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Soluble and Insoluble-Bound Antioxidants

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A special issue of Antioxidants (ISSN 2076-3921). This special issue belongs to the section "Natural and Synthetic Antioxidants".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 20888

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Special Issue Editors

Dr. Adriano Costa de Camargo

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Guest Editor

Nutrition and Food Technology Institute, University of Chile, Santiago 7830490, Chile
Interests: food chemistry; functional foods; nutraceuticals; lipids; phenolics; non-communicable diseases; food irradiation; ultrasound; oxidative stress; antioxidants
Special Issues, Collections and Topics in MDPI journals

Dr. Raquel Bridi

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Guest Editor

Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380000, Chile
Interests: natural products; bioactive compounds; secondary metabolites; phytochemistry; medicinal plants; bee products; antioxidants; hepatoprotection; bioaccessibility
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Although phenolics and other minor compounds in plant foods and by-products thereof also occur as soluble compounds, a significant but often neglected portion of these compounds also occurs as insoluble-bound forms. Insoluble-bound phenolics are linked to cell wall components (indigestible fibers, cellulose, hemicellulose, and lignin). The presence of insoluble-bound alkaloids have also been recently reported by our research team. Unfortunately, despite the fact that plant food phenolics and other minor compounds are well recognized for their potential application as natural additives and bioactive properties, those present in the insoluble-bound form have, in general, received comparatively little attention. Accordingly, it is not surprising to find many gaps in the existing literature even regarding some traditional feedstocks, industrial products, and related by-products. In fact, due to proper fractionation and identification techniques, several unreported compounds were found in some plant foods and their by-products. We invite all research groups around the globe to contribute to this Special Issue by submitting comprehensive/short reviews or original articles. Manuscripts addressing the identification and quantification of soluble and/or insoluble-bound phenolics and other minor compounds are welcome. A farm to fork focus is planned for this Special Issue. Therefore, contributions addressing the effect of agronomic practices, postharvest, food processing, development of natural additives, bioaccessibility, and bioavailability, as well as biological effects in vitro and in vivo of soluble and insoluble-bound antioxidants, will be considered.

Dr. Adriano Costa de Camargo
Dr. Raquel Bridi
Guest Editors

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Keywords

functional foods
nutraceuticals
dietary bioactives
identification
quantification
biosynthesis
natural additives
food additives
bioaccessibility
bioavailability
biological effects
phenolics and polyphenolics
alkaloids

Published Papers (9 papers)

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Research

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16 pages, 792 KiB

Open AccessArticle

In Vitro Digestion of Peanut Skin Releases Bioactive Compounds and Increases Cancer Cell Toxicity

by Karina Cordeiro-Massironi, Rosana Aparecida M. Soares-Freitas, Geni Rodrigues Sampaio, Ana Clara da C. Pinaffi-Langley, Raquel Bridi, Adriano Costa de Camargo and Elizabeth Aparecida F. S. Torres

Antioxidants 2023, 12(7), 1356; https://doi.org/10.3390/antiox12071356 - 28 Jun 2023

Viewed by 1484

Abstract

Peanut skin is a rich source of bioactive compounds which may be able to reduce the risk factors associated with metabolic syndromes. This study aimed to characterize bio-compounds from peanut skin (Arachis hypogaea) and their bioactivity (antioxidant activity, inhibition of lipase, and carbohydrase enzymes) and to evaluate their anti-proliferative properties in colorectal cancer cells (HCT116) upon in vitro digestion. Peanut skin was digested in two sequential phases, and the final content, named phase-1 (P1) and phase-2 (P2) extracts, was evaluated. Several bioactive compounds were positively identified and quantified by liquid chromatography, including quinic acid, released especially after in vitro digestion. The total phenolic content and, regardless of the method, the antioxidant activity of P1 was higher than P2. P1 also showed a lower enzyme inhibitory concentration IC₅₀ than P2, lipase, and α-glucosidase. For cell viability in HCT116 cells, lower concentrations of P1 were found for IC₅₀ compared to P2. In conclusion, bioactive compounds were released mainly during the first phase of the in vitro digestion. The digested samples presented antioxidant activity, enzyme inhibitory activity, and cancer cell cytotoxicity, especially those from the P1 extract. The potential applications of such a by-product in human health are reported. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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16 pages, 2267 KiB

Open AccessArticle

Synthesis and Characterization of a Novel Resveratrol Xylobioside Obtained Using a Mutagenic Variant of a GH10 Endoxylanase

by Ana Pozo-Rodríguez, Juan A. Méndez-Líter, Rocío García-Villalba, David Beltrán, Eva Calviño, Andrés G. Santana, Laura I. de Eugenio, Francisco Javier Cañada, Alicia Prieto, Jorge Barriuso, Francisco A. Tomás-Barberán and María Jesús Martínez

