Protein-precipitating capacity of bearberry-leaf (Arctostaphylos uva-ursi L. Sprengel) polyphenolics |
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Authors: | Marian Naczk Ronald B. Pegg Ryszard Amarowicz |
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Affiliation: | 1. Department of Human Nutrition, St. Francis Xavier University, Antigonish, P.O. Box 5000, NS, Canada B2G 2W5;2. Department of Food Science and Technology, The University of Georgia, 100 Cedar Street, Athens, GA 30602-7610, USA;3. Division of Food Science, Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, ul. Tuwima 10, 10-747 Olsztyn, Poland |
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Abstract: | Polyphenolics (PP) from bearberry (Arctostaphylos uva-ursi L. Sprengel) leaves were extracted with 70% (v/v) acetone. The lyophilised crude PP extract was then separated on a Sephadex LH-20 column using first 95% (v/v) ethanol as a mobile phase to elute fraction I low in tannins, and then 50% (v/v) acetone to elute fraction II rich in hydrolysable and condensed tannins. Bovine serum albumin (BSA) was effectively precipitated by PP in the bearberry-leaf crude extract and fraction II at pH values between 3.8 and 4.5. A statistically significant (P = 0.0001) linear relationship exists between the amount of PP-protein complex formed and the quantity of PP added to the reaction mixture. The slope values of these lines indicate that fraction II from the crude extract was a more effective precipitant of proteins than other examined preparations. Based on the quantity of gelatine, fetuin, and BSA required to inhibit 50% of dye-labelled PP–BSA complex precipitation, gelatine was 3–6 times more effective as a precipitation inhibitor than both unlabelled BSA and fetuin. |
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Keywords: | Bearberry Polyphenolics Tannins Phenolic&ndash protein interactions Protein-precipitating capacity |
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