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Special Issue "The Antioxidant Capacities of Natural Products"

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

Deadline for manuscript submissions: closed (30 June 2018)

Special Issue Editor

Guest Editor
Dr. Susana M. Cardoso

QOPNA &Department of Chemistry, Universidade de Aveiro, 3810-193 Aveiro, Portugal
Website | E-Mail
Interests: phenolic compounds; structural analysis; antioxidant activity; food chemistry; food analysis; nutritional value; functional foods

Special Issue Information

Dear Colleagues,

Antioxidant abilities are one of the main pursued bioactive mechanisms, due to their role in the prevention of oxidative-stress events and their related diseases, such as inflammation, cardiovascular diseases, aging related disorders, cancer, among others. This perception, along with general consumers’ acceptance of natural products, make antioxidants from natural origin very attractive to be used as health-promoting agents in a variety of products, including functional foods, supplements, cosmetics and pharmaceuticals.

Contributions for this Special Issue, both in form of original research and review articles, may cover all aspects of antioxidants from natural products, including their extraction by conventional and non-conventional methods; purification and structural characterization of new compounds; in vitro and in vivo biological activities of extracts, isolated compounds or new formulated products; structure-bioactive relations; interaction with other substances in the formulated matrices; bioavailability and innovative delivery systems for antioxidants; safety and stability of new formulated products.

Dr. Susana M. Cardoso
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • natural products
  • antioxidants
  • bioactive effects
  • structure-bioactivity relations
  • new functional products
  • bioavailability
  • delivery systems
  • safety

Published Papers (29 papers)

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Research

Open AccessFeature PaperArticle Long-Term Effect on Bioactive Components and Antioxidant Activity of Thermal and High-Pressure Pasteurization of Orange Juice
Molecules 2018, 23(10), 2706; https://doi.org/10.3390/molecules23102706
Received: 1 October 2018 / Revised: 18 October 2018 / Accepted: 18 October 2018 / Published: 20 October 2018
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Abstract
The long-term effect of thermal pasteurization (TP) and high-pressure processing (HPP) of orange juices stored under refrigeration, on the bioactive components and antioxidant activity, was compared. Total phenolic content (TPC), flavonoid, anthocyanin, and carotenoid contents, the individual content of major phenolic components, and
[...] Read more.
The long-term effect of thermal pasteurization (TP) and high-pressure processing (HPP) of orange juices stored under refrigeration, on the bioactive components and antioxidant activity, was compared. Total phenolic content (TPC), flavonoid, anthocyanin, and carotenoid contents, the individual content of major phenolic components, and the antioxidant activity, were evaluated in TP- and HPP-treated juices over a 36-day period. At day 0, no significant differences in TPC, and a decrease in carotenoid content after both treatments, were observed. TP caused a decrease of flavonoid and anthocyanin contents, while HPP increased flavonoid content. Three major phenolic components were identified: apigenin-6,8-di-C-glucoside, naringenin-7-O-rutinoside, and hesperetin-7-O-rutinoside, the latter increasing ca. 45% immediately after HPP. During storage, a decrease in TPC, and in the anthocyanin and carotenoid contents of both treated juices was observed, with higher anthocyanin and phenolic contents in HPP juices. A significant increase of hesperetin-7-O-rutinoside content was observed in HPP juice. Both treatments caused a decrease (26% and 13%, respectively) of antioxidant activity. Most of the kinetic profiles followed zero-order patterns, with HPP juices showing a considerably higher half-life than TP ones. These results clearly demonstrate the advantages of HPP for orange juice preservation allowing, also, their nutritional benefits to be enhanced by increasing the content of some bioactive components. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Antioxidant Properties of the Vam3 Derivative of Resveratrol
Molecules 2018, 23(10), 2446; https://doi.org/10.3390/molecules23102446
Received: 16 July 2018 / Revised: 10 September 2018 / Accepted: 20 September 2018 / Published: 25 September 2018
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Abstract
A considerable number of studies has shown that many constituents of foods derived from plants are effective and safe antioxidants. This explains the growing interest in natural antioxidants in food applications. The goal of this investigation was to evaluate the antioxidant properties of
[...] Read more.
A considerable number of studies has shown that many constituents of foods derived from plants are effective and safe antioxidants. This explains the growing interest in natural antioxidants in food applications. The goal of this investigation was to evaluate the antioxidant properties of the Vam3, a resveratrol derivative, firstly isolated from ethanol extracts of Vitis amurensis Rupr as a secondary product, and to carry out a comparison with resveratrol and other phenolic compounds which are currently in the limelight all over the world due to their beneficial effects on the human body. The potential of Vam3 as an antioxidant was determined through the evaluation of some key thermodynamic parameters which are commonly used for this purpose and describe the antioxidant activity quite well. Various mechanisms through which antioxidants usually can carry out their action were also explored both in water and in apolar environment. The results indicated that Vam3 is an excellent candidate as a natural antioxidant. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Effects of Germination on Protein, γ-Aminobutyric Acid, Phenolic Acids, and Antioxidant Capacity in Wheat
Molecules 2018, 23(9), 2244; https://doi.org/10.3390/molecules23092244
Received: 4 July 2018 / Revised: 28 August 2018 / Accepted: 31 August 2018 / Published: 3 September 2018
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Abstract
Germinated wheat is a food material with potential health benefits due to its high phenolic and antioxidant content, but the reason why germination increases this content is unclear. The aim of this study was to investigate the relationships between protein changes (determined by
[...] Read more.
Germinated wheat is a food material with potential health benefits due to its high phenolic and antioxidant content, but the reason why germination increases this content is unclear. The aim of this study was to investigate the relationships between protein changes (determined by two-dimensional gel electrophoresis (2-DE)), phenolics, γ-aminobutyric acid (GABA) levels, and antioxidant capacity of wheat germinated for various periods (24, 48, 72, and 96 h) compared to control. Each phenolic acid tended to increase with increasing germination time. The GABA content was highest (39.98 mg/100 g dwb) after 96 h of germination. The total oxygen radical absorbance capacity (ORAC) was 1.97 times higher after 96 h than in ungerminated seeds. Fifteen proteins, among 82 proteins separated by 2-DE, were highly related with ORAC and were identified by peptide mass fingerprinting (PMS). The PMS revealed strong expression of granule bound starch synthase (GBSS) and glutathione S-transferase (GSTF) after 96 h of germination. Overall, the ORAC at 96 h exhibited a close relationship with the levels of phenolic acids, GABA, and proteins such as GBSS and GSTF. In conclusion, these findings add to the existing knowledge of wheat protein changes and their relationship to the antioxidant properties of germinating wheat seeds. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessFeature PaperArticle Plant Growth Modulates Metabolites and Biological Activities in Retama raetam (Forssk.) Webb
Molecules 2018, 23(9), 2177; https://doi.org/10.3390/molecules23092177
Received: 20 July 2018 / Revised: 16 August 2018 / Accepted: 24 August 2018 / Published: 29 August 2018
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Abstract
This work focuses on the variability of Retama raetam (Forssk.) Webb bioactive compounds as a function of the plant cycle. The main results showed that it exhibited the highest percentage of polyunsaturated fatty acids, along with superior levels of vitamin C and total
[...] Read more.
