title: Evaluation of antioxidant activity of hydromethanolic extracts of some medicinal species from South Algeria.
abstract: BACKGROUND
  Phytochemicals are found in abundance at different levels in many medicinal plants. It is important to measure the total phenolic compounds correctly in such medicinal plants, the better to assess their antioxidant capacity.
  
  
  METHODS
  Our study sought to evaluate the total phenolic, flavonoid, and tannin contents of three Algerian medicinal plants: Echium pycnanthum Pomel, Haloxylon articulatum Boiss, and Solenostemma oleifolium Bull. & Bruce. We employed six different testing methods to help ascertain whether these compounds have an antioxidant capacity, including total antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid(+), β-carotene, reducing, and chelating assays.
  
  
  RESULTS
  Our study showed that these medicinal plants exhibited significantly different total polyphenol contents varying from 27.3 ± 2.1 mg to 120.3 ± 5.6 mg gallic acid equivalents/g dry weight. The phenolic content in H. articulatum was superior to those in E. pycnanthum and S. oleifolium. The same tendency was observed for the relative amounts of flavonoids and condensed tannins in the three medicinal plants. The antioxidant activities varied greatly among the different plants used in this study. Indeed, H. articulatum shoots exhibited the strongest antioxidant activity, with the lowest IC50 (6.3 ± 0.25 μg/mL) and EC50 (0.21 ± 0.01 mg/mL) values for 1,1-diphenyl-2-picrylhydrazyl and iron reducing tests, respectively. In addition, the superiority of this plant was more marked as compared to positive controls. Strong and positive correlations were found between phenolic classes and antioxidant activities with a correlation coefficient reaching R ≥ 0.99.
  
  
  CONCLUSIONS
  This investigation confirmed that several medicinal herbs from South Algeria possess high in vitro antioxidant potency. Overall, our results can be considered very promising in the continuing effort to utilize plant species successfully for medicinal purposes in humans, providing further justification for the hypothesis that phenolic compounds in these plants can provide substantial antioxidant activity.
authors.affiliation: Laboratory of Natural Products, Department of Biology, Faculty of Sciences, Abou Bekr Belkaïd University, Tlemcen, Algeria. Electronic address: kiratcqa@yahoo.fr.
authors.forename: Tarik Mohammed
authors.initials: TM
authors.lastname: Chaouche
authors.affiliation: Laboratory of Natural Products, Department of Biology, Faculty of Sciences, Abou Bekr Belkaïd University, Tlemcen, Algeria.
authors.forename: Farah
authors.initials: F
authors.lastname: Haddouchi
authors.affiliation: Laboratoty of Extremophile Plant, Biotechnologic Center in Borj-Cedria Technopol (CBBC), Hammam-Lif, Tunisia.
authors.forename: Riadh
authors.initials: R
authors.lastname: Ksouri
authors.affiliation: Laboratory of Natural Products, Department of Biology, Faculty of Sciences, Abou Bekr Belkaïd University, Tlemcen, Algeria.
authors.forename: Fouzia
authors.initials: F
authors.lastname: Atik-Bekkara
mesh_terms: D000462:Algeria; D000975:Antioxidants / Q000032:analysis*; D010636:Phenols; D010936:Plant Extracts / Q000032:analysis*; D010946:Plants, Medicinal / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D010636:Phenols; D010936:Plant Extracts
keywords: antioxidant activity; correlation coefficients; extracts; medicinal plants; percentage inhibition; quantification of phenolics