Exploration des potentiels anti-radicaux des extraits de quelques espèces extrêmophiles au Sahara Algérien

Abstract

This work aims to valorize four plant species: Pituranthos chloranthus (Guezzah), Cleome amblyocarpa (Netil), Cymbopogon schoenanthus (Lemmed), and Marrubium deserti de Noé (Jâada), which grow spontaneously in the Ghardaïa region, located in the northern Algerian Sahara. This is achieved through a contribution to their phytochemical study and the evaluation of the antioxidant potential of aqueous crude extracts from their aerial parts. These plant species are widely used by the local population for their numerous traditional therapeutic properties. They belong to five different families: Capparaceae, Apiaceae, Lamiaceae, and Poaceae, and all are xerophytic species to this end, phytochemical screening tests were carried out to identify the presence or absence of key secondary metabolites. Aqueous maceration extractions were performed, and the total polyphenol content of the crude extracts was determined. The antioxidant activity of the extracts was evaluated against free radicals: DPPH, ABTS, and FRAP. From the overall results obtained, the phytochemical screening tests revealed the presence of certain secondary metabolites in all the studied species, particularly phenolic compounds, as well as the absence of some other important compounds. Regarding the yield of the aqueous crude extract, Marrubium deserti showed the highest yield, exceeding 50%. However, Cleome amblyocarpa appeared to be richer in total polyphenols, with a content of 600.68 mg GAE/g dry matter.The antioxidant activity assays allowed the evaluation of the capacity of the isolated extracts to scavenge free radicals (DPPH and ABTS) and to reduce ferric ions to ferrous ions through the FRAP test. The results showed that these extracts are highly active and exhibit strong antioxidant power, particularly the extracts of Pituranthos chloranthus (P1) and Cymbopogon schoenanthus (P4). Compared to standard antioxidants, the extracts of P1 and P4 generally showed superior activity than Trolox. These results are very promising and partly justify the extensive traditional medicinal use of these xerophytic species by the populations of the Algerian Sahara region.