Treatment of dermatitis caused by the sesquiterpene lactone helenin.

Many sesquiterpene lactones, terpenoid compounds present in members of the Compositae (Asteraceae) family of plants, are known to cause allergic contact dermatitis. There is no treatment of this skin disease. We report on the use of an amino acid, L-cysteine, to control dermatitis in guinea pigs sensitized to the sesquiterpene lactone, helenin. The cysteine treatment of allergic reactions induced by helenin reduced the recovery time of the animals by about 50%. The effect of cysteine treatment might be explained by: cysteine reaction with free helenin, and substitution of skin proteins from the protein-helenin complex by cysteine through competitive reactions. Cysteine treatment present a new promising way for control of this type of allergy in humans.