This work focuses on the variability of Retama raetam (Forssk.) Webb bioactive compounds as a function of the plant cycle. The main results showed that it exhibited the highest percentage of polyunsaturated fatty acids, along with superior levels of vitamin C and total phenolic compounds (66.49%, 645.6 mg·100 g1 FW and 23.9 mg GAE·g1, respectively) at the vegetative stage. Instead, at the flowering and mature fruiting stages, R. raetam (Forssk.) Webb exhibited notable contents of proline (25.4 μmol·g1 DW) and carotenoids (27.2 μg·g1 FW), respectively. The gathered data concerning the antioxidant activity highlighted the effectiveness of the vegetative stage in comparison to the other periods. Actually, IC50 and EC50 values of the hydromethanolic extract obtained from the plant shoots at the vegetative stage were of 23, 380, 410, 1160 and 960 μg·mL−1 (DPPH and ABTS•+ radicals scavenging activity, reducing power, chelating power and β-carotene bleaching activity, respectively). Furthermore, the four studied stages showed appreciable antibacterial capacities against human pathogens with a higher efficiency of the vegetative stage extract. Finally, the LC-DAD-ESI/MSn analysis revealed the predominance of isoflavonoids as main class of phenolic compounds and demonstrates that individual phenolic biosynthesis was clearly different as a function of plant growth. These findings highlight that reaching the optimum efficiency of R. raetam (Forssk.) Webb is closely linked to the physiological stage. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Aqueous-Methanol Extracts of Orange-Fleshed Sweet Potato (Ipomoea batatas) Ameliorate Oxidative Stress and Modulate Type 2 Diabetes Associated Genes in Insulin Resistant C2C12 Cells
Molecules 2018, 23(8), 2058; https://doi.org/10.3390/molecules23082058
Received: 17 June 2018 / Revised: 6 August 2018 / Accepted: 8 August 2018 / Published: 17 August 2018
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Abstract
Edible plants such as sweet potato are sources of natural antioxidants that can be exploited in the management and treatment of insulin resistance. This present study investigated the effects of the extracts of an orange-fleshed sweet potato on oxidative stress biomarkers (glutathione status
[...] Read more.
Edible plants such as sweet potato are sources of natural antioxidants that can be exploited in the management and treatment of insulin resistance. This present study investigated the effects of the extracts of an orange-fleshed sweet potato on oxidative stress biomarkers (glutathione status and lipid peroxidation) and activities of antioxidant enzymes (catalase, CAT and glutathione peroxidase, GPx) in palmitate-induced insulin resistant C2C12 cells. The intracellular antioxidant status of the cells was also measured using Ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays. Furthermore, this study determined the effect of the extracts on the regulation of some type 2 diabetes associated genes; glucose transporter 4 (glut4), Nuclear respiratory factor 1 (nrf1), Myocyte enhanced factor 2A (mef2a), Carnitine palmitoyltransferase 1 (cpt1) and Acetyl-CoA carboxylase 2 (acc2). The results showed a significant (p < 0.05) increase in intracellular GSH level, a significant reduction in the level of malonaldehyde and a significant improvement in the intracellular antioxidant status upon treatment of the insulin resistant cells with the extracts. The extracts were also able to positively modulate the expression levels of the type 2 diabetes associated genes. On the other hand, HPLC-MS analysis of the extracts showed the presence of polyphenols which could have contributed to the bioactivity of the extracts through their antioxidant effects. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Characteristics of Biologically Active Compounds in Cornelian Cherry Meads
Molecules 2018, 23(8), 2024; https://doi.org/10.3390/molecules23082024
Received: 17 July 2018 / Revised: 7 August 2018 / Accepted: 12 August 2018 / Published: 14 August 2018
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Abstract
In this study, we investigated the effect of Cornelian cherry cultivars differing in fruit color (“Yantaryi”—yellow fruits, “Koralovyi”—coral fruits, “Podolski”—red fruits) on physicochemical characteristics, antioxidative properties, and contents of iridoids and polyphenols in meads with the addition of juices made of their fruits.
[...] Read more.
In this study, we investigated the effect of Cornelian cherry cultivars differing in fruit color (“Yantaryi”—yellow fruits, “Koralovyi”—coral fruits, “Podolski”—red fruits) on physicochemical characteristics, antioxidative properties, and contents of iridoids and polyphenols in meads with the addition of juices made of their fruits. “Trójniak” type meads (1:2 honey to water volume) were manufactured from multifloral honey, to which Cornelian cherry fruit juice was added before fermentation. Concentrations of individual iridoids and polyphenols were determined using HPLC analysis with a thermostat refractometric detector, model RID-10A. The total polyphenol content was determined based on testing with Folin–Ciocalteu (F-C) reagent, whereas the antioxidative properties were determined using DPPH (2,2-Diphenyl-2-picryl-hydrazyl), ABTS•⁺ (2,2′-Azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid), and FRAP (ferric reducing antioxidant power) assays. Cultivar of Cornelian cherry fruits influenced both the antioxidative properties and the concentrations of polyphenols and iridoids. The highest concentration of total polyphenols (F-C), accounting for 898.7 mg gallic acid (GAE)/L, was determined in the mead with juice made of red fruits; this mead was also characterized by the strongest antioxidative capabilities measured with ABTS•⁺ and FRAP assays. Among the iridoids determined in the Cornelian cherry meads, loganic acid was found to prevail and its highest concentration, reaching 77.8 mg loganic acid (LA)/L mead, was determined in the mead with the coral-fruit juice. Study results indicate that Cornelian cherry meads have a high content of biologically active iridoids and phenolic acids which display valuable antioxidative properties. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
Open AccessArticle Antioxidant Potential of Hemp and Flax Fibers Depending on Their Chemical Composition
Molecules 2018, 23(8), 1993; https://doi.org/10.3390/molecules23081993
Received: 9 July 2018 / Revised: 3 August 2018 / Accepted: 5 August 2018 / Published: 10 August 2018
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Abstract
Flax and hemp fibers are known as textile raw materials with pro-health properties. This paper presents results of research aimed at investigating the antioxidant activity of the fibers in order to explain a mechanism for the favorable influence of textiles made of these
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Flax and hemp fibers are known as textile raw materials with pro-health properties. This paper presents results of research aimed at investigating the antioxidant activity of the fibers in order to explain a mechanism for the favorable influence of textiles made of these fibers when in contact with human skin. The study presents a new approach in evaluation of textile fibers in terms of their inherent pro-health properties. Antioxidant properties of flax and hemp fibers were tested with the use of FRAP and DPPH methods. The content of phenolic acids: syringic, sinapinic, p-coumaric and ferulic acid was determined with the use of HPLC. The results proved that the antioxidant activity of the tested fibers depends on a type and variety of fibrous plants, a method of fiber extraction and subsequent stages of preliminary processing of the fibers. Both decorticated flax and hemp fibers showed higher antioxidant activity in comparison to the fibers obtained with other extraction methods, while decorticated flax of different varieties presented the highest value of the FRAP. Wet methods of fiber extraction and processing caused reduction of phenolic acids content and significantly lower values of the FRAP and DPPH. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle E-Configuration Improves Antioxidant and Cytoprotective Capacities of Resveratrols
Molecules 2018, 23(7), 1790; https://doi.org/10.3390/molecules23071790
Received: 27 June 2018 / Revised: 16 July 2018 / Accepted: 18 July 2018 / Published: 20 July 2018
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Abstract
The antioxidant and cytoprotective capacities of E-resveratrol and Z-resveratrol were compared using chemical and cellular assays. Chemical assays revealed that the two isomers were dose-dependently active in •O2-scavenging, ferric reducing antioxidant power (FRAP), Cu2+-reducing antioxidant capacity
[...] Read more.
