Structures of a Novel 2-Arylbenzofuran Derivative and Two Flavone Derivatives from the Cultivated Mulberry Tree (Morus lhou KOIDZ.)

A new 2-arylbenzofuran derivative, mulberrofuran H and two isoprenylated flavones, kuwanons S and T, were isolated from the ethyl acetate extract of the root bark of cultivated mulberry tree (Japanese name "Roso, "a cultivated variety of Morus lhou KOIDZ.). The structures of mulberrofuran H and kuwanons S and T were shown to be 1, 2, and 3, respectively, on the basis of spectral evidence. Mulberrofuran H can be regarded biogenetically as a variation of a Diels-Alder type adduct of a chalcone derivative and a dehydroprenyl-2-arylbenzofuran derivative.