Petrosamine B, an Inhibitor of the <i>Helicobacter</i> <i>p</i><i>ylori</i> Enzyme Aspartyl Semialdehyde Dehydrogenase from the Australian Sponge <i>Oceanapia</i> sp.

Abstract

Bioassay-guided fractionation of the MeOH extract of the sponge Oceanapia sp. using the Helicobacter pylori enzyme, aspartyl semialdehyde dehydrogenase, ASD, to detect antibacterial activity, led to the isolation of a new pyridoacridine alkaloid, petrosamine B (1). Petrosamine B is a bright blue compound that is sparingly soluble in many organic solvents. The structure of 1 was determined from detailed NMR studies performed in TFA/D2O. Petrosamine B was found to be a weak inhibitor of ASD with an IC50 of 306 microM.