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Polyphenols and Phenolic Compounds: From Biology to Biotechnology and Human Health

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (31 January 2021) | Viewed by 79721

Special Issue Editors


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Guest Editor
1. Department of Science and Technology, Parthenope University of Naples, Centro Direzionale - Isola C4, 80143 Napoli, Italy
2. Institute of Biomolecular Chemistry, National Research Council of Italy, Via Campi Flegrei, 34, 80078 Pozzuoli (NA), Italy
Interests: microbial exopolysaccharides; vegetable polysaccharides; extremophilic microorganisms

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Guest Editor
Department of Chemical, Materials and Production Engineering (DICMaPI) University of Naples Federico II Piazzale Tecchio, 80 80125 Napoli, Italy
Interests: nanomaterials synthesis; hybrid materials design, bioinspired multifunctional systems; surface functionalization of nanostructured materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In the last two decades, natural polyphenols have gained more and more interest, as witnessed by the number of publications in various research areas, including biochemistry, biology, medicine, pharmacology, and material science. This picture stems from the positioning of polyphenols and phenolic compounds at the crossroads of chemistry, biology, and medicine, where these substances play key roles thanks to their origin, chemistry, and (bio)activity. Indeed, these natural compounds have been investigated for their ability to act as natural antioxidants and anti-microbial compounds, as new leads in drug discovery, and as nutraceutical compounds, for their beneficial effects on human microbioma and skin and for their potential industrial applications in the materials field.

This Special Issue, collecting topics from an interdisciplinary viewpoint, aims to provide a resourceful background for readers, addressing and collecting the newest insights and potential applications of polyphenols and phenolic compounds.

Reviews and original research articles from the fields of chemistry, biochemistry, pharmacology, analytical chemistry, and material science are of interest to this Special Issue.

Dr. Paola Di Donato
Dr. Brigida Silvestri
Guest Editor

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Keywords

  • Natural products
  • Antioxidants
  • Natural antibiotics
  • Food additives
  • Nutraceuticals
  • Skin protection
  • Human microbiome
  • Natural plasticizers
  • Analytical techniques
  • Polyphenols chemistry.

Published Papers (19 papers)

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Research

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14 pages, 2639 KiB  
Article
Chemical Composition of Tomato Seed Flours, and Their Radical Scavenging, Anti-Inflammatory and Gut Microbiota Modulating Properties
by Uyory Choe, Jianghao Sun, Elena Bailoni, Pei Chen, Yanfang Li, Boyan Gao, Thomas T. Y. Wang, Jiajia Rao and Liangli (Lucy) Yu
Molecules 2021, 26(5), 1478; https://doi.org/10.3390/molecules26051478 - 09 Mar 2021
Cited by 15 | Viewed by 3339
Abstract
In the current study, the chemical composition and total phenolic content of tomato seed flours, along with potential health beneficial properties, including free radical scavenging capacities, anti-inflammatory capacities, and gut microbiota profile modulation, were examined using two different batches. Eight compounds were identified [...] Read more.
In the current study, the chemical composition and total phenolic content of tomato seed flours, along with potential health beneficial properties, including free radical scavenging capacities, anti-inflammatory capacities, and gut microbiota profile modulation, were examined using two different batches. Eight compounds were identified in the tomato seed flour, including malic acid, 2-hydroxyadipic acid, salicylic acid, naringin, N-acetyl-tryptophan, quercetin-di-O-hexoside, kaempferol-di-O-hexoside, and azelaic acid. The total phenolic contents of tomato seed flour were 1.97–2.00 mg gallic acid equivalents/g. Oxygen radical absorbing capacities (ORAC), 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacities (DPPH), and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical scavenging capacities (ABTS) were 86.32–88.57, 3.57–3.81, and 3.39–3.58 µmoles Trolox equivalents/g, respectively, on a per flour dry weight basis. The mRNA expression of the pro-inflammatory markers, interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α), were dose-dependently suppressed by tomato seed flour extracts. The extracts altered five of the eight bacterial phyla and genera evaluated. The results may provide some scientific support for the use of tomato seed flour as value-added food ingredients. Full article
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12 pages, 2846 KiB  
Article
Benzenetriol-Derived Compounds against Citrus Canker
by Lúcia Bonci Cavalca, Ciaran W. Lahive, Fleur Gijsbers, Fernando Rogério Pavan, Dirk-Jan Scheffers and Peter J. Deuss
Molecules 2021, 26(5), 1436; https://doi.org/10.3390/molecules26051436 - 06 Mar 2021
Cited by 2 | Viewed by 2768
Abstract
In order to replace the huge amounts of copper salts used in citrus orchards, alternatives have been sought in the form of organic compounds of natural origin with activity against the causative agent of citrus canker, the phytopathogen Xanthomonas citri subsp. Citri. [...] Read more.
