Capacity of some Graphidaceous lichens to scavenge superoxide and inhibition of tyrosinase and xanthine oxidase activities

The results of the screening of thirty-one species belonging to the lichen family Graphidaceae for their ability to scavenge superoxide and inhibition of tyrosinase and xanthine oxidase activities have been presented. Graphina glaucorufa, Graphina multistriata, Graphina salacinilabiata, Graphis assamensis, Graphis nakanishiana and Phaeographopsis indica showed strong inhibition of tyrosinase and xanthine oxidase with an additional capacity to scavenge superoxide. Half-inhibiting concentration (IC50, μg/ml) of the lichen extracts for inhibition of tyrosinase and xanthine oxidase was much lower than the standard tyrosinase and xanthine oxidase inhibitors.