Pomegranate (Punica granatum L.) Extract and Its Anthocyanin and Copigment Fractions-Free Radical Scavenging Activity and Influence on Cellular Oxidative Stress.

Tina Kostka,Peter Winterhalter,Karlis Briviba,Johanna Josefine Ostberg-Potthoff,Tuba Esatbeyoglu,Seiichi Matsugo

doi:10.3390/foods9111617

Abstract

Secondary plant metabolites, e.g., polyphenols, are widely known as health-improving compounds that occur in natural functional foods such as pomegranates. While extracts generated from these fruits inhibit oxidative stress, the allocation of these effects to the different subgroups of substances, e.g., anthocyanins, “copigments” (polyphenols without anthocyanins), or polymeric compounds, is still unknown. Therefore, in the present study, polyphenols from pomegranate juice were extracted and separated into an anthocyanin and copigment fraction using adsorptive membrane chromatography. Phenolic compounds were determined by high performance liquid chromatography with photodiode array (HPLC–PDA) detection and HPLC-PDA electrospray ionization tandem mass spectrometry (HPLC–PDA–ESI–MS/MS), while the free radical scavenging activity of the pomegranate XAD‑7 extract and its fractions was evaluated by the Trolox equivalent antioxidant capacity (TEAC) assay and electron spin resonance (ESR) spectroscopy. Compared to juice, the total phenolic content and free radical scavenging potential was significantly higher in the pomegranate XAD-7 extract and its fractions. In comparison to the anthocyanin and copigment fraction, pomegranate XAD-7 extract showed the highest radical scavenging activity against galvinoxyl and DPPH radicals. Moreover, the enriched XAD-7 extract and its fractions were able to protect human hepatocellular HepG2 cells against oxidative stress induced by hydrogen peroxide. Overall, these results indicated that anthocyanins and copigments act together in reducing oxidative stress.

Highlights

Over recent years, the consumption of so-called “superfoods” has become a new food trend as part of healthier and more conscious nutrition
In order to detect substance specific differences and the most effective compounds concerning the bioactivity of the extract and the separated fractions, we examined their radical scavenging activity as well as the cellular-protective potential against oxidative stress
Chemical Characterization of pomegranate extracts (PE) and Its Fractions Obtained by Membrane Chromatography

Summary

Introduction

The consumption of so-called “superfoods” has become a new food trend as part of healthier and more conscious nutrition. The tightly packed juicy arils of pomegranate are a rich source of punicalagins, ellagic acid, and flavonoids, such as anthocyanins [5,11]. While these secondary metabolites are associated with antioxidant activity, inhibition of DNA damage, and suppression of cancer cell growth [7,12,13,14,15], their bioavailability in the small intestine is low [16,17]. The consumption of 300 g of red fruits led to non-detectable contents of anthocyanins and ellagic acids in human plasma samples [17]

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