Khaled Djokhdem, Amar Djeridane, Nourelhouda Renane, Mohamed Yousfi
The antioxidant activity and phenolic content of extracts and solvent–solvent partition fractions from the aerial parts of three medicinal plants were evaluated. Aerial parts of Hammada elegans, Plantago ciliata and Thymelaea microphylla were extracted using the polarity gradients of different solvents. The samples were extracted by liquid–liquid partition with different organic solvents to obtain 16 fractions. Next, the phenolic contents of all fractions were analysed using the Folin-Ciocalteu method and their inhibition of the peroxidation of linoleic acid and sunflower oil was evaluated by the lipid peroxide ammonium thiocyanate method.
The total phenolic content of the different Hammada elegans fractions varied from 0.045 to 0.0714 mg/g dry weight, expressed as gallic acid equivalents (GAE). The percentage inhibition of peroxidation of linoleic acid and sunflower oil was found to be higher in methanolic fractions and was comparable to that of α-tocopherol, Trolox, butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). In this study, a direct relationship between total phenolic content and inhibition of lipid peroxidation was observed. This indicates that phenolics are the main contributors to the observed antioxidant activities of the different plant extracts.
These results indicate that the level of antioxidant activity in these plants varies greatly. They also suggest that the phenolics in these plants provide a substantial amount of antioxidants. Additional research may reveal further benefits of these medicinal plants. The flora of Algeria appears to be a rich and interesting source of plants for ethnomedicinal and phytochemical studies.