Determination of polyphenols in legumes by HPLC-DAD and study of antioxidant activity and correlation with color

Legumes, are one of the most important basic staple food for human worldwide that provide a broad range of healthy micro- and macro-nutrients such as proteins, carbohydrates (dietary fiber), minerals, vitamins and phytochemical like phenolics. Phenolics compounds have been ascribed as antioxidants able to delay or inhibit oxidative damage, thus preventing the onset of oxidative stress related diseases in human. flavonoids represent one of the group of major interest among phenolics exhibiting a very strong antioxidant activity. Legumes are a source of flavonoids, namely flavonols, flavan-3-ols and anthocyanins. The aim of this work was develop an analytical method to identify and quantify simultaneously 14 polyphenols in 36 legume varieties through HPLC-DAD. Phenolic compounds quantified in all the legume samples ranged from 3 mg/kg to 1630,5 mg/kg in red dehulled lentils and ruviotto beans respectively. Additionally total phenolic content (TPC) has been evaluated by means of Folin Ciocalteau assay and the antioxidant power of extracts was evaluate by their ability to scavenge the 1,1-diphenil-2-picryl-hydrazyl (DPPH) radical. The highest antioxidant activity was shown by the dark testa samples (black lentil and diavoli beans) with respect to the pale ones and a positive correlation was found between total phenolic content (TPC) and IC50 for dark colored varieties.