In order to replace the huge amounts of copper salts used in citrus orchards, alternatives have been sought in the form of organic compounds of natural origin with activity against the causative agent of citrus canker, the phytopathogen Xanthomonas citri subsp. Citri. We synthesized a series of 4-alkoxy-1,2-benzene diols (alkyl-BDOs) using 1,2,4-benzenetriol (BTO) as a starting material through a three-step synthesis route and evaluated their suitability as antibacterial compounds. Our results show that alkyl ethers derived from 1,2,4-benzenetriol have bactericidal activity against X. citri, disrupting the bacterial cell membrane within 15 min. Alkyl-BDOs were also shown to remain active against the bacteria while in solution, and presented low toxicity to (human) MRC-5 cells. Therefore, we have demonstrated that 1,2,4-benzenetriol—a molecule that can be obtained from agricultural residues—is an adequate precursor for the synthesis of new compounds with activity against X. citri. Full article
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15 pages, 3094 KiB  
Article
Stability and Photoisomerization of Stilbenes Isolated from the Bark of Norway Spruce Roots
by Harri Latva-Mäenpää, Riziwanguli Wufu, Daniel Mulat, Tytti Sarjala, Pekka Saranpää and Kristiina Wähälä
Molecules 2021, 26(4), 1036; https://doi.org/10.3390/molecules26041036 - 16 Feb 2021
Cited by 17 | Viewed by 2592
Abstract
Stilbenes or stilbenoids, major polyphenolic compounds of the bark of Norway spruce (Picea abies L. Karst), have potential future applications as drugs, preservatives and other functional ingredients due to their antioxidative, antibacterial and antifungal properties. Stilbenes are photosensitive and UV and fluorescent [...] Read more.
Stilbenes or stilbenoids, major polyphenolic compounds of the bark of Norway spruce (Picea abies L. Karst), have potential future applications as drugs, preservatives and other functional ingredients due to their antioxidative, antibacterial and antifungal properties. Stilbenes are photosensitive and UV and fluorescent light induce trans to cis isomerisation via intramolecular cyclization. So far, the characterizations of possible new compounds derived from trans-stilbenes under UV light exposure have been mainly tentative based only on UV or MS spectra without utilizing more detailed structural spectroscopy techniques such as NMR. The objective of this work was to study the stability of biologically interesting and readily available stilbenes such as astringin and isorhapontin and their aglucones piceatannol and isorhapontigenin, which have not been studied previously. The effects of fluorescent and UV light and storage on the stability of trans stilbenes were assessed and the identification and characterisation of new compounds formed during our experiments were carried out by chromatographic (HPLC, GC) and spectroscopic techniques (UV, MS, NMR). The stilbenes undergo a trans to cis isomerisation under extended UV irradiation by intramolecular cyclisation (by the formation of a new C-C bond and the loss of two hydrogens) to phenanthrene structures. The characterised compounds are novel and not described previously. Full article
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15 pages, 4043 KiB  
Article
The Influence of UV Radiation on the Degradation of Pharmaceutical Formulations Containing Quercetin
by Iwona Golonka, Stanisław Wilk and Witold Musiał
Molecules 2020, 25(22), 5454; https://doi.org/10.3390/molecules25225454 - 20 Nov 2020
Cited by 19 | Viewed by 5724
Abstract
The aim of this study was to assess the photostability of quercetin in the presence of anionic and nonionic polymeric gels with varied compositions of an added component—glycerol. The samples were irradiated continuously at constant temperature. The stability of quercetin in solution and [...] Read more.
The aim of this study was to assess the photostability of quercetin in the presence of anionic and nonionic polymeric gels with varied compositions of an added component—glycerol. The samples were irradiated continuously at constant temperature. The stability of quercetin in solution and incorporated into the gels was evaluated by an UV-Vis spectrophotometer. FTIR spectroscopy (Fourier-transform infrared spectroscopy) was used to detect the changes in the structure of quercetin depending on the polymer used in the gel, and on the exposure time. Photostabilization is an important aspect of quality assurance in photosensitive compounds. The decomposition rate of quercetin in the ionic preparation of polyacrylic acid (PAA) with glycerol was 1.952·10−3 min−1, whereas the absence of glycerol resulted in a decay rate of 5.032·10−4 min−1. The formulation containing non-ionic methylcellulose resulted in a decomposition rate of quercetin in the range of 1.679·10−3 min−1. The decay rate of quercetin under light influence depended on the composition of the gel. It was found that the cross-linked PAA stabilized quercetin and the addition of glycerol accelerated the photodegradation. Full article
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14 pages, 2529 KiB  
Article
Investigating the Modes of Action of the Antimicrobial Chalcones BC1 and T9A
by Luana G. Morão, André S. G. Lorenzoni, Parichita Chakraborty, Gabriela M. Ayusso, Lucia B. Cavalca, Mariana B. Santos, Beatriz C. Marques, Guilherme Dilarri, Caio Zamuner, Luis O. Regasini, Henrique Ferreira and Dirk-Jan Scheffers
Molecules 2020, 25(20), 4596; https://doi.org/10.3390/molecules25204596 - 09 Oct 2020
Cited by 7 | Viewed by 2082
Abstract
Xanthomonas citri subsp. citri (X. citri) is an important phytopathogen and causes Asiatic Citrus Canker (ACC). To control ACC, copper sprays are commonly used. As copper is an environmentally damaging heavy metal, new antimicrobials are needed to combat citrus canker. Here, [...] Read more.
