THE BIOSYNTHESIS OF LUNARINE IN SEEDS OF LUNARIA-ANNUA

Using an optimized precursor feeding system, the biosynthesis of the a lkaloid lunarine in Lunaria annua seeds was investigated. The synthesi s of radioactively labelled precursors for the application experiments is described. Lunarine was shown to be synthesized by stereo-selectiv e phenol-oxidative coupling of N-1,N-10-bis(p-coumaroyl)spermidine. p- Coumaric acid for the biosynthesis of this dimer is formed from L-phen ylalanine via trans-cinnamic acid. The polyamine moiety of lunarine, s permidine, and its immediate precursor putrescine are preferentially s ynthesized from arginine. Enzyme studies with microsomes of Lunaria an nua seeds indicated that a cytochrome P-450 enzyme might be responsibl e for the phenol-oxidative coupling of N-1,N-10-bis(p-coumaroyl)spermi dine yielding the hexahydrodibenzofuran ring of lunarine. Copyright (C ) 1997 Elsevier Science Ltd. All rights reserved.