A Novel Class of Complex Flavonoids from the Frond Exudate of Pityrogramma trifoliata

Fronds o f the neotropical fern Pityrogramma trifoliata produce a farinose exudate which consists mainly o f a dihydrochalcone. The structure o f som e minor constituents has been elucidated by spectroscopic methods. They are shown to be representatives o f a novel class o f complex flavonoids, composed o f a flavonoid and a neoflavonoid moiety. In other terms, they are 5,7-dihydroxy-8-cinnamoyl-4-phenyl-dihydrocoumarins. The occurence o f these and closely related compounds in this fern’s exudate supports its inclusion in the genus Pityrogramma.