Synthesis and in vitro antibacterial activity of catechol-spiramycin conjugates

Area of Science:

• Medicinal Chemistry
• Microbiology
• Drug Delivery

Background:

• Macrolide antibiotics like spiramycin and neospiramycin exhibit limited efficacy against gram-negative bacteria due to their inability to penetrate the outer membrane.
• Siderophores are high-affinity iron-chelating compounds that can facilitate bacterial entry, offering a potential strategy to overcome membrane barriers.

Purpose of the Study:

• To synthesize novel siderophore conjugates of spiramycin and neospiramycin.
• To evaluate the antibacterial activity of these conjugates against gram-negative bacteria.

Main Methods:

• Regioselective acylation was employed to link a dihydroxybenzoic acid siderophore ligand, via a carboxyl group spacer, to a hydroxyl function on spiramycin and neospiramycin.
• Preliminary biological evaluations were conducted under standard and iron-depleted conditions to assess antibacterial efficacy.

Main Results:

• The synthesis of novel siderophore-macrolide conjugates (spiramycin and neospiramycin) was successfully achieved.
• Preliminary biological data indicated that the antibacterial activity of the novel conjugates was comparable to that of the parent macrolide antibiotics, spiramycin and neospiramycin.

Conclusions:

• Siderophore conjugation represents a viable strategy to potentially enhance the delivery and efficacy of macrolide antibiotics against gram-negative bacteria.
• Further research is warranted to optimize these conjugates and confirm their therapeutic potential in overcoming outer membrane barriers.