Antioxidant activity of some lichen metabolites

Antioxidant activity of several classes of lichen metabolites were assessed in the in vitro superoxide radical (SOR), nitric oxide radical and 2,2-diphenyl-1-picrylhydrazil radical scavenging assays. The despsides sekikaic acid and lecanoric acid showed promising antioxidant activity in SOR assay with IC50 values of 82.0 +/- 0.3 mu mol and 91.5 +/- 2.1 mu mol, respectively, while the depsidone lobaric acid exhibited an IC50 value of 97.9 +/- 1.6 mu mol, all relative to the standard, propyl gallate (IC50 = 106.0 +/- 1.7 mu mol). One of the most abundant mononuclear phenolic compounds, methyl-beta-orcinol carboxylate was found to be a potent NO scavenger (IC50 = 84.7 +/- 0.1 mu mol), compared to the standard rutin (IC50 = 86.8 +/- 1.9 mu mol).