Biosynthesis of chalcomoracin and kuwanon J, the Diels-Alder type adducts, in Morus alba L. cell cultures.

Abstract

Experiments with [1-13C]-, [2-13C]- and [1, 2-13C2]-acetates administered to Morus alba cell cultures revealed that both optically active Diels-Alder type adducts chalcomoracin (1) and kuwanon J (2) are formed through the condensation of two molecules of cinnamoylpolyketide-derived skeletons. The 2-arylbenzofuran skeleton of 1 is formed by a novel type cyclization of the cinnamoylpolyketide, followed by decarboxylation. The 13C-labeling of [2-13C] acetate was incorporated into the starter acetate carbons in the biosynthesis of the prenyl moieties of chalcomoracin (1), while that of [1-13C] acetate was not incorporated into the prenyl moieties of 1.