A systematic determination of polyphenols constituents and cytotoxic ability in fruit parts of pomegranates derived from five Chinese cultivars

Ellagitannin content and anti-enterohemorrhagic Escherichia coli activity of aqueous extracts derived from commercial pomegranate products

This study compared the efficacy of aqueous extracts of commercially available pomegranate peel products and a juice powder in inhibiting the growth of two enterohemorrhagic Escherichia coli strains. Cell suspension of each E. coli strain (5 Log CFU/ml) was added into tryptic soy broth amended with 9 or 23% of each extract prepared with two different methods. After treatment for 5, 10, and 24 h at 25 °C, surviving E. coli cells were enumerated on tryptic soy agar to determine cell population reduction compared to the controls. The concentrations of six different ellagitannins and titratable activity in each treatment system were determined and correlated to E. coli cell population reduction. The extracts from three powdered pomegranate peels caused a significantly greater (p ≤ 0.05) reduction in E. coli population than the extract from the whole peel and juice powder. The higher dose of extracts resulted in a greater cell population reduction than the lower dose. The level of E. coli population reduction correlated positively with the total ellagitannins content (R2 0.67-0.98) and the titratable acidity (R2 0.69-0.98) in the treatment systems. The study suggests that pomegranate peels are promising natural additives or preservatives to control pathogens like EHEC.

Direct Polyphenol Attachment on the Surfaces of Magnetite Nanoparticles, Using Vitis vinifera, Vaccinium corymbosum, or Punica granatum

This study presents an alternative approach to directly synthesizing magnetite nanoparticles (MNPs) in the presence of Vitis vinifera, Vaccinium corymbosum, and Punica granatum derived from natural sources (grapes, blueberries, and pomegranates, respectively). A modified co-precipitation method that combines phytochemical techniques was developed to produce semispherical MNPs that range in size from 7.7 to 8.8 nm and are coated with a ~1.5 nm thick layer of polyphenols. The observed structure, composition, and surface properties of the MNPs@polyphenols demonstrated the dual functionality of the phenolic groups as both reducing agents and capping molecules that are bonding with Fe ions on the surfaces of the MNPs via -OH groups. Magnetic force microscopy images revealed the uniaxial orientation of single magnetic domains (SMDs) associated with the inverse spinel structure of the magnetite (Fe3O4). The samples' inductive heating (H0 = 28.9 kA/m, f = 764 kHz), measured via the specific loss power (SLP) of the samples, yielded values of up to 187.2 W/g and showed the influence of the average particle size. A cell viability assessment was conducted via the MTT and NRu tests to estimate the metabolic and lysosomal activities of the MNPs@polyphenols in K562 (chronic myelogenous leukemia, ATCC) cells.

Pomegranate (Punica granatum L.) Attenuates Neuroinflammation Involved in Neurodegenerative Diseases

Food scientists have studied the many health benefits of polyphenols against pernicious human diseases. Evidence from scientific studies has shown that earlier healthy lifestyle changes, particularly in nutrition patterns, can reduce the burden of age-related diseases. In this context, a large number of plant-derived components belonging to the class of polyphenols have been reported to possess neuroprotective benefits. In this review, we examined studies on the effect of dietary polyphenols, notably from Punica granatum L., on neurodegenerative disease, including Alzheimer's disease, which is symptomatically characterized by impairment of cognitive functions. Clinical trials are in favor of the role of some polyphenols in maintaining neuronal homeostasis and attenuating clinical presentations of the disease. However, discrepancies in study design often bring inconsistent findings on the same component and display differences in their effectiveness due to interindividual variability, bioavailability in the body after administration, molecular structures, cross-blood-brain barrier, and signaling pathways such as nuclear factor kappa B (NF-κB). Based on preclinical and clinical trials, it appears that pomegranate may prove valuable in treating neurodegenerative disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD). Therefore, due to the lack of information on human clinical trials, future in-depth studies, focusing on human beings, of several bioactive components of pomegranate's polyphenols and their synergic effects should be carried out to evaluate their curative treatment.

