Synthesis of furanocoumarins: mevalonate-independent prenylation of umbelliferone in Apium graveolens (Apiaceae)

Preincubation of detached leaves of Apium graveolens with deuterium labelle d [5,5-H-2(2)]-deoxy-D-xylulose prior to the elicitation of furanocoumarin biosynthesis by jasmonic acid, resulted in high incorporation of a deuterat ed prenyl segment into all genuine furanocoumarins. Psoralen, xanthotoxin, bergapten and iso-pimpinellin consistently showed at C-3' of the furan moie ty the presence of a single deuterium atom (31% H-2). With respect to previ ous studies, that indicated only a very low incorporation of mevalonate int o furanocoumarins, our results clearly demonstrate that the prenylation of umbelliferone in A. graveolens is achieved via the novel mevalonate indepen dent pathway. This is the first example of the participation of DOX-derived DMAPP in a prenylation reaction. (C) 1999 Elsevier Science Ltd. All rights reserved.