The antioxidant and cytoprotective capacities of E-resveratrol and Z-resveratrol were compared using chemical and cellular assays. Chemical assays revealed that the two isomers were dose-dependently active in •O2-scavenging, ferric reducing antioxidant power (FRAP), Cu2+-reducing antioxidant capacity (CUPRAC), 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radical (PTIO•)-scavenging (pH 7.4 and pH 4.5), and 1,1-diphenyl-2-picryl-hydrazyl (DPPH•)-scavenging assays. The cellular assay indicated that the two isomers could also increase cell viabilities. However, quantitative analyses suggested that E-resveratrol exhibited stronger effects than Z-resveratrol in all chemical and cellular assays. Finally, the conformations of E-resveratrol and Z-resveratrol were analyzed. It can be concluded that both E-resveratrol and Z-resveratrol can promote redox-related pathways to exhibit antioxidant action and consequently protect bone marrow-derived mesenchymal stem cells (bmMSCs) from oxidative damage. These pathways include electron transfer (ET) and H+-transfer, and likely include hydrogen atom transfer (HAT). The E-configuration, however, improves antioxidant and cytoprotective capacities of resveratrols. The detrimental effect of the Z-configuration may be attributed to the non-planar preferential conformation, where two dihedral angles block the extension of the conjugative system. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Protective Mechanism of Sulforaphane on Cadmium-Induced Sertoli Cell Injury in Mice Testis via Nrf2/ARE Signaling Pathway
Molecules 2018, 23(7), 1774; https://doi.org/10.3390/molecules23071774
Received: 25 June 2018 / Revised: 12 July 2018 / Accepted: 15 July 2018 / Published: 19 July 2018
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Abstract
The present study evaluated the mechanism underlying the protective effect of sulforaphane (SFN) on cadmium (Cd)-induced Sertoli cell (TM4 cells) injury in mice. The apoptosis rate of cells in each group was detected by flow cytometry. It was determined the effect of SFN
[...] Read more.
The present study evaluated the mechanism underlying the protective effect of sulforaphane (SFN) on cadmium (Cd)-induced Sertoli cell (TM4 cells) injury in mice. The apoptosis rate of cells in each group was detected by flow cytometry. It was determined the effect of SFN on the expression of downstream molecular targets of Nrf2/ARE axis and on the lipid peroxide content. The related genes involved in the nuclear factor E2-related factor 2(Nrf2)/antioxidant response element (ARE) signaling pathway were evaluated by RT-PCR; for example, the mRNA expression levels of Nrf2, heme oxygenase-1 (HO-1), glutathione peroxidase (GSH-Px), quinone oxidoreductase 1 (NQO1), and γ-glutamylcysteine synthetase (γ-GCS), while the protein expression levels were assessed by Western blot. Our results showed that the mRNA and protein expression levels of Nrf2, HO-1, NQO1, GSH-Px, and γ-GCS were increased in various degree when the Sertoli cells were to added different concentrations of SFN. Our results also showed that SFN reduced the apoptosis rate, increased the activity of T-SOD, inhibited the increase of the MDA content caused by Cd. Meanwhile, SFN could increase the mRNA and protein expression levels of Nrf2, HO-1 and NQO1 and reduced the mRNA and protein expression levels of GSH-Px and γ-GCS caused by Cd in Sertoli cells (p < 0.01). Taken together, SFN could improve the antioxidant capacity of Sertoli cells, and exert a protective effect on the oxidative damage and apoptosis of Cd-induced Sertoli cells through the activation of Nrf2/ARE signal transduction pathway. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Antioxidant and Antibacterial Activity of Roseroot (Rhodiola rosea L.) Dry Extracts
Molecules 2018, 23(7), 1767; https://doi.org/10.3390/molecules23071767
Received: 26 June 2018 / Revised: 13 July 2018 / Accepted: 17 July 2018 / Published: 18 July 2018
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Abstract
Roseroot (Rhodiola rosea L.) belongs to plants revealing adaptogenic properties, which are attributed to the presence of specific phenolic compounds and are reflected mainly as antioxidant activity. The aim of the present study was to determine the antioxidant and antibacterial activity of
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Roseroot (Rhodiola rosea L.) belongs to plants revealing adaptogenic properties, which are attributed to the presence of specific phenolic compounds and are reflected mainly as antioxidant activity. The aim of the present study was to determine the antioxidant and antibacterial activity of various products obtained from R. rosea (underground organs as well as their aqueous and ethanolic dry extracts) in relation to the chemical profiles of phenolic and essential oil compounds. The chemical profiles were determined by High-performance Liquid Chromatography with a diode-array detector (HPLC-DAD) and Gas chromatography-mass spectrometry (GC-MS), antioxidant activity by (1,1-Diphenyl-2-picrylhydrazyl) Scavenging Capacity Assay (DPPH), (2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) Scavenging Capacity Assay (ABTS) and Ferric Reducing Antioxidant Power Assay (FRAP) and antimicrobial properties were expressed as minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) values following the broth microdilutions method. The results show that the investigated samples differed in terms of their chemical compositions and biological activities. The extracts were more abundant in phenolic compounds (salidroside, tyrosol, and rosavin derivatives) in comparison to dried underground organs. The content of the determined phenolics in the analyzed extracts was affected by the solvent used for extraction. The ethanolic extract was characterized by the highest content of these substances in comparison to the aqueous one and the dried raw material, especially with regard to rosavin (969.71 mg/100 g). In parallel, this extract showed the strongest antioxidant and antibacterial activity. However, dried R. rosea underground organs also revealed strong antibacterial effects against, for example, Staphylococcus strains. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
Open AccessArticle 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide Radical (PTIO•) Trapping Activity and Mechanisms of 16 Phenolic Xanthones
Molecules 2018, 23(7), 1692; https://doi.org/10.3390/molecules23071692
Received: 13 June 2018 / Revised: 8 July 2018 / Accepted: 10 July 2018 / Published: 11 July 2018
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Abstract
This study used the 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radical (PTIO•) trapping model to study the antioxidant activities of 16 natural xanthones in aqueous solution, including garcinone C, γ-mangostin, subelliptenone G, mangiferin, 1,6,7-trihydroxy-xanthone, 1,2,5-trihydroxyxanthone, 1,5,6-trihydroxyxanthone, norathyriol, 1,3,5,6-tetrahydroxy-xanthone, isojacareubin, 1,3,5,8-tetrahydroxyxanthone, isomangiferin, 2-hydroxyxanthone, 7-O-methylmangiferin, neomangiferin, and
[...] Read more.
