STRUCTURE ELUCIDATION OF HELIOSCOPINOLIDE-D AND HELIOSCOPINOLIDE-E FROM EUPHORBIA-CALYPTRATA CELL-CULTURES

Two novel diterpene lactones 1 and 4, belonging to the group of helioscopinolides, have been isolated, together with the already known helioscopinolides C [2] and A [3], from suspension cultures of Euphorbia calyptrata, a poisonous plant growing in the Sahara desert. All compounds have been extensively characterized by ms, H-1 nmr, and C-13 nmr (COSY, NOESY, and HETCOR). Complete nmr assignments, together with the determination of conformation and configuration, are given for 1 and 4, as well as for the known 2 and 3. The isolation of all compounds is also described.