Actinomycetes 12-membered ring macrolides

Two 8-membered ring macrolides, octalactins A (Fig. 2, 1) and B, are known to be produced by marine Streptomyces (see Chapter 2, Section II.A.l) [7]. Only one 9-membered ring macrolide, juglorubin (2), has been reported to be produced by actinomycetes [8]. 

Fig. 2. Structures of 8- to 10-membered ring macrolides produced by actinomycetes.

Williams, P.G., Miller, E.D., Asolkar, R.N., Jensen, P.R., and Fenical, W. (2007b) Arenicolides A-C, 26 membered ring macrolides from the marine actinomycete Salinispora arenicola. J. Org. Chem., 72, 5025-5034. 

Actinomycetes are the largest source of natural macrolides. They produce more than three hundred 16-membered macrolides (including spiroacetals) and nearly one hundred 14-membered macrolides (Table III). They also produce various sizes of macrolides up to a 60-membered ring, including polyene macrolides, macrodiolides, macrotetrolides, and immunosuppressive macrolide lactams. Compounds already described in the first edition of this book [1] are mentioned here briefly. 

Bacteria other than actinomycetes also produce macrolides. About 100 macrolides have been produced by myxobacteria, and about 40 by other bacteria (Tables IV and V). Myxobacteria produce macrolides with up to 42-membered rings including polyene macrolides, macrodiolides, macrolide lactams, and oxazole-containing macrolides. The other bacteria produce macrolides with up to 26-membered rings including polyene macrolides, macrodiolides, and macrotriolides. 

Macrolides are a group of antibiotics, produced in nature by many actinomycetes strains, that are composed of a 12- to 16-membered lactone ring, to which one or more sugar substituents is attached. They target the peptidyl transferase center on the 50S ribosomal subunit and function primarily by interfering with movement of the nascent peptide away from the active site and into the exit tunnel. 

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