Determination of antioxidant activity of extractable and macromolecular polyphenols and identification of lupanine in white lupinus ( Lupinus albus)

Abstract

The white Lupin (Lupinus albus) is a legume of the genus Lupinus, originally from the Mediterranean region, prominent nutritional value, due to your high level of dietary fiber, carbohydrates, proteins and lipids balanced profile. In addition, it has bioactive compounds, mainly polyphenols, with significant antioxidant capacity. Even if the present low level of white Lupin alkaloids, as the lupanine, yet the presence of these compounds can be a limiting factor for your consumption. However, despite being an antinutricional factor, possible effect antihypertensive and anti-hiperglicemic of lupanine are being reported. In this way, this work aimed to evaluate the content of total polyphenols (extractable and macromolecular), antioxidant capacity and identify the presence of lupanine in white Lupin beans, subjected or not to heat treatment. Quantification of polyphenols was carried out by the Folin-Ciocalteau assay, antioxidant activity tests TEAC and DPPH and lupanine identification by gas chromatography coupled to mass spectrometry. In all samples analysed, it was possible to identify the lupanine. The levels of total polyphenols found in control and treated thermally samples were 6142,50 and 6418,44 (mg GAE/100 g), respectively. With respect to the antioxidant capacity of the Lupine the EC50 ranged from 3473,49 ± 201,98 to 3832,65 ± 235,87 (g sample/g DPPH). Using the ABTS radical, the antioxidant activity presented values TEAC that ranged from 250,14 ± 14,32 to 270,39 ± 8,37 (µM trolox/g sample). Greater antioxidant capacity was linked to macromolecular polyphenols. Heat treatment did not interfere in the contents of polyphenols and antioxidant capacity of white Lupin beans.

Keywords

• non-extractable polyphenols
• macromolecular antioxidants