Lichen acids lecanoric acid

These lichens contain a number of peculiar acids (lecanoric acid erythric acid, roccellic acid, c.), which are split up by alkalies, the final products being orcin, CeH3CH3(OH)2, and erythrite, C4H10O,. 

Maass WSG (1975a) The phenolic constituents of Peltigera aphthosa. Phytochemistry 14 2487-2489 Maass WSG (1975b) Lichen substances. V. Methylated derivatives of orsellinic acid, lecanoric acid, and gyrophoric acid from Pseudocyphellaria crocata. Can J Bot 53 1031-1039... 

Depsides, tridepsides, and tetradepsides consist of two, three, and four hydroxybenzoic acid residues linked by ester groups. These are the most numerous classes of secondary metabolites in lichens. More than one hundred Uchen compounds are depsidones, which have an additional ether bond between aromatic rings. Depsidones in Uchen are believed to arise by oxidative cycUzation of depsides. It has been found that depsidone and depside compounds such as atranorin, divaricatic acid, lecanoric acid, evemic acid, salazinic acid, physodic acid, and stictic acid possess important antimicrobial activity (Manojlovic et al. 2012 Kosanic et al. 2013, 2014a Rankovic et al. 2014). 

Lichen Substances V. Methylated Derivatives of Orsellinic Acid, Lecanoric Acid and Gyrophoric Acid from Pseudocyphellaria crocata. Can. J. Bot. 53, 1031 (1975). 

Cudbear. Crottle. Common names for the lichen Ochrolechia tartarea L., Lecanoraceae and for the coloring matter from this and other lichens, especially Lecanoraceae and Roccellaceae. A source of litmus, q.v. Acids in lichens (e.g. lecanoric acid) hydrolyze to orcinol, q. v., which, in the presence of ammonia can be oxidized to the dye orcein, q.v. The dyes French Purple, Persio, Orchil, and Orseitles derive from the salts of orcein Colour Index Vol. 3 (3rd ed-, 1971) p 3241. 

CH2OH R = H, CHj. Most D. are didepsides, such as, e.g., atranorin, chloroatranorin, gyrophoric acid, and lecanoric acid. In some D. (e. g., alectorialic acid and barbatolic acid) the acid part (S) is linked with a benzylic hydroxy group of the A part. The structures of about 100 D. isolated from lichens have been elucidated by hydrolysis and alcoholysis to the corresponding carboxylic acids or esters (S part) and to the phenols (A part), respectively. 

C20H22O10, Mr422.39, needles, mp. 156-157 °C, [aJo +8°. Ester of lecanoric acid with erythritol. E. occurs, e. g., in the lichen family Roccellaceae and furnishes the bitter-tasting montagnetol (C12H1JO7, Mr 272.25,... 

Depsides, in which esterification to links two polyketide-derived units [such as lecanoric acid (50)] (Fig. 5.24), are quite common among lichens (Weiss and Edwards, 1980). Many of these compounds are strongly allelopathic and are responsible for the death of trees inhabited by the dense growth of lichens (Cutler, 1992). 

Fischer followed Schiff and supposed that tannins are condensation products of substituted hydroxybenzoic acids. He found that these, which he called depsides SeifieiVy to tan), have some resemblance to tannins. Tannin is a condensation product of gallic acid but always contains glucose. A synthetic pentadigalloylglucose had some resemblance to tannin. A compound of this kind with a mol. wt. 4021 was prepared. From experiments of Kostanecki and V. Lampe, Freudenberg assumed that catechin is related to the flavones and anthocyanidins (see p. 863). Orsellinic acid (see p. 400) was shown to be closely related to gallic acid, and lecanoric acid from lichens to be a didepside (/)-diorsellinic acid). ... 

This view was confirmed more directly when 5-methylorcylaldehyde (XXIV) but not orcylaldehyde was converted to substituted toluquinols and gliorosein (XXV) by Gliocladium roseum, implying that the C-methyltrans-ferase concerned could not accept the aromatic orcylaldehyde (Steward and Packter, 1968). In addition, whereas acetate (Yamazaki et al., 1%5) and or-sellinic acid (Yamazaki and Shibata, 1966) were both incorporated into the depside lecanoric acid (XXVI) (derived by esterification of two molecules of orsellinic acid) in the lichen Parmelia tinctorum, orsellinic acid was not converted to the related atranorin (XXVIl) (Yamazaki and Shibata, 1966) this... 

Hamada N, Ueno T (1990) Lecanoric acid from the mycobiont of the lichen Stereocaulon curtatum. Phytochemistry 29 678-679... 

Manojlovic et al. (2005) reported antifungal activity of the anthraquinone parietin isolated from Caloplaca cerina. A potent fungitoxic compotmd, lecanoric acid, was isolated from Parmotrema tinctorum lichen and tested against the fungus... 

Jayaprakasha and Rao (2000) extracted with benzene and acetone the lichen Parmotrema stuppeum in order to investigate its antioxidant effect. Both the extracts were fractionated on 1 % oxalic acid impregnated silica gel column to obtain methyl orsenillate, orsellinic acid, atranorin and lecanoric acid, respectively. Antioxidant activities of benzene extract, acetone extract and isolated compounds were evaluated in a carotene-linoleate model system. The obtained results showed that the pure compounds and extracts have moderate antioxidant activity. 

Rapid formation of soluble colored complexes when lichen compounds or ground lichen thalli were shaken with water suspensions of minerals and rocks was reported by Schatz (1963) and Syers (1969) no information was obtained, however, for the amounts of cations complexed. Of the six lichen compounds investigated by Iskandar and Syers (1972), four formed soluble, colored complexes with biotite. The extract obtained from the interactions of lecanoric acid, a depside of the orcinol type, and biotite was reddish-yellow in color. The formation of a reddish-yellow complex when lecanoric acid is allowed to react with calcium salts is used as a specific color test for this acid (Culberson, 1969). Because a complex may be colorless or adsorbed by the silicate phase, the fact that a lichen compound does not form a colored complex does not necessarily indicate that complex formation has not occurred. Iskandar and Syers (1972) showed that significant amounts of Ca, Mg, Fe, and Al were complexed by lichen compounds. In general, greater amounts of divalent than trivalent cations were complexed. For a particular cation, a similar amount was released from the silicates by solutions of the lichen compounds and by solid lichen compounds. These findings suggest that lichen compounds are sufficiently soluble in water to form soluble metal complexes. 

The amount of lichen substances contained in the different species varies greatly. From Parmelia tinctorum, 23.5% of lecanoric acid alone was obtained from Lepraria chlorina, 10.5% of vulpinic acid from Alectoriaochro-leuca, 5.5% of usnic acid (Zopf, 1907), whereas the content of the protoli-chesterinic acids in Iceland moss amounts to only a few promilles. The normal amount is possibly around 1%. 

Fig. 1. Color reactions of lichen substances. The structural part responsible for the color reaction is drawn in heavy lines, (a) C+ compounds lecanoric acid (left) and norlichexanthone (right) (b) PD+ thamnolic acid reacting with /7-phenylenediamine (c) KC+ lobaric acid hydrolyzed with KOH to yield a compound with 2 free m-hydroxyls (d)lichexanthone reacting with Dimroth s reagent to give a fluorescent compound.

Yoshimura I, Kurokawa T (1991) Biogenesis of Lecanoric Acid in Lichen Thalli and its Related Substances. Bull Kochi Gakuen Coll 22 663... 

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