Acylated Kaempferol Glycosides from Laurus nobilis Leaves and Their Inhibitory Effects on Na+/K+-Adenosine Triphosphatase

Na+/K+-adenosine triphosphatase (ATPase) inhibitors have considerable therapeutic potential against some heart diseases like congestive heart failure and cardiac arrhythmias. Through bioassay-guided separation of the leaf extract of Laurus nobilis, six acylated kaempferol glycosides (compounds 1-6) were isolated. Their structures were determined on the basis of spectroscopic analysis and comparison with reported data. All the isolates were subjected to in vitro bioassays to evaluate their inhibitory activities against Na+/K+-ATPase from porcine cerebral cortex and bacterial growth. These studies led to the identification of compounds 1-6 as potent Na+/K+-ATPase inhibitors, with IC50 values in the range of 4.0 +/- 0.1-10.4 +/- 0.64 mu m. These compounds also exhibited a broad spectrum of antibacterial activity. In particular, compounds 4 and 6 showed potent inhibitory activities against several bacterial strains, except Escherichia coli, with minimum inhibitory concentration (MIC) values in the range of 0.65-2.08 mu g/mL. Thus, L. nobilis-derived acylated kaempferol glycosides may have a potential to be leads for the development of Na+/K+ ATPase inhibitors (1-6) and antibacterial agents (4, 6).