GC-IRMS and enantioselective analysis in biochemical studies in dill (Anethum graveolens L.)

Abstract

The analysis of the δ13CPDB-values and the enantiomeric distribution in combination with the composition of the essential oil of dill (Anethum graveolens L.) at various developing stages of different plant parts allows us to draw valuable conclusions about the biosynthesis of the monoterpenes in the entire plant. The composition of the essential oil is different for the various plant parts and changes significantly during the ripening of the dill umbels. While α-phellandrene, β-phellandrene, dill ether and carvone occur enantiomerically pure in all investigated plant parts and during all stages of maturity, both enantiomers of limonene are detected. The enantiomeric composition of limonene is different for the various plant parts and changes during the development of the umbels. The δ13CPDB-values of the different monoterpenes also change with development. (R)-Limonene and carvone show absolutely the same behaviour in their δ13CPDB-values during the whole development of the umbels up to the seeds. In addition the δ13CPDB-values themselves are absolutely the same. Also α-phellandrene and dill ether show the same behaviour in their δ13CPDB-values, but the δ13CPDB-values themselves differ around 1.5–2‰. Based on the results of these investigations, a biochemical pathway of the monoterpenes in dill is postulated, according to which a very close biogenetic relationship is established for limonene and carvone and also for α-phellandrene and dill ether. © 1997 John Wiley & Sons, Ltd.