Derivatives of Ribosome-Inhibiting Antibiotic Chloramphenicol Inhibit the Biosynthesis of Bacterial Cell Wall

• Published in: ACS infectious diseases 2018-07, Vol.4 (7), p.1121-1129
• Main Authors: Louzoun Zada, Sivan, Green, Keith D, Shrestha, Sanjib K, Herzog, Ido M, Garneau-Tsodikova, Sylvie, Fridman, Micha
• Format: Article
• Language: English
• ISSN: 2373-8227; 2373-8227
• DOI: 10.1021/acsinfecdis.8b00078

Here, we describe the preparation and evaluation of α,β-unsaturated carbonyl derivatives of the bacterial translation inhibiting antibiotic chloramphenicol (CAM). Compared to the parent antibiotic, two compounds containing α,β-unsaturated ketones (1 and 4) displayed a broader spectrum of activity against a panel of Gram-positive pathogens with a minimum inhibitory concentration range of 2–32 μg/mL. Interestingly, unlike the parent CAM, these compounds do not inhibit bacterial translation. Microscopic evidence and metabolic labeling of a cell wall peptidoglycan suggested that compounds 1 and 4 caused extensive damage to the envelope of Staphylococcus aureus cells by inhibition of the early stage of cell wall peptidoglycan biosynthesis. Unlike the effect of membrane-disrupting antimicrobial cationic amphiphiles, these compounds did not rapidly permeabilize the bacterial membrane. Like the parent antibiotic CAM, compounds 1 and 4 had a bacteriostatic effect on S. aureus. Both compounds 1 and 4 were cytotoxic to immortalized nucleated mammalian cells; however, neither caused measurable membrane damage to mammalian red blood cells. These data suggest that the reported CAM-derived antimicrobial agents offer a new molecular scaffold for development of novel bacterial cell wall biosynthesis inhibiting antibiotics.