PYRROLIZIDINE ALKALOID COMPOSITION IN 6 BRAZILIAN SENECIO SPECIES

Four macrocyclic pyrrolizidine alkaloids (PA) could be identified and quantified in extracts of the Brazilian Senecio oxiphyllus by means of proton- and inverse-gated decoupling C-13 NMR spectroscopy. Seasonal and local differences were found in PA composition. Reinvestigation of five other Senecio species by the same method led to the identificati on of various retronecine- and otonecine-based PA, exceeding prior res ults in both qualitative and quantitative respects. In the extract of S. selloi, a new alkaloid was found, which was identified as 18-hydrox yjaconine dihydro-12,15,18-trihydroxysenecionan-11,16-dione) according to NMR and CC-mass spectrometry data. Copyright (C) 1996 Elsevier Sci ence Ltd