It has been suggested that in response Tanespimycin price to these extreme conditions, natural selection has favored species producing high concentrations of characteristic compounds, such as depsides, depsidones, depsones, dibenzofurans, and chromones, among others (Schmitt and Lumbsch, 2004). The majority of compounds synthesized via the polyketide pathway are unique to lichens (Blanco et al., 2005). These compounds were reported to exhibit antibiotic,

anti-mycobacterial, antiviral, anti-inflammatory, analgesic, antipyretic, antiproliferative or cytotoxic activities (Oksanen, 2006 and Stocker-Worgotter, 2008). Lichen extracts have been long used for medicinal applications, probably due to the biological activity of their endogenous secondary metabolites; besides, the strong UV absorption properties of some of these compounds, which are a result of the lichen’s adaptation to high solar radiation exposure, have been explored for the development of sunscreens

and other cosmetic formulations for skin (Bernard et al., 2003 and Muller, 2001). Atranorin (ATR) is the main compound from the lichen Cladina kalbii Ahti which grows in the arid lands of the Brazilian Northeast. ATR is an important member of the depside group and is found in a variety of lichen species ( Kristmundsdottir et al., 2005). The molecular structures of these depsides ( Fig. 1) present aromatic esters containing click here Interleukin-2 receptor the methyl ester group on the terminal ring ( Edwards et al., 2003). Studies on bioactive properties of extracts containing ATR have revealed antimycobacterial/antimicrobial activity ( Honda et al., 2010, Ingolfsdottir et al., 1998 and Yilmaz et al., 2004), antinociceptive and antiinflammatory properties ( Bugni et al., 2009) and photoprotective capacity ( Fernandez et al.,

1998). Isolated ATR was observed exhibit antinociceptive effects ( Melo et al., 2008) and to inhibit leukotriene B4 synthesis in leukocytes, which might affect inflammatory processes ( Kumar and Muller, 1999). Besides, ATR was reported to exhibit antibiotic action against M. aurum ( Ingolfsdottir et al., 1998) and exhibited anti-proliferative action against malignant cell lines ( Kristmundsdottir et al., 2005). In a study of the mitochondrial uncoupling activity of lichen metabolites, ATR was the only compound which did not exhibited toxic effects, indicating it could substitute other related lichen metabolite, usnic acid, which also presents potential medicinal applications, in the formulation of novel therapeutic compounds ( Abo-Khatwa et al., 1996). However, little has been explored on the mechanisms of ATR biological effects.