Application of metabolic engineering to the production of scopolamine

Scopolamine is an alkaloid widely used in medicine for its anticholinergic activity. The aim of this review is to show that metabolic engineering techniques constitute a suitable tool to improve the production of tropane alkaloids, focusing in particular on scopolamine. We present an overview of results obtained by various research groups, including our own, who have studied the overexpression of genes involved in the biosynthesis of scopolamine in different plant species that produce tropane alkaloids. Experiments carried out to improve production in hairy root cultures will also be described, as well as those attempting to biotransform hyoscyamine into scopolamine in roots and transgenic tobacco cells.

Biosynthesis of panaxynol and panaxydol in Panax ginseng

The natural formation of the bioactive C17-polyacetylenes (−)-(R)-panaxynol and panaxydol was analyzed by 13C-labeling experiments. For this purpose, plants of Panax ginseng were supplied with 13CO2 under field conditions or, alternatively, sterile root cultures of P. ginseng were supplemented with [U-13C6]glucose. The polyynes were isolated from the labeled roots or hairy root cultures, respectively, and analyzed by quantitative NMR spectroscopy. The same mixtures of eight doubly 13C-labeled isotopologues and one single labeled isotopologue were observed in the C17-polyacetylenes obtained from the two experiments. The polyketide-type labeling pattern is in line with the biosynthetic origin of the compounds via decarboxylation of fatty acids, probably of crepenynic acid. The 13C-study now provides experimental evidence for the biosynthesis of panaxynol and related polyacetylenes in P. ginseng under in planta conditions as well as in root cultures. The data also show that 13CO2 experiments under field conditions are useful to elucidate the biosynthetic pathways of metabolites, including those from roots.

Biosynthesis of panaxynol and panaxydol in Panax ginseng

The natural formation of the bioactive C17-polyacetylenes (−)-(R)-panaxynol and panaxydol was analyzed by 13C-labeling experiments. For this purpose, plants of Panax ginseng were supplied with 13CO2 under field conditions or, alternatively, sterile root cultures of P. ginseng were supplemented with [U-13C6]glucose. The polyynes were isolated from the labeled roots or hairy root cultures, respectively, and analyzed by quantitative NMR spectroscopy. The same mixtures of eight doubly 13C-labeled isotopologues and one single labeled isotopologue were observed in the C17-polyacetylenes obtained from the two experiments. The polyketide-type labeling pattern is in line with the biosynthetic origin of the compounds via decarboxylation of fatty acids, probably of crepenynic acid. The 13C-study now provides experimental evidence for the biosynthesis of panaxynol and related polyacetylenes in P. ginseng under in planta conditions as well as in root cultures. The data also show that 13CO2 experiments under field conditions are useful to elucidate the biosynthetic pathways of metabolites, including those from roots.