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Antioxidants from Natural Sources: Separation and Characterization

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

Deadline for manuscript submissions: closed (15 September 2021) | Viewed by 43280

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Special Issue Editor

Prof. Dr. Petras Rimantas Venskutonis

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Guest Editor

Kaunas University of Technology, Kaunas, Lithuania
Interests: isolation; fractionation, and characterization of natural antioxidants and other substances from various natural sources which are valuable for human consumption; particularly plant-origin materials and their processing byproducts; preferably using methods meeting green chemistry principles

Special Issue Information

Dear Colleagues,

Living organisms, through long periods of evolution, have developed various self-protection mechanisms and learned to biosynthesize a vast diversity of molecules which are important for survival, among them antioxidant properties possessing microconstituents. The interest in discovery of the structures of natural antioxidants, their isolation, purification, and, finally, application in foods, nutraceuticals, cosmeceuticals, and pharmaceuticals has remarkably increased during the last few decades. Consumer preferences towards natural additives and ingredients in foods and other products for human consumption have also fostered the search and characterization of natural antioxidants. Thousands of antioxidants belonging to various chemical classes have been isolated and characterized to date. For instance, a large number of polyphenolics antioxidants such as flavonoids, phenolic acids and their derivatives, carotenoids, terpenoids, vitamins, and others have been identified and quantified in various plants, while many antioxidant peptides have been reported in animal- and marine-origin materials. However, regardless of the various considerable scientific achievements, their industrial production and commercialization still remains a challenge requiring technological upscaling solutions and development of economically feasible processes. Natural antioxidants are usually incorporated in a very complex biomatrix, and their content may be rather small; therefore, development of effective separation methods of natural antioxidants remains a topical research issue. Depending on the expected application, the process may include several steps of isolation, fractionation, and purification. From this point of view, nutraceutical, cosmeceutical, and pharmaceutical applications require standardized ingredients with the specified purity and concentration of active constituents. Last but not least, green chemistry principles and the use of biorefining concept for developing zero-waste technological schemes have also become very important issues in modern society. The results of original studies as well as review manuscripts covering the above-defined topics are invited for submission to this Special Issue of Molecules.

Prof. Dr. Petras Rimantas Venskutonis
Guest Editor

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Keywords

extraction of natural antioxidants
fractionation of natural antioxidants
purification of natural antioxidants
biorefining of natural sources for antioxidants
characterization of natural antioxidants
radical scavenging capacity
chromatographic analysis of antioxidants
spectroscopic analysis of antioxidants
bio-guided assays of antioxidants

Published Papers (14 papers)

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Research

Jump to: Review

15 pages, 2895 KiB

Open AccessArticle

Cannabis sativa Extract Induces Apoptosis in Human Pancreatic 3D Cancer Models: Importance of Major Antioxidant Molecules Present Therein

by Fathi Emhemmed, Minjie Zhao, Selvi Yorulmaz, Damien Steyer, Celine Leitao, Marion Alignan, Muriel Cerny, Alexandra Paillard, Franck Milone Delacourt, Diane Julien-David and Christian D. Muller

Molecules 2022, 27(4), 1214; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27041214 - 11 Feb 2022

Cited by 4 | Viewed by 5323

Abstract

In recent years, interest in Cannabis sativa L. has been rising, as legislation is moving in the right direction. This plant has been known and used for thousands of years for its many active ingredients that lead to various therapeutic effects (pain management, anti-inflammatory, antioxidant, etc.). In this report, our objective was to optimize a method for the extraction of cannabinoids from a clone of Cannabis sativa L. #138 resulting from an agronomic test (LaFleur, Angers, FR). Thus, we wished to identify compounds with anticancer activity on human pancreatic tumor cell lines. Three static maceration procedures, with different extraction parameters, were compared based on their median inhibitory concentration (IC₅₀) values and cannabinoid extraction yield. As CBD emerged as the molecule responsible for inducing apoptosis in the human pancreatic cancer cell line, a CBD-rich cannabis strain remains attractive for therapeutic applications. Additionally, while gemcitabine, a gold standard drug in the treatment of pancreatic cancer, only triggers cell cycle arrest in G0/G1, CBD also activates the cell signaling cascade to lead to programmed cell death. Our results emphasize the potential of natural products issued from medicinal hemp for pancreatic cancer therapy, as they lead to an accumulation of intracellular superoxide ions, affect the mitochondrial membrane potential, induce G1 cell cycle arrest, and ultimately drive the pancreatic cancer cell to lethal apoptosis. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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18 pages, 2037 KiB

Open AccessArticle

The Effects of Acyl Chain Length on Antioxidant Efficacy of Mono- and Multi-Acylated Resveratrol: A Comparative Assessment

by Han Peng and Fereidoon Shahidi

Molecules 2022, 27(3), 1001; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27031001 - 02 Feb 2022

Cited by 10 | Viewed by 1685

Abstract

Acylated derivatives of the dietary phenolic, resveratrol, were prepared via enzymatic and chemical transesterification modification with selected vinyl fatty acids to expand the potential application of resveratrol and its acylated derivatives in functional supplement, cosmetic/skincare, and pharmaceutical fields. The acylation was implemented using eight vinyl fatty acids with varying chain lengths (C2:0-C18:0). Eight monoesters enzymatically prepared, eight diesters and four triesters, chemically prepared, were isolated and purified and identified via MS (mass spectra) or