Biosynthesis of pseudoisoeugenols in tissue cultures ofPimpinella anisum |
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Authors: | Jü rgen Reichling, Birgitt Kemmerer Hedwig Sauer-Gü rth |
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Affiliation: | (1) Institut für Pharmazeutische Biologie der Universität Heidelberg, Im Neuenheimer Feld 364, W-69120 Heidelberg, Germany |
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Abstract: | The genusPimpinella contains pseudoisoeugenols, phenylpropanoids with a rare 2,5-dioxy substitution pattern on the phenyl ring. To study the biosynthesis of these compounds, we set up a leaf-differentiating tissue culture ofPimpinella anisum. These cultures mainly produce epoxy-pseudoisoeugenol-(2-methylbutyrate). To corroborate the biosynthetic pathway of epoxy-pseudoisoeugenol-(2-methylbutyrate) as proposed on the basis of investigations with13C/14C-labelled precursors, the key steps of the pathway were investigated at an enzyme level. Experiments with cell-free homogenates clearly revealed that L-phenylalanine is converted to (E)-cinnamic acid by phenylalanine ammonia lyase and that (E)-cinnamic acid is converted top-coumaric acid by cinnamic acid 4-hydroxylase. L-2-aminooxy-3-phenylpropionic acid, an analogue of L-phenylalanine, inhibited the incorporation of L-[3-13C]phenylalanine into epoxy-pseudoisoeugenol-(2-methylbutyrate). Up to 2% of the precursor DL-[3-13C]phenyllactate was incorporated into epoxy-pseudoisoeugenol-(2-methylbutyrate). Inhibition experiments with oxalacetic acid clearly showed that cinnamic acid is not formed by dehydration of phenyllactic acid in this leaf-differentiating tissue culture ofP. anisum. |
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Keywords: | Biosynthesis Cell-free system Cinnamic acid 4-hydroxylase Enzyme activity Pimpinella anisum Phenylpropanoids Phenylalanine ammonia lyase Pseudoisoeugenols Tissue culture |
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