This study used the 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radical (PTIO•) trapping model to study the antioxidant activities of 16 natural xanthones in aqueous solution, including garcinone C, γ-mangostin, subelliptenone G, mangiferin, 1,6,7-trihydroxy-xanthone, 1,2,5-trihydroxyxanthone, 1,5,6-trihydroxyxanthone, norathyriol, 1,3,5,6-tetrahydroxy-xanthone, isojacareubin, 1,3,5,8-tetrahydroxyxanthone, isomangiferin, 2-hydroxyxanthone, 7-O-methylmangiferin, neomangiferin, and lancerin. It was observed that most of the 16 xanthones could scavenge the PTIO• radical in a dose-dependent manner at pH 4.5 and 7.4. Among them, 12 xanthones of the para-di-OHs (or ortho-di-OHs) type always exhibited lower half maximal inhibitory concentration (IC50) values than those not of the para-di-OHs (or ortho-di-OHs) type. Ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) analysis revealed that most of these xanthones gave xanthone-xanthone dimers after incubation with PTIO•, except for neomangiferin. Based on these data, we concluded that the antioxidant activity of phenolic xanthone may be mediated by electron-transfer (ET) plus H+-transfer mechanisms. Through these mechanisms, some xanthones can further dimerize unless they bear huge substituents with steric hindrance. Four substituent types (i.e., para-di-OHs, 5,6-di-OHs, 6,7-di-OHs, and 7,8-di-OHs) dominate the antioxidant activity of phenolic xanthones, while other substituents (including isoprenyl and 3-hydroxy-3-methylbutyl substituents) play a minor role as long as they do not break the above four types. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Proanthocyanidins Protect Epithelial Cells from Zearalenone-Induced Apoptosis via Inhibition of Endoplasmic Reticulum Stress-Induced Apoptosis Pathways in Mouse Small Intestines
Molecules 2018, 23(7), 1508; https://doi.org/10.3390/molecules23071508
Received: 24 May 2018 / Revised: 17 June 2018 / Accepted: 19 June 2018 / Published: 21 June 2018
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Abstract
This study evaluated the protective effect of proanthocyanidins (PCs) on reducing apoptosis in the mouse intestinal epithelial cell model MODE-K exposed to zearalenone (ZEA) through inhibition of the endoplasmic reticulum stress (ERS)-induced apoptosis pathway. Our results showed that PCs could reduce the rate
[...] Read more.
This study evaluated the protective effect of proanthocyanidins (PCs) on reducing apoptosis in the mouse intestinal epithelial cell model MODE-K exposed to zearalenone (ZEA) through inhibition of the endoplasmic reticulum stress (ERS)-induced apoptosis pathway. Our results showed that PCs could reduce the rate of apoptosis in MODE-K cells exposed to ZEA (p < 0.01). PCs significantly increased the ZEA-induced antioxidant protective effects on the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and on the content of GSH. PCs also significantly decreased the ZEA-induced increase in the content of malondialdehyde (MDA). The analysis indicated that ZEA increased both mRNA and protein expression levels of C/EBP homologous protein (CHOP), GRP78, c-Jun N-terminal kinase (JNK), and cysteinyl aspartate specific proteinase 12 (caspase-12) (p < 0.05), which are related to the ERS-induced apoptosis pathway. ZEA decreased levels of the pro-apoptotic related protein Bcl-2 (p < 0.05) and increased the anti-apoptotic related protein Bax (p < 0.05). Co-treatment with PCs was also shown to significantly reverse the expression levels of these proteins in MODE-K cells. The results demonstrated that PCs could protect MODE-K cells from oxidative stress and apoptosis induced by ZEA. The underlying mechanism may be that PCs can alleviate apoptosis in mouse intestinal epithelial cells by inhibition of the ERS-induced apoptosis pathway. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle UPLC-ESI-QTOF-MS2-Based Identification and Antioxidant Activity Assessment of Phenolic Compounds from Red Corn Cob (Zea mays L.)
Molecules 2018, 23(6), 1425; https://doi.org/10.3390/molecules23061425
Received: 10 May 2018 / Revised: 9 June 2018 / Accepted: 11 June 2018 / Published: 12 June 2018
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Abstract
In this study, the extraction of phenolic antioxidants from red corn cob was carried out using ultrasound-assisted extraction (UAE). The solid:liquid ratio and extraction time were evaluated when obtaining these bioactive compounds. The total phenolic contents were evaluated using the Folin Ciocalteu method,
[...] Read more.
In this study, the extraction of phenolic antioxidants from red corn cob was carried out using ultrasound-assisted extraction (UAE). The solid:liquid ratio and extraction time were evaluated when obtaining these bioactive compounds. The total phenolic contents were evaluated using the Folin Ciocalteu method, while the antioxidant activity was measured by ABTS•+ and DPPH assays. The amount of phenolic compounds ranged from 215.17 ± 33.49 to 527.33 ± 103.79 GAE mg/100 g and, overall, high solid:liquid ratios and time periods release more phenolic compounds. Moreover, the red corn cob extracts showed higher radical scavenging capacity according to the results obtained using the ABTS•+ technique compared to the DPPH test. The coupling of liquid chromatography and mass spectrometry assay allowed the determination of 11 phenolic compounds, including phenolic acids and flavonoids. Thus, our results demonstrated for the first time the potential of red corn cob as a source of bioactive compounds, which might be included in food and pharmacological preparations. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Effect of Sterilization Process and Storage on the Antioxidative Properties of Runner Bean
Molecules 2018, 23(6), 1409; https://doi.org/10.3390/molecules23061409
Received: 3 March 2018 / Revised: 7 May 2018 / Accepted: 5 June 2018 / Published: 11 June 2018
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Abstract
In this study, we investigated the effect of standard preservation of bean seeds on changes in contents and activity of their selected components: dry matter, ash, different forms of nitrogen, composition of protein fractions; total phenolics and condensed tannins; ability to chelate iron(II)
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In this study, we investigated the effect of standard preservation of bean seeds on changes in contents and activity of their selected components: dry matter, ash, different forms of nitrogen, composition of protein fractions; total phenolics and condensed tannins; ability to chelate iron(II) ions; antiradical activity against ABTS•+ and DPPH; and capability for inhibiting autoxidation and enzymatic oxidation of linoleic acid. The conducted technological process caused various changes in contents of nitrogen forms and partial loss of phenolic compounds. The antiradical and antioxidative activity of the extracts decreased significantly, while an increase was observed in their ability to chelate Fe(II). These changes were due to the migration of active compounds to the brine, and to their structural transformations and degradation. Longer storage of the sterilized product caused restoration of part of the antiradical activity of the seeds. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle In Vitro Antioxidant Activities of Phenols and Oleanolic Acid from Mango Peel and Their Cytotoxic Effect on A549 Cell Line
Molecules 2018, 23(6), 1395; https://doi.org/10.3390/molecules23061395
Received: 15 May 2018 / Revised: 5 June 2018 / Accepted: 7 June 2018 / Published: 8 June 2018
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Abstract
Mango peel, the main by-product of juice processing, possesses appreciable quantities of bioactive phenolic compounds and is worthy of further utilization. The present work reports for the first time the HPLC analysis and in vitro antioxidant evaluation of mango peel phenols (MPPs) and
