(Daisy or Sunflower family)
- Helichrysum Mill.
Some 500 species are distributed in southern Europe, tropical and southern Africa, Madagascar, south-west Asia, southern India, and Australia. About 200 species occur in southern Africa. The genus is classified in the tribe Inuleae.
The dried flower-heads of some species are used as "everlasting flowers" or "immortelles" in dried flower arrangements. Since they retain their colour, the flowers of Helichrysum stoechas DC. (popularly known as goldilocks) are used in pot-pourri (Wren 1975).
The hairs on the seeds can produce small, yellow conjunctival nodules (Duke-Elder & MacFaul 1972).
- Helichrysum angustifolium DC.
This species yields an oil of perfumery (Furia and Bellanca 1971). Helichrysum oil, which is also known as everlasting flower oil or immortelle oil, and is prepared by steam distillation of the plant material, was found to be slightly irritating when applied to guinea pig skin for 24 hours under occlusion. At a dilution of 4% in petrolatum, neither irritant (48 hour closed patch test) nor sensitising (maximisation test) properties could be demonstrated in 26 human volunteers. Phototoxicity also could not be demonstrated with the undiluted oil applied to the skin of mice and swine (Opdyke 1978, p. 769). Another fragrance raw material, immortelle absolute (also known as helichrysum absolute or everlasting absolute), is prepared by solvent extraction of the plant material. This was found to be moderately irritant when applied to rabbit skin for 24 hours under occlusion, but otherwise no irritant, sensitising, nor phototoxic effects could be demonstrated (Opdyke 1979, p. 821).
- Helichrysum bracteatum Andrews
The plant, displayed in the dried state as "everlasting flowers", produced keratitis and a nodose type of conjunctivitis, apparently from mechanical rather than toxic action. The lesion was not reproducible in rabbits (Karbe 1923).
- Helichrysum diosmaefolium Sweet
- (syn. Helichrysum diosmifolium Less.)
Mair (1968) received a report of recurrent eczema from contact with the plant. The affected individual developed blistering of the mouth after trying to eat the leaves in order to dispel the allergy. An unaffected individual noted a sharp taste and stinging of the tongue from nibbling the plant.
- Helichrysum polycladum Klatt
Bohlmann et al. (1980a) found α-terthienyl in the leaves of this species, but not in 24 other species of Helichrysum. α-Terthienyl has phototoxic properties when applied to human skin (see Tagetes L. below).
- Heterotheca subaxillaris Britton & Rusby
- Camphor Daisy
In an investigation of "weed dermatitis", two of 50 patients gave positive patch test reactions to an extract of this plant (Shelmire 1939a).
- Hieracium L.
Perhaps 5000 apomictic micro-species or 1000 macro-species occur in temperate regions, excluding Australasia, and on tropical mountains. The genus is classified in the tribe Lactuceae (Cichorieae).
- Hieracium x floribunda Wimmer & Grab.
- (syns Hieracium auricula L., Hieracium cochleatum Norrlin, Hieracium longiscapum Zahn)
This is a hybrid species, intermediate between H. caespitosum Dumort. and H. lactucella Wallr. The plant, used as rabbit food, caused recurrent springtime dermatitis of the face and forearms in a rabbit breeder (Bellonne 1948).
- Hulsea heterochroma A.Gray
The juice derived from the glands of the plant is very irritating to the skin (von Reis Altschul 1973).
Reynolds & Rodriguez (1981) demonstrated the presence of mexicanin I, a potentially allergenic sesquiterpene lactone (Mitchell & Dupuis 1971), in the trichome exudate of this species, thus providing support for the inclusion of the genus Hulsea in the tribe Heliantheae rather than in the tribe Senecioneae.
- Inula L.
About 200 species are to be found in Europe, Asia, and Africa. The genus is classified in the tribe Inuleae.
Potentially allergenic sesquiterpene lactones have been reported from the following species:
- Inula aschersoniana Janka
- Inula grandis Schrenk
- Inula indica L.
- Inula japonica Thunb.
- Inula magnifica Lipsky
- Inula oculus-christi L.
Other species are considered in the monographs below.
- Inula britannica L.
Exposure to hay containing this plant caused dermatitis on exposed skin. Patch test reactions were positive to this species and to Inula germanica L., negative to four other Inula species (Hegyi 1967).
Potentially allergenic sesquiterpene lactones have been reported from this species.
- Inula germanica L.
Hegyi (1967) reported a positive patch test reaction to this species (see Inula britannica L. above).
Germanins A and B, two potentially allergenic sesquiterpene lactones, have been reported from this species.
- Inula helenium L.
- Elecampane, Scabwort
Alantolactone, otherwise known as alant camphor, elecampane camphor, inula camphor, or helenin, is obtained from the rhizomes of this species. It has been used both orally and rectally as an anthelmintic (Wade 1977).
In NW Moroccan traditional medicine, the leaves are used externally as an astringent and antiseptic (Merzouki et al. 2000). Piyankova & Nugmanova (1975) described cases of allergic dermatitis following contact with the plant. Apparently, it is widely used in the Soviet Union for self-treatment of skin ailments. A sesquiterpene lactone, alantolactone, derived from it is an active sensitiser at a concentration of 1% in petrolatum (Hjorth 1970, Mitchell JC 1970 — unpublished observation). Both alantolactone and the co-occurring isoalantolactone were reported by Stampf et al. (1982) to be sensitisers in guinea pigs. It has previously been demonstrated (Stampf et al. 1978) that cross-sensitivity reactions between alantolactone and isoalantolactone could be demonstrated in both guinea pigs and in man.
Mitchell et al. (1970) observed positive patch test reactions to alantolactone in some individuals who were contact sensitive to various members of the Compositae and to liverworts of the genus Frullania Raddi, (fam. Jubulaceae).
Alantolactone is toxic to cultured human lymphocytes (Dupuis & Brisson 1976), but this activity does not seem to depend on the presence of a methylene group on the lactone. Dupuis et al. (1974) described the reaction of alantolactone with some amino acids. Subsequently, Dupuis et al. (1980) induced contact sensitivity in guinea pigs with an alantolactone-skin protein conjugate.
The fragrance raw material alantroot oil, otherwise known as elecampane oil or oil of Inula, was found to be non-irritant but a strong sensitiser when applied to the skin of human volunteers at a concentration of 4% in petrolatum (Opdyke 1976, p. 307). Some extremely severe reactions were observed. Experimental sensitisation of humans to alantroot oil was described by Marzulli & Maibach (1980).
In addition to alantolactone and isoalantolactone, a number of other potentially allergenic sesquiterpene lactones have been reported from the plant.
- Inula racemosa Hook.f.
This species provides mano roots, which have often been found as adulterants of kuth roots (Saussurea costus Lipsch.). Mano contains sesquiterpene lactones, principally alantolactone and isoalantolactone (Arora et al. 1980). Both of these compounds are known to be contact sensitisers (Stampf et al. 1982).
An extract of the root was found to have phototoxic and weak antibiotic properties against three test micro-organisms (Wat et al. 1980b), suggesting the presence of polyacetylenes and/or thiophenes (see Bidens pilosa L. above and Tagetes L. below).