Characterization of Date (Deglet Nour) Seed Free and Bound Polyphenols by High‐Performance Liquid Chromatography‐Mass Spectrometry

Abstract

Date (Pheonix dactylifera L.) seeds are a valuable and abundant by-product with various potential food applications. Free polyphenols (FPPs) and bound polyphenols (BPPs) of date seeds from Deglet Nour variety grown in Australia were investigated using high-performance liquid chromatography-mass spectrometry. The FPP fraction contained the following main phenolic compounds per gram of date seed powder; procyanidin B1 (499.8 ± 7.8 μg), procyanidin B2 (288.6 ± 6.1 μg), catechin (167.6 ± 2.1 μg), epicatechin (39.44 ± 0.39 μg), and protocatechuic acid (1.77 ± 0.22 μg). Additionally, one of the 2 A-type dimers was confirmed as procyanidin A2 (24.05 ± 0.12 μg/g). A-type dimers have not been reported before in date seeds. The BPP fraction contained epicatechin (52.59 ± 0.76 μg/g) and procyanidin B2 (294.2 ± 3.7 μg/g), while several peaks exhibiting ESI m/z of 153 indicated dihydroxybenzoic acid isomers including protocatechuic acid (2.138 ± 0.025 μg/g). These findings contributed to our knowledge of date seed phytochemicals and understanding of their contribution to the reported bioactivities.

Simulated gastrointestinal digestion and in vitro colonic fermentation of date (Phoenix dactylifera L.) seed polyphenols

“…In this study, two monomeric and three dimeric polyphenols from the seeds of Phoenix dactylifera L. were monitored in gastric and intestinal digestion stages. These polyphenols were identified in a previous study using HPLC-MS as date seeds extractable polyphenols (EPP) and included, catechin, epicatechin, procyanidin B1, procyanidin B2, procyanidin A2 (Sirisena et al, 2017). These were the most abundant date seed polyphenols, and those confirmed with HPLC-MS and internal standard spiking therefore were selected to be monitored in this digestion study.…”

“…Ferulic acid was detected at fairly high levels in DSP (140 AE 9.1 to 216 AE 6.3 lg g À1 DSP) and DSPY (372 AE 8.2 to 456 AE 10 lg g À1 DSP). Free ferulic acid has previously been detected in some date seed varieties (Al-Farsi & Lee, 2008), however, not in the Deglet nour (Habib et al, 2014;Sirisena et al, 2017). Ferulic acid is usually found esterified with hemicelluloses (Aura, 2008), and it has been reported that fibrebound ferulic acid is released in human colon by the action of human colonic microbiota (Kroon et al, 1997;Rondini et al, 2004).…”

“…We focused on five major DSP polyphenols (catechin, epicatechin, procyanidin B1, procyanidin B2, and procyanidin A2) that were previously identified by HPLC-MS (Sirisena et al, 2017). Their stability and in vitro bioaccessibility were monitored in gastric and intestinal digestion stages.…”

“…Therefore, it is a potential low-cost ingredient which can be added to various food products to increase polyphenol and dietary fibre contents. The polyphenol contents in date seeds contained organic solvent extractable polyphenols (EPP) and nonextractable polyphenols (NEPP) (Sirisena et al, 2017). The EPP included flavan-3-ol monomers, dimers and oligomers, as well as glycosylated flavones and flavonols.…”

Induction of Apoptosis and Cell Cycle Arrest in two Human Cancer A549 and HT29 Cells Lines by Barhi Date Palm Kernels Extracts and Three Isolated Cytotoxic Compounds

“…For the NEPP acid hydrolysis, the residue post-EPP extraction process under optimized conditions was collected and was used for the extraction of NEPP following the method described by [31]. The extraction process was conducted in the absence of a metal catalyst.…”