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Mango peel, the main by-product of juice processing, possesses appreciable quantities of bioactive phenolic compounds and is worthy of further utilization. The present work reports for the first time the HPLC analysis and in vitro antioxidant evaluation of mango peel phenols (MPPs) and their cytotoxic effect on the A549 lung cancer cell line. These results indicated that mango peel has the total phenolic content of 723.2 ± 0.93 mg·kg−1 dry mango peel (DMP), which consisted mainly of vanillic aldehyde, caffeic acid, chlorogenic acid, gallic acid, procyanidin B2 and oleanolic acid. Antioxidant assays showed that MPPs had strong antioxidant activities, with 92 ± 4.2% of DPPH radical scavenging rate, 79 ± 2.5% of ABTS radical inhibition rate and 4.7 ± 0.5 μM Trolox equivalents per kg−1 DMP of ferric reducing power. Gallic acid possess a stronger antioxidant capacity than other phenols. In vitro cytotoxic tests suggested that mango peel extract (MPE) had an IC50 value of 15 mg·mL−1 and MPPs had a stronger inhibitory effect on the A549 cell line. Oleanolic acid exhibited the strongest cytotoxicity, with an IC50 value of 4.7 μM, which was similar with that of the positive control 5-fluorouracil. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessFeature PaperArticle Scabiosa stellata L. Phenolic Content Clarifies Its Antioxidant Activity
Molecules 2018, 23(6), 1285; https://doi.org/10.3390/molecules23061285
Received: 14 April 2018 / Revised: 22 May 2018 / Accepted: 24 May 2018 / Published: 27 May 2018
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Abstract
The phenolic profile of Scabiosa stellata L., a species used in Moroccan traditional medicine, is disclosed. To obtain that profile the species extract was analyzed by ultra-high-performance chromatography coupled to photodiode-array detection and electrospray ionization/ion trap mass spectrometry (UHPLC-DAD-ESI/MSn). Twenty-five phenolic
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The phenolic profile of Scabiosa stellata L., a species used in Moroccan traditional medicine, is disclosed. To obtain that profile the species extract was analyzed by ultra-high-performance chromatography coupled to photodiode-array detection and electrospray ionization/ion trap mass spectrometry (UHPLC-DAD-ESI/MSn). Twenty-five phenolic compounds were identified from which isoorientin and 4-O-caffeoylquinic acid can be highlighted because they are the major ones. The antioxidant activity was significantly controlled by the fraction type, with the n-butanol fraction showing the highest antioxidant activity (FRS50 = 64.46 µg/mL in the DPPH assay, FRS50 = 27.87 µg/mL in the ABTS assay and EC50 = 161.11 µg/mL in the reducing power assay). A phytochemical study of the n-butanol fraction was performed, and some important flavone glycosides were isolated. Among them the tamarixetin derivatives—the less common ones—can be emphasized. This phytochemical study and polyphenolic profile can be correlated with S. stellata extracts in vitro antioxidant activity. Moreover, it can be regarded as an evidence of its medicinal use and can incentivize its consumption. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Effect of Microwave Vacuum Drying on the Drying Characteristics, Color, Microstructure, and Antioxidant Activity of Green Coffee Beans
Molecules 2018, 23(5), 1146; https://doi.org/10.3390/molecules23051146
Received: 16 April 2018 / Revised: 3 May 2018 / Accepted: 6 May 2018 / Published: 11 May 2018
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Abstract
The aim of this study is to investigate the effect of microwave vacuum drying (MVD) on the drying characteristics and quality attributes of green coffee beans. We specifically focused on the effective moisture diffusion coefficient (Deff), surface temperature, glass transition
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The aim of this study is to investigate the effect of microwave vacuum drying (MVD) on the drying characteristics and quality attributes of green coffee beans. We specifically focused on the effective moisture diffusion coefficient (Deff), surface temperature, glass transition temperature (Tg), water state, and microstructure. The kinetics of color changes during drying, total phenolic content (TPC), and antioxidant activity (DPPH, FRAP, and ABTS) were also characterized. Microwave power during MVD affected the porosity of coffee beans, their color, TPC, and antioxidant activity. The Allometric 1 model was the most suitable for simulating surface temperature rise kinetics. Thermal processing of green coffee beans resulted in increased b*, L*, ΔE, and TPC values, and greater antioxidant capacity. These findings may provide a theoretical reference for the technical improvement, mechanisms of flavor compound formation, and quality control of dried green coffee beans. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Antioxidant and Cytoprotective Effects of Kukoamines A and B: Comparison and Positional Isomeric Effect
Molecules 2018, 23(4), 973; https://doi.org/10.3390/molecules23040973
Received: 26 March 2018 / Revised: 13 April 2018 / Accepted: 17 April 2018 / Published: 21 April 2018
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Abstract
In this study, two natural phenolic polyamines, kukoamine A and B, were comparatively investigated for their antioxidant and cytoprotective effects in Fenton-damaged bone marrow-derived mesenchymal stem cells (bmMSCs). When compared with kukoamine B, kukoamine A consistently demonstrated higher IC50 values in PTIO•-scavenging
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In this study, two natural phenolic polyamines, kukoamine A and B, were comparatively investigated for their antioxidant and cytoprotective effects in Fenton-damaged bone marrow-derived mesenchymal stem cells (bmMSCs). When compared with kukoamine B, kukoamine A consistently demonstrated higher IC50 values in PTIO•-scavenging (pH 7.4), Cu2+-reducing, DPPH•-scavenging, •O2-scavenging, and •OH-scavenging assays. However, in the PTIO•-scavenging assay, the IC50 values of each kukoamine varied with pH value. In the Fe2+-chelating assay, kukoamine B presented greater UV-Vis absorption and darker color than kukoamine A. In the HPLC–ESI–MS/MS analysis, kukoamine A with DPPH• produced radical-adduct-formation (RAF) peaks (m/z 922 and 713). The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl (MTT) assay suggested that both kukoamines concentration-dependently increased the viabilities of Fenton-damaged bmMSCs at 56.5–188.4 μM. However, kukoamine A showed lower viability percentages than kukoamine B. In conclusion, the two isomers kukoamine A and B can protect bmMSCs from Fenton-induced damage, possibly through direct or indirect antioxidant pathways, including electron-transfer, proton-transfer, hydrogen atom transfer, RAF, and Fe2+-chelating. Since kukoamine B possesses higher potentials than kukoamine A in these pathways, kukoamine B is thus superior to kukoamine A in terms of cytoprotection. These differences can ultimately be attributed to positional isomeric effects. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Light Emission from the Fe2+-EGTA-H2O2 System: Possible Application for the Determination of Antioxidant Activity of Plant Phenolics
Molecules 2018, 23(4), 866; https://doi.org/10.3390/molecules23040866
Received: 20 March 2018 / Revised: 3 April 2018 / Accepted: 5 April 2018 / Published: 10 April 2018
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Abstract
Oxidative reactions can result in the formation of electronically excited species that undergo radiative decay depending on electronic transition from the excited state to the ground state with subsequent ultra-weak photon emission (UPE). We investigated the UPE from the Fe2+-EGTA (ethylene
