New aspirin-chitosan conjugates as potential anti-Staphylococcus aureus agents

Two novel aspirin-chitosan conjugates were successfully designed and synthesized: A phenyl acetate derivative (PAD)/chitosan conjugate and an acetoxybenzoate derivative (ABD)/chitosan conjugate. The conjugates were prepared via freeze-drying methodology, where chitosan was reacted with the phenyl acetate derivative (PAD) 3a and the acetoxybenzoate derivative (ABD) 3b through nucleophilic attack of chitosan's amino groups on the carbonyl carbons of the aspirin-containing derivatives, forming stable amide linkages. The resulting conjugates were comprehensively characterized using infrared spectroscopy (IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) to confirm successful conjugation and evaluate structural properties. Antibacterial activity was assessed against methicillin-resistant Staphylococcus aureus (MRSA) using colony-forming unit (CFU) assays. Results demonstrated that the Cs/3a conjugate exhibited superior antibacterial efficacy, achieving a significant reduction in S. aureus growth compared to other formulations. These findings suggest that aspirin-chitosan conjugation represents a promising strategy for developing antimicrobial biomaterials with enhanced therapeutic potential against drug-resistant bacterial pathogens.