Antioxidant, Antimicrobial, and Metabolomic Characterization of Blanched Pomegranate Peel Extracts: Effect of Cultivar

Hot water blanching at 80 °C for 3 min can be used as a novel pre-treatment step in pomegranate peel to preserve the integrity of the phytochemical content within the peel extracts by lowering or inactivating enzymes such as polyphenol (PPO) oxidase and peroxidase (POD) that are responsible for the break-down of phytochemicals within the peel. The aim of this study was to investigate the effect of hot water blanching pre-treatment on yield, bioactive compounds, antioxidants, enzyme inactivation, and antibacterial activity of ‘Wonderful’, ‘Acco’, and ‘Herskawitz’ pomegranate peel extracts. We used a variety of spectrophotometric-based assays and liquid chromatography mass spectrometry (LC-MS)-based approach to characterize and quantify metabolites within the peel extracts. Blanching significantly (p < 0.05) reduced PPO activity in all peel extracts, with the highest PPO reduction in ‘Herskawitz’ peel extracts at 0.25 U/mL. Furthermore, higher antioxidant activity in ‘Herskawitz’ blanched peel extracts using 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, ferric ion reducing antioxidant power (FRAP), and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity at 567.78 ± 9.47 µmol Trolox/g DM, 800.05 ± 1.60 µmol Trolox/g DM, and 915.27 ± 0.61 µmol Trolox/g DM, respectively, was noted. ‘Herskawitz’ blanched peel extracts were recorded with the lowest minimum inhibitory concentration (MIC) value of 80 µg/mL for Gram-positive Bacillus subtilis and Gram-negative Klebsiella pneumoniae bacteria strains. A total of 30 metabolites were present in ‘Acco’ and ‘Herskawitz’ peel extracts and were tentatively identified after LC-MS profiling. This study demonstrates that blanched peel extracts from ‘Herskawitz’ cultivar have great potential for commercial use in value-added products in the nutraceutical, cosmeceutical, and pharmacological industries.

Antiviral activity of plant juices and green tea against SARS-CoV-2 and influenza virus

Respiratory viruses pose a significant threat to global health. They initially infect the naso- and oropharyngeal regions, where they amplify, cause symptoms, and may also be transmitted to new hosts. Preventing initial infection or reducing viral loads upon infection might soothe symptoms, prevent dissemination into the lower airways, or transmission to the next individual. Several natural products have well-described direct antiviral activity or may ameliorate symptoms of respiratory infections. We thus analyzed the potential of plant-derived products to inactivate respiratory viral pathogens and determined the antiviral activity of black chokeberry (Aronia melanocarpae [Michx.] Elliott), elderberry (Sambucus nigra L.), and pomegranate (Punica granatum L.) juice, as well as green tea (Camellia sinensis [L.] Kuntze) on the infectivity of the surrogate-modified vaccinia virus Ankara, and the respiratory viruses severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IAV), and adenovirus Type 5. Black chokeberry and pomegranate juice, and green tea reduced SARS-CoV-2 and IAV titers by ≥80% or ≥99%. This suggests that oral rinsing with these products may reduce viral loads in the oral cavity which might prevent viral transmission.

Stabilization of PE with Pomegranate Extract: Contradictions and Possible Mechanisms

Dry pomegranate peel was extracted with acetone and the extract was added to a Phillips type polyethylene. The concentration of the extract was changed from 0 to 1000 ppm in six steps and stabilization efficiency was checked by the multiple extrusion of the polymer followed by the characterization of chemical structure, processing, and residual stability. The results confirmed the excellent processing stabilization efficiency of the extract, but also the poor long-term stability of PE containing it in accordance with previously published results. The extract is amorphous and its solubility is relatively large in the polymer; thus, these factors cannot be the reason for the poor stabilization efficiency in an oxygen-rich environment. Chemical factors like the self-interaction of the polyphenol molecules, the stability of the radicals forming after hydrogen abstraction, and the lack of hydrogens with the necessary reactivity must be considered during the evaluation of the efficiency of the extract. These factors as well as the insufficient number of active hydrogens hinder the reaction of the additive molecules with oxygen-centered radicals, thus leading to inferior long-term stability. The extract can be used for the processing stabilization of polymers, but for applications requiring long-term stability, it must be combined with other natural antioxidants like flavonoids or Vitamin E.

