In this study, molecular Torin 1 docking simulations suggested that berberine binds into the Cterminal interdomain cleft of FtsZ, projecting the 9-methoxy group AB1010 in vivo towards the outside of the cavity. Based on the docking results, a new series of 9-phenoxyalkyl berberine derivatives was hypothesized to establish additional favorable interactions with FtsZ. The 9-phenoxyalkyl substituted derivatives exhibited potent antimicrobial activity against Gram-positive bacterial strains such as ampicillin- and methicillin-resistant S. aureus, and broader spectrum of activity than the parent compound berberine. Biochemical evaluations demonstrated that the new berberine derivatives target the bacterial FtsZ protein. The compounds were potent inhibitors of the GTPase activity of FtsZ and were able to inhibit the FtsZ polymerization in a dose-dependent manner. These results suggest that the binding of berberine derivatives into the interdomain cleft interferes with the GTPase activity of FtsZ, which in turn destabilizes the formation of FtsZ polymers. In summary, the results of this study demonstrate the potential of the berberine scaffold for chemical optimization into potent 
inhibitors of FtsZ with broad-spectrum antibacterial activity. The ubiquitin proteasome system is the major non-lysosomal degradative machinery responsible for regulated degradation of most intracellular proteins. A key component of this machinery is the 26S proteasome that accounts for recognizing, unfolding, and ultimately destroying proteins. Most proteasome targeted proteins must first be tagged with polyubiquitin chains, generally at the. The 26S proteasome is a 2-MDa complex which made up of two sub-complexes: the catalytic particle and the regulatory particle. The 20S proteasome is a cylindrical protease complex consisting of 28 subunits configured into four stacks of heptameric rings. On the other hand, the 19S consists of more than 18 subunits, including 6 putative ATPases and 12 non-ATPase subunits. The 26S proteasome is known to require ATP hydrolysis to degrade ubiquitinated substrates and for its assembly. It emerged that deregulation of the proteasome causes inappropriate destruction or accumulation of specific proteins and ensuing pathological consequences. The proteasome system is now recognized as a regulator of the cell cycle and cell division, immune responses and antigen presentation, apoptosis, and cell signaling. The proteasome has been implicated in certain cancers such as multiple myeloma, in neurodegenerative disorders such as Alzheimer’s disease, Huntington’s disease and amyotrophic lateral sclerosis. In recent years, alteration in 26S proteasomes has been documented in conventional and proteasome reporter mouse models of diabetes. Importantly, a difference in proteasome has been identified in identical twins discordant for diabetes in humans. A common feature of diabetic vascular complications is thought to be endothelial dysfunction, resulting from, at least in part, the reduced bioavailability of nitric oxide derived from endothelial NO synthase. Provided that eNOS is well recognized in endothelial function and the 26S proteasome is increasingly appreciated in endothelial dysfunction, it would be important to understand the relationship between eNOSgenerated NO and 26S proteasomes. However, it is yet to be established whether NO regulates 26S proteasome functionality in vascular endothelial cells. NO is a free radical gaseous molecule with a well-described role as a signal transduction messenger molecule in several biological processes such as cell proliferation and apoptosis. Nitric oxide synthase mediates a critical rate-limiting step in the production of NO through oxidation of the guanidine nitrogen of arginine. One isoform of the enzyme, eNOS, is a constitutive Ca +2 -dependent NOS.