Rediscovery of Tetronomycin as a Broad-Spectrum and Potent Antibiotic against Drug-Resistant Gram-Positive Bacteria

[Image: see text] Tetronomycin (1), first isolated from a cultured broth of Streptomyces sp. by Juslen et al. in 1974, is a polycyclic polyether compound. However, the biological activity of 1 has not been thoroughly examined. In this study, we found that 1 exhibits more potent antibacterial activity than two well-known antibacterial drugs (vancomycin and linezolid) and is effective against several drug-resistant clinical isolates including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci. Furthermore, we reassigned the (13)C NMR spectra of 1 and performed a preliminary structure–activity relationship study of 1 to synthesize a chemical probe for target identification, which implied different targets based on its ionophore activity.