Free radical-scavenging capacity, antioxidant activity, and phenolic composition of green lentil (Lens culinaris)
2010
Amarowicz, Ryszard | Estrella, Isabel | Hernandez, Teresa | Robredo, Sergio | Troszyńska, Agnieszka | Kosińska, Agnieszka | Pegg, Ronald B.
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.
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