The antioxidant activity of aqueous-ethanolic extracts from nettle leaf (Urtica dioica L.)

The antioxidant activity of aqueous-ethanolic extracts from nettle leaf (Urtica dioica L.) was investigated in this work by using DPPH, FRAP and H2O2 methods. Aqueous-ethanolic extracts from nettle leaf were obtained by using different extraction techniques (maceration at room and boiling temperatures, ultrasonic, Soxhlet and Tillepape extraction). The content of total phenolics and flavonoids was determined spectrophotometrically by Folin-Ciocalteu method and with AlCl3, respectively. The highest phenolic (630.21 mg GKE/g of dry extract) and flavonoids (21.06 mg RE/g of dry extract) content was determined in the extract obtained by Soxhlet extraction. The aqueous-ethanolic extract obtained by Soxhlet extraction showed the highest antioxidant activity, independently of the applied antioxidant methods. The presented data indicate that the bioactive substances, phenols and flavonoids, are probably mainly responsible for the antioxidant activity of the obtained extracts obtained. Aqueous-ethanolic extracts from nettle leaf are a potential source of natural antioxidants.