Rational molecular hybridization of indole-vinyl-substituted 4,5-diphenyloxazolium derivatives enables dual membrane and intracellular targeting for broad-spectrum antibacterial activity.

The escalating crisis of antibiotic resistance poses a severe threat to global public health systems and food safety, which have substantially compromised the therapeutic efficacy of existing antibacterial agents. In this study, a rational molecular hybridization strategy was employed to design and identify a novel amphiphilic small-molecule antibacterial candidate, H14d. In vitro studies demonstrated that H14d exhibits potent broad-spectrum antibacterial activity (MIC = 0.125-4 μg/mL), with MIC values of 0.25 μg/mL against Methicillin-resistant Staphylococcus aureus ATCC43300 (MRSA) and 2 μg/mL against Acinetobacter baumannii ATCC19606. In addition, H14d displayed rapid bactericidal kinetics, a low propensity for resistance development, favorable biosafety profiles, and an exceptional ability to significantly reduce mature bacterial biofilms. Mechanistic investigations revealed that H14d specifically binds to phosphatidylglycerol (PG), a key phospholipid component of bacterial cell membranes, while concurrently inhibiting the essential cell division protein FtsZ, thereby exerting antibacterial activity through a dual-target mode of action. Pharmacokinetic studies showed that H14d displayed stable elimination kinetics (t1/2 = 10.6-10.9 h) and a large apparent volume of distribution in mice. In vivo efficacy evaluations further demonstrated that H14d outperformed the frontline clinical antibiotic linezolid in a MRSA-infected Galleria mellonella model and multiple murine infection models. Collectively, this study provides valuable insights for the treatment of drug-resistant infections and offers a rational framework for the design and development of next-generation new antibacterial agents.