Plicatic acid is a

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

from the resin acid group. It is naturally found in ''

Thuja ''Thuja'' ( ) is a genus of coniferous tree or shrub in the Cupressaceae (cypress family). There are five species in the genus, two native to North America and three native to eastern Asia. The genus is monophyletic and sister to ''Thujopsis''. M ...

'' and

cypress Cypress is a common name for various coniferous trees or shrubs from the ''Cupressus'' genus of the '' Cupressaceae'' family, typically found in temperate climates and subtropical regions of Asia, Europe, and North America. The word ''cypress'' ...

resin, and the main irritant and contact allergen present in thuja wood; in contrast to

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...

, where the primary irritant is abietic acid. The highest concentrations of plicatic acid can be found in ''

Thuja plicata ''Thuja plicata'' is a large evergreen coniferous tree in the family Cupressaceae, native to the Pacific Northwest of North America. Its common name is western redcedar in the U.S. or western red cedar in the UK, and it is also called pacific re ...

'' (western red cedar), but '' Thuja occidentalis'' (eastern arborvitae) and ''

Cryptomeria japonica ''Cryptomeria'' (literally "hidden parts") is a monotypic genus of conifer in the cypress family Cupressaceae. It includes only one species, ''Cryptomeria japonica'' ( syn. ''Cupressus japonica'' L.f.). It is considered to be endemic to Japa ...

'' (sugi) contain it in significant proportions as well. Exposure to plicatic acid or ''Thuja'' wood dust can worsen

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

and provoke

allergic reaction Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allergy, food al ...

References

{{reflist O-methylated natural phenols Cupressaceae