Iron Transport-Mediated Drug Delivery: Practical Syntheses and In Vitro Antibacterial Studies of Tris-Catecholate Siderophore–Aminopenicillin Conjugates Reveals Selectively Potent Antipseudomonal Activity

An artificial tris-catecolate siderophore with a tripodal backbone and its conjugates with ampicillin and amoxicillin were synthesized. Both conjugates exhibited significantly enhanced in vitro antibacterial activities against Gram-negative species compared to the parent drugs, especially against Pseudomonas aeruginosa . The conjugates appeared to be assimilated by an induced bacterial iron transport process as their activities were inversely related to iron concentration. The easily synthesized tris-catecolate siderophore has great potential for future development of various drug conjugates to target antibiotic-resistant Gram-negative bacteria.