Xanthomonas citri subsp. citri (X. citri) is an important phytopathogen and causes Asiatic Citrus Canker (ACC). To control ACC, copper sprays are commonly used. As copper is an environmentally damaging heavy metal, new antimicrobials are needed to combat citrus canker. Here, we explored the antimicrobial activity of chalcones, specifically the methoxychalcone BC1 and the hydroxychalcone T9A, against X. citri and the model organism Bacillus subtilis. BC1 and T9A prevented growth of X. citri and B. subtilis in concentrations varying from 20 µg/mL to 40 µg/mL. BC1 and T9A decreased incorporation of radiolabeled precursors of DNA, RNA, protein, and peptidoglycan in X. citri and B. subtilis. Both compounds mildly affected respiratory activity in X. citri, but T9A strongly decreased respiratory activity in B. subtilis. In line with that finding, intracellular ATP decreased strongly in B. subtilis upon T9A treatment, whereas BC1 increased intracellular ATP. In X. citri, both compounds resulted in a decrease in intracellular ATP. Cell division seems not to be affected in X. citri, and, although in B. subtilis the formation of FtsZ-rings is affected, a FtsZ GTPase activity assay suggests that this is an indirect effect. The chalcones studied here represent a sustainable alternative to copper for the control of ACC, and further studies are ongoing to elucidate their precise modes of action. Full article
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16 pages, 10178 KiB  
Article
Transformed Shoots of Dracocephalum forrestii W.W. Smith from Different Bioreactor Systems as a Rich Source of Natural Phenolic Compounds
by Izabela Weremczuk-Jeżyna, Paweł Lisiecki, Weronika Gonciarz, Łukasz Kuźma, Magdalena Szemraj, Magdalena Chmiela and Izabela Grzegorczyk-Karolak
Molecules 2020, 25(19), 4533; https://doi.org/10.3390/molecules25194533 - 03 Oct 2020
Cited by 12 | Viewed by 2905
Abstract
Transformed shoots of the Tibetan medicinal plant Dracocephalum forrestii were cultured in temporary immersion bioreactors (RITA and Plantform) and in nutrient sprinkle bioreactor (NSB) for 3 weeks in MS (Murashige and Skoog) liquid medium with 0.5 mg/L BPA (N-benzyl-9-(2-tetrahydropyranyl)-adenine) and 0.2 [...] Read more.
Transformed shoots of the Tibetan medicinal plant Dracocephalum forrestii were cultured in temporary immersion bioreactors (RITA and Plantform) and in nutrient sprinkle bioreactor (NSB) for 3 weeks in MS (Murashige and Skoog) liquid medium with 0.5 mg/L BPA (N-benzyl-9-(2-tetrahydropyranyl)-adenine) and 0.2 mg/L IAA (indole-3-acetic acid). The greatest biomass growth index (GI = 52.06 fresh weight (FW) and 55.67 dry weight (DW)) was observed for shoots in the RITA bioreactor, while the highest multiplication rate was found in the NSB (838 shoots per bioreactor). The levels of three phenolic acids and five flavonoid derivatives in the shoot hydromethanolic extract were evaluated using UHPLC (ultra-high performance liquid chromatography). The predominant metabolite was rosmarinic acid (RA)—the highest RA level (18.35 mg/g DW) and total evaluated phenol content (24.15 mg/g DW) were observed in shoots grown in NSB. The NSB culture, i.e., the most productive one, was evaluated for its antioxidant activity on the basis of reduction of ferric ions (ferric reducing antioxidant power, FRAP) and two scavenging radical (O2 and DPPH, 1,1-diphenyl-2-picrylhydrazyl radical) assays; its antibacterial, antifungal, and antiproliative potential against L929 cells was also tested (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) test). The plant material revealed moderate antioxidant and antimicrobial activities and demonstrated high safety in the MTT test—no cytotoxicity at concentrations up to 50 mg/mL was found, and less than a 20% decrease in L929 cell viability was observed at this concentration. Full article
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16 pages, 3071 KiB  
Article
Isoliquiritigenin Pretreatment Induces Endoplasmic Reticulum Stress-Mediated Hormesis and Attenuates Cisplatin-Induced Oxidative Stress and Damage in LLC-PK1 Cells
by Tania Gómez-Sierra, Omar Noel Medina-Campos, José D. Solano, María Elena Ibarra-Rubio and José Pedraza-Chaverri
Molecules 2020, 25(19), 4442; https://doi.org/10.3390/molecules25194442 - 27 Sep 2020
Cited by 19 | Viewed by 2828
Abstract
Isoliquiritigenin (IsoLQ) is a flavonoid with antioxidant properties and inducer of endoplasmic reticulum (ER) stress. In vitro and in vivo studies show that ER stress-mediated hormesis is cytoprotective; therefore, natural antioxidants and ER stress inducers have been used to prevent renal injury. Oxidative [...] Read more.
