Determination of polyphenols and Antioxidant activity of Melilotus off. and Elaeagnus angustifolia L

The aim of this study was to determine the relation between the content of polyphenols in Melilotus officinalis Desr. and Elaeagnus angustifolia L. and the antioxidant activity of their aqueous and methanolic extracts. Both plants are used in folk medicine in Syria [1,2].

Antioxidant activities of aqueous and methanolic extracts of the aerial parts and roots from Melilotus officinalis Desr. and leaves and roots from Elaeagnus angustifolia L. have been studied by use of the TEAC-assay (Trolox Equivalent Antioxidant Capacity) [3], in which Trolox (6-Hydroxy-2,5,7,8-tetramethylchroman-2-carbonic acid, a Vitamin-E derivative) is used as reference compound in a concentration of 1mmol/l. The content of polyphenols in the extracts was determinend by the folin-ciocalteau method [4].

The extracts in a concentration of 20mg/ml each had an antioxidant capacity equivalent to approximately 2–4 Trolox units. Highest and comparable antioxidant activity could be obseved in aqueous and methanolic extracts of roots from Melilotus officinalis and the methanolic extract from Eleagnus angustifolia, whereas lowest activity showed aqueous extracts of roots of the latter plant. There was only restricted correlation between the polyphenol content of the extracts and their antioxidant activity indicating that not only the amount of phenolic compounds, but most notably their structure is of great importance.

References: [1] Ramezani, M. et al. (1992) Ann. Allergy 69: 493–496. [2] Melilot – Melilotus officinalis: Pharmacopoeia Francaise. [3] Miller, N.J: et al. (1993) Clin. Sci. (Lond.) 84: 407–412. [4] Javanmardi et al. (2003) Food Chem. 83: 547–550