New bioactive plant heliannuols from cultivar sunflower leaves

From an aqueous extract of Helianthus annuus L, cvs. SH-222 and VYP leaves, six new heliannuols have been isolated: three 7,10-heliannanes, heliannuol s F (1), I (4), and J (5) and three 7,11-heliannanes, heliannuols G (2), H (3) and K (6). Their structure elucidation was based on extensive spectral studies. The phytotoxicity exhibited by compounds 1-4 and 6 suggests that t hese new bioactive sesquiterpenes may be involved in plant defense against dicotyledons.