Isoliquiritigenin (IsoLQ) is a flavonoid with antioxidant properties and inducer of endoplasmic reticulum (ER) stress. In vitro and in vivo studies show that ER stress-mediated hormesis is cytoprotective; therefore, natural antioxidants and ER stress inducers have been used to prevent renal injury. Oxidative stress and ER stress are some of the mechanisms of damage involved in cisplatin (CP)-induced nephrotoxicity. This study aims to explore whether IsoLQ pretreatment induces ER stress and produces hormesis to protect against CP-induced nephrotoxicity in Lilly Laboratories Cell-Porcine Kidney 1 (LLC-PK1) cells. During the first stage of this study, both IsoLQ protective concentration and pretreatment time against CP-induced toxicity were determined by cell viability. At the second stage, the effect of IsoLQ pretreatment on cell viability, ER stress, and oxidative stress were evaluated. IsoLQ pretreatment in CP-treated cells induces expression of glucose-related proteins 78 and 94 kDa (GRP78 and GRP94, respectively), attenuates CP-induced cell death, decreases reactive oxygen species (ROS) production, and prevents the decrease in glutathione/glutathione disulfide (GSH/GSSG) ratio, free thiols levels, and glutathione reductase (GR) activity. These data suggest that IsoLQ pretreatment has a moderately protective effect on CP-induced toxicity in LLC-PK1 cells, through ER stress-mediated hormesis, as well as by the antioxidant properties of IsoLQ. Full article
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13 pages, 1583 KiB  
Article
Comparison of Bioactive Phenolic Compounds and Antioxidant Activities of Different Parts of Taraxacum mongolicum
by Li Duan, Chenmeng Zhang, Yang Zhao, Yanzhong Chang and Long Guo
Molecules 2020, 25(14), 3260; https://doi.org/10.3390/molecules25143260 - 17 Jul 2020
Cited by 31 | Viewed by 3231
Abstract
Herbs derived from Taraxacum genus have been used as traditional medicines and food supplements in China for hundreds of years. Taraxacum mongolicum is a famous traditional Chinese medicine derived from Taraxacum genus for the treatment of inflammatory disorders and viral infectious diseases. In [...] Read more.
Herbs derived from Taraxacum genus have been used as traditional medicines and food supplements in China for hundreds of years. Taraxacum mongolicum is a famous traditional Chinese medicine derived from Taraxacum genus for the treatment of inflammatory disorders and viral infectious diseases. In the present study, the bioactive phenolic chemical profiles and antioxidant activities of flowers, leaves, and roots of Taraxacum mongolicum were investigated. Firstly, a high performance liquid chromatography method combined with segmental monitoring strategy was employed to simultaneously determine six bioactive phenolic compounds in Taraxacum mongolicum samples. Moreover, multivariate statistical analysis, including hierarchical clustering analysis, principal component analysis, and partial least squares discriminant analysis were performed to compare and discriminate different parts of Taraxacum mongolicum based on the quantitative data. The results showed that three phenolic compounds, caftaric acid, caffeic acid, and luteolin, could be regarded as chemical markers for the differences of flowers, leaves, and roots of Taraxacum mongolicum. In parallel, total phenolic contents, total flavonoid contents and antioxidant activities of different parts of Taraxacum mongolicum were also evaluated and compared. It is clear that Taraxacum mongolicum had antioxidant properties, and the antioxidant capacities of different parts of Taraxacum mongolicum in three antioxidant assays showed a similar tendency: Flowers ≈ leaves > roots, which revealed a positive relationship with their total phenolic and flavonoid contents. Furthermore, to find the potential antioxidant components of Taraxacum mongolicum, the latent relationships of the six bioactive phenolic compounds and antioxidant activities of Taraxacum mongolicum were investigated by Pearson correlation analysis. The results indicated caftaric acid and caffeic acid could be the potential antioxidant ingredients of Taraxacum mongolicum. The present work may facilitate better understanding of differences of bioactive phenolic constituents and antioxidant activities of different parts of Taraxacum mongolicum and provide useful information for utilization of this herbal medicine. Full article
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12 pages, 1556 KiB  
Article
Synthesis, Redox Properties and Antibacterial Activity of Hindered Phenols Linked to Heterocycles
by Vladimir N. Koshelev, Olga V. Primerova, Stepan V. Vorobyev and Ludmila V. Ivanova
Molecules 2020, 25(10), 2370; https://doi.org/10.3390/molecules25102370 - 20 May 2020
Cited by 10 | Viewed by 3176
Abstract
A series of benzotriazole, cyclic amides and pyrimidine derivatives, containing 2,6-di-tert-butyl-phenol fragments, were synthesized. The redox properties of obtained compounds were studied using the cyclic voltammetry on a platinum electrode in acetonitrile. The oxidation potentials of all substances were comparable to [...] Read more.