Antioxidants 2023, 12(1), 85; https://doi.org/10.3390/antiox12010085 - 30 Dec 2022

Cited by 3 | Viewed by 2016

Abstract

Resveratrol is a natural polyphenol with antioxidant activity and numerous health benefits. However, in vivo application of this compound is still a challenge due to its poor aqueous solubility and rapid metabolism, which leads to an extremely low bioavailability in the target tissues. In this work, rXynSOS-E236G glycosynthase, designed from a GH10 endoxylanase of the fungus Talaromyces amestolkiae, was used to glycosylate resveratrol by using xylobiosyl-fluoride as a sugar donor. The major product from this reaction was identified by NMR as 3-O-ꞵ-d-xylobiosyl resveratrol, together with other glycosides produced in a lower amount as 4′-O-ꞵ-d-xylobiosyl resveratrol and 3-O-ꞵ-d-xylotetraosyl resveratrol. The application of response surface methodology made it possible to optimize the reaction, producing 35% of 3-O-ꞵ-d-xylobiosyl resveratrol. Since other minor glycosides are obtained in addition to this compound, the transformation of the phenolic substrate amounted to 70%. Xylobiosylation decreased the antioxidant capacity of resveratrol by 2.21-fold, but, in return, produced a staggering 4,866-fold improvement in solubility, facilitating the delivery of large amounts of the molecule and its transit to the colon. A preliminary study has also shown that the colonic microbiota is capable of releasing resveratrol from 3-O-ꞵ-d-xylobiosyl resveratrol. These results support the potential of mutagenic variants of glycosyl hydrolases to synthesize highly soluble resveratrol glycosides, which could, in turn, improve the bioavailability and bioactive properties of this polyphenol. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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14 pages, 2372 KiB

Open AccessArticle

Sex Differences in X-ray-Induced Endothelial Damage: Effect of Taurine and N-Acetylcysteine

by Ilaria Campesi, Antonio Brunetti, Giampiero Capobianco, Adriana Galistu, Andrea Montella, Francesca Ieri and Flavia Franconi

Antioxidants 2023, 12(1), 77; https://doi.org/10.3390/antiox12010077 - 29 Dec 2022

Cited by 3 | Viewed by 2704

Abstract

Ionizing radiation (IR) can induce some associated pathological conditions due to numerous cell damages. The influence of sex is scarcely known, and even less known is whether the effect of antioxidants is sex-dependent. Given the increased use of IR, we investigated whether male human umbilical vein endothelial cells (MHUVECs) and female human umbilical vein endothelial cells (FHUVECs) respond differently to IR exposure and whether the antioxidants 10 mM taurine (TAU) and 5 mM N-acetylcysteine (NAC) can prevent IR-induced damage in a sex-dependent way. In untreated cells, sex differences were observed only during autophagy, which was higher in FHUVECs. In non-irradiated cells, preincubation with TAU and NAC did not modify viability, lactate dehydrogenase (LDH) release, migration, or autophagy, whereas only NAC increased malondialdehyde (MDA) levels in FHUVECs. X-ray irradiation increased LDH release and reduced viability and migration in a sex-independent manner. TAU and NAC did not affect viability while reduced LDH release in irradiated cells: they have the same protective effect in FHUVECs, while, TAU was more protective than NAC in male cells.. Moreover, TAU and NAC significantly promoted the closure of wounds in both sexes in irradiated cells, but NAC was more effective at doing this in FHUVECs. In irradiated cells, TAU did not change autophagy, while NAC attenuated the differences between the sexes. Finally, NAC significantly decreased MDA in MHUVECs and increased MDA in FHUVECs. In conclusion, FHUVECs appear to be more susceptible to IR damage, and the effects of the two antioxidants present some sex differences, suggesting the need to study the influence of sex in radiation mitigators. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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14 pages, 630 KiB

Open AccessArticle

Apple Antioxidant Properties as an Effect of N Dose and Rate—Mycorrhization Involvement: A Long-Term Study

by Barbara Łata, Sylwia Żakowska-Biemans and Dariusz Wrona

Antioxidants 2022, 11(12), 2446; https://doi.org/10.3390/antiox11122446 - 12 Dec 2022

Cited by 1 | Viewed by 1187

Abstract

The genetic and/or the agronomic approaches are two main ways to enhance concentrations of biologically active compounds in fruits and vegetables. In this study, the apple antioxidant status was evaluated from the second to the fourth year after planting in relation to an increasing N-dose applied—with or without plant microbial inoculation in the field conditions. Cultivar ‘Šampion Arno’ was selected to test these relationships. In the growing season, N treatment and inoculation effects were monitored for the apple peel total phenolics and selected individual phenolic compounds ((+)-catechin, (−)-epicatechin, chlorogenic and caffeic acids, rutin and phloridzin) and total ascorbate concentration. Additionally, as an environmental stress marker measurement of glutathione reductase, ascorbate peroxidase and catalase activity were conducted. The year effect was most pronounced, while the N or applied inoculum effects were much weaker. Great differences in antioxidative enzyme activity and phenolic concentrations between years were revealed. Nitrogen fertilization reduced the fruit’s global phenolic accumulation compared to the control, but the N-effect varied depending on individual phenolic compounds, N dose and N application method. None of the tested factors influenced the ascorbate concentration. There was a certain tendency to increase antioxidant properties in the control group (without mineral N fertilization) but with the application of bio-fertilizer, which may seem promising for future research in this scope. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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14 pages, 691 KiB

