Lichen-derived substances

Given this background of generalized biological effects of lichen-derived substances, antiviral activity of lichen-derived compounds should be anticipated. 

Takani, M., Yajima, T., Masuda, H. Yamauchi, O. (2002). Spectroscopic and structural characterization of copper(II) and palladium(II) complexes of a lichen substance usnic acid and its derivatives. Possible forms of environmental metals retained in lichens. Journal of Inorganic Biochemistry, 91, 139-50. 

Mosbach, K. On the Biosynthesis of Lichen Substances 2. The Pulvinic Acid Derivative Vulpinic Acid. Biochem. Biophys. Res. Commun. 17, 363 (1964). 

Contact Dermatitis Newsletter (8) i77-i79 Mitchell JC (1981) Industrial aspects of 112 cases of allergic contact dermatitis from Frullania in British Columbia during a 10-year period. Contact Dermatitis 7 268-269 Mitchell JC (1986) Frullania (liverwort) phytodermatitis (woodcutter s eczema). Clin Dermatol 4 62-64 Mitchell JC, Shibata S (1969) Immunologic activity of some substances derived from lichenized fungi. J Invest Dermatol 52 517-520... 

Mass spectrometry is another useful tool for the identification and structural elucidation of lichen substances. Tlje principles of the method are given in a review by Lehmann and Schulten (1976). The mass spectra (MS) of numerous depsides, depsidones, depsones, dibenzofuranes and diphenylbutadienes have been discussed by Huneck et al. (1968a). In the same year, Letcher (1968) published the MS of some pulvinic acid derivatives. Martinez and Mestres (1972) recorded the MS of depsidones derived from norstictic acid, and Holland and... 

Gas liquid chromatography (GLC) has found only limited application in lichen chemistry because most lichen substances are very polar and have low volatility. To overcome this problem, more volatile derivatives are used. Nishikawa et al. (1973) analyzed the low molecular weight carbohydrates of eight lichen species as their acetyl, trifluoroacetyl and trimethylsilyl derivatives by GLC under the following conditions Hj,... 

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... 

The most common phenolic acid units derived by the acetate-polymalonate pathway and combined to form the characteristic lichen substances are of two types the orcinol-type units and p-orcinol-type units. While compounds formed from these two types of units are similar in many ways, differences in their structure and especially in their distributimi among the lichens suggest that the usual tendency to consider the orcinol and p-orcinol compounds separately probably has a biosynthetic justification. 

There is a growing interest in the pharmaceutical properties of compounds derived from lichens. However, relatively few lichen substances have been screened in detail for biological activity and therapeutic potential, due principally to difficulties in obtaining them in quantities and purities sufficient for structural elucidation and pharmacological testing. Additionally, precise lichen determinatirHi is essential and requires taxonomic expertise (Boustie and Grube 2005). 

Rankovic B, Misic M, Sukdolak S (2008) The antimicrobial activity of substances derived from the lichens Physcia aipolia, Umbilicaria polyphylla, Parmelia caperata and Hypogymnia physodes. World J Microbiol Biotechnol 24 1239-1242 Rankovic B, Kosanic M, Manojlovic N et al (2014) Chemical composition of Hypogymnia physodes lichen and biological activities of some its major metabolites. Med Chem Res 23 408-416 Rezanka T, Dembitsky V (1999) Novel brominated lipidic compounds from lichcms of Central Asia. Phytochemistry 51 963-968... 

Lichens had to evolve diverse biosynthetic pathways to produce such complex arrays of secondary metabolites polyketide, shikimic acid, and mevalonic acid pathways. Most of the lichen substances are phenolic compounds. Polyketide-derived aromatic compounds, depsides, depsidones, dibenzofurans, xanthones, and naphthoquinones, are of great interest. Compounds from other pathways are esters, terpenes, steroids, terphenylquinones, and pulvinic acid (Fahselt 1994 Cohen and Towers 1995 Muller 2001 Brunauer et al. 2006, 2007 Stocker-Worgotter and Elix 2002 Johnson et al. 2011 Manojlovic et al. 2012). So, many lichens and lichen products have proved to be a source of important secondary metabolites for food and pharmaceutical industries (Huneck 1999 Oksanen 2006)... 

Benzo-l,4-quinoid structures occur in nature as the final oxidation products ofvarious mono- and polycyclic compounds. Most simple benzo-1,4-quin ones occur in microorganisms (moulds), higher fungi and lichens, and less frequently in higher plants and some insects. Common substances are glycosides occurring in colourless reduced forms (such as derivatives of hydroquinone known by the systematic name of benzene-l,4-diol). Coloured quinones are formed from these precursors by hydrolysis catalysed by saccharases and by enzymatic oxidation or autoxidation of aglycones. 

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