A potent contact allergen of Phacelia (Hydrophyllaceae)

  title={A potent contact allergen of Phacelia (Hydrophyllaceae)},
  author={Gary W. Reynolds and William L. Epstein and Diane Terry and Eloy Rodr{\'i}guez},
  journal={Contact Dermatitis},
The major contact allergen of Phacelia crenulata (Hydrophyllaceae) has been identified as geranylhydroquinone. A maximization test of geranylhydroquinone showed this to be a potent sensitizer comparable in degree to poison oak/ivy urushiol. Comparative patch testing on humans with urushiol established that the Phacelia allergen does not cross‐react with poison oak or ivy. 
Unusual contact allergens from plants in the family Hydrophyllaceae
The dermatitic constituents of the glandular hairs of plants in the family Hydrophyllaceae comprise a class of uncommon natural products called “phacelioids”, which are equivalent to the urushiols of Toxicadendron (Rhus) in their capacity to sensitize humans.
Contact allergens of an urban shrub Wigandia caracasana
The principal dermatitic constituents of W. caracasana were isolated from the glandular hairs and identified as unusual prenylated quinones and prenylated phenols. Potentials to elicit irritant and
Human maximization test of falcarinol, the principal contact allergen of English ivy and Algerian ivy (Hedera helix, H. canariensis)
In a human maximization test of 5% falcarinol isolated isolated from Hedera helix, 10 of 20 subjects were sensitized and became sensitive to 1%, with 3 of these giving 3+ to 4+ bullous reactions.
Oro‐pharyngeal mucosal reaction to fenoterol
A potent contact allergen of Phacelia (Hydrophyllaceae) is found in Ginkgo tree dermatitis and it is found to be injurious to the skin in humans and animals.
Angio‐oedema without hives, IgE and omalizumab
Theorized that many cases of ACD diagnosed as poison oak dermatitis in the western USA were not caused by Rhus plants, but rather by various Phacelia species, concluding that Phac Amelia plants have an allergenic capacity comparable to Rhus species.
Miscellaneous dermatitis-inducing plants.
Leaves of Ginkgo bitoba not allergenic for Toxicodendron‐sensitive subjects
The increased response to the exposed patch test in my patient indicated that the Wood's ultraviolet light exposure over 30 min had had an effect, but exposure to daylight had also played a part.
Häufige und seltene Kontaktallergene
Die Zahl der niedermolekularen Verbindungen, die als Berufs- und Umweltnoxen eine allergische Kontaktdermatitis verursachen konnen, ist fast unubersehbar gros. Die Induktion einer


Poison oak hyposensitization. Evaluation of purified urushiol.
It is shown that large amounts of urushiol taken over a period of three or more months produced measurable hyposensitization, as detected by repeated patch testing.
Dermatitis venenata from Phacelia crenulata.
Shortly after one of us (S. I. S.) started practicing dermatology in Tucson, Ariz., in 1949, he noticed that every few years, in the spring, there was quite a number of cases of dermatitis venenata
Updating the maximization test for identifying contact allergens
The maximization test for detecting contact allergens has proved to possess both sensitivity and specificity. However, modifications have become necessary because of excessive irritancy reactions to
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