Search

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. Keywords: Antioxidant activity, Phenolic compounds, Pseudevernia furfuracea, Evernia prunastri, Ramalina farinacea, DPPH

The purpose of this work was to assess chemical composition, antibacterial activity against Staphylococcus aureus isolates from catheter-associated infections and antioxidant activity of methanol extracts of three lichens collected from Morocco. The phytochemical analysis of the methanol extracts of these lichens was performed by HPLC–UV method, the predominant phenolic compounds were evernic acid, physodalic acid and usnic acid for Evernia prunastri, Pseudevernia furfuracea and Ramalina farinacea, respectively. Total phenolic compounds and total flavonoid content of all extracts were also determined. As a result, Pseudevernia furfuracea extract had the strongest effect and the highest phenolic compounds content. All extracts showed antibacterial activity against all tested strains (MIC values ranging from 0.078 to 0.625 mg/mL), the strongest inhibition was obtained with the extract of Evernia prunastri.

Background. Lichens present a complex symbiotic relationship between a filamentous fungus, photoautotrophic partner (algae or cyanobacteria), and bacterial community. The Objective of the Study. This study aimed at investigating the chemical composition and cytotoxic, antioxidant, and antimicrobial activities of acetone extracts of Moroccan Evernia prunastri (E. prunastri), Ramalina farinacea (R. farinacea), and Pseudevernia furfuracea (P. furfuracea). Materials and Methods. The phytochemical analysis was carried out by HPLC-UV. The cytotoxic effect was assessed on human prostate cancer (22RV1), human colon carcinoma (HT-29), human hepatocellular carcinoma (Hep-G2), and Hamster ovarian cancer (CHO) cells lines by WST1 assay. The antioxidant power was assessed by DPPH and FRAP assays. The antibacterial effect was obtained using the broth microdilution method. Results. The findings of phytochemical analysis showed that the lichens studied possess interesting bioactive molecules such as physodalic acid, evernic acid, and usnic acid, as well as protocetraric acid. According to the American National Cancer Institute guidelines, the WST-1 test showed that all crude extracts did not show significant cytotoxic effects against all concerous cell lines, and IC50 values ranged from 42.30 to 140.24 µg/mL. Regarding the antioxidant activity, P. furfuracea extract showed the highest free-radical-scavenging ability (IC50 = 498.40 µg/mL). The most potent antibacterial extract was recorded for P. furfuracea extract with a minimum inhibitory concentration (MIC) ranging from 0.039 to 0.31 mg/mL. Conclusion. In this research work, we report that the studied lichen extracts exhibit an important biological effect, supporting that lichens represent a hopeful source of original natural products for the research of new bioactive molecules having a pharmaceutical interest.

This study focused on the determination of phenolic compounds and the evaluation of the biological activity of Ocotea comorensis Kosterm (Lauraceae) extracts, an endemic and the only species of Ocotea genus from the Comoros archipelago. Leaf Extracts of O. comorensis were obtained by maceration in 50% hydro-methanol, acetone and cyclohexane. Their total phenolic and flavonoids contents were quantified and their antioxidant activity, determined by both the Ferric Reducing Power and the DPPH radical scavenging assays. The hydromethanolic extract (MEOc) exhibited the highest DPPH radical scavenging activity (IC50 = 9.28 ± 0.58 μg. mL−1) and the largest reducing capacity of ferrous ions. The most relevant contents in total phenolics (733.33 ± 20.272 µg Gallic Acid Equivalent. mg−1) and flavonoids (142.6 ± 8.20 μg catechin equivalent. mg−1) were also observed in the MEOc. Significant correlations were established between antioxidant activity and total phenolic and flavonoids contents. The antibacterial activity was carried out using microdilution method on Methicilin-Resistant Staphylococcus aureus (MRSA) isolates from burn wounds. The results revealed remarkable anti-MRSA activities with MICs ranging from 0.08 mg mL−1 to 13.41 mg.mL−1and the MEOc displayed the most important anti-MRSA activity. While this is the first study concerning extracts from O. Comorensis, our findings highlighted the richeness in phenolic compounds of these extracts and their great potential as source of antioxidants and antibacterial agents.