A novel extracellular diterpenoid with antibacterial activity from the cyanobacterium Nostoc commune

A novel extracellular metabolite with an unprecedented diterpenoid skeleton , 8-[(5-carboxy-2-hydroxy)benzyl]-2-hydroxy-1,1,4a,7,8-pentamethyl-1,2,3,4, 4a,6,7,8,8a,9,10,10a-dodecahydrophenanthrene has been isolated from the cul ture medium of the terrestrial cyanobacterium Nostoc commune Vaucher (EAWAG 122b) by means of bioguided isolation. The molecule was designated as nosc omin. The structure was determined by spectroscopic methods, mainly NMR and mass spectrometry. Noscomin exhibited antibacterial activity against Bacil lus cereus, Staphylococcus epidermidis, and Escherichia coli.