Polyphenols contents and antioxidant Activity of extracts from Leaves and flowers of Thymelaea hirsuta

Abstract

Thymelaea hirsuta is a medicinal plant, belonging to the genus Thymelaea (Thymelaeaceae) widely used in Mediterranean countries especially in Algeria. In this study, we have evaluated the total polyphenols and flavonoids contents of methanolic and aqueous extracts of Leaves and flowers of Thymelaea hirsuta as well as its antioxidant activity using the DPPH (2'2-diphenylpicrylhydrazyl) and β-carotene /linoleic acid bleaching assays. The yield of the methanolic and aqueous extract was 11, 55% and 13, 25% respectively. The total polyphenols content of the methanolic extract was 295, 22 µg GAE/ mg extract and flavonoids was 09, 40 µg QE/mg and 26, 42 µg RE/ mg extract. The total polyphenols content of the aqueous extract was 57, 95 µg GAE/ mg extract and flavonoids was 4.59 µg QE/ mg and 10.66 µg RE/ mg extract. In the DPPH assay, methanolic extract showed the higher scavenging capacity (IC50 = 0.03 ± 0.004 mg/ml), followed by aqueous extract with IC50 of 0.275 ± 0.019 mg/ml. In the test of β-carotene /linoleic acid, the percentage of inhibition was 39.1±1.33% for the aqueous extract and 41.05±2.72% for methanolic extract.
 Keywords: Thymelaea hirsuta, antioxidant activity, polyphenols, DPPH scavenging, β-carotene.