Allergic contact dermatitis due to sesquiterpene lactones.

Several compounds containing the α-methylene-γ-butyrolactone moiety have been tested on human volunteers and on guinea-pigs; the animals were experimentally sensitized by alantolactone, iso-alantolactone and laurel oil. Of the two new lactones, spirolactone was the more reactive: this was confirmed by both animal and human testing. The synthetic lactones are less reactive than natura1 ones. α-Methylene-γ-butyrolactone itself does not elicit cross-reactions in guinea-pigs sensitive either to alantolactone or to isoalantolactone, or in patients sensitive to sesquiterpene lactones. The α- methylene-γ-butyrolactone group is necessary for cross-reaction, but to be active, it has first to be substituted. It was also found that isoalantolactone, allegedly not allergenic, is in fact a sensitizer and cross-reacts with alantolactone. The cross-reaction between laurel and Frullania, found in man, also occurs in guinea-pigs. It is more evident when sesquiterpene lactone is the sensitizer and laurel used to elicit reaction. [ABSTRACT FROM AUTHOR]