Lichen phenols

Reindeer lichen Phenolics Jack pine and white... 

Phenolic compounds are widespread products of secondary metabolism of lichen, and antioxidant activity is most frequently associated with their presence. Lichen phenolics are mainly depsides, depsidones and dibenzofurans, whereas vascular plant phenolics include tannins, lignins and flavonoids. Orsellinic acid is the basic unit in the biosynthesis of hchen phenolics. Lichen phenols are generally secreted by the fungal partner and deposited as crystals on the surface of the ceU wall of the fungal hyphae. Lichen phenols are primarily acetate-polymalonate derived with the exception of pulvinic acid derivates which are synthesised via... 

They are called didepsides, tridepsides, poly-depsides, etc., depending on the number of phenol residues they contain. Obtained from lichens, present in tea. 

Tar preparations are used mainly in the treatment of psoriasis, dermatitis, and lichen simplex chronicus. The phenolic constituents endow these compounds with antipruritic properties, making them particularly valuable in the treatment of chronic lichenified dermatitis. Acute dermatitis with vesiculation and oozing may be irritated by even weak tar preparations, which should be avoided. However, in the subacute and chronic stages of dermatitis and psoriasis, these preparations are quite useful and offer an alternative to the use of topical corticosteroids. 

Choudhary MI, Azizuddin, Jalil S, Atta-ur-Rahman (2005) Bioactive Phenolic Compounds from a Medicinal Lichen, Usnea longissima. Phytochemistry 66 2346... 

C-Methylation also features in the biosynthesis of usnic acid (Figure 3.41), an antibacterial metabolite found in many lichens, e.g. Usnea and Clado-nia species, which are symbiotic combinations of alga and fungus. However, the principal structural modification encountered involves phenolic oxidative coupling (see page 28). Two molecules of methylphloracetophenone are incorporated, and these are known to derive from a pre-aromatization methylation reaction and not by... 

Phenoloxidase activity has recently been found in lichenized ascomycetes belonging to a variety of taxonomic groups (Zavarzina and Zavarzin, 2006). The researchers concluded that the oxidases discovered may play an important role in the phenolic metabolism of lichens and be involved in the formation of humus during primary soil formation processes, which may be a previously unknown geochemical function of lichens. 

Atranorin (phenolic) Parmelia tinctorum (lichen) Uncoupler (<5)... 

Jayaprakasha, G.K. Rao, L.J. Singh, R.P. Sakariah, K.K. 1998. Improved chro-matographie method for the purification of phenolic constituents of the lichen parmotrema tinctorum (Nyl.) Hale. J. Chromatogr. Sci. 36 8-10. 

The total synthesis of the lichen diphenyl ether epiphorellic acid 1 was achieved in the laboratory of J.A. Elix using the Smiles rearrangement as the key step. The diaryl phenolic ester substrate was heated in dry DMSO in the presence of potassium carbonate, which brought about the rearrangement. The resulting carboxylic acid was converted to the methyl ester with diazomethane and was debenzylated under catalytic hydrogenation conditions. 

Increments in phenolics content after UV-B exposure have been recorded for a number of plant species (e.g. Caldwell et al., 1983 Chaves et al., 1997 Turunen et al., 1999). For example, a 10-fold increase in flavonoid concentration occurred in grape vine plants Vitis viniferd) exposed to natural sunlight relative to plants in which UV-A and UV-B radiation had been filtered out (Kolb et al., 2001). Similar responses include UV-B tolerant Arabidopsis mutants (Bieza and Lois, 2001) and lichens in which a clear attenuation of high frequency photons within the thallus was observed due to chemical filtration (Hall et al., 2002). Birch Betula... 

Usnic acid (7.53)—a highly biologically active dibenzofuran—is a phenol oxidation product of an acylphlorogludnol. It is produced by numerous lichens, including several Usnea species. Apart from its antibiotic and anti-leukemic activity, it has insect anti-feedant activity. Its presence may account for the observation that many lichens are resistant to serious insect attack. 

Lichens and mosses are extracted to isolate their aromatic components that are widely used in the fragrance industry. Oakmoss, the lichen Evemia pnmastri (L.) grows on oak trees. Its extract has a penetrating sweet, smoky, earthy odor due to a complex mixture of many compounds, including the characterizing methyl 2,4-dihydroxy-3,6-dimethyl benzoate (evemyl), and 3-methoxy-2,5-dimethyl phenol (orcinol). 

D. are condensation products of aromatic hydroxy-carboxylic acids in which the carboxy group of the acidic molecule (S) is esterified by the phenolic hydroxy group of the 2nd acidic molecule (A, alcohol). Depending on the number of hydroxycarboxylic acids in the molecule distinction is made between di- and tridep-sides and on the linkage between para- and meta-de-psides. D. occur mainly in lichens ( lichen substances) where the substituents in the above formula can be r, R =CHj, n-CjH, n-CsH, R, R =H, CHj, CHO,... 

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. 

CigHiftO, Mr 344.32, yellow prisms, mp. 150-152 °C, [a]o +490° or-490° (dioxan). A dibenzofuran derivative from lichen the (+)-form occurs in Cladonia mitis and Sphaerophorus ramulifer, the (-)-form in Cladoniapleurota. I. is considerably less common than usnic acid. The biosynthesis involves phenol oxidation of methylphloracetophenone. 

CigHisO, Mr 344.32, yellow prisms, mp. 203 °C, [a] +495° and -495° (CHCl,), respectively. A biologically highly active dibenzofuran derivative, occurring both as the (+)- and the (-)-forms in numerous lichens (especially in Usnea species) antibiotic, antileukemic, growth regulatory (in plants), and antifeedant (in insects) activities have been described. It is used as the free acid and as the sodium salt in pharmaceutical preparations. The biosynthesis presumably proceeds via phenolic oxidation. Other dibenzofuran derivatives from lichens are didymic acid, pannaric acid, pla-codiolic acid, and schizopeltic acid. 

Aluminum bromohydrate Aluminum chloride anhydrous Aluminum chlorohydrate Aluminum citrate Aluminum dichlorohydrate Aluminum phenolsulfonate Aluminum sesquichlorohydrate Aluminum sulfate Aluminum zirconium octachlorohydrate Aluminum zirconium octachlorohydrex GLY Aluminum zirconium pentachlorohydrate Aluminum zirconium pentachlorohydrex GLY Aluminum/zirconium tetrachlorohydrate Aluminum zirconium tetrachlorohydrex GLY Aluminum zirconium trichlorohydrate Aluminum/zirconium trichlorohydrex GLY Ammonium phenolsulfonate Cetyl pyridinium chloride Chlorothymol Cloflucarban Farnesol Lapyrium chloride Lichen (Usnea barbata) extract Linalool Methylbenzethonium chloride Phenethyl alcohol Phenol 2-Phenylethyl acetate Potassium alum anhydrous Quaternium-18 methosulfate Sodium aluminum chlorohydroxy lactate Sodium phenolsulfonate Steapyrium... 

F Odabasoglu, A Aslan, A Cakir, H Suleyman, Y Karagoz, M Halid and Y Bayir, Comparison of antioxidant actidty and phenolic content of three lichen species, Phytotherepy Research, W0418 938-941. 

Acyclic sugar alcohols are considered as the most important agents for osmosis in plants, related to the maintenance of the water potential in many lower and higher plants living in arid conditions. Many lichens accumulate erythritol, mannitol, arabitol, or sorbitol as the main system to maintain a convenient, residual amount of water to survive. Flowever, a balanced [polyol]/[hexose] ratio is required to avoid catabolite repression of many enzymes related to amino acids and phenolics metabolism. 

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