Lichens as possible sources of antioxidants.

Acetone, methanol and aqueous extracts of the lichen Cetraria islandica, Lecanora atra, Parmelia pertusa, Pseudoevernia furfuraceae and Umbilicaria cylindrica were investigated for antioxidant activity by five different methods: DPPH radical scavenging, superoxide anion radical scavenging, reducing power, determination of total phenolic compounds and determination of total flavonoid content. Different antioxidant activities of the tested extracts were studied in comparison to known antioxidants such as ascorbic acid, butylated hydroxyanisole (BHA) and α-tocopherol. The tested extracts had strong antioxidant activity. The DPPH radical scavenging activity ranging from 32.68-94.70%. For reducing power, measured values of absorbance varied from 0.016 to 0.109. The superoxide anion scavenging activity for different extracts was 7.31-84.51%. In addition, the high contents of total phenolic compounds (12-76.42 μg of pyrocatechol equivalent) and total flavonoids (1.37-54.77 μg of rutin equivalent) suggests that phenols and flavonoids might be the major antioxidant compounds in studied extracts. Tested lichen species were found to possess effective antioxidant activities and can be used as good natural sources of antioxidants.