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

Engeda Dessalegn

doi:10.7176/fsqm/94-04

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 (IC 50 = 10.96 ± 0.42 mg/ml) iron reducing power (IC 50 = 123.97 ± 3.23 mg/ml), total antioxidant activity (105.32 ± 10.67 mg ascorbic acid equivalent/g), and iron chelating activity (IC 50 = 81.31 ± 15.94 mg/ml) than other four solvents used. Total phenolics well correlated with DPPH (R 2 = 0.88, p < 0.05) and Ferric reducing power (R 2 = 0.77 p < 0.05). Whereas, total flavonoid content well correlated with total antioxidant (R 2 = 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

Highlights

The genus Lippia (Verbenaceae) is widely distributed in tropical and subtropical regions of the Americas and Africa, and it consists of approximately 200 species of herbs, shrubs, and small trees (Terblanche & Kornelius, 1996)
L. adoensis is one of the five indigenous Lippia species in Ethiopia where it occurs as an erect woody shrub up to 1-3m tall (Hedberg et al, 2006)
The study showed that total phenolic and flavonoid contents of L. adoensis var. koseret were highest in the aqueous: methanol (20:80, v/v) and acetone extracts, respectively

Summary

Introduction

The genus Lippia (Verbenaceae) is widely distributed in tropical and subtropical regions of the Americas and Africa, and it consists of approximately 200 species of herbs, shrubs, and small trees (Terblanche & Kornelius, 1996). Most of these species are traditionally utilized in the indigenous systems of medicine for the treatment of a variety of human aliments. The special taste and flavor of the Gurage kitfo (minced meat with spiced butter) is attributed to essential oil imparted by the leaves (Nigist & Sebsebe, 2009). The chemical compositions of L. adoensis var koseret, investigated so far are essential oils. Lonalool is the major component, and appreciable amount of sesquiterpene hydrocarbons (germacrene, α-copaene, β-cadinene, and, βcaryophyllene) and uncommon monoterpene ketone, 2-methyl-6-methylene-2, 7-octadien-4-one (ipsdienone), were found in the essential oil (Berhanu A. et al, 2001)

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