Discovery of Antimicrobial Oligoindoles from a Cold-Seep-Derived Halomonas Strain.

Mining bioactive secondary metabolites from microorganisms originating from deep-sea cold seep holds significant potential for discovering novel drug lead compounds. In this study, three known indole derivatives (1-3) were isolated from cold-seep-derived Halomonas meridiana OUCLQ22-B7. Subsequently, two-new indole dimers, meribisindole A (4) and meribisindole B (5), with nine known metabolites (6-14) were obtained via indole precursor feeding strategy. The structure of these compounds was elucidated via a combination of spectroscopic methods and circular dichroism (CD) measurement. Antimicrobial assays revealed that compounds 4, 7 and 8 exhibited potent inhibitory activity against Fusarium oxysporum CICC 41029 with minimal inhibitory concentrations (MICs) of 0.39-12.5 μg/mL, and compound 11 showed significant growth inhibition against Staphylococcus aureus CCARM 3090 with MIC value at 0.098 μg/mL.