Synthesis and antibacterial activity of fluoroquinolones with sterically hindered phenolic moieties

Fluoroquinolone antibiotics (norfloxacin, ciprofloxacin, and moxifloxacin) modified at the piperazine ring by sterically hindered phenolic moieties were synthesized and evaluated for antibacterial activity. It was found that this modification can lead to an increase in the antibacterial activity against Gram-positive strains of the bacteria Staphylococcus aureus ATCC 29213 and St. epidermis compared to parent fluoroquinolones. Modified compounds additionally containing the phosphonate moiety exhibit the highest activity against St. epidermis. Moxifloxacin containing the 3,5-di-tert-butyl-4-hydroxybenzyl moiety is more active against Escherichia coli ATCC 25922 than all the characterized unmodified fluoroquinolones. Ciprofloxacin derivatives bearing sterically hindered phenolic moieties exhibited high activity against clinical isolates of Gram-negative bacteria.

Automated summary

In this study, fluoroquinolone antibiotics modified with sterically hindered phenolic moieties were synthesized and evaluated for their antibacterial activity. The modification resulted in increased activity against certain strains of Staphylococcus aureus and St. epidermis, particularly when combined with a phosphonate moiety. Moxifloxacin with a 3,5-di-tert-butyl-4-hydroxybenzyl moiety exhibited higher activity against Escherichia coli compared to unmodified fluoroquinolones, while ciprofloxacin derivatives with sterically hindered phenolic moieties showed high activity against Gram-negative bacteria.