A series of novobiocin-like coumarincarboxylic acids has been prepared bearing the L- rhamnosyl moiety as the sugar portion of the molecule. The similar DNA gyrase inhibitory activity of the novel class of coumarins to that of novobiocin demonstrates that L-rhamnose can effectively replace L-noviose. Introduction of alkyl side-chains at C-5 of coumarin leads to improved in vitro antibacterial properties in the novel series.