Open AccessArticle

Eco-Efficient Quantification of Glucosinolates in Camelina Seed, Oil, and Defatted Meal: Optimization, Development, and Validation of a UPLC-DAD Method

by Salvador Meza, Yucheng Zhou, Jonathan Chastain, Yingying Yang, Hope Hua Cheng, Diliara Iassonova, Jason Rivest and Hong You

Antioxidants 2022, 11(12), 2441; https://doi.org/10.3390/antiox11122441 - 10 Dec 2022

Cited by 1 | Viewed by 1597

Abstract

Camelina sativa (camelina) seed, oil, and defatted meal are widely used for food, animal feed, and other purposes. The accurate quantification of camelina glucosinolates is critical as their functionalities are highly dose-dependent. The classic quantification of glucosinolates in camelina products involves tedious desulfation steps, toxic reagents, and a lengthy instrument time because glucosinolates are easy to degrade and subject to interference in the liquid chromatography. Thus, we developed and validated an eco-efficient UPLC-DAD method for determining glucoarabin (GS9), glucocamelinin (GS10), and homoglucocamelinin (GS11) in camelina seed, oil, and defatted meal. Glucosinolates were extracted using 80% cold methanol to denature myrosinase, and were separated by an HSS T3 column without desulfation. Glucotropaeolin was used as an internal standard to track analyte degradation and loss during sample preparation. The method has shown high precision (relative standard deviations ranging from 4.12% to 6.54%) and accuracy (>94.4% spike recovery) for GS9-11, and all validation parameters passed the industry-consensus AOAC Appendix F criteria. To our best knowledge, this is the first eco-efficient and low-cost analytical method that is validated against strict AOAC criteria for the quantification of intact camelina glucosinolates. The method is suitable to be adopted as a new industrial testing standard to assist in the quality control of camelina products. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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16 pages, 1321 KiB

Open AccessArticle

Conventional vs. Green Extraction Using Natural Deep Eutectic Solvents—Differences in the Composition of Soluble Unbound Phenolic Compounds and Antioxidant Activity

by Milica Martinović, Nemanja Krgović, Ivana Nešić, Ana Žugić and Vanja Milija Tadić

Antioxidants 2022, 11(11), 2295; https://doi.org/10.3390/antiox11112295 - 20 Nov 2022

Cited by 5 | Viewed by 2589

Abstract

The aim of this study was to investigate the effect of the use of green solvents, natural deep eutectic solvents (NaDES), in comparison with conventional solvents on the extraction of free unbound phenolic compounds and the antioxidant activity of extracts of dried bilberry fruit, bilberry leaves and green tea leaves. After preparation of the extracts via ultrasound-assisted extraction using NaDES and conventional solvents (water and ethanol), spectrophotometric determination of total phenolic and flavonoid content, HPLC analysis of extracted polyphenols and antioxidant determination using FRAP, DPPH and ABTS assays were conducted. The results showed that NaDES have a great potential as agents for the extraction of phenolic compounds with potent antioxidant activity; the highest values of phenolic content and antioxidant activity were detected in the samples obtained by extraction using the NaDES combination betaine + urea. The bilberry leaves exhibited the highest flavonoid content among all extracts and turned out to be more active than bilberry fruits, to which they are often just a by-product during processing. The most active extract of all was the betaine-urea green tea leaves extract. Further research into the most active NaDES extracts should be performed. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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17 pages, 1979 KiB

Open AccessArticle

Characterization of Polysaccharides Sequentially Extracted from Allium roseum Leaves and Their Hepatoprotective Effects against Cadmium Induced Toxicity in Mouse Liver

by Nesrine Teka, Fahad M. Alminderej, Ghada Souid, Yassine El-Ghoul, Didier Le Cerf and Hatem Majdoub

Antioxidants 2022, 11(10), 1866; https://doi.org/10.3390/antiox11101866 - 21 Sep 2022

