Fallacinal 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. Th ...

in the structural class of chemicals known as anthraquinones. It is found in many species of the lichen family Teloschistaceae.

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 ''Oxneria fallax'', also known as the hooded sunburst lichen, is a small yellow-orange to red-orange foliose lichen that grows on bark or rarely on rock or bone. It is found all over the world except very dry areas, with 10 species common in Nort ...

''), found growing on the bark of mulberry trees. They isolated a

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic comp ...

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 In chemistry, 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, ...

of C₁₆H₁₂O₆. Using information from additional chemical tests, they proposed a tentative structural formula for fallacin. In 1949, T. R. Seshadri 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'', family Teloschistaceae. Recognized by its safron coloured pigmentation, this species grows on rocks and branches of ...

'', 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, a co-occurring substance, using several rounds of column chromatography, 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 from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...

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 CrO3. It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name. This compound is a dark-purple ...

, converting that into its acid chloride, and then performing catalytic reduction on this compound using the Rosenmund reduction followed by

deacetylation : In organic 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 opposit ...

. 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 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. In ...

, 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 the Teloschistaceae, a large

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of mostly lichen-forming

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

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

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

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

green alga The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( Embryophytes) have emerged deep in the Charophyte alg ...

l , still produces fallacinal. Yoshio Hirose and colleagues proposed a synthesis of fallacinal in 1982 involving the

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 ...

of fallacinol (a.k.a. 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 is methylated to give parietin, which then undergoes three successive

s, sequentially forming fallacinol, fallacinal, and then

parietinic acid Parietinic acid is an organic compound in the structural class of chemicals known as anthraquinones. It is found in many species of the lichen family Teloschistaceae. The substance was first reported in the literature by the German chemist Walter ...

. 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 ''

'' 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 Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

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

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bon ...

s, respectively, while the third peak indicates the

aromatic In chemistry, aromaticity is a chemical property of cyclic (ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to sat ...

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

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 {{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 , series=A , page=67 , 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 Anthraquinones Lichen products Polyketides Methoxy compounds Aromatic aldehydes