Fallacinal 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 ...

History

In 1936, Japanese chemists Mitizo Asano and Sinobu Fuziwara reported on their investigations into the colour pigments of the lichen ''Xanthoria fallax'' (now known as '' Oxneria fallax''), found growing on the bark of

mulberry ''Morus'', a genus of flowering plants in the family Moraceae, consists of 19 species of deciduous trees commonly known as mulberries, growing wild and under cultivation in many temperate world regions. Generally, the genus has 64 subordinat ...

trees. They isolated a

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

they named fallacin. A few years later Asano and Yosio Arata further purified the crude material from this lichen, ultimately obtaining an orange-yellow compound with a

molecular formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as paren ...

of C₁₆H₁₂O₆. Using information from additional chemical tests, they proposed a tentative

structural formula The structural formula of a chemical compound is a graphic representation of the molecular structure (determined by structural chemistry methods), showing how the atoms are connected to one another. The chemical bonding within the molecule is al ...

for fallacin. In 1949,

T. R. Seshadri Thiruvengadam Rajendram Seshadri FNA, FRS was an Indian chemist, academic, writer and the Head of the Department of Chemistry at the University of Delhi, known for his researches on the Indian medicinal and other plants. He was a Fellow of the ...

and S. Subramanian described their work with the Indian lichen ''

Teloschistes flavicans ''Teloschistes flavicans'', also known as the golden hair-lichen, is a lichenized species of fungus in the genus ''Teloschistes'' (meaning "split-ends"; a reference to the plant's finely divided thallus and dense coils which appear almost like Br ...

'', in which they isolated an orange substance they named teloschistin, and which had a structural formula identical to that of fallacin proposed by Asano and Arata years earlier. In 1956, Takao Murakami reported reexamining the crude pigment obtainable from ''Xanthoria fallax'' using Asano's original 1936 procedure. He separated out fallacin from

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 ...

, a co-occurring substance, using several rounds of

column chromatography Column chromatography in chemistry is a chromatography method used to isolate a single chemical compounds, chemical compound from a mixture. Chromatography is able to separate substances based on differential absorption of compounds to the adsorbe ...

, and showed that Asano's original pigment was actually a combination of two pigments with different

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 ...

s, which he designated as fallacin-A and fallacin-B. Murakami determined fallacin-A to have a melting point of and a molecular formula of C₁₆H₁₀O₆. He established the structure of the compound synthetically by oxidizing it with

chromium trioxide Chromium trioxide (also known as chromium(VI) oxide or chromic anhydride) is an inorganic compound with the formula . It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name. This compound is a dark-purple solid ...

, converting that into its

acid chloride In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example o ...

, and then performing catalytic reduction on this compound using the

Rosenmund reduction The Rosenmund reduction is a hydrogenation process in which an acyl chloride is selectively reduced to an aldehyde. The reaction was named after Karl Wilhelm Rosenmund, who first reported it in 1918. The reaction, a hydrogenolysis, is cataly ...

followed by

deacetylation : In chemistry, acetylation is an organic esterification reaction with acetic acid. It introduces an acetyl group into a chemical compound. Such compounds are termed ''acetate esters'' or simply ''acetates''. Deacetylation is the opposite react ...

. The resultant product was confirmed to be identical to fallacin-A, and so he designated this substance as fallacinal. He named fallacin-B as fallacinol, a closely related substance that, because of Seshadri and Subramanian's work, is also known as "teloschistin" in the literature.

Occurrence

Liquen Xanthoria fallax Enfoque 2012-1-21 SierraMadrona

Fallacinal occurs in many species of

, a large

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of mostly

-forming

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. Historically, the substance was most associated with ''

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 ...

'', '' Teloschistes'', and '' Xanthoria'', but these genera have since been subdivided into many smaller,

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

genera. The cultivated mycobiont of ''Xanthoria fallax'', grown in isolation with the

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

l , still produces fallacinal. Yoshio Hirose and colleagues proposed a

synthesis Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organi ...

of fallacinal in 1982 involving the

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 ...

of fallacinol (teloschistin). In 1970, the Swedish chemist 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 anthraquinone compounds commonly found in the lichen genus ''

''. 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

, which then undergoes three successive

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 fallacinol, fallacinal, parietinic acid, and emodin.

