Lichen acids

Chemical Designations - Synonyms Allomaleic acid Boletic acid trans-Butenedioic acid trans-1,2-Ethylenedicarboxylic acid Lichenic acid Chemical Formula H02CCH=CHC02H. 

Allomaleic acid 2-butenedioic acid trans-butenedioic acid boletic acid lichenic acid trans-l,2-ethenedicarboxylic acid... 

Fig. 2.12 Compounds 57-59, triterpene methyl ethers (TMEs), from Chionochloa. Compounds 60-64, lichen-acid derivatives from European Ramalina siliquosa...

Fig. 5.3 Compounds 395-405, lichen acids from species of Pseudevernia, Rhizoplaca, and Thamnolia...

Fig. 5.4 Compounds 406 24, lichen acids and other compounds from species of Lobaria,...

Gardner, C.R. and Mueller D.M.J. (1981). Factors affecting the toxicity of several lichen acids effect of pH and lichen acid concentration. American Journal of Botany 68 87-95. 

Although not part of soil, lichens, by virtue of their solubilising action on rocks, contribute to the elemental enrichment of soil. Several studies have identified lichen acids as complexing agents for the iron and aluminium of rocks (95, 96). An examination of the various structures indicates that the basic structure responsible for the chelation is the carboxylic acid group with an orthophenolic group. Grodzinskii (97) has found lichens to be intense accumulators of elements in the uranium-radium, actinouranium and thorium orders. 

Lichenic Acid Light Naphtha Light Naphtha Light Oil... 

Another intriguing link between metals and organic acids has been claimed for the ubiquitous lichens, which are known to be able to dissolve minerals from rocks and to absorb the nutrients within their tissues. The basic unit of the lichen acids implicated is a chelating a-hydroxy carboxylic moiety (7). 

Abo-Khatwa, A. N., Al-Robai, A. A., and Al-Jawhari, D. A., 1996. Lichen acids as uncouplers of oxidative phosphorylation of mouse-liver mitochondria. Nat. Toxins 4, 96-102. 

At present it is difficult to compare the effects of different lichen taxa, or different lichen acids, on bulk silicate mineral weathering rates under field conditions. An abundant literature depicts the physical and chemical distribution of minerals, alteration products and organic components during lichen growth, mostly provided through SEM, EDS, XRD and... 

Acid-base titration studies measuring the concentrations and acid dissociation properties of functional groups on lichen cell walls, extracellular polysaccharides and lichen acids. 

Spectroscopic and bulk aqueous complexation studies of major lichen acids, including derivation of the structures and stabilities of metal-organic complexes and precipitates involving a wide range of elements. 

Experimental studies quantifying LPD reaction equilibria and kinetics involving major rock-forming minerals and important lichen acids. 

Schatz, A. (1963). Soil microorganisms and soil chelation. The pedogenic action of lichens and lichen acids. Agricultural and Food Chemistry, 11, pp. 112-18. 

SYNS ALLOMALEIC ACID BOLETIC ACID trans-BUTENEDIOIC ACID (E)-BUTENEDIOIC ACID trans-l,2-ETHYLENEDICARBOXYLICACID (E)l,2-ETH il.ENEDICARBOXI LIC ACID KYSELINA EUM. ROVA (CZECH) LICHENIC ACID NSC-2752 U-1149 USAF EK-P-583... 

Allomaleic acid allomalenic acid boletic acid butenedioic acid E297 1,2-ethenedicarboxylic acid lichenic acid trans-butenedioic acid NSC-2752 traMs-l,2-ethylenedicarboxylic acid U-1149 USAF EK-P-583. 

Schatz, A., 1962. Pedogenic (soil-forming) activity of lichen acids. Naturwissenschaften, 49 518-519. 

ICELAND MOSS, Lichen islandicus consists of the dried thallus of Cetraria islandica (L.) Acharius sensu latiore, family Parmeliaceae. Characteristic constituents include bitter-tasting lichen acids usnic acid gives the bitter-taste and has antibacterial effects. It also contains polysaccharides, which form a mucilage Lichenin, a linear cellulose-like polymer of D-glucose, is soluble in hot water, and on cooling it forms a gel. The other polysaccharide is isolichenin, a linear starch-like polymer of D-glucose, soluble in cold water. 

In the form of decoctions Iceland moss is used to treat dry coughs. Here the antibiotic and bacteriostatic lichen acids may be of significance. A further indication is lack of appetite and gastro-enteritis. 

It contains more than 50% of a mucilage which is soluble in warm water and consists of two polysaccharides, lichenin, which is built of 60-200 glucose molecules, and isolichenin, which is soluble in cold water and built of about 40 glucose molecules. The bitter taste is due to the occmrence of lichen acids. 

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