The metabolites produced by liquid cultures of Phoma etheridgei, a new
fungus isolated from black galls of aspen, have been examined. This f
ungus is antagonistic to the aspen decay fungus Phellinus tremulae. Th
e compound responsible for this antagonism has been isolated and its s
tructure elucidated. Phomalone (1) is a previously undescribed natural
product that possesses the same carbon skeleton as the Phoma pigmenti
vora metabolite LL-D253 alpha The structure was determined by physical
methods, mainly H-1 and C-13 NMR. INAPT experiments played an importa
nt role. Some chemical transformations of phomalone (1) are described
and it is shown by C-13 labelling experiments to be derived from six a
cetate units. Phomalone is active against Phellinus tremulae. Compound
s 4, 6, 7, and 8 are also new natural products produced by P. etheridg
ei.