Properties

In its purified form, fallacinal exists as orange-red needles with a

of . Its ultraviolet spectrum has five peaks of maximum absorption (λ_max) at 244, 264, 280, 340, and 425 nm. 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 three peaks at 1625, 1675, and 1720 cm⁻¹; the first two of these peaks corresponds to the

chelated Chelation () is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These l ...

and non-chelated

ketone In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

s, respectively, while the third peak indicates the

aromatic In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

grouping.

References

{{Reflist, colwidth=30em, refs= {{cite journal , last1=Arup , first1=Ulf , last2=Søchting , first2=Ulrik , last3=Frödén , first3=Patrik , title=A new taxonomy of the family Teloschistaceae , journal=Nordic Journal of Botany , volume=31 , issue=1 , year=2013 , pages=16–83 , doi=10.1111/j.1756-1051.2013.00062.x {{cite journal , last1=Asano , first1=M. , last2=Arata , first2=Y. , year=1941 , title=Über die Bestandteile von ''Xanthoria fallax'' (Hepp.) Arn , journal=Journal of the Pharmaceutical Society of Japan , volume=60 , issue=10 , pages=521–525 , doi=10.1248/yakushi1881.60.10_521 , doi-access=free {{cite journal , last1=Asano , first1=Mitizo , last2=Fuziwara , first2=Sinobu , year=1936 , title=Über das Farbstoff von ''Xanthoria fallax'' (Hepp.) Arn. (Vorläufige Mitteil.) , journal=Journal of the Pharmaceutical Society of Japan , volume=56 , issue=12 , pages=1007–1010 , doi=10.1248/yakushi1881.56.12_1007 , doi-access=free {{cite journal , last1=Hirose , first1=Yoshio , last2=Suehiro , first2=Yoshihisa , last3=Furukawa , first3=Yumiko , last4=Murakami , first4=Takao , title=Chemische Studien ueber natuerliche Anthrachinone. II. Synthese von Citreoroseine, Fallacinol und Fallacinal , trans-title=Chemical Studies on Natural Anthraquinones. II. Synthesis of Citreorosein, Fallacinol, and Fallacinal , journal=Chemical and Pharmaceutical Bulletin , volume=30 , issue=11 , year=1982 , doi=10.1248/cpb.30.4186 , pages=4186–4188 , language=de {{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 , pages=173–174 {{cite journal , last=Muramaki , first=Takao , year=1956 , title=The coloring matters of ''Xanthoria fallax'' (Hepp.) Arn. Fallacinal and fallacinol , journal=Pharmaceutical Bulletin , volume=4 , issue=4 , pages=298–302, doi=10.1248/cpb1953.4.298 , pmid=13378955 {{cite journal , last1=Nakano , first1=H. , last2=Komiya , first2=T. , last3=Shibata , first3=S. , title=Anthraquinones of the lichens of ''Xanthoria'' and ''Caloplaca'' and their cultivated mycobionts , journal=Phytochemistry , volume=11 , issue=12 , year=1972 , doi=10.1016/s0031-9422(00)89847-7 , pages=3505–3508 {{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=Seshadri , first1=T.R. , last2=Subramanian , first2=S. Sankara , year=1949 , title=Chemical investigation of Indian lichens - Part VIII. Some lichens growing on sandal trees (''Ramalina tayloriana'' and ''Roccella montagnei'') , journal=Proceedings of the Indian Academy of Sciences , volume=30 , page=67 , doi=10.1007/BF03049096 , url=https://www.ias.ac.in/describe/article/seca/030/01/0015-0022 {{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 , doi=10.1007/s11557-006-0023-x Anthraquinones Lichen products Polyketides Methoxy compounds Aromatic aldehydes Fungal pigments