Helenium amarum

Abstract: Experimental studies in guinea pigs using ether extracts of 20 different species of the Compositae plant family were carried out with the open epicutaneous method (OET) and the guinea pig maximization test (GPMT). The results demonstrate that Cnicus benedictus (blessed thistle), Chrysanthemum leucanthemum (marguerite, ox-eye daisy) and Helianthus debilis (dwarf sunflower) are strong sensitizers while Helenium amarum (bitterweed), Gaillardia amblyodon (blanket flower), Artemisia ludoviciana (prairie sage), Ambrosia trifida (giant ragweed) and Solidago virgaurea (goldenrod) are medium sensitizers. Twelfe species revealed only a weak or no sensitizing capacity; among those were corn flower, wormwood, mugwort, coltsfoot and dandelion. Cross-reactivities were observed in a considerable number of the investigated plant species. The sensitizing power as well as the observed cross-reactions depend on the occurrence of sesquiterpene lactones which have an α-methylene group exocyclic to the lactone in common (“immunologic requisite”). As a practical consequence, patients suffering from allergic contact dermatitis due to Compositae species are strictly requested to avoid contact with the offending species and all related species to prevent recurrences of their skin lesions.

Abstract: Tenulin [1], a sesquiterpene lactone from Helenuim amarum, is a potent antifeedant to the European corn borer Ostrinia nubilalis. At 3 mumol/g in artificial diets, 1 reduced growth and delayed larval development of O. nubilalis and the variegated cutworm Peridroma saucia larvae. An especially pronouned carry-over effect in O. nubilis was substantial reduction in fecundity of adult moths resulting from treated larvae. The LD50 (lethal dose for 50% mortality) of 1 by injection in the migratory grasshopper Melanoplus sanguinipes was 0.88 mumol/insect. Toxicity in M. sanguinipes was antagonized by co-administration of cysteine, suggesting that the cyclopentenone group of tenulin undergoes Michael addition of biological nucleophiles in vivo. This mechanism was partially confirmed by the finding that only tenulin analogues capable of acting as electrophic acceptors had significant antifeedant activity.