Irpexine, an Isoindolinone Alkaloid Produced by Coculture of Endophytic Fungi, Irpex lacteus and Phaeosphaeria oryzae

A new isoindolinone alkaloid, irpexine (1), was isolated as a racemate, along with a known green pigment, hypoxyxylerone (2), from the coculture of two endophytic fungi, Irpex lacteus and Phaeosphaeria oryzae. Compound 1 was found to be a newly produced metabolite of I. lacteus in the coculture with P. oryzae. Although 2 was produced in a monoculture of I. lacteus, its production was markedly enhanced by the coculture.