Usnea

SH RO2C 1 / C02H R = CH3, (CH2)2CH3, Lichen - Usnea sp. Ambeweiamides A and B -epidithiapiperazinediones with antineopiastic property 280... 

Usnea diffracta Dill, ex Adans. U. longissima Acharius Lao Jium Xiu Song Lo (whole plant) Barbaric acid, usnic acid, diffractaic acid, ramalic acid, lichenin.54 Treat throat discharges, malaria, headache, cough, a detoxicant. 

Geranium eriostemon Fisch. ex DC f. hypoleucum (Nakai) Y. C. Chu, G. dahuricum DC, G. eriostemon Fisch. ex DC, G. wilfordi Maxim., G. wlassowianum Fisch. ex Link, G. sibiricum L., G. eriostemon Fisch. ex DC f. megalanthum (Nakai) Y. C. Chu Usnea diffracta Dill, ex Adans. 

Lycopus lucidus, L. maackianus, L. parviflorus, L. ramosissimus, L. fargesii, L. veitchii Usnea diffraeta, U. longissima... 

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... 

Dibenzofurans (Phe furan Phe) include various fungal infection-induced plant antifungal compounds (phytoalexins) such as the Rosaceae-derived cotonefuran (from Cotoneaster lactea) and a-pyrofurans (from Pyrus communis). Usnic acid from lichens (notably Usnea species) is anti-mycobacterial, anti-mitotic, an uncoupler and a potent inhibitor of plant protoporphyrinogen synthetase and 4-hydroxphenylpyruvate dioxygenase. 

Usnic acid Usnea articulata (lichen) Uncoupler (< 1)... 

In addition, lichens add significantly to the aesthetics of the ecosystems in which they occur. The lovely orange and yellow colors of Caloplaca and Xanthoria lichens add much to the ambience of rocky seashores and tundras. And the intricate webs of filamentous Usnea lichens hanging in profusion from tree branches give a mysterious aspect to humid forests. These and other, less charismatic lichens are integral components of their natural ecosystems. These lichens are intrinsically important for this reason, as well as for the relatively minor benefits that they provide to humans. 

Table 6.9. Trace elements contents in Usnea aurantiacoatra and Usnea antarctica from Potter Cove, King George Island ((xg g dry weight)...

The objective of this preliminary study was to assess levels of Cd, Cu, Fe, Mn, Pb and Zn in two species of epilithic macrolichens Usnea aurantiacoatra (only found in maritime Antarctica) and Usnea antarctica (found in maritime and continental Antarctica) (57). Usnea antarctica has an antarctic circumpolar distribution continental and subantarctic regions. New Zealand and Tierra del Fuego (58). Table 6.9 shows the concentrations of Cd, Cu, Fe, Mn, Pb and Zn in specimens of the Antarctic lichens Usnea aurantiacoatra and Usnea antarctica in areas close to Jubany Station. Two different trends of trace metals accumulation have been identified, namely ... 

A better understanding of the different trends in the accumulation of metals observed in Usnea antarctica and Usnea aurantiacoatra demand more studies, such as the estimation of the age of lichens, their growing rate and the composition of the soil and rocky substrates in eontact with them. 

Lichens Usnea aurantiacoatra and Usnea antarctica) could be useful as monitors to evaluate the Antarctic ecosystem and to identify patterns of the deposition of atmospherically transported heavy metals. Thus, it would be possible to study variations in the spatial distribution of these elements not only at the local, but also at the regional scale. Knowing the effect of the different local and regional growth rates and evaluating metal contents of the soil, it would be possible to perform metal biomonitoring in different zones of Antarctica and of the southern hemisphere. 

Derivation From Usnea barbata, a lichen growing on trees. 

Source Usnea palmata. Molecular formula Cig Hie O7. Biological activity Antibacterial. 

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. 

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