Antioxidant activity of some algerian medicinal plants extracts containing phenolic compounds

Phytochemicals are extensively found at different levels in many medicinal plants. This work had two objectives: the first, to evaluate the total phenolic or flavonoid contents of 11 Algerian medicinal plants and second, to determine whether these compounds have an antioxidant capacity toward free radical propagation. The polyphenolic extractions of the dried powdered samples have been performed using 70% ethanol. The total phenolic content, analyzed using Folin-Ciocalteu's reagent, of the samples varied from 3.13 to 32.32 mg/g dry weight, expressed as gallic acid equivalents (GAE). The total flavonoid concentrations, detected using 2% aluminum chloride, varied from 1.62 to 13.12 mg rutin equivalents (RE)/g dry weight. To analyze the antioxidant activity, a common stable radical chromogen, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS(.+)), was used. The antioxidant activity measurement, expressed as Trolox equivalent antioxidant capacity (TEAC), ranged from 9.40 to 33.06 mM Trolox equivalents. With further data analysis it was found that there was a positive correlation between the total phenolic content of a given sample and its antioxidant activity, R-2 = 0.7931, whereas the correlation between the total flavonoids and antioxidant activity was determined to be R-2 = 0.7802. These results suggest that the level of antioxidant activity in these plants varies to a great extent. They also suggest that phenolics in these plants provide substantial antioxidant activity. Upon achievement of this survey, and using more samples, an extra benefit of these medicinal plants may be found. Flora of Algeria appears to be a rich and interesting source for supplementary ethnomedicinal and phytochemical studies. (c) 2005 Elsevier Ltd. All rights reserved.