Parietinic acid is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

in the structural class of chemicals known as

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxo ...

s. It is found in many species of the

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Teloschistaceae The Teloschistaceae are a large family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. The family, estimated to contain over 1800 species, was extensively revised in 2013, including the creation o ...

. The substance was first reported in the literature by the German chemist Walter Eschrich in 1958.

Occurrence

Originally isolated from the lichen ''

Xanthoria parietina ''Xanthoria parietina'' is a foliose lichen in the family Teloschistaceae. It has wide distribution, and many common names such as common orange lichen, yellow scale, maritime sunburst lichen and shore lichen. It can be found near the shore on ro ...

'', it has since been identified in many lichens of the family

Teloschistaceae The Teloschistaceae are a large family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. The family, estimated to contain over 1800 species, was extensively revised in 2013, including the creation o ...

. In 1970, Johan Santesson proposed a possible

biogenetic A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of p ...

relationship between the anthraqunone compounds commonly found in ''

Caloplaca ''Caloplaca'' is a lichen genus comprising a number of distinct species. Members of the genus are commonly called firedot lichen, jewel lichen.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, gold lichens, "ora ...

''. According to this scheme,

emodin Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is a chemical compound, of the anthraquinone family, that can be isolated from rhubarb, buckthorn, and Japanese knotweed (''Reynoutria japonica'' syn. ''Polygonum cuspidatum''). Emodin is particular ...

methylated In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...

to give

parietin Parietin is the predominant cortical pigment of lichens in the genus '' Caloplaca'', a secondary product of the lichen ''Xanthoria parietina'', and a pigment found in the roots of Curled Dock (''Rumex crispus''). It has an orangy-yellow color and ...

, which then undergoes three successive

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

s, sequentially forming fallacinol, fallacinal, and then parietinic acid. A is a set of biosynthetically related compounds produced by a lichen. In 2002, Ulrik Søchting and Patrik Frödén identified chemosyndrome A, the most common chemosyndrome in the genus ''

Teloschistes ''Teloschistes'' is a genus of lichens in the family Teloschistaceae. It was circumscribed by Norwegian botanist Johannes Musaeus Norman in 1852. The name of the genus means "split ends". Species *'' Teloschistes chrysophthalmus'' *'' Teloschis ...

'' and in the entire family Teloschistaceae, which features parietin as the main substance and smaller proportions of teloschistin, fallacinal, parietinic acid, and emodin.

Properties

In its purified form, parietinic acid exists as orange needles with a

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...

of . Its ultraviolet spectrum has two peaks of maximum absorption (λ_max) at 325 and 435 nm, and its

infrared spectrum Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

has two peaks at 1629 and 1700 cm⁻¹. Parietinic acid was shown to have antifungal activity and antibacterial activity in laboratory tests.

References

{{Reflist, refs= {{cite journal , last=Eschrich , first=Walter , year=1958 , title=Parietic acid, a new component of the yellow wall lichen ''Xanthoria parietina'' (L.) Th. Fr , journal=Biochemische Zeitschrift , volume=330 , issue=1 , pages=73–78 , pmid=13535618 , language=de {{cite journal , last1=Manojlovic , first1=Nedeljko T. , last2=Solujic , first2=Slavica , last3=Sukdolak , first3=Slobodan , title=Antimicrobial activity of an extract and anthraquinones from ''Caloplaca schaereri'' , journal=The Lichenologist , volume=34 , issue=1 , year=2002 , doi=10.1006/lich.2001.0365 , pages=83–85 {{cite book , last=Huneck , first=Siegfried , title=Identification of Lichen Substances , publisher=Springer Berlin Heidelberg , publication-place=Berlin, Heidelberg , year=1996 , isbn=978-3-642-85245-9 , oclc=851387266 , page=180 {{cite journal , last1=Łaska , first1=G. , last2=Kiercul , first2=S. , last3=Piotrowska-Niczyporuk , first3=A. , last4=Jacob , first4=M. , last5=Pasco , first5=D. , title=Secondary metabolites isolated from ''Xanthoria parietina'' (L.) Th. Fr. lichen and their biological activity , journal=Planta Medica , volume=81 , issue=S 01 , year=2016 , doi=10.1055/s-0036-1596402 , pages=S1–S381 {{cite journal , last1=Santesson , first1=Johan , title=Anthraquinones in ''Caloplaca'' , journal=Phytochemistry , volume=9 , issue=10 , year=1970 , doi=10.1016/S0031-9422(00)85380-7 , pages=2149–2166 {{cite journal , last1=Søchting , first1=Ulrik , last2=Frödén , first2=Patrik , year=2002 , title=Chemosyndromes in the lichen genus ''Teloschistes'' (Teloschistaceae, Lecanorales) , journal=Mycological Progress , volume=1 , issue=3 , pages=257–266 Anthraquinones Lichen products