Allergenic sesquiterpene lactones from cushion bush (Leucophyta brownii Cass.): new and old sensitizers in a shrub-turned-a-pot plant.

BACKGROUND The Australian cushion bush (Leucophyta brownii) of the Compositae family of plants has become a popular pot and container plant. The plant produces the sesquiterpene lactone allergen calocephalin. OBJECTIVES To assess the sensitizing potential of sesquiterpene lactones from cushion bush. PATIENTS/MATERIALS/METHODS Eleven Compositae-sensitive patients were patch tested with seven sesquiterpene lactones isolated from cushion bush. RESULTS Six of seven sesquiterpene lactones elicited positive reactions in 4 of 11 patients. CONCLUSIONS The well-known sesquiterpene lactone pseudoivalin and its derivative pseudoivalin acetate, as well as calocephalin and tomentosin, were confirmed to be sensitizers, whereas leucophytalin A and 4α-hydroxy-5αH,10αH-1,11(13)-guaidien-8β,12-olide were shown to be allergenic for the first time. The patch test reaction patterns seem to follow the chemical patterns, which may eventually make it possible to trace primary sensitizers and advise patients more precisely.