Infections associated with methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium have resulted in increasing nosocomial health concerns for both patients and medical professionals. Thus, there is an urgent need for new antibacterial agents with innovative mechanisms of action. Filamenting temperature-sensitive mutant Z, an analogue of eukaryotic tubulin, is an essential and highly conserved bacterial cytokinesis protein. GSK1363089 During bacterial cell division, FtsZ monomers self-assemble into a Z-ring, a highly dynamic cytoskeleton scaffold generated at the site of septum formation. The mechanism regulating assembly and organization of FtsZ into a ring-like structure involves GTP binding and hydrolysis, modulated by the interaction of the N-terminal nucleotide binding domain of one FtsZ monomer with the C-terminal GTPase activating domain on the adjacent FtsZ monomer. Subsequently, FtsZ recruits other proteins to form a cell-division complex known as the divisome. Once the divisome is fully assembled, bacterial cell division is achieved by coordinated constriction and splitting of the daughter cells. Everolimus recent studies suggest that inhibition of bacterial cell division proteins with an essential role in bacterial cytokinesis, such as FtsZ, is a promising approach against antibiotic-resistant bacterial infections. A number of small molecule inhibitors of FtsZ have already been shown to prevent FtsZ polymerization and inhibit bacterial cell division. The molecules bind to one of two alternative sites of FtsZ : at the N-terminal GTP binding site, or at the C-terminal interdomain cleft. Compounds targeting the highly conserved GTP binding site mimic the natural substrate of the enzyme and might have potential advantages for developing broad-spectrum antibacterial agents. However, because GTP binding sites are present in a number of human proteins, GTP-mimetic compounds might have potential liabilities related to the off-target-associated activity. Thus, the C-terminal interdomain cleft formed by residues from the C-terminal b-sheet, T7-loop and H7-helix, offers an alternative opportunity for the design of FtsZ inhibitors with therapeutic potential in antibiotic-resistant bacterial diseases. Berberine is a plant alkaloid with a long history of medicinal use in traditional Chinese and native American medicines. Berberine extracts show significant antimicrobial activity against bacteria, viruses and fungi. Its potential mechanisms of antimicrobial activity include the suppression of cell adhesion and migration, and inhibition of microbial enzymes. Moreover, recent literature reports demonstrated that berberine is active against Gram-positive bacteria with minimum inhibitory concentration values in the range of 100�C 400 mg/mL by targeting the cell division protein FtsZ. Therefore, berberine is an attractive lead for the development of potent FtsZ inhibitors. Given the availability of X-ray crystal structures of FtsZ, molecular docking is particularly appealing for guiding the chemical derivatization of berberine. Previous studies suggested that berberine binds FtsZ in a hydrophobic pocket. In this paper we report the design and biological study of a series of 9-phenoxyalkyl berberine derivatives with potent inhibition of FtsZ GTPase activity and broadspectrum of antibacterial activity. Natural products and semi-synthetic derivatives provide a rich source of bioactive compounds for the development of new antibacterial agents. However, in the past decade most of the new chemical entities that reached the clinical practice were derived from the same natural scaffolds. Berberine has been traditionally used to treat microbial infections. At the doses commonly used, the compound is considered safe.