A series of benzotriazole, cyclic amides and pyrimidine derivatives, containing 2,6-di-tert-butyl-phenol fragments, were synthesized. The redox properties of obtained compounds were studied using the cyclic voltammetry on a platinum electrode in acetonitrile. The oxidation potentials of all substances were comparable to those of BHT. The obtained compounds were tested for their antibacterial activity, and N-(2-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-oxoethyl)isatin (32 μg/mL) exerted good activity against Staphylococcus aureus. Full article
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22 pages, 3554 KiB  
Article
Analysis of Antioxidant Activity and Flavonoids Metabolites in Peel and Flesh of Red-Fleshed Apple Varieties
by Xiang Zhang, Jihua Xu, Zhaobo Xu, Xiaohong Sun, Jun Zhu and Yugang Zhang
Molecules 2020, 25(8), 1968; https://doi.org/10.3390/molecules25081968 - 23 Apr 2020
Cited by 20 | Viewed by 3330
Abstract
In this research, we compared the phenotypical characters, total anthocyanins content, total phenols content, and antioxidant activity of red-fleshed apple cultivars ‘XJ4’, ‘QN-5’, ‘DH’ and ‘HX1’ at three fruit developmental stages. A further flavonoids metabolites study was conducted in ‘XJ4’ and ‘DH’. We [...] Read more.
In this research, we compared the phenotypical characters, total anthocyanins content, total phenols content, and antioxidant activity of red-fleshed apple cultivars ‘XJ4’, ‘QN-5’, ‘DH’ and ‘HX1’ at three fruit developmental stages. A further flavonoids metabolites study was conducted in ‘XJ4’ and ‘DH’. We found broader variation of total anthocyanins content in the peel of the four cultivars, which might result in larger differences of free radicals scavenging rate. The most significant difference in fruit phenotype, anthocyanins content, and DPPH scavenging rate was observed between ‘XJ4’ and ‘DH’ at mature stage. Therefore, the flavonoids metabolites of ‘XJ4’ and ‘DH’ at mature stage were compared to unveil the details of anthocyanins compounds. The unique compounds pelargonidin 3-O-β-d-glucoside and cyanidin-3-O-malonylhexoside were detected only in peel and flesh of ‘XJ4’ but not in ‘DH’, which might contribute to the purple peel and dark-red flesh color of ‘XJ4’. Significantly decreased upstream metabolites in the early biosynthetic genes regulated domain were found only in ‘XJ4’ peel but not in the flesh. This might explain why the anthocyanins content in ‘XJ4’ peel was decreased largely at the mature stage. Taken together, our findings will give some insight into the metabolites study in flavonoid biosynthetic pathway of red-fleshed apple. Full article
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17 pages, 5374 KiB  
Article
Analysis of Binding Interactions of Ramipril and Quercetin on Human Serum Albumin: A Novel Method in Affinity Evaluation
by Zuzana Vaneková, Lukáš Hubčík, José Luis Toca-Herrera, Paul Georg Furtműller, Pavel Mučaji and Milan Nagy
Molecules 2020, 25(3), 547; https://doi.org/10.3390/molecules25030547 - 27 Jan 2020
Cited by 12 | Viewed by 3751
Abstract
The aim of this study was to analyze the binding interactions between a common antihypertensive drug (ramipril, R) and the widely distributed plant flavonoid quercetin (Q), in the presence of human serum albumin (HSA). From the observed fluorescence spectra of the (HSA + [...] Read more.