Profiling Phenolic Composition in Pomegranate Peel From Nine Selected Cultivars Using UHPLC-QTOF-MS and UPLC-QQQ-MS

Pomegranate is widely cultivated across China, and the phenolics in its peel are principal components associated with health benefits. Ultra-high performance liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer (UHPLC-QTOF-MS) and ultra-performance liquid chromatography coupled to a triple quadrupole mass spectrometer (UPLC-QQQ-MS) were used in this study, aiming at profiling the total phenolic composition in pomegranate peel from nine selected cultivars in 7 production areas. Sixty-four phenolic compounds were identified or annotated, and 23 of them were firstly reported in pomegranate peel. Principal component analysis (PCA) plots show differences and similarities of phenolics among nine cultivars. Furthermore, 15 phenolic compounds were quantified with the standards, and punicalagin, ellagic acid, gallocatechin, punicalin, catechin, and corilagin were found to be dominant. Punicalagin weighed the highest content (28.03–104.14 mg/g). This study can provide a deeper and more detailed insight into the phenolic composition in pomegranate peel and facilitate the health-promoting utilization of phenolics.

Analysis of the Phytochemical Composition of Pomegranate Fruit Juices, Peels and Kernels: A Comparative Study on Four Cultivars Grown in Southern Italy

The increasing popularity of pomegranate (Punica granatum L.), driven by the awareness of its nutraceutical properties and excellent environmental adaptability, is promoting a global expansion of its production area. This investigation reports the variability in the weight, moisture, pH, total soluble solids, carbohydrates, organic acids, phenolic compounds, fatty acids, antioxidant activities, and element composition of different fruit parts (juices, peels, and kernels) from four (Ako, Emek, Kamel, and Wonderful One) of the most widely cultivated Israeli pomegranate varieties in Salento (South Italy). To the best of our knowledge, this is the first systematic characterization of different fruit parts from pomegranate cultivars grown simultaneously in the same orchard and subjected to identical agronomic and environmental conditions. Significant genotype-dependent variability was observed for many of the investigated parameters, though without any correlation among fruit parts. The levels of phenols, flavonoids, anthocyanins, and ascorbic and dehydroascorbic acids of all samples were higher than the literature-reported data, as was the antioxidant activity. This is likely due to positive interactions among genotypes, the environment, and good agricultural practices. This study also confirms that pomegranate kernels and peels are, respectively, rich sources of punicic acid and phenols together, with several other bioactive molecules. However, the variability in their levels emphasizes the need for further research to better exploit their agro-industrial potential and thereby increase juice-production chain sustainability. This study will help to assist breeders and growers to respond to consumer and industrial preferences and encourage the development of biorefinery strategies for the utilization of pomegranate by-products as nutraceuticals or value-added ingredients for custom-tailored supplemented foods.

Plant-Derived and Dietary Hydroxybenzoic Acids-A Comprehensive Study of Structural, Anti-/Pro-Oxidant, Lipophilic, Antimicrobial, and Cytotoxic Activity in MDA-MB-231 and MCF-7 Cell Lines

Seven derivatives of plant-derived hydroxybenzoic acid (HBA)—including 2,3-dihydroxybenzoic (2,3-DHB, pyrocatechuic), 2,4-dihydroxybenzoic (2,4-DHB, β-resorcylic), 2,5-dihydroxybenzoic (2,5-DHB, gentisic), 2,6-dihydroxybenzoic (2,6-DHB, γ-resorcylic acid), 3,4-dihydroxybenzoic (3,4-DHB, protocatechuic), 3,5-dihydroxybenzoic (3,5-DHB, α-resorcylic), and 3,4,5-trihydroxybenzoic (3,4,5-THB, gallic) acids—were studied for their structural and biological properties. Anti-/pro-oxidant properties were evaluated by using DPPH^• (2,2-diphenyl-1-picrylhydrazyl), ABTS^•+ (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric-reducing antioxidant power), CUPRAC (cupric-reducing antioxidant power), and Trolox oxidation assays. Lipophilicity was estimated by means of experimental (HPLC) and theoretical methods. The antimicrobial activity against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Salmonella enteritidis (S. enteritidis), and Candida albicans (C. albicans) was studied. The cytotoxicity of HBAs in MCF-7 and MDA-MB-231 cell lines was estimated. Moreover, the structure of HBAs was studied by means of experimental (FTIR, ¹H, and ¹³C NMR) and quantum chemical DFT methods (the NBO and CHelpG charges, electrostatic potential maps, and electronic parameters based on the energy of HOMO and LUMO orbitals). The aromaticity of HBA was studied based on the calculated geometric and magnetic aromaticity indices (HOMA, Aj, BAC, I6, NICS). The biological activity of hydroxybenzoic acids was discussed in relation to their geometry, the electronic charge distribution in their molecules, their lipophilicity, and their acidity. Principal component analysis (PCA) was used in the statistical analysis of the obtained data and the discussion of the dependency between the structure and activity (SAR: structure–activity relationship) of HBAs. This work provides valuable information on the potential application of hydroxybenzoic acids as bioactive components in dietary supplements, functional foods, or even drugs.

