Effect of Extraction Solvents on Total Phenolic Contents and in vitro Antioxidant Activity of the Leaves of Lippia adoensis var. Koseret Sebsebe

Abstract

Lippia. adoensis var. koseret is an endemic herb to Ethiopia and is traditionally used as food flavoring and traditional medicine. This paper reported the total phenolic and flavonoid contents, and in vitro antioxidant activity of  various extracts from the dried leaf of this herb. Aqueous: methanol (20:80, v/v) extract contained highest amount of total phenolic (67.61 ± 9.89 mg of gallic acid equivalent/g). Total flavonoid contents were highest in acetone extract (25.24 ± 0.43 mg of quercetin equivalent/g). An increase in the extracted concentration resulted in an increase of antioxidant power for all the extracts. The aqueous: methanol (20:80, v/v) extract showed highest DPPH radical scavenging (IC₅₀ = 10.96 ± 0.42 mg/ml) iron reducing power (IC₅₀ = 123.97 ± 3.23 mg/ml), total antioxidant activity (105.32 ± 10.67 mg ascorbic acid equivalent/g), and iron chelating activity (IC₅₀ = 81.31 ± 15.94 mg/ml) than other four solvents used. Total phenolics well correlated with DPPH (R² = 0.88, p < 0.05) and Ferric reducing power (R² = 0.77 p < 0.05). Whereas, total flavonoid content well correlated with total antioxidant (R² = 0.73 p < 0.05). The study showed the antioxidants activities of the crude extract were variable when extracted by different solvents indicating a high potential to be used as natural antioxidants in preventing various oxidative stresses and as food preservatives.

Keywords: Antioxidant; α- Amylase; Phenolic compounds; Herbs; Lippia adoensis var. koseret

DOI: 10.7176/FSQM/94-04

Publication date: February 29^th 2020