Secondary Metabolites and Antioxidant Capacity of the Tunisian Lichen Diploschistes Ocellatus (Ascomycota)

This study, the first to assess the total phenolic, flavonoid, tannins, and proanthocyanidin content of the Tunisian lichen Diploschistes ocellatus, determined the antioxidant capacity in scavenging 2,2 diphenyl-1-picrylhydrazyl (DPPH), as well as the ferric-reducing and iron-chelating powers. The phenolic compound content of D. ocellatus was shown to be related to antioxidant activity. The highest phenolic and flavonoid contents of extracts were obtained with acetone (286.3 μg GAE/g DW and 3.24 μg CE/g DW, respectively), while the highest tannin and proanthocyanidin contents were obtained with methanol (5.5 μg TAE/g DW and 35.12 μg CE/g DW, respectively). The highest DPPH' scavenging capacity and iron-chelating power of extracts were obtained with methanol (concentration providing 50% inhibition [IC50] = 0.029 mg/mL and IC50 = 0.425 mg/mL, respectively), while acetone extracts showed a higher reducing power (IC50 = 0.118 mg/mL).