| Summary: | Chemical investigations of a marine sponge-associated <i>Bacillus</i> revealed six new imidazolium-containing compounds, bacillimidazoles A–F (<b>1</b>–<b>6</b>). Previous reports of related imidazolium-containing natural products are rare. Initially unveiled by timsTOF (trapped ion mobility spectrometry) MS data, extensive HRMS and 1D and 2D NMR analyses enabled the structural elucidation of <b>1</b>–<b>6</b>. In addition, a plausible biosynthetic pathway to bacillimidazoles is proposed based on isotopic labeling experiments and invokes the highly reactive glycolytic adduct 2,3-butanedione. Combined, the results of structure elucidation efforts, isotopic labeling studies and bioinformatics suggest that <b>1</b>–<b>6</b> result from a fascinating intersection of primary and secondary metabolic pathways in <i>Bacillus</i> sp. WMMC1349. Antimicrobial assays revealed that, of <b>1</b>–<b>6</b>, only compound <b>six</b> displayed discernible antibacterial activity, despite the close structural similarities shared by all six natural products.
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