Physodic acid

Congeneric chemotypes show simple replacement of one compound. Pseudevernia furfuracea (L.) Zopf occurs in Europe in two races containing olivetoric or physodic acids, while the race from North America synthesizes lecanoric acid. 

Deriv Methyl physodate, prisms (EtOH-HjO), mp 157 °C, from physodic acid with an equimolar amount of CHjNj... 

The best known depsidones are physodic acid, lobaric acid, norlobaridone, grayanic acid, alectoronic acid, diploicin, 4-0-methylphysodic acid, a-collatolic acid, lividic acid and variolaric acid. 

Physodic acid Antibacterial, antifungal, antioxidant, anticancer Turk et al. (2006), Rankovic et al. (2008, 2014), Kosanid et al. (2013)... 

Norstictic acid, physodic acid, evemic acid, usnic acid, salazinic acid, fumar-protocetraric acid, protocetraric acid, atranorin and zeorin isolated from different lichen species are relatively strong antioxidant, antimicrobial and anticancer agents (Kosanic et al. 2010, 2013, 2014 Manojlovic et al. 2012 Rankovic et al. 2014). 

Turk AO, Yilmaz M, Kivanc M et al (2003) The antimicrobial activity of extracts of the lichen Cetraria aculeata and its protolichesterinic acid constituent. Z Naturforsch 58 850-854 Turk H, Yilmaz M, Tay T et al (2006) Antimicrobial activity of extracts of chemical races of the lichen Pseudevernia furfuracea and their physodic acid, chloroatranorin, atranorin, and olivetoric acid constituents. Z Naturforsch C 61 499-507 Verma N, Behera BC, Parizadeh H et al (2011) Bactericidal activity of some lichen secondary compounds of Cladonia ochrochlora, Parmotrema nilgherrensis aadParmotrema sancti-angelii. Int J Drug Dev Res 3 222-232... 

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). 

Evernia prunastri and Pseudevernia furfuracea lichens and their major metabolites evemic acid and physodic acid were screened for their antioxidant effects by Kosanic et al. (2013a) who found varying antioxidant success in free radical scavenging, superoxide anion radical scavenging and reducing power, and physodic acid was fotmd to be the most effective. 

Antioxidant activities of major lichen metabolites in Hypogymnia physodes lichen (physodic acids, atranorin and usnic acid) were studied by Rankovic et al. (2014b). An physodic acid was found to be the most effective antioxidant in free radical and superoxide anion scavenging, as well as in reducing power assays among tested lichen metabolites. 

Physodic acid (from Hypogymnia enteromorph) Ames TAIOO No Shibamoto and Wei (1984)... 

The biogenesis of depsidones was first explained 12, 135) by the attractive theory that they arose from intramolecular phenolic oxidative coupling of / ara-depsides, and although at least nine / flfm-depside-depsidone pairs of corresponding structures exist they usually occur in widely separated lichen genera. However in several lichens 62, 63) the pair olivetoric acid (294) and physodic acid (295) actually co-occur. 

Elix(772) and Yosioka and his co-workers 163) have reported the isolation and structural elucidation of the O-methylphysodic acid (359) from Hypogymnia billardieri and H.vittata, where it co-occurs with physodic acid (295). In this connection Elix developed the useful technique of treating the mixture of lichen acids with phenyldiazomethane, which... 

The structure of lividic acid (368), a further example of a physodic acid type (Scheme 44) isolated from Parmelia formosana and containing a hydroxy group not inherent in its polyketide derivation, was demonstrated... 

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