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Antioxidant activity of various fractions of non-tannin phenolics of canola hulls.

Cyclone canola hulls were extracted with 70% (v/v) acetone. The dried crude extract was dissolved in ethanol and fractionated on a Sephadex LH-20 column using 95% (v/v) ethanol as the mobile phase. Five major fractions were isolated according to the UV absorption. All fractions exhibited marked antioxidant activity in a beta-carotene-linoleate model system. Fractions I and II showed the best preventive effect against the bleaching of beta-carotene. The scavenging effect of fractions I, III, and V, at 1 mg, on alpha, alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical was 67.4%, 80.7%, and 63.3%, respectively. Fractions II and IV showed weak DPPH scavenging effects. The reducing power of phenolics present in fractions IV and V was greater than that of fractions I-III, and the observed data correlated well (r(2) = 0.937; P = 0.007) with the total content of phenolics present in each fraction.

Antioxidants↗

Tannins in Puccinellia arctica: possible deterrents to herbivory by Canada geese.

Urban populations of Canada geese, Branta canadensis, pose a nuisance problem throughout most of the eastern United States and in other parts of the United States and Canada. Puccinellia arctica is a species of arctic grass that is unpalatable to Canada geese on the North Slope of Alaska and may prove to be an effective long-term and nonlethal means of controlling the growing populations of urban Canada geese. A comparative study of the secondary metabolites of both P. arctica and Puccinellia langeana and Poa pratensis, two palatable grass species that Canada geese generally consume, revealed no significant differences. However, ellagitannin levels were higher in P. arctica than in the palatable grass species and may be contributing to its unpalatability to Canada geese. These results support the potential to use P. arctica in public areas to control geese intrusions.

Animals↗

Testing the effects of drying methods on willow flavonoids, tannins, and salicylates.

In this study, we compared the effects of several preservation methods on the secondary phenolics of the mature leaves of purple willow (Salix purpurea L., salicaceae) with results obtained with fresh leaf analyses. Conventional freeze-drying, in which the leaves were first frozen with liquid nitrogen and then placed in a freeze-dryer, produced substantial qualitative and quantitative changes in purple willow flavonoids and salicylates. Modified freeze-drying, in which leaves were put into a freeze-dryer without being prefrozen, gave concentrations that, for most secondary components, were comparable with those found in fresh leaves. Reducing the freeze-dryer chamber temperature hindered the decomposition of phenolics in prefrozen leaves and in leaves dried without prefreezing. Heat drying induced substantial changes in the composition of all phenolics, except for apigenin-7-glucoside. Vacuum drying at room temperature gave the highest concentrations for nearly all phenolics, while room-drying with desiccation gave results that were comparable with those obtained by fresh leaf analyses.

Flavonoids↗