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Oxidative reactions can result in the formation of electronically excited species that undergo radiative decay depending on electronic transition from the excited state to the ground state with subsequent ultra-weak photon emission (UPE). We investigated the UPE from the Fe2+-EGTA (ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid)–H2O2 system with a multitube luminometer (Peltier-cooled photon counter, spectral range 380 to 630 nm). The UPE of 92.6 µmol/L Fe2+—185.2 µmol/L EGTA—2.6 mmol/L H2O2 reached 4319 ± 755 relative light units during 2 min measurement and was about seven times higher (p < 0.001) than the UPE of incomplete systems (Fe2+-H2O2, EGTA-H2O2) and medium alone. Substitution of Fe2+ with Cr2+, Co2+, Mn2+ or Cu2+ as well as of EGTA with EDTA (ethylenediaminetetraacetic acid) or citrate completely abolished UPE. Experiments with ROS scavengers revealed the dependence of UPE on hydroxyl radicals suggesting occurrence of oxidative attack and cleavage of the ether bond in EGTA backbone structure and formation of triplet excited carbonyl groups with subsequent light emission. Plant phenolics (ferulic, chlorogenic and caffec acids) at concentration 87 µmol/L and ascorbate at 0.46 mmol/L inhibited UPE by 90 ± 4%, 90 ± 5%, 97 ± 2% and 92 ± 1%, respectively. Quenching of UPE from Fe2+-EGTA-H2O2 system can be used for evaluation of antioxidant activity of phytochemicals. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Optimization of the Ultrasonic-Assisted Extraction of Phenolic Compounds from Oryza Sativa L. ‘Violet Nori’ and Determination of the Antioxidant Properties of its Caryopses and Leaves
Molecules 2018, 23(4), 844; https://doi.org/10.3390/molecules23040844
Received: 13 March 2018 / Revised: 29 March 2018 / Accepted: 4 April 2018 / Published: 7 April 2018
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Abstract
‘Violet Nori’ is a new spontaneous growing violet rice variety showing a peculiar violet color in its fresh leaves as well. In this paper, the antioxidant properties and the content of total phenols, radical scavengers, and anthocyanins in ‘Violet Nori’ caryopses, flour, and
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‘Violet Nori’ is a new spontaneous growing violet rice variety showing a peculiar violet color in its fresh leaves as well. In this paper, the antioxidant properties and the content of total phenols, radical scavengers, and anthocyanins in ‘Violet Nori’ caryopses, flour, and leaves are explored and compared. Ultrasonic-Assisted Extraction (UAE) is employed for the extraction of phenolic compounds, improving the extraction conditions by Design of Experiments (DoE). The obtained results show that the Radical Scavenging Activities (RSAs), the Total Phenolic Contents (TPCs), and the anthocyanin amounts (1000–1500 μg/g, expressed as cyanidin-3-glucoside) of ‘Violet Nori’ caryopses are higher than those in the other analyzed colored rice samples (300–900 μg/g as cyanidin-3-glucoside), with the exception of the cultivars ‘Artemide’ and ‘Nerone’, which show comparable values of RSAs and TPCs. The study of ‘Violet Nori’ leaves at different plant maturation stages shows that their anthocyanin content is 2–3 times higher than in the caryopses and in the flour, reaching the highest levels at about 60 days from seeding. Thus, the estimated extraction yield of 4 kg anthocyanins/t makes fresh leaves very interesting for the extraction of anthocyanins on an industrial scale, whereas violet caryopses are a very interesting dietetic source of valuable anthocyanins and other antioxidant compounds. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Antioxidant Activities of Phenolic Metabolites from Flemingia philippinensis Merr. et Rolfe and Their Application to DNA Damage Protection
Molecules 2018, 23(4), 816; https://doi.org/10.3390/molecules23040816
Received: 11 March 2018 / Revised: 31 March 2018 / Accepted: 2 April 2018 / Published: 2 April 2018
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Abstract
F. philippinensis Merr. et Rolfe has been cultivated on a large scale and is widely consumed by local inhabitants as an important nutraceutical, especially against rheumatism which has a deep connection with antioxidants. In this study, a total of 18 different phenolic
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F. philippinensis Merr. et Rolfe has been cultivated on a large scale and is widely consumed by local inhabitants as an important nutraceutical, especially against rheumatism which has a deep connection with antioxidants. In this study, a total of 18 different phenolic metabolite compounds in F. philippinensis were isolated and identified, and evaluated for their antioxidant and DNA damage protection potential. The antioxidant activity of the 18 identified compounds was screened using DPPH, ORAC, hydroxyl and superoxide radical scavenging assays. The antioxidant potential of the compounds was found to differ by functionality and skeleton. However, most compounds showed a good antioxidant potential. In particular, seven of the identified compounds, namely, compounds 2, 3, 6, 10, 11, 15 and 16, showed significant protective effects on pBR322 plasmid DNA against the mutagenic and toxic effects of Fenton’s reaction. The most active compound, compound 2, displayed a dose-dependent DNA damage protection potential in the range of 7.5~60.0 μM. The DNA damage protective effect of the identified compounds was significantly correlated with the hydroxyl radical scavenging activity. Compounds that exhibited effective (IC50 = 5.4~12.5 μg/mL) hydroxyl radical scavenging activity were found to be the ones with higher DNA damage protection potential. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Protective Effect of Polyphenol-Rich Extract from Bee Pollen in a High-Fat Diet
Molecules 2018, 23(4), 805; https://doi.org/10.3390/molecules23040805
Received: 9 March 2018 / Revised: 30 March 2018 / Accepted: 31 March 2018 / Published: 31 March 2018
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Abstract
We have studied a preventive effect of polyphenol-rich bee pollen ethanol extract (EEP) against histological changes in the liver and cardiac blood vessels, abnormalities of lipid profile, and the levels of oxidized low density lipoproteins (ox-LDL), asymmetric dimethylarginine (ADMA), angiotensin-converting enzyme (ACE), and
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We have studied a preventive effect of polyphenol-rich bee pollen ethanol extract (EEP) against histological changes in the liver and cardiac blood vessels, abnormalities of lipid profile, and the levels of oxidized low density lipoproteins (ox-LDL), asymmetric dimethylarginine (ADMA), angiotensin-converting enzyme (ACE), and angiotensin II (ANG II) caused by a high-fat diet in C57BL6 mice. Supplementing the diet with EEP in the doses of 0.1 g/kg body mass (BM) and 1 g/kg BM resulted in a decrease of total cholesterol by 31% and 35%, respectively. It also decreased the level of low density lipoproteins by 67% and 90%, respectively. No differences in the levels of high density lipoprotein and triacylglycerols were observed. EEP reduced the level of ox-LDL by 33% and 47%, ADMA by 13% and 51%, ACE by 17% and 30%, as well as ANG II by 11% and 15% in a dose-dependent manner, which proves a protective effect of EEP in a high-fat diet. EEP reduces and/or prevents hepatic steatosis and degenerative changes caused by a high-fat diet in C57BL6 mice, which indicates its hepatoprotective effect. EEP used with standard feed does not disturb a normal concentration of the assayed parameters. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle UHPLC-MS Metabolome Fingerprinting: The Isolation of Main Compounds and Antioxidant Activity of the Andean Species Tetraglochin ameghinoi (Speg.) Speg.
