CUCURBITANE-TYPE COMPOUNDS FROM HEMSLEYA-CARNOSIFLORA ANTAGONIZE ECDYSTEROID ACTION IN THE DROSOPHILA-MELANOGASTER B-11 CELL-LINE

The ecdysteroid agonist and antagonist activities of 3 cucurbitanes, 2 cucurbitane glycosides and 2 cucurbitacins isolated from Hemsleya car nosiflora (Cucurbitaceae) have been determined in the Drosophila melan ogaster B-11 bioassay. Carnosiflogenins A and C and carnosiflosides II and VI possess antagonistic activity. Carnosiflogenin A was also foun d to induce the formation of spindle-shaped cells with high frequency in both the agonist and antagonist assays. At 10(-3) M, carnosiflogeni ns B and C were cytotoxic. 23,24-Dihydrocucurbitacin F and 25-acetoxy- 23,24-dihydrocucurbitacin F are also antagonistic at high concentratio ns. The concentration dependencies of the antagonistic activities of t hese two cucurbitacins, carnosiflosides II and VI and carnosiflogenin C are presented. The biological and ecological significance of these r esults are discussed in relationship to the concentrations present in the rhizomes of H. carnosiflora.