Abstract
A novel bis-indole, bis-guanidinium alkaloid, clathriamine A (1), has been isolated from a Western Australian marine sponge, Clathria (Thalysias) sp. (order: Poecilosclerida, family: Microcionidae). The structure of 1 was elucidated via comprehensive NMR analyses as well as TD-DFT predictions of ECD spectra. Biological evaluation against a panel of microorganisms and cell lines revealed potent and selective antibacterial activity for compound 1.