Pyrrolizidine alkaloids from Anchusa strigosa and their antifeedant activity

The pyrrolizidine alkaloid (PA) content of flowers, leaves, and roots of Anchusa strigosa (Boraginaceae) was analysed by ESI-LC-MS. Six PAs, including two new natural compounds were detected, characterized by NMR spectroscopy, and quantified in each plant organ. The highest total concentration of PAs was in the leaves, followed by the flowers, and finally by the roots. All PAs isolated were subjected to Spodoptera exigua and Pieris brassicae larvae. Feeding activity by both herbivore species using a bioassay was inhibited up to circa 75% depending on applied concentration and PA.