Mindapyrroles A-C, Pyoluteorin Analogues from a Shipworm-Associated Bacterium

Three new pyoluteorin analogues, mindapyrroles A-C (1-3), were purified from Pseudomonas aeruginosa strain 1682U.R.0a.27, a gill-associated bacterium isolated from the tissue homogenate of the giant shipworm Kuphus polythalamius. Mindapyrroles B and C inhibit the growth of multiple pathogenic bacteria, with mindapyrrole B (2) showing the most potent antimicrobial activity and widest selectivity index over mammalian cells. Preliminary structure-activity relationship analysis showed that dimerization of the pyoluteorin moiety through a C-C linkage is detrimental to the antimicrobial activity, but addition of an aerugine unit in the methylene bridge is favorable for both the antimicrobial activity and selectivity index.