Content of major classes of polyphenolic compounds, antioxidant, antiproliferative, and cell protective activity of pecan crude extracts and their fractions

Acetonic extracts of pecan kernels and nutshells were fractionated using Sephadex LH-20 and three fractions were obtained from each. Only fraction II of both extracts contained simple polyphenols: catechin, epicatechin and ellagic acid were identified in kernel fraction II, while only epicatechin and ellagic acid were found in shell fraction II. Total gallic and ellagic acids were quantified in acid-hydrolyzed extracts: kernels contained 1.8 and 3.6 mg g−1, respectively, while nutshells contained 2.3 and 0.8 mg g−1, respectively. Kernel fraction III, containing high molecular weight compounds, showed the highest antioxidant activity and better antiproliferative activity in a cancer than a non-cancer cell line. Crude extracts showed cytotoxic activity in cerebellar granule neurons (CGNs), but shell extract was more cytotoxic; in contrast only kernel extract protected CGNs from H2O2-induced cell death. Thus, high molecular weight compounds of pecan kernel show noticeable bioactive properties and should be further characterised and analyzed as a rich source of bioactive polyphenols.