Molecules 2018, 23(4), 793; https://doi.org/10.3390/molecules23040793
Received: 8 February 2018 / Revised: 22 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
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Abstract
The seriated extracts of petroleum ether (PE-E), dichloromethane (DCM-E) and methanol extracts (MeOH-E) from the aerial parts of the native South American plant Tetraglochin ameghinoi (Rosaceae), were evaluated regarding their antioxidant and antibacterial activities. The antioxidant properties were evaluated by free radical scavenging
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The seriated extracts of petroleum ether (PE-E), dichloromethane (DCM-E) and methanol extracts (MeOH-E) from the aerial parts of the native South American plant Tetraglochin ameghinoi (Rosaceae), were evaluated regarding their antioxidant and antibacterial activities. The antioxidant properties were evaluated by free radical scavenging methods (DPPH and TEAC), ferric-reducing antioxidant power (FRAP) and lipoperoxidation in erythrocytes (LP), while the antibacterial activity was performed against Gram-positive and Gram-negative bacteria according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The chemical and biological analyses of this plant are very important since this bush is currently used in traditional medicine as a cholagogue and digestive. The polar MeOH-E showed the highest antioxidant activities (17.70 µg/mL in the DPPH assay, 381.43 ± 22.38 mM TE/g extract in the FRAP assay, 387.76 ± 91.93 mg TE/g extract in the TEAC assay and 93.23 + 6.77% in the LP assay) and it was selected for chromatographic isolation of its components. These components were found to be four acetophenones, including the new phloracetophenone glucoside: 4′,6′,-dihydroxy-2′-O-(6″-acetyl)-β-d-glucopyranosylacetophenone or IUPAC name: (6-(2-acetyl-3,5-dihydroxyphenoxy)-3,4,5-trihydroxytetrahydro-2H-pyran-2-yl)methyl acetate, whose structure was elucidated by NMR and MS methods. In addition, twenty-six compounds, including five of these acetophenone derivatives, two sugars, six flavonoids, eleven phenolic acids and two triterpenes, were identified based on UHPLC-OT-MS and PDA analysis on the MeOH-E. The results support the medicinal use of the plant. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessCommunication Effect of Double Bond Position on 2-Phenyl-benzofuran Antioxidants: A Comparative Study of Moracin C and Iso-Moracin C
Molecules 2018, 23(4), 754; https://doi.org/10.3390/molecules23040754
Received: 9 February 2018 / Revised: 16 March 2018 / Accepted: 22 March 2018 / Published: 24 March 2018
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Abstract
Two 2-phenyl-benzofurans, moracin C {2-[3′,5′-dihydroxy-4′-(3-methlbut-2-enyl)phenyl]-6-hydroxybenzofuran} and its isomer iso-moracin C{2-[3′,5′-dihydroxy-4′-(3-methlbut-1-enyl)phenyl]-6-hydroxybenzofuran}, were comparatively studied using redox-related antioxidant assays and non-redox antioxidant assays. Moracin C always resulted in higher IC50 values than iso-moracin C in the redox-related antioxidant assays, including •O2
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Two 2-phenyl-benzofurans, moracin C {2-[3′,5′-dihydroxy-4′-(3-methlbut-2-enyl)phenyl]-6-hydroxybenzofuran} and its isomer iso-moracin C{2-[3′,5′-dihydroxy-4′-(3-methlbut-1-enyl)phenyl]-6-hydroxybenzofuran}, were comparatively studied using redox-related antioxidant assays and non-redox antioxidant assays. Moracin C always resulted in higher IC50 values than iso-moracin C in the redox-related antioxidant assays, including •O2-inhibition, Cu2+-reducing power, DPPH•-inhibition, and ABTS+•-inhibition assays. In the non-redox antioxidant assay, moracin C and iso-moracin C underwent similar radical-adduct-formation (RAF), evidenced by the peaks at m/z 704 and m/z 618 in HPLC-MS spectra. In conclusion, both moracin C and iso-moracin C can act as 2-phenyl-benzofuran antioxidants; their antioxidant mechanisms may include redox-related ET and H+-transfer, and non-redox RAF. A double bond at the conjugation position can enhance the redox-related antioxidant potential, but hardly affects the RAF potential. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Physicochemical Characterization and Antioxidant Activity of Humic Acids Isolated from Peat of Various Origins
Molecules 2018, 23(4), 753; https://doi.org/10.3390/molecules23040753
Received: 5 March 2018 / Revised: 20 March 2018 / Accepted: 22 March 2018 / Published: 24 March 2018
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Abstract
Although humic acids (HAs) from peat exhibit various therapeutic properties, there is little information available concerning their physicochemical and antioxidant properties. To address this issue, nine different types of peat, including oligotrophic, mesotrophic, and minerotrophic peat samples, were used for isolation of HA
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Although humic acids (HAs) from peat exhibit various therapeutic properties, there is little information available concerning their physicochemical and antioxidant properties. To address this issue, nine different types of peat, including oligotrophic, mesotrophic, and minerotrophic peat samples, were used for isolation of HA fractions by basic (HAb) and pyrophosphate (HAp) extractions. Physical parameters of the HAs were analyzed by UV-Vis, fluorescent, infrared (IR), and electron paramagnetic resonance (EPR) spectroscopy. Average Mr of the fractions ranged from 17.2 to 39.7 kDa, while their humification index (HIX) varied from 0.49 to 1.21. HAp fractions had a higher content of aromatic structures compared to HAb fractions. Moreover, HAp fractions had a significantly higher content of phenolic OH groups (3.6 ± 0.5 mmol/g) versus HAb (3.1 ± 0.5 mmol/g). All HA fractions exhibited antioxidant activity in radical scavenging and electrochemical assays, and their EPR signal had a single line with g = 2.0035, which is consistent with semiquinone type radicals. Furthermore, the HIX was found to be important in determining the number of semiquinone-type free radicals in the HA structures. Overall, these data provide a molecular basis to explain at least part of the beneficial therapeutic properties of peat-derived HAs. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessCommunication π-π Conjugation Enhances Oligostilbene’s Antioxidant Capacity: Evidence from α-Viniferin and Caraphenol A
Molecules 2018, 23(3), 694; https://doi.org/10.3390/molecules23030694
Received: 9 February 2018 / Revised: 15 March 2018 / Accepted: 18 March 2018 / Published: 19 March 2018
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Abstract
α-Viniferin and caraphenol A, the two oligostilbenes, have the sole difference of the presence or absence of an exocyclic double bond at the π-π conjugative site. In this study, the antioxidant capacity and relevant mechanisms for α-viniferin and caraphenol A were comparatively explored
