Investigation into the Presence of Pyrrolizidine Alkaloids in Eupatorium cannabinum by Means of Positive and Negative Ion Chemical Ionization GC-MS

Abstract

It is demonstrated that the combination of positive ion chemical ionization and negative ion chemical ionization GC-MS analyses of herb and root extracts of Eupatorium cannabinum L. offers a rapid, tentative structure elucidation of pyrrolizidine alkaloids (PAs). Compounds identified in aerial parts of E. cannahimum in this way are four echinatine isomers, like lycopsamine and intermedine, and a number of their β-acetyl, β-angelyl/tiglyl and β-(iso)valeryl esters. PAs without a substituent at C-7 were tentatively identified as supinine and amabiline. In addition to a number of these alkaloids, some β-(iso)butyryl, β-angelyl/tiglyl, and β-(iso)valeryl esters of supinine or amabiline were detected in subterranean parts of the plant. PAS with a saturated necine base like the three trachelanthamine isomers and some β-anglyl/tiglyl esters could be detected in the root material only. A C-9-viridifloryl/trachelanthyl ester of a saturated amino-alcohol like turneforcidine and one of its β-angelyl/tiglyl esters have also been found. The latter 2 compounds, the β-(iso)butyryl, the β-(iso)valeryl, and the β-angelyl/tiglyl esters of supinine or amabiline and the β-(iso)valeryl ester of an echinatine isomer have not been described in nature before.