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Thuggacins, Macrolide Antibiotics Active against Mycobacterium tuberculosis : Isolation from Myxobacteria, Structure Elucidation, Conformation Analysis and Biosynthesis
Author(s) -
Steinmetz Heinrich,
Irschik Herbert,
Kunze Brigitte,
Reichenbach Hans,
Höfle Gerhard,
Jansen Rolf
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700269
Subject(s) - myxobacteria , stereochemistry , chemistry , thiazole , lactone , macrolide antibiotics , side chain , mycobacterium tuberculosis , polyketide , ring (chemistry) , methyl group , biosynthesis , antibiotics , biochemistry , group (periodic table) , erythromycin , bacteria , tuberculosis , biology , genetics , organic chemistry , enzyme , medicine , polymer , pathology
Two novel antibiotics, thuggacin A ( 1 ) and B ( 2 ), were isolated from the myxobacterium Sorangium cellulosum . 1 and 2 are unique thiazole‐containing macrolides with side chains on both sides of the lactone group. Upon standing in solution, thuggacin A ( 1 ) rearranges by acyl migration of the lactone group to give a mixture with thuggacins B ( 2 ) and C ( 3 ). NOEs and vicinal coupling constants within the lactone ring provided distinct data for the generation of a structure model by PM3 calculations, which allowed an analysis of the conformation in solution and the relative configuration of six asymmetric centres. A minor sorangium metabolite was identified as 13‐methyl‐thuggacin A ( 4 ). Furthermore, two natural thuggacin variants, 5 and 6 , were found in another myxobacterium, Chondromyces crocatus . In these variants, one side chain is replaced by a methyl group and a hydroxy group is repositioned to give a primary alcohol at the former methyl site, in an α position with respect to the thiazole ring. 1 proved to be active against clinical isolates and reference strains of Mycobacterium tuberculosis. Preliminary studies on the mechanism of action indicate inhibition of the cellular electron‐transport chain.