Alternative approaches utilizing click chemistry to develop next-generation analogs of solithromycin.

The marked rise in bacterial drug resistance has created an urgent need for novel antibacterials belonging to new drug classes and ideally possessing new mechanisms of action. The superior biological activity of solithromycin against streptococci and other bacteria causative of community-acquired pneumonia pathogens, compared to telithromycin and other macrolides encouraged us to extensively explore this class of antibiotics. We, thus, present the design and synthesis of a novel series of solithromycin analogs. Three main strategies were pursued in structure-activity relationship studies covering the N-11 side chain and the desosamine motif, which are both chief elements for establishing strong interactions with the bacterial ribosome as the molecular target. Minimal inhibitory concentration assays were determined to assess the in vitro potency of the various analogs in relation to solithromycin. Two analogs exhibited improved activity compared to solithromycin against resistant strains, which can be assessed in further pre-clinical studies.