Investigations of Secondary Metabolites and antioxidant activity of methanolic, ethanolic and acetonic extracts of lichen (Xantoria parietina L.) from Northestern Algeria

This study aims to evaluate Xantoria parietina (L.), a plant indigenous to north-western Algeria. We analyzed ethanolic (EE), methanolic (ME) and acetonic (EE) extracts obtained from the thalli and apothecia of this plant. Our main focus was on secondary metabolites, specifically polyphenols, flavonoids, condensed and hydrolysable tannins. We additionally assessed their antioxidant characteristics. The Folin-Ciocalteu method was employed to quantify the polyphenol content, while the DPPH (2,2-diphenyl-1-picrylhydrazyl) reduction and FRAP (ferric ion-reducing power) tests were utilized to assess the free radical scavenging activity. The findings show that the methanolic and ethanolic extracts exhibited the highest concentration of polyphenols with 27.839 mg EAG/g (EE) and 27.55 mg EAG/g (ME). The results also indicated significant antioxidant activities in the DPPH compared to ascorbic acid and FRAP assay.In addition, the acetone extract of X. parietina exhibited a significant tannin content of 420.33 mg EC/g of condensed tannins, whereas the ethanolic extract displayed a lower content of 0.187 mg EC/g. This underscores the substantial presence of tannins in the plant. Analyses by high-performance liquid chromatography (HPLC) confirmed the presence of quercetin, gallic acid, chlorogenic acid, catechin narenginin. The findings suggest that X. parietina is a notable source of polyphenols, which are compounds recognized for their antioxidant characteristics.