PROTEIN SYNTHESIS INHIBITORS
We noted previously that inhibition of protein synthesis is one of the
five major clinically validated antibacterial pathways (Figure 5), with
most antibiotics in this class targeting the ribosome.116 These have
spurred at least one company Ribex to use structure-based approaches
to design next-generation ribosome-directed antibiotics. We also
noted new developments in tetracycline chemistry70 and still more
structural information is being reported on this class of antibiotics.216
The clinical progression of second-generation oxazolidinones into
phase II studies was also mentioned.74–80 Achaogen is working to
bring forward new aminoglycoside protein synthesis inhibitors, such
as plazomicin (ACHN-490), which successfully completed a phase II
trial for urinary tract infections.217 Novartis has converted the natural
thiopeptide GE2270A, an inhibitor of elongation factor Tu,218 to a
semisynthetic version with a 105 increase in aqueous solubility and
moved it into phase II trials for C. difficile infections.219 Other protein
synthesis halting antibacterials currently in various stages of clinical
development include members of the pleuromutilin (BC-3781, BC-
7013, BC-3205) and macrolide (Cethromycin) structural classes.73