Spermine conjugates of non-steroidal anti-inflammatory drugs as potent antibacterials against multidrug-resistant S....

The rapid emergence of multidrug-resistant (MDR) bacterial pathogens necessitates the development of new antibacterial chemotherapeutics with improved efficacy and additional therapeutic benefits. Here, in this study we have conjugated spermine with non-steroidal anti-inflammatory drugs (NSAID) as potent antibacterials with anti-inflammatory properties. Among the synthesized compounds, RNP-11, a gemini amphiphilic conjugate of spermine and flufenamic acid, exhibited potent antibacterial activity with minimum inhibitory concentrations (MICs) of 2-4 μg/mL against a broad panel of Staphylococcal and Enterococcus species, including clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). Interestingly, RNP-11 exhibited a superior post-antibiotic effect relative to vancomycin as the RNP-11 did not induce any detectable resistance even after thirty-three generations of bacterial exposure. Mechanistic investigations revealed a concentration-dependent membrane-disruptive antibacterial mode of action, wherein RNP-11 visibly disrupts and damages bacterial membranes at 5×MIC. Furthermore, RNP-11 retained the anti-inflammatory characteristics of its parent NSAID, displaying selective COX-2 inhibition and suppression of pro-inflammatory cytokine production. This dual-action capability allows the molecule to simultaneously eradicate pathogens and mitigate the host's inflammatory response. The therapeutic viability of this hybrid strategy was successfully validated in a murine skin-infection model, where RNP-11 achieved significant bacterial reduction of S. aureus. Collectively, these findings establish spermine-NSAID conjugation as an effective strategy for developing dual-action antibacterial agents for the treatment of persistent drug-resistant infections.