The novel metabolites, named macommelin, macommelin-9-ol, macommelin-8-ol and macommelin-8, 9-diol, were isolated from the culture broth of Macrophoma commelinae IFO 9570. The structures were determined to be 5-ethyl-, 5-(2'-hydroxyethyl)-, 5-(1'S-hydroxyethyl)- and 5-(1'S, 2'-dihydroxyethyl)-4-methoxy-6-methyl-2H-pyran-2-one, respectively. This fungus also produced rosellisin, an antibiotic α-pyrone.