Creation of a macrolide antibiotic against non-tuberculous <i>Mycobacterium</i> using late-stage boron-mediated aglycon delivery

Non-tuberculous mycobacteria (NTM) is gaining clinical recognition as a recently emerging pulmonary pathogen. <i>Mycobacterium avium</i> complex (MAC), the most common NTM, is the cause of pulmonary MAC disease. Currently, the macrolide azithromycin (AZM) is the standard first-line antibiotic for treatment of the disease. However, the rise of drug-resistant MAC necessitates the development of alternative therapeutics. Here, we present a late-stage boron-mediated aglycon delivery strategy for selective modification of AZM, generating a library of potential anti-MAC drugs designated <b>KU01</b> to <b>KU13</b>. Screening of <b>KU01</b> to <b>KU13</b> revealed that <b>KU13</b> exhibited enhanced antimicrobial activity against wild-type and macrolide-resistant MAC compared to AZM. Cryo-electron microscopy analysis indicated that the inserted tercyclic moiety of <b>KU13</b> formed a robust anchor on the bacterial ribosome, creating a binding pocket with base flipping of U2847, potentially bypassing the standard mechanism of macrolide resistance. These results position <b>KU13</b> as a promising lead for therapeutics against macrolide-resistant MAC.