Parietinic acid is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

in the structural class of chemicals known as

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic hydrocarbon, aromatic organic compound with formula . Several isomers exist but these terms usually refer to 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein th ...

s. It is found in many species of the

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

family

Teloschistaceae The Teloschistaceae are a large family (biology), family of mostly lichen-forming fungi belonging to the class (taxonomy), class Lecanoromycetes in the division (botany), division Ascomycota. The family has a cosmopolitan distribution, althoug ...

. 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 common and widespread lichen-forming fungus in the family Teloschistaceae. Commonly known as the yellow wall lichen, common orange lichen, or maritime sunburst lichen, this foliose lichen, leafy lichen is known f ...

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

. 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 an organic compound. Classified as an anthraquinone, it can be isolated from rhubarb, buckthorn, and Japanese knotweed ('' Reynoutria japonica'' syn. ''Polygonum cuspidatum''). Emodin is part ...

methylated Methylation, in the chemical sciences, is 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 term ...

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 orange-yellow color ...

, which then undergoes three successive

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

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'' and in the entire family Teloschistaceae, which features parietin as the main substance and smaller proportions of

teloschistin Fallacinol (teloschistin) is an organic compound in the structural class of chemicals known as anthraquinones. It is found in some lichens, particularly in the family Teloschistaceae, as well as a couple of plants and non lichen-forming fungi. ...

, 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 of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilib ...

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 that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those of ...

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