DNA gyrase inhibitors: Progress and synthesis of potent compounds as antibacterial agents.

DNA gyrase is classified as topoisomerase II, an ATP-dependent enzyme that is vital in the transcription, replication of DNA and chromosome segregation processes. It plays a crucial role in all bacteria except higher eukaryotes and this makes it a desirable and viable therapeutic target for development of new antibacterial agents. Fluoroquinolones are commonly used effective antibacterial agents that target DNA gyrase, however the spectrum of side-effects and emerging bacterial resistance with no new drugs in the antibacterial pipeline has fuelled intensive research in this area. New chemical entities with varied scaffolds possessing DNA gyrase inhibiting properties have been determined by screening chemical libraries that could serve as good leads for antibacterial drug development. A wide range of natural products and protein-based compounds have been identified and studied as DNA gyrase inhibitors and this adds a huge amount of structural diversity that can be exploited and harnessed in the discovery of new antibacterial agents. The development of new chemical compounds with DNA gyrase inhibitory activity (from natural sources, random screens or rational design) will further validate/corroborate the potential of this enzyme as a useful target. This review presents an overview of the DNA gyrase inhibitors obtained from natural and synthetic sources, their syntheses schemes and spectrum of biological activity of a variety of scaffolds and their analogues. The authors hope to provide focused direction for development of new chemical entities, synthetic routes for analogue synthesis, structure activity relationships and biological activity. The most potent ones can be used as templates to design novel compounds targeting DNA gyrase and are effective against resistant bacterial strains and biofilms.