Quinolizidine alkaloid composition of plants and of photomixotrophic cell suspension cultures of Sarothamnus scoparius and Orobanche rapum-genistae

Abstract

The alkaloid composition of Sarothamnus scoparius cell cultures, plants and of its root parasite Orobanche rapum-genistae were analyzed by capillary gas-liquid chromatography (GLC) and capillary GLC/mass spectrometry. S. scoparius plants were found to contain the already known isosparteine, sparteine, 17-oxosparteine, lupanine and other quinolizidine alkaloids such as ammodendrine, N-methylangustifoline, alpha-isolupanine, 5,6-dehydrolupanine, 4-hydroxylupanine, 17-oxolupanine and five 13-hydroxylupanine esters. Two new alkaloids could be identified, a dehydrosparteine (presumably the 11,12-dehydroderivative) and a dihydroxylupanine (presumably 4,13-dihydroxylupanine). The distribution of these alkaloids within the different plant organs is reported. Orobanche rapum-genistae plants contain the already known sparteine, lupanine and 13-hydroxylupanine and 12 other lupin alkaloids, which are present in the Sarothamnus host plant. Photomixotrophic cell suspension cultures of S. scoparius accumulate lupanine as the main alkaloid. On tissue differentiation (bud formation) the cultures accumulate sparteine as well as lupanine. Whereas sparteine is stored in the cells, lupanine is excreted into the medium. Alkaloid formation of the cell cultures is positively correlated with chlorophyll content of the cells. The alkaloid pattern found in S. scoparius supports the hypothesis that lupanine biosynthesis is the common route of quinolizidine alkaloid biosynthesis from which the other alkaloids such as sparteine are derived.