Biosynthesis of cyclic bis(bibenzyls) in Marchantia polymorpha

Using sterile thallus tissue of Marchantia polymorpha, the biosynthesis of the cyclic bis(bibenzyl) marchantin A was investigated. The synthesis of th e radioactively and C-13-labelled precursors for the application experiment s is described. Feeding experiments showed that rings A and C of the marcha ntin molecule are derived from the benzene ring of L-phenylalanine via tran s-cinnamic acid and p-coumaric acid. Further application of C-13-labelled p recursor with subsequent C-13 NMR spectroscopy proved that dihydro-p-coumar ic acid is an intermediate in marchantin biosynthesis. A phenylpropane/poly malonate pathway using dihydro-p-coumaric acid and acetate/malonate is prop osed for the biosynthesis of the bibenzyl monomers which were confirmed to be the building blocks of the marchantin molecule. The bibenzyls in turn ar e coupled in a unique way to form the bis(bibenzyl) structure. (C) 1998 Els evier Science Ltd. All rights reserved.