Hemibastadin Alkaloid Analogues as Potential Anti-Biofilm Leads against Multi-Species Biofilms

A focused library of hemibastadin-inspired analogues was generated through a modular click chemistry strategy to assess their potential as antibiofilm agents targeting marine multispecies bacterial communities. The resulting triazole-amide derivatives (4a-h) were evaluated for their ability to inhibit initial bacterial adhesion and subsequent biofilm development in three Gram-negative strains. Clear structure-activity relationships emerged, highlighting the critical influence of aromatic bromination and methylation patterns on biofilm inhibition. Among the series, compounds 4g and 4h exhibited the most pronounced activity, with EC50 values of 25 - 90 μM, while exerting minimal effects on planktonic bacterial growth. Their potency was further confirmed in an original multispecies biofilm model, where both analogues achieved near-complete suppression of biofilm formation without detectable cytotoxicity, except toward a single more sensitive strain. Taken together, these findings identify 4g and 4h as promising nontoxic leads for the development of cobiocidal or coantibiotic strategies aimed at preventing persistent biofilms on medical or industrial surfaces. The modularity of the synthetic route and the clear SAR trends provide a solid foundation for future optimization.