Bioactive saturated pyrrolizidine alkaloids from Heliotropium floridum

Here we describe the isolation and structural determination of the new saturated pyrrolizidine monoester alkaloids, 3'-acetyltrachelanthamine, floridine, floridinine and floridimine, along with the known one, heliovicine, from Heliotropium floridum. Their structures were established by high resolution NMR (including 2D NMR experiments), mass spectrometry, chemical reactions and by correlation with published data of known compounds. Bioassays of the alkaloidal extract and its major components against several insect pests and plant pathogens showed that 3'-acetyltrachelanthamine is a strong anti-feedant, with low toxicity against Leptinotarsa decemlineata and a moderate anti-fungal agent against Fusarium monoliforme; floridinine only showed the anti-fungal effect. (C) 1997 Elsevier Science Ltd.