Evaluation of the antioxidant activity of Stevia rebaudiana | Évaluation de l’activité antioxydante de Stevia rebaudiana
2016
Hebi, M. | Eddouks, M.
This work aimed to evaluate the antioxydant activity of Stevia rebaudiana. The antioxydant activity of the ethanolic extracts 70% resulting from leaves of three varieties of Stevia rebaudiana was evaluated by the method of trapping of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The varieties 5, 6 and 7 respectively showed inhibitory concentrations of 50% of free radicals (IC50) of 340.12, 268.31 and 282.72 µg/ml. The synthetic antioxidant butylhydroxytoluene (BHT) has shown an IC50 equal to 13.71µg/ml. Moreover, the phytochemical tests allowed quantifying the total polyphenols and total flavonoids in extracts of Stevia rebaudiana leaves respectively by the method of Folin-Ciocalteu and aluminum trichloride (AlCl₃). In fact, the content in total polyphenols was variable, the ethanolic extract of the leaves of the variety 7 presented the highest content (125.33 ± 2.52 mg EAG /g of extract), the contents of 95.00 ± 0.50 and 94.60 ± 3.13 mg EAG / g of extract are shown respectively for the extract varieties 6 and 5. According to the total flavonoids, the highest content was observed in the ethanol extract 70% of the variety 6 (59.70 ± 2.41 mg EQ/g of extract), the extract variety 7 (50.66 ± 0.35 mg EQ/g of extract) and the extract variety 5 (31.03 ± 0.48 mg EQ/g extract).
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