We evaluated purified 6 for both biofilm inhibition and disruption properties in dose-dependency against S. aureus. Compound 6 inhibited biofilm formation with an IC50 of 34.1 μg/mL with no impact on overall growth of the pathogen (Fig. and Fig. ) and exhibited only minimal biofilm disruption activity (30% disruption at 200 μg/mL -Fig. ). However, neither S. aureus nor P. aeruginosa are ecologically relevant as they are not commonly found in the marine environment. Thus, we investigated the ability of 6 to suppress biofilm growth of bacterial strains found associated with moon snail egg masses. Compound 6 was screened against five biofilm forming bacterial strains that were isolated from the same source as P. piscicida, and these strains represent three genera (Bacilli, Actinobacteria, and Alphaproteobacteria) (Fig. Siderophores are known to inhibit biofilm formation through sequestration of iron, 30 therefore we presume that 6's affinity for Fe 3+ correlates to its biofilm inhibition properties. Iron, an essential nutrient, is critical to many life processes, including bacterial biofilm formation. Under physiological conditions, iron is mostly in its insoluble form (Fe 3+ ) and not readily bioavailable. Hence, siderophores have evolved to have high affinity for Fe 3+ to capture this essential element. We hypothesize that 6 inhibits biofilm formation in S. aureus by preventing the uptake of Fe 3+ by chelating it. Chelator 6 binds iron in a 1:1 ratio, thus iron concentration above that of 6 should curtail its biofilm disruption activity. Recent work supports this hypothesis as increased concentration of available iron serves as a signal for biofilm development in P. aeruginosa. When P. aeruginosa is grown with low concentrations of iron, cells cannot form mature biofilms. We tested this hypothesis by repeating the biofilm formation assay with S. aureus in media with and without FeCl3 (12.5 μM). FeCl3 supplementation abolished 6's antibiofilm activity (Fig. ). Thus, confirming that 6 is impacting S. aureus biofilm by reducing overall Fe 3+ bioavailability.