High in vitro Antioxidant Capacities of Algerian Cleome arabica Leaves’ Extracts

The aim of this study was to evaluate the antioxidant capacities of Cleome arabica leaves’ extract collected on two seasons in the town of Laghouat steppe region of Algeria. Five common tests for measuring antioxidant capacities were used to compare with three standard antioxidants: measurement of free radical scavenging activity with 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) and 2,2ʹ- azinobis(3-ethylbenzo-thiazo-line-6-sulfonate) (ABTS·+ ) radical cation, measurement of total antioxidant capacities with phosphomolybdenum, ferric reducing, and cupric reducing methods. The amount of the phenolic compounds was carried out by the quantification of total phenolic, total flavonoid, and condensed tannin contents in three organic solvents with varying polarities. The results show that the ethyl acetate is the best extractor solvent of flavonoids, while petroleum ether has the ability to extract more of terpenes. The values of quantification ranged from 0.341 to 0.751 mg of gallic acid equivalent/g of dry matter, from 0.172 to 0.682 mg of quercetin equivalent/g of dry matter and from 0.172 to 0.332 mg of catechin equivalent/g of dry matter for the total phenolic, flavonoids, and the condensed tannins, respectively. All the extract shows strong antioxidant activity, whose best are found in the ABTS and DPPH assay with IC50 values of 0.01 and 0.017 mg/ml, respectively, in a different season. These results suggest that the level of antioxidant activity in this plant varies to a great extent. They also suggest that phenolics in this plant provide substantial antioxidant activity. Upon achievement of this survey, an extra benefit of this medicinal plant may be found.