POTENTIAL ALLELOPATHIC GUAIANOLIDES FROM CULTIVAR SUNFLOWER LEAVES, VAR SH-222

The leaf aqueous extracts of cultivar sunflower (Helianthus annuus L.) var. SH-222(R) afforded, from the medium polar fractions, five new gu aianolides, the annuolides A-E which have been tested as allelochemica ls. Their structures and stereochemistry were elucidated by spectrosco pic analysis. A series of aqueous solutions at 10(-4)-10(-9) M of annu olides A-E were tested for their effects on the germination and growth of the dicotyledon Lactuca sativa and the monocotyledon Hordeum vulga re species. All five guaianolides posses potential allelopathic activi ty, in particular over dicotyledon species, and are likely to be signi ficantly involved in the allelopathic action of cultivar sunflowers.