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α-Viniferin and caraphenol A, the two oligostilbenes, have the sole difference of the presence or absence of an exocyclic double bond at the π-π conjugative site. In this study, the antioxidant capacity and relevant mechanisms for α-viniferin and caraphenol A were comparatively explored using spectrophotometry, UV-visible spectral analysis, and electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC–ESI–Q–TOF–MS/MS) analysis. The spectrophotometric results suggested that caraphenol A always gave lower IC50 values than α-viniferin in cupric ion-reducing antioxidant capacity assay, ferric-reducing antioxidant power assay, 1,1-diphenyl-2-picryl-hydrazl radical (DPPH•)-scavenging, and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radical-scavenging assays. In UV-visible spectra analysis, caraphenol A was observed to show enhanced peaks at 250–350 nm when mixed with Fe2+, but α-viniferin exhibited no similar effects. UPLC–ESI–Q–TOF–MS/MS analysis revealed that α-viniferin mixed with DPPH• produced radical adduct formation (RAF) peak (m/z = 1070–1072). We conclude that the antioxidant action of α-viniferin and caraphenol A may involve both redox-mediated mechanisms (especially electron transfer and H+-transfer) and non-redox-mediated mechanisms (including Fe2+-chelating or RAF). The π-π conjugation of the exocyclic double bond in caraphenol A can greatly enhance the redox-mediated antioxidant mechanisms and partially promote the Fe2+-chelating mechanism. This makes caraphenol A far superior to α-viniferin in total antioxidant levels. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Anthocyanin-Rich Grape Pomace Extract (Vitis vinifera L.) from Wine Industry Affects Mitochondrial Bioenergetics and Glucose Metabolism in Human Hepatocarcinoma HepG2 Cells
Molecules 2018, 23(3), 611; https://doi.org/10.3390/molecules23030611
Received: 19 February 2018 / Revised: 5 March 2018 / Accepted: 6 March 2018 / Published: 8 March 2018
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Abstract
Cancer cells demand high ATP provisions to support proliferation, and targeting of energy metabolism is a good strategy to increase their sensitivity to treatments. In Brazil, wine manufacture is expanding, increasing the amount of pomace that is produced. We determined the phenolic composition
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Cancer cells demand high ATP provisions to support proliferation, and targeting of energy metabolism is a good strategy to increase their sensitivity to treatments. In Brazil, wine manufacture is expanding, increasing the amount of pomace that is produced. We determined the phenolic composition and antioxidant properties of a dark skin Grape Pomace Extract and its effects on metabolism and redox state in human hepatocarcinoma HepG2 cells. The material and the methods used represented the industrial process since pomace derived from white wine production and the extract concentrated by pilot plant scale reverse osmosis. Grape pomace extract was rich in polyphenols, mainly anthocyanins, and presented high antioxidant capacity. Short-term metabolic effects, irrespective of any cytotoxicity, involved increased mitochondrial respiration and antioxidant capacity and decreased glycolytic metabolism. Long-term incubation was cytotoxic and cells died by necrosis and GPE was not toxic to non-cancer human fibroblasts. To the best of our knowledge, this is the first report to characterize pomace extract from white wine production from Brazilian winemaking regarding its effects on energy metabolism, suggesting its potential use for pharmaceutical and nutraceutical purposes. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Antioxidation and Cytoprotection of Acteoside and Its Derivatives: Comparison and Mechanistic Chemistry
Molecules 2018, 23(2), 498; https://doi.org/10.3390/molecules23020498
Received: 24 January 2018 / Revised: 20 February 2018 / Accepted: 20 February 2018 / Published: 23 February 2018
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Abstract
The study tried to explore the role of sugar-residues and mechanisms of phenolic phenylpropanoid antioxidants. Acteoside, along with its apioside forsythoside B and rhamnoside poliumoside, were comparatively investigated using various antioxidant assays. In three electron-transfer (ET)-based assays (FRAP, CUPRAC, PTIO•-scavenging at pH 4.5),
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The study tried to explore the role of sugar-residues and mechanisms of phenolic phenylpropanoid antioxidants. Acteoside, along with its apioside forsythoside B and rhamnoside poliumoside, were comparatively investigated using various antioxidant assays. In three electron-transfer (ET)-based assays (FRAP, CUPRAC, PTIO•-scavenging at pH 4.5), the relative antioxidant levels roughly ruled as: acteoside >forsythoside B > poliumoside. Such order was also observed in H+-transfer-involved PTIO•-scavenging assay at pH 7.4, and in three multiple-pathway-involved radical-scavenging assays, i.e., ABTS+•-scavenging, DPPH•-scavenging, and •O2-scavenging. In UV-vis spectra, each of them displayed a red-shift at 335→364 nm and two weak peaks (480 and 719 nm), when mixed with Fe2+; however, acteoside gave the weakest absorption. In Ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC−ESI−Q−TOF−MS/MS) analysis, no radical-adduct-formation (RAF) peak was found. MTT assay revealed that poliumoside exhibited the highest viability of oxidative-stressed bone marrow-derived mesenchymal stem cells. In conclusion, acteoside, forsythoside B, and poliumoside may be involved in multiple-pathways to exert the antioxidant action, including ET, H+-transfer, or Fe2+-chelating, but not RAF. The ET and H+-transfer may be hindered by rhamnosyl and apiosyl moieties; however, the Fe2+-chelating potential can be enhanced by two sugar-residues (especially rhamnosyl moiety). The general effect of rhamnosyl and apiosyl moieties is to improve the antioxidant or cytoprotective effects. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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Open AccessArticle Yacon (Smallanthus sonchifolius Poepp. & Endl.) as a Novel Source of Health Promoting Compounds: Antioxidant Activity, Phytochemicals and Sugar Content in Flesh, Peel, and Whole Tubers of Seven Cultivars
Molecules 2018, 23(2), 278; https://doi.org/10.3390/molecules23020278
Received: 9 January 2018 / Revised: 26 January 2018 / Accepted: 28 January 2018 / Published: 29 January 2018
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Abstract
The aim of this study was to evaluate the quality characteristics of seven yacon (Smallanthus sonchifolius Poepp. and Endl.) cultivars (Cajamarca, Cusco, Early White, Late Red, Morado, New Zealand and Quinault) cultivated in the southwest of Germany. The following phyto/chemical traits were
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The aim of this study was to evaluate the quality characteristics of seven yacon (Smallanthus sonchifolius Poepp. and Endl.) cultivars (Cajamarca, Cusco, Early White, Late Red, Morado, New Zealand and Quinault) cultivated in the southwest of Germany. The following phyto/chemical traits were investigated in different yacon tuber parts (flesh, peel, and whole tubers): total dry matter, sugar content (fructose, glucose, and sucrose content), total phenolic content (TPC), total flavonoid content (TFC), 2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and Ferric reducing antioxidant power (FRAP). The results indicated a significant interaction between cultivar and tuber part on all of the examined traits (p < 0.0001). Of flesh and whole tuber, cv. Late Red, cv. Morado, and cv. Cajamarca had the highest TPC, TFC, DPPH radical scavenging activity, and FRAP. They also had relatively higher total sugar content. Cv. New Zealand had the lowest amount of sugars, TPC, TFC, DPPH radical scavenging activity, and FRAP, but the highest ABTS radical scavenging activity content in its flesh and whole tuber. Moreover, the results indicated that the peel of yacon tubers contained considerably high amounts of phytochemicals while possessing low sugar contents. Overall, this study provides a broad insight into the phyto/chemical content of yacon tubers from different cultivars, which can be used for further breeding programs, and the selection of proper cultivars for specific food product development. Full article
(This article belongs to the Special Issue The Antioxidant Capacities of Natural Products)
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