Plicatic acid

Plicatic acid is a carboxylic acid from the resin acid group. It is naturally found in Thuja and cypress resin, and the main irritant and contact allergen present in thuja wood; in contrast to pine, where the primary irritant is abietic acid.

Plicatic acid

Names
IUPAC name (7′β,8β,8′α)-3′,4,4′,8,8′,9-Hexahydroxy-5,5′-dimethoxy-2,7′-cyclolignan-9-oic acid
Systematic IUPAC name (1S,2S,3R)-1-(3,4-Dihydroxy-5-methoxyphenyl)-2,3,7-trihydroxy-3-(hydroxymethyl)-6-methoxy-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid
Identifiers
CAS Number	16462-65-0 Y
3D model (JSmol)	Interactive image
ChemSpider	94630 Y
PubChem CID	104836
UNII	G3VF11QD86 Y
CompTox Dashboard (EPA)	DTXSID40894748
InChI InChI=1S/C20H22O10/c1-29-14-5-10-7-19(27,8-21)20(28,18(25)26)16(11(10)6-12(14)22)9-3-13(23)17(24)15(4-9)30-2/h3-6,16,21-24,27-28H,7-8H2,1-2H3,(H,25,26)/t16-,19+,20+/m0/s1 Y Key: PGFBYAIGHPJFFJ-PWIZWCRZSA-N Y InChI=1/C20H22O10/c1-29-14-5-10-7-19(27,8-21)20(28,18(25)26)16(11(10)6-12(14)22)9-3-13(23)17(24)15(4-9)30-2/h3-6,16,21-24,27-28H,7-8H2,1-2H3,(H,25,26)/t16-,19+,20+/m0/s1 Key: PGFBYAIGHPJFFJ-PWIZWCRZBT
SMILES O=C(O)[C@]2(O)[C@H](c1c(cc(OC)c(O)c1)C[C@@]2(O)CO)c3cc(O)c(O)c(OC)c3
Properties
Chemical formula	C20H22O10
Molar mass	422.386 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

The highest concentrations of plicatic acid can be found in Thuja plicata (western red cedar), but Thuja occidentalis (eastern arborvitae) and Cryptomeria japonica (sugi) contain it in significant proportions as well.

Exposure to plicatic acid or Thuja wood dust can worsen asthma and provoke allergic reactions.^[1]