Cited by 4 | Viewed by 2104

Abstract

Allium roseum is one of the medicinal plants of the Liliaceae family, widely used in the food industry and traditional medicine. It is known for its various biological properties, such as its antioxidant, antiviral, antidiabetic, and anti-inflammatory activities. The present work aims to extract the polysaccharides from Allium roseum leaves and evaluate their antioxidant activities and hepatoprotective effects in vivo. Three polysaccharides from the leaves of Allium roseum were sequentially extracted in three media: water, chelating, and basic, respectively. They were characterized by size exclusion chromatography, gas chromatography mass spectrometry, FTIR-ATR, and NMR spectroscopy (1D and 2D). The different polysaccharides principally consist of glucose, galactose, mannose, rhamnose, xylose, and galacturonic acid. The antioxidant activity and hepatoprotective effect of the extracts against Cd-caused oxidative stress in liver mouse were tested. Cd treatment, during 24 h, enhanced significantly lipid peroxidation by a high production of malondyaldehyd (MDA) and superoxide dismutase (SOD) activity. In contrast, catalase activity (CAT) was decreased after the same period of exposure to the metal. The polysaccharides pre-treatment improved the antioxidant defense system to a great degree, mainly explained by the modulating levels of oxydative stress biomarkers (MDA, SOD, and CAT). This research clearly shows that Allium roseum polysaccharides, especially those extracted in aqueous medium, can be used as natural antioxidants with hepatoprotective properties. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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17 pages, 1516 KiB

Open AccessArticle

Soluble Free, Esterified and Insoluble-Bound Phenolic Antioxidants from Chickpeas Prevent Cytotoxicity in Human Hepatoma HuH-7 Cells Induced by Peroxyl Radicals

by Adriano Costa de Camargo, Alina Concepción Alvarez, María Fernanda Arias-Santé, Juan Esteban Oyarzún, Marcelo E. Andia, Sergio Uribe, Paula Núñez Pizarro, Simón M. Bustos, Andrés R. Schwember, Fereidoon Shahidi and Raquel Bridi

Antioxidants 2022, 11(6), 1139; https://doi.org/10.3390/antiox11061139 - 10 Jun 2022

Cited by 8 | Viewed by 2315

Abstract

Chickpeas are rich sources of bioactive compounds such as phenolic acids, flavonoids, and isoflavonoids. However, the contribution of insoluble-bound phenolics to their antioxidant properties remains unclear. Four varieties of chickpeas were evaluated for the presence of soluble (free and esterified) and insoluble-bound phenolics as well as their antiradical activity, reducing power and inhibition of peroxyl-induced cytotoxicity in human HuH-7 cells. In general, the insoluble-bound fraction showed a higher total phenolic content. Phenolic acids, flavonoids, and isoflavonoids were identified and quantified by UPLC-MS/MS. Taxifolin was identified for the first time in chickpeas. However, m-hydroxybenzoic acid, taxifolin, and biochanin A were the main phenolics found. Biochanin A was mostly found in the free fraction, while m-hydroxybenzoic acid was present mainly in the insoluble-bound form. The insoluble-bound fraction made a significant contribution to the reducing power and antiradical activity towards peroxyl radical. Furthermore, all extracts decreased the oxidative damage of human HuH-7 cells induced by peroxyl radicals, thus indicating their hepatoprotective potential. This study demonstrates that the antioxidant properties and bioactive potential of insoluble-bound phenolics of chickpeas should not be neglected. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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28 pages, 1463 KiB

Open AccessReview

Importance of Insoluble-Bound Phenolics to the Antioxidant Potential Is Dictated by Source Material

by Fereidoon Shahidi and Abul Hossain

Antioxidants 2023, 12(1), 203; https://doi.org/10.3390/antiox12010203 - 15 Jan 2023

Cited by 18 | Viewed by 3528

Abstract

Insoluble-bound phenolics (IBPs) are extensively found in the cell wall and distributed in various tissues/organs of plants, mainly cereals, legumes, and pulses. In particular, IBPs are mainly distributed in the protective tissues, such as seed coat, pericarp, and hull, and are also available in nutritional tissues, including germ, epicotyl, hypocotyl radicle, and endosperm, among others. IBPs account for 20–60% of the total phenolics in food matrices and can exceed 70% in leaves, flowers, peels, pulps, seeds, and other counterparts of fruits and vegetables, and up to 99% in cereal brans. These phenolics are mostly covalently bound to various macromolecules such as hemicellulose, cellulose, structural protein, arabinoxylan, and pectin, which can be extracted by acid, alkali, or enzymatic hydrolysis along with various thermal and non-thermal treatments. IBPs obtained from various sources exhibited a wide range of biological activities, including antioxidant, anti-inflammatory, antihypertensive, anticancer, anti-obesity, and anti-diabetic properties. In this contribution, the chemistry, distribution, biological activities, metabolism, and extraction methods of IBPs, and how they are affected by various treatments, are summarized. In particular, the effect of thermal and non-thermal processing on the release of IBPs and their antioxidant potential is discussed. Full article

(This article belongs to the Special Issue Soluble and Insoluble-Bound Antioxidants)

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