesOu-^ 



C2 5H4,,06N 

 C.,5H4 50,„X 



CssHeoOisN 



C42H670l6^^ 



C41-42H67-69O15-I6N 



C:i7H670i:iN 

 C37H67O1.N 



C36H6.5O1.-iN 



C28H48O8N 



C33-38H54-66O11-13N 



C41H69O16N 



C20H4..O7N 



C.:8H4707N 

 C25H4.3O7N 



C35H6I-63O12N 



C25H43O7N 



C2-H47O8N 



C2sH4a08N 



C24H4,06N 



C45H78O10N2 



C47H8oO,6N2 



C48H82O16N2 



C45-46H75-79O17-I8N 



C42H69O16N 



C43H71O17N 



C28H43O16N 



name "macrolide" must be reserved for this 

 group of sul)stances. Howe\'er, the polyenic 

 macrocyclic lactones can be called "polyenic 

 macrolides." 



Picromycin was the first compound defi- 

 nitely known to belong to the macrolides, 

 but the first antibiotics of this group to be 

 isolated were the proactinomycins reported 

 by CJardner and Chain in l'.)42 (see also 

 Marston, 1949). 



The macrolides are soluble in most organic 

 solvents and, because of their amino sugar 

 moiety, they are basic. Because of unsatura- 

 tion in the molecule, most of these com- 

 pounds absorb ultraviolet light. Table 17 

 indicates the variation in the size of the 

 molecule from a carbon skeleton composed 

 of 24 carbons atoms (proactinomycin C) to 

 one composed of some 50 carbon atoms 

 (angolamycin). The spiramycins are uni(iue 

 in that they contain two atoms of nitrogen 

 per molecule. 



Enjthromiicin is the best known of the 

 macrolides. It has the following structure: 



()H 



CH3CH: 



CH3O 



It contains two sugar moieties — a netitral 

 sugar, cladinose, and an amino sugar, de- 

 sosamine. Erythromycin B has a similar 

 structure except that one of the hydroxyl 

 groups (marked above with a star) is re- 

 placed by a hydrogen atom, and erythro- 

 mycin V difters in that the cladinose moiety 



