Design, Synthesis, and Antibacterial Evaluation of Rifampicin-Siderophore Conjugates

Area of Science:

• Microbiology
• Medicinal Chemistry
• Drug Discovery

Background:

• Antibiotic resistance is a growing global health threat.
• Gram-negative bacteria possess an outer membrane hindering antibiotic entry.
• Rifampicin is effective against Gram-positive bacteria but not Gram-negative pathogens.

Purpose of the Study:

• To develop novel rifampicin-siderophore conjugates.
• To enhance rifampicin's efficacy against Gram-negative bacteria.
• To investigate the structure-activity relationship of these conjugates.

Main Methods:

• Design and synthesis of rifampicin-siderophore conjugates.
• Evaluation of conjugate activity against Gram-negative pathogens.
• Structure-activity relationship analysis focusing on linker and catechol components.

Main Results:

• Several rifampicin-siderophore conjugates demonstrated enhanced activity against Gram-negative bacteria.
• Compound 33, featuring rifampicin linked to chlorocatechol via an ester, showed up to a 32-fold increase in activity.
• The structural characteristics of the linker and catechol moiety are critical for conjugate efficacy.

Conclusions:

• Rifampicin-siderophore conjugates represent a promising strategy to overcome Gram-negative bacterial resistance.
• The "Trojan horse" approach effectively delivers antibiotics by utilizing bacterial iron uptake systems.
• Optimized conjugate structures, like compound 33, can significantly broaden the therapeutic potential of existing antibiotics.