Bacillusin A, an Antibacterial Macrodiolide from <i>Bacillus amyloliquefaciens</i> AP183

Abstract

Bioassay-guided fractionation of the organic extracts of a <i>Bacillus amyloliquefaciens</i> strain (AP183) led to the discovery of a new macrocyclic polyene antibiotic, bacillusin A (<b>1</b>). Its structure was assigned by interpretation of NMR and MS spectroscopic data as a novel macrodiolide composed of dimeric 4-hydroxy-2-methoxy-6-alkenylbenzoic acid lactones with conjugated pentaene-hexahydroxy polyketide chains. Compound <b>1</b> showed potent antibacterial activities against methicillin-resistant <i>Staphylococcus aureus</i> and vancomycin-resistant <i>Enterococcus faecium</i> with minimum inhibitory concentrations in a range of 0.6 to 1.2 μg/mL. The biosynthetic significance of this unique class of antibiotic compounds is briefly discussed