The aim of this study was to analyze the binding interactions between a common antihypertensive drug (ramipril, R) and the widely distributed plant flavonoid quercetin (Q), in the presence of human serum albumin (HSA). From the observed fluorescence spectra of the (HSA + R) system we can assume that ramipril is also one of the Site 3 ligands—similar to fusidic acid—the binding of which has been proven by RTG crystallography. Our claim is supported by near-UV CD spectroscopy, microscale themophoresis and molecular modeling. The presence of R slightly inhibited the subsequent binding of Q to HSA and, on the contrary, the pre-incubation of HSA with Q caused a stronger binding of R, most likely due to allosteric interactions. At high concentrations, R is also able to displace Q from its binding site. The dissociation constant KD for the binding of R is more than hundredfold larger than for Q, which means that R is a very weak binder to HSA. The knowledge of qualitative and quantitative parameters of R, as well as the methods used in this study, are important for future research into HSA binding. This study shows the importance of implementing other methods for KD determination. Microscale thermophoresis has proved to be a novel, practical and accurate method for KD determination on HSA, especially in cases when fluorescence spectroscopy is unable to produce usable results. Full article
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13 pages, 1257 KiB  
Article
Development and Validation of Methods for the Determination of Anthocyanins in Physiological Fluids via UHPLC-MSn
by Michael Kaiser, Lisa Müller-Ehl, Maike Passon and Andreas Schieber
Molecules 2020, 25(3), 518; https://doi.org/10.3390/molecules25030518 - 24 Jan 2020
Cited by 6 | Viewed by 2970
Abstract
Recent in vitro and in vivo studies on anthocyanins confirmed numerous health-promoting effects in humans. Daily anthocyanin intake can be estimated via food databases, but the amount absorbed by the organism still remains uncertain because anthocyanin bioavailability is yet to be elucidated in [...] Read more.
Recent in vitro and in vivo studies on anthocyanins confirmed numerous health-promoting effects in humans. Daily anthocyanin intake can be estimated via food databases, but the amount absorbed by the organism still remains uncertain because anthocyanin bioavailability is yet to be elucidated in its entirety. For this purpose, suitable and validated methods of sample preparation and analysis are required. Therefore, a sample preparation method for anthocyanin metabolite analysis in plasma was successfully established and validated. The validation yielded acceptable results for the anthocyanins in terms of recovery (54–108%) and precision (coefficient of variation (CV) < 15%). The UHPLC-MS method used in the consecutive reaction monitoring (CRM) mode was sufficiently sensitive, resulting in limits of detection <2.3 ng/mL and limits of quantification < 8.1 ng/mL with associated repeatability of the MS system with CVs of <5.1%. In addition, a method for the sum parameter determination of anthocyanidins in urine comprising solely the evaporation of acidified samples was developed, validated, and successfully applied to real samples. The results showed that this method is applicable for the methylated anthocyanidins, but not for the hydroxylated anthocyanidins, due to the chosen CRM modes required for optimum selectivity. Full article
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14 pages, 1635 KiB  
Article
Polyphenols, Antioxidant, Antibacterial, and Biofilm Inhibitory Activities of Peel and Pulp of Citrus medica L., Citrus bergamia, and Citrus medica cv. Salò Cultivated in Southern Italy
by Florinda Fratianni, Autilia Cozzolino, Vincenzo De Feo, Raffaele Coppola, Maria Neve Ombra and Filomena Nazzaro
Molecules 2019, 24(24), 4577; https://doi.org/10.3390/molecules24244577 - 13 Dec 2019
Cited by 40 | Viewed by 4808
Abstract
The aim of this paper was to study the polyphenols of peel and pulp of three Citrus taxa—Citrus medica, Citrus bergamia, and Citrus medica cv. Salò—cultivated in the Cosenza province, Southern Italy, and to evaluate their antioxidant and antibacterial activity, performed [...] Read more.
The aim of this paper was to study the polyphenols of peel and pulp of three Citrus taxa—Citrus medica, Citrus bergamia, and Citrus medica cv. Salò—cultivated in the Cosenza province, Southern Italy, and to evaluate their antioxidant and antibacterial activity, performed against Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus, and Pectobacterium carotovorum. Furthermore, we assessed the inhibitory effect of the extracts on bacterial capacity to form biofilm, and on the metabolic activity of the cells present therein. The results indicated that such extracts could find new potential applications in the field of natural antioxidant and anti-bacterial agents in pharmaceutics, agriculture, and food fields. Full article
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Review

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36 pages, 3761 KiB  
Review
Nanoformulations to Enhance the Bioavailability and Physiological Functions of Polyphenols
by Bingyan Yang, Yixin Dong, Fei Wang and Yu Zhang
Molecules 2020, 25(20), 4613; https://doi.org/10.3390/molecules25204613 - 10 Oct 2020
Cited by 94 | Viewed by 6545
Abstract
Polyphenols are micronutrients that are widely present in human daily diets. Numerous studies have demonstrated their potential as antioxidants and anti-inflammatory agents, and for cancer prevention, heart protection and the treatment of neurodegenerative diseases. However, due to their vulnerability to environmental conditions and [...] Read more.
Polyphenols are micronutrients that are widely present in human daily diets. Numerous studies have demonstrated their potential as antioxidants and anti-inflammatory agents, and for cancer prevention, heart protection and the treatment of neurodegenerative diseases. However, due to their vulnerability to environmental conditions and low bioavailability, their application in the food and medical fields is greatly limited. Nanoformulations, as excellent drug delivery systems, can overcome these limitations and maximize the pharmacological effects of polyphenols. In this review, we summarize the biological activities of polyphenols, together with systems for their delivery, including phospholipid complexes, lipid-based nanoparticles, protein-based nanoparticles, niosomes, polymers, micelles, emulsions and metal nanoparticles. The application of polyphenol nanoparticles in food and medicine is also discussed. Although loading into nanoparticles solves the main limitation to application of polyphenolic compounds, there are some concerns about their toxicological safety after entry into the human body. It is therefore necessary to conduct toxicity studies and residue analysis on the carrier. Full article
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10 pages, 2284 KiB  
Review
Volatile Phenols—Important Contributors to the Aroma of Plant-Derived Foods
by Andreas Schieber and Matthias Wüst
Molecules 2020, 25(19), 4529; https://doi.org/10.3390/molecules25194529 - 02 Oct 2020
Cited by 22 | Viewed by 3515
Abstract
Volatile phenols like phenylpropanoid and benzoid compounds originate from the aromatic amino acid phenylalanine, which is biosynthesized via the shikimate/arogenate pathway. These volatile compounds contribute to the aroma of a number of economically important plant-derived foods like herbs, spices and fruits. The sequestration [...] Read more.
Volatile phenols like phenylpropanoid and benzoid compounds originate from the aromatic amino acid phenylalanine, which is biosynthesized via the shikimate/arogenate pathway. These volatile compounds contribute to the aroma of a number of economically important plant-derived foods like herbs, spices and fruits. The sequestration of numerous phenylpropanoid and benzoid compounds as glycosides occurs widely in fruits, and this pool represents an important source of flavor that can be released during storage and processing. Therefore, this review will provide an overview of the biosynthesis of free and glycosylated phenylpropanoid and benzoid compounds and their reactions during food processing, which both lead to the generation of odor-active volatile phenols in plant-derived foods. Full article
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23 pages, 786 KiB  
Review
Antifungal Activity of Phenolic and Polyphenolic Compounds from Different Matrices of Vitis vinifera L. against Human Pathogens
by Giovanna Simonetti, Elisa Brasili and Gabriella Pasqua
Molecules 2020, 25(16), 3748; https://doi.org/10.3390/molecules25163748 - 17 Aug 2020
Cited by 51 | Viewed by 6835
Abstract
Phenolic compounds, the most widely distributed class of natural products in the plants, show several biological properties including antifungal activity. Phenolics contained in grapes can be classified in two main groups, flavonoids and non-flavonoids compounds. Variability and yield extraction of phenolic and polyphenolic [...] Read more.
Phenolic compounds, the most widely distributed class of natural products in the plants, show several biological properties including antifungal activity. Phenolics contained in grapes can be classified in two main groups, flavonoids and non-flavonoids compounds. Variability and yield extraction of phenolic and polyphenolic compounds from different matrices of Vitis vinifera depends of cultivar, climate, soil condition and process technology. Unripe grapes, berry skins and seeds, leaves, canes and stems and not-fermented and fermented pomaces represent large reusable and valuable wastes from agricultural and agro-industrial processes. This review summarizes studies that examine the extraction method, chemical characterization, and antifungal activity of phenolic and polyphenolic compounds from edible and non-edible V. vinifera matrices against human fungal pathogens. In the world, around one billion people have fungal diseases related to skin, nail or hair and around 150 million have systemic diseases caused by fungi. Few studies on antifungal activity of plant extracts have been performed. This review provides useful information for the application of V. vinifera phenolics in the field of antifungals for human use. Full article
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22 pages, 1416 KiB  
Review
Flavonoids and Mitochondria: Activation of Cytoprotective Pathways?
by Anna Kicinska and Wieslawa Jarmuszkiewicz
Molecules 2020, 25(13), 3060; https://doi.org/10.3390/molecules25133060 - 04 Jul 2020
Cited by 64 | Viewed by 5450
Abstract
A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and [...] Read more.
A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and biosynthesis these organelles are triggers and/or end-effectors of a large number of signaling pathways. Their role in the regulation of the intrinsic apoptotic pathway, calcium homeostasis, and reactive oxygen species signaling is well documented. In this review, we aim to characterize the prospects of influencing cytoprotective mitochondrial signaling routes by natural substances of plant origin, namely, flavonoids (e.g., flavanones, flavones, flavonols, flavan-3-ols, anthocyanidins, and isoflavones). Flavonoids are a family of widely distributed plant secondary metabolites known for their beneficial effects on human health and are widely applied in traditional medicine. Their pharmacological characteristics include antioxidative, anticarcinogenic, anti-inflammatory, antibacterial, and antidiabetic properties. Here, we focus on presenting mitochondria-mediated cytoprotection against various insults. Thus, the role of flavonoids as antioxidants and modulators of antioxidant cellular response, apoptosis, mitochondrial biogenesis, autophagy, and fission and fusion is reported. Finally, an emerging field of flavonoid-mediated changes in the activity of mitochondrial ion channels and their role in cytoprotection is outlined. Full article
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33 pages, 3387 KiB  
Review
Combretastatins: An Overview of Structure, Probable Mechanisms of Action and Potential Applications
by Gökçe Şeker Karatoprak, Esra Küpeli Akkol, Yasin Genç, Hilal Bardakcı, Çiğdem Yücel and Eduardo Sobarzo-Sánchez
Molecules 2020, 25(11), 2560; https://doi.org/10.3390/molecules25112560 - 31 May 2020
Cited by 65 | Viewed by 5782
Abstract
Combretastatins are a class of closely related stilbenes (combretastatins A), dihydrostilbenes (combretastatins B), phenanthrenes (combretastatins C) and macrocyclic lactones (combretastatins D) found in the bark of Combretum caffrum (Eckl. & Zeyh.) Kuntze, commonly known as the South African bush willow. Some of the [...] Read more.
Combretastatins are a class of closely related stilbenes (combretastatins A), dihydrostilbenes (combretastatins B), phenanthrenes (combretastatins C) and macrocyclic lactones (combretastatins D) found in the bark of Combretum caffrum (Eckl. & Zeyh.) Kuntze, commonly known as the South African bush willow. Some of the compounds in this series have been shown to be among the most potent antitubulin agents known. Due to their structural simplicity many analogs have also been synthesized. Combretastatin A4 phosphate is the most frequently tested compounds in preclinical and clinical trials. It is a water-soluble prodrug that the body can rapidly metabolize to combretastatin A4, which exhibits anti-tumor properties. In addition, in vitro and in vivo studies on combretastatins have determined that these compounds also have antioxidant, anti-inflammatory and antimicrobial effects. Nano-based formulations of natural or synthetic active agents such as combretastatin A4 phosphate exhibit several clear advantages, including improved low water solubility, prolonged circulation, drug targeting properties, enhanced efficiency, as well as fewer side effects. In this review, a synopsis of the recent literature exploring the combretastatins, their potential effects and nanoformulations as lead compounds in clinical applications is provided. Full article
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24 pages, 2680 KiB  
Review
Advanced Research on the Antioxidant Activity and Mechanism of Polyphenols from Hippophae Species—A Review
by Mingyue Ji, Xue Gong, Xue Li, Congcong Wang and Minhui Li
Molecules 2020, 25(4), 917; https://doi.org/10.3390/molecules25040917 - 19 Feb 2020
Cited by 79 | Viewed by 6163
Abstract
Oxidation is a normal consequence of metabolism in biological organisms. The result is the formation of detrimental reactive oxygen species (ROS) and reactive nitrogen species (RNS). A large number of studies have shown that polyphenolic compounds have good antioxidant properties. Hippophae species plants [...] Read more.
Oxidation is a normal consequence of metabolism in biological organisms. The result is the formation of detrimental reactive oxygen species (ROS) and reactive nitrogen species (RNS). A large number of studies have shown that polyphenolic compounds have good antioxidant properties. Hippophae species plants have high polyphenolic content and are widely used in food, medicinal, or the cosmetic field. The main polyphenols in Hippophae species are flavonoids, phenolic acids and tannins, which have multiple effects. However, there is a limited number of studies on polyphenols in Hippophae species plants. This review systematically summarizes the polyphenols compounds and antioxidant activity of Hippophae species plants, and it is noteworthy that the main mechanisms of the polyphenols of Hippophae with antioxidant activity have been summarized as follows: regulating enzyme activity, affect the antioxidant reaction of cells, and others. This review provides useful information for the further study and application of Hippophae species polyphenols and their antioxidant activity. Full article
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