Bacillimidazoles A-F, Imidazolium-Containing Compounds Isolated from a Marine .

Chemical investigations of a marine sponge-associated revealed six new imidazolium-containing compounds, bacillimidazoles A-F (-). 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 -. 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 - result from a fascinating intersection of primary and secondary metabolic pathways in sp. WMMC1349. Antimicrobial assays revealed that, of -, only compound displayed discernible antibacterial activity, despite the close structural similarities shared by all six natural products.