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

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.

Anthocyanins from Pomegranate (Punica granatum L.) and Their Role in Antioxidant Capacities in Vitro

“…The authors inferred that there may be a different oxidation mechanism of Pg in ⋅ OH scavenging activities [100] . An inhibition against H 2 O 2 ‐induced oxidative stress was observed in cultured human hepatocellular HepG2 cells when performed with separated anthocyanins and copigment fraction from pomegranate juice, [39] indicating their potential action as cellular ROS scavengers. Inhibitory effects of anthocyanins on H 2 O 2 ‐induced lipid peroxidation were determined in rat brain homogenates, with an order of Dp>Cy>Pg, which was in line with the results of radical scavenging activity [100] …”

“…More recently, Kostka et al. revealed no significant differences between the anthocyanin and polyphenol of pomegranate towards radical scavenging activity against DPPH and galvinoxyl radicals, thus suggesting equal importance of the anthocyanins and polyphenols in terms of antioxidant capacities in pomegranate juices [39] …”

Tropical Fruits and Their Co-Products as Bioactive Compounds and Their Health Effects: A Review

“…In pomegranate (Punica granatum L.) it is possible to find numerous types of phytochemicals including flavonoids such as anthocyanins, including cyanidin-3-O-glucoside (22.77 mg/g), cyanidin-3,5-O-diglucoside (25.36 mg/g) and pelargonidin-3,5-O-diglucoside 11.16 mg/g) [26], flavons and flavonols (kaempferol, luteolin, quercetin, rutin, naringin) and flavan-3-ols (catechin, epicatechin, gallo-catechin) [41], and condensed and hydrolysable tannins including punicalagin with values ranging between 87.8 and 453 mg/g, and punicalin [42] and non-flavonoid phenolics such as ellagic acid, caffeic acid, ferulic acid, chlorogenic acid, and gallic acid, among others [43]. As regards anthocyanin content, this are mainly concentrated in the arils and, therefore, in the juice.…”

Elucidation of Volatiles, Anthocyanins, Antioxidant and Sensory Properties of cv. Caner Pomegranate (Punica granatum L.) Juices Produced from Three Juice Extraction Methods

“…In addition to their contribution to sensory profiles, they are also important for health with their antitumor, antioxidant, antimicrobial, and anti-inflammatory effects. As pomegranates and their products are rich in phenolics, specifically anthocyanins, they display these health beneficial properties, and [ 14 , 15 ]. Kostka et al [ 15 ] extracted and separated pomegranate polyphenolics into an anthocyanin and copigment fraction with the aid of the adsorptive membrane technique.…”

“…As pomegranates and their products are rich in phenolics, specifically anthocyanins, they display these health beneficial properties, and [ 14 , 15 ]. Kostka et al [ 15 ] extracted and separated pomegranate polyphenolics into an anthocyanin and copigment fraction with the aid of the adsorptive membrane technique. They elucidated that the total phenolics and free radical scavenging activity were considerably higher in the XAD-7 extract compared to the juice and that anthocyanins and copigments act together in decreasing oxidative stress.…”