Blanching Pre-Treatment Promotes High Yields, Bioactive Compounds, Antioxidants, Enzyme Inactivation and Antibacterial Activity of 'Wonderful' Pomegranate Peel Extracts at Three Different Harvest Maturities

'Wonderful' pomegranate (Punica granatum L.) peel contains a wide range of phytochemicals including vitamins, dietary fibre, phenolic compounds, and antioxidant properties. Yet, it is often used as animal feed or discarded in landfills, which is not the best eco-friendly way to utilize this phenolic-rich bioresource. Finding novel ways of utilizing pomegranate peel waste could prove a more profitable and eco-friendlier alternative that is far more beneficial to the economy. Adding a blanching pre-treatment step at optimal conditions prior to processing of pomegranate peel aids in the inactivation of quality changing enzymes such as polyphenol oxidase (PPO) and peroxidase (POD), which are accountable for the degradation reactions that cause breakdown of nutrients and phytochemicals. This study aimed to determine the effect of blanching at 80 °C for 3 min on the yield, polyphenol content, antioxidant properties, enzyme inactivation, and antibacterial activity of 'Wonderful' pomegranate peel ethanolic extracts from three different harvest maturities (unripe, ripe, and over ripe), including a comprehensive characterization and quantification using liquid chromatography-mass spectrometry (LC-MS). The blanched unripe peel extracts exhibited the highest total phenolic content, total tannin content, 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity and ferric ion reducing antioxidant power (FRAP) at 14.0 mg gallic acid equivalent (GAE)/g dry mass (DM), 1.0 mg GAE/g DM, 359.1 µmol Trolox/g DM, 912.2 µmol Trolox/g DM and 802.5 µmol Trolox/g DM, respectively. There was significant (p < 0.05) decrease in PPO and POD activity of all blanched pomegranate peel extracts. The blanched unripe peel extracts had the lowest PPO activity at 0.2 U/g fresh weight (FW), with a 70% PPO inactivation compared to ripe and over ripe harvest, whereas the highest POD inactivation was recorded at 67% in over ripe peel extracts. All blanched peel extracts, irrespective of harvest maturity, had minimum inhibitory concentration (MIC) values at 160 µg/mL against all four bacteria strains tested, which included two Gram-positive bacterial strains (Bacillus subtilis ATCC 6051 and Staphylococcus aureus ATCC 12600) and two Gram-negative bacteria (Escherichia coli 11775 and Klebsiella pneumonia ATCC 13883). A total of 25 metabolites including phenolic acids (4), organic acids (1), flavonoids (4), ellagitannins (13), and other polyphenols (3) in all three pomegranate peel samples were tentatively identified after LC-MS profiling. The blanched unripe peel extracts showed significantly higher punicalin α and β, β punicalagin, catechin, epicatechin content at 414 mg/g, and 678 mg/g, 151 mg/g, 229 mg/g, respectively, compared to peel extracts from other harvest maturities. This study provides supportive information for the commercial utilization of pomegranate fruit peel as source of value-added ingredients for the development of novel food, cosmetics, and pharmacological products.

Punicalagin Ameliorates Lupus Nephritis via Inhibition of PAR2

Lupus nephritis (LN) is the most frequent phenotype in patients with systemic lupus erythematosus (SLE) and has a high rate of progression to end-stage renal disease, in spite of intensive treatment and maintenance therapies. Recent evidence suggests that protease-activated receptor-2 (PAR2) is a therapeutic target for glomerulonephritis. In this study, we performed a cell-based high-throughput screening and identified a novel potent PAR2 antagonist, punicalagin (PCG, a major polyphenol enriched in pomegranate), and evaluated the effects of PCG on LN. The effect of PCG on PAR2 inhibition was observed in the human podocyte cell line and its effect on LN was evaluated in NZB/W F1 mice. In the human podocyte cell line, PCG potently inhibited PAR2 (IC₅₀ = 1.5 ± 0.03 µM) and significantly reduced the PAR2-mediated activation of ERK1/2 and NF-κB signaling pathway. In addition, PCG significantly decreased PAR2-induced increases in ICAM-1 and VCAM-1 as well as in IL-8, IFN-γ, and TNF-α expression. Notably, the intraperitoneal administration of PCG significantly alleviated kidney injury and splenomegaly and reduced proteinuria and renal ICAM-1 and VCAM-1 expression in NZB/W F1 mice. Our results suggest that PCG has beneficial effects on LN via inhibition of PAR2, and PCG is a potential therapeutic agent for LN.

Synthesis, characterization, and their some chemical and biological properties of PVA/PAA/nPS hydrogel nanocomposites: Hydrogel and wound dressing

The nanocomposite hydrogels were prepared by dispersing of the nanopomegranate seed particles into poly(vinyl alcohol)/poly(acrylic acid) blend matrix in an aqueous medium by the solvent casting method. These hydrogels were characterized using scanning electron microscopy, Fourier transform infrared spectra, differential scanning calorimetry, and optical contact angle instruments. The nanopomegranate seed, blend, and hydrogel nanocomposites were tested for microbial activity. In addition, cytocompatibilities of these blend and hydrogel nanocomposites/composites were tested on human lymphocyte with in vitro MTS cell viability assays. Fourier transform infrared spectra revealed that esterification reaction took place among functional groups in the structure of poly(vinyl alcohol) and poly(acrylic acid). The hydrophilic properties of all hydrogels decreased with increasing nanopomegranate seed content. The mean diameters of the nanopomegranate seed particles were about 88 nm. Nanopomegranate seed particles demonstrated antibacterial properties against gram-positive bacteria, Staphylococcus aureus, and gram-negative bacteria, Escherichia coli. The lymphocyte viabilities increased after addition of nanopomegranate seeds into the polymer blend. The swelling behavior of blend and hydrogels was dependent on the cross-linking density created by the reaction between poly(vinyl alcohol)/poly(acrylic acid) blend and nanopomegranate seed. Scanning electron microscopy images were highly consistent with Fourier transform infrared spectra, differential scanning calorimetry, and antibacterial activity results.

Primary Metabolites, Anthocyanins, and Hydrolyzable Tannins in the Pomegranate Fruit

Pomegranate (Punica granatum L.) is an important and interesting fruit tree that is cultivated in many parts of the world. In recent years, along with the increase in its cultivation and consumption there has been a dramatic increase in the scientific interest in its biology, methods of cultivation, adaptation to environmental cues and its health-promoting properties. Quite a large proportion of the various metabolites produced in the pomegranate were determined and their content in the bark, roots, leaves, and fruit was reported. Many reviews on polyphenolic compound content, antioxidant activity and health-promoting compounds were published recently. However, only very few recent reports were dedicated to primary metabolites, despite the fact that much work was done on organic acids, sugars, proteins, lipids, and amino acids of the pomegranate fruit. In this review, a special effort was made to present these recent studies and the review is devoted to primary metabolites. The reported data show high variation in the content of primary metabolites within the pomegranate fruit; therefore the data is presented (whenever possible) according to fruit tissues (peel, arils, and seeds), developmental stages of the fruit, environmental and climatic conditions, and genetic background. Most of the data on pomegranate is based on metabolic content and contains no genetic or molecular analysis except for work done on anthocyanins and hydrolyzable tannins. In those cases, gene assignment and genetic control studies were pointed out in the review. The recent publication of the genome sequences from several pomegranate varieties and transcriptomic data from fruits, flowers, and leaves is expected to facilitate the understanding of genetic control of metabolites in pomegranate.