Five new chromones possessing monoamine oxidase inhibitory activity from an Ascomycete, Chaetomium quadrangulatum

Five novel chromones (1,4-benzopyran-4-ones), among which three are tetracyclic and one contains a sulfonyl group, have been isolated from an Ascomycete, Chaetomium quadrangulatum, as monoamine oxidase inhibitory features, and named chaetoquadrins A (1)-E (5).