Design, Synthesis and Biological Evaluation of Conjugates of 3-O-Descladinose-azithromycin and Nucleobases against rRNA A2058G- or A2059G-Mutated Strains.

Structurally unrelated antibiotics MLSB (macrolide-lincosamide-streptogramin B) compromised with clinically resistant pathogens because of the cross-resistance resulting from the structural modification of rRNA A2058. The structure-activity relationships of a novel 3-O-descladinose azithromycin chemotype conjugating with nucleobases were fully explored with the aid of engineered E. coli SQ110DTC and SQ110LPTD. The conjugates of macrolides with nucleobases, especially adenine, displayed antibacterial superiority over telithromycin, azithromycin and clindamycin against rRNA A2058/2059-mutated engineered E. coli strains at the cost of lowering permeability and increasing vulnerability to efflux proteins against clinical isolates.