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Free radical-scavenging capacity, antioxidant activity, and phenolic composition of green lentil (Lens culinaris)

Amarowicz, Ryszard, Estrella, Isabel, Hernández, Teresa, Robredo, Sergio, Troszyńska, Agnieszka, Kosińska, Agnieszka, Pegg, Ronald B.
Food chemistry 2010 v.121 no.3 pp. 705-711
lentils, Lens culinaris, antioxidant activity, free radical scavengers, phenolic compounds, food composition, phytochemicals, plant extracts, fractionation, tannins, catechin, epicatechin, glucosides, procyanidins, quercetin, p-coumaric acid
Phenolics were extracted from green lentil seeds with 80% (v/v) aqueous acetone, and the resultant extracts were further separated on a Sephadex® LH-20 column. Fraction I, comprising low-molecular-weight phenolics, was eluted from the column with 95% (v/v) ethanol. Fraction II, consisting predominantly of tannins, was obtained using acetone:water (1:1; v/v) as the mobile phase. Phenolic compounds present in the preparations showed antioxidant and radical-scavenging properties as revealed by a β-carotene-linoleate model system, the total antioxidant activity (TAA) method, the DPPH scavenging activity assay, and a reducing power assay. Data from these tests showed the greatest efficacies coming from the tannins (i.e., fraction II); the mean TAA of the tannin fraction was 6.09μmol Trolox eq./mg fraction (d.w.), whereas the crude extract and fraction I showed 0.75 and 0.33μmolTroloxeq./mg extract or fraction (d.w.), respectively. The content of total phenolics in fraction II was the highest (338mgcatechineq./g fraction, d.w.), and the tannin content, as determined by the vanillin/HCl method and expressed as absorbance units at 500nm per 1g, was 252. Twenty compounds (hydroxycinnamates, procyanidins, gallates, flavonols, dihydroflavonols, dihydrochalcones) were identified in the crude extracts by HPLC-PAD and HPLC-ESI-MS techniques. Catechin and epicatechin glucosides, procyanidin dimers, quercetin diglycoside, and trans-p-coumaric acid were the dominant phenolics in green lentils.