The effect of complexation of 3-formylrifamycin SV macrocyclic ether derivatives with metal cations and small nitrogen-containing organic molecules on antibacterial activity against S. aureus and S. epidermidis

Spectroscopic studies of ether rifamycins (1–9) have shown that all these compounds tend to be zwitterions with different localizations of intramolecularly transferred proton, which influences their solubility and log P values. According to ESI MS studies, rifamycins 3 and 4 form complexes with Li+ or Na+, while the other ones (7–9) coordinate small organic molecules, which can be further replaced by Na+ cation. Biological assays revealed that the use of 7–9 in the form of complexes with small organic molecules improves their antibacterial potency as a result of changed: log P, solubility and binding mode with bacterial RNA polymerases.

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