Seasonal variation of antioxidant activity and phenolic content of Pseudevernia furfuracea, Evernia prunastri and Ramalina farinacea from Morocco

The present study was carried out to evaluate the effect of environmental conditions on the phenolic content and antioxidant activity of acetone extracts of thalli of Pseudevernia furfuracea (L.) Zopf, Evernia prunastri (L.) Ach. and Ramalina farinacea (L.) Ach. harvested in the Middle Atlas (MA) in Morocco during autamn, summer, spring, and winter. The antioxidant activity was performed in vitro by DPPH (2,2-diphenyl-1-picryl-hydrazyl) radical scavenging method. Total phenolic compounds and flavonoid contents of all the extracts were also determined. These extracts showed significant antioxidant activity, which varied relatively from one species to another and also depended on the season of collection. A significant relationship between the antioxidant capacity and total phenolics content was found. Higher values of antioxidant activity and polyphenols content of all species were registered in late winter and spring. The acetone extract of Pseudevernia furfuracea (L.) Zopf. showed the highest DPPH scavenging activity with IC50 = 498 ± 44 µg/mL and the highest total phenolic content (TPC = 328 ± 27 μg GAE/mg of dry extract). Our study showed that harvesting season had significant effect on phenolic content and antioxidant capacity of the studied lichen species and their harvesting should be done during spring season to achieve better antioxidant potential.