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-8ß,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.

Guaianolides and a seco-Eudesmane from the Resinous Exudates of Cushion Bush (Leucophyta brownii) and Evaluation of Their Cytostatic and Anti-inflammatory Activity.

A detailed phytochemical investigation of a dichloromethane extract of the resinous exudates of the cushion bush plant (Leucophyta brownii) resulted in the isolation of the new 8,12-guaianolides leucophytalins A (5) and B (6), the new 1,10-seco-eudesmane leucophytalin C (10), six rare 8,12-guaianolides (1-4, 7, and 8), and the xanthanolide tomentosin (9). The structures of all isolated compounds were elucidated on the basis of spectroscopic and spectrometric analyses. The structures of compounds isolated in crystalline form, including leucophytalins A and C, were further confirmed by X-ray crystallography. The crude extract exhibited moderate cytostatic activity against a breast cancer (MCF-7) and human colon cancer (HT-29) cell line with IC50 values of 9.3 and 18 µg/mL, respectively, and anti-inflammatory activity against the macrophage-like cell line RAW 264.7 with IC50 values of 3.9 and 6.1 µg/mL for thromboxane B2 and prostaglandin E2 production, respectively. The isolated compounds were evaluated for their cytostatic activity against MCF-7 and HT-29 cells (1, 3-10) and their anti-inflammatory activity against RAW 264.7 cells (1-10). All isolated compounds are most likely derived from (+)-germacrene A, and a biosynthetic pathway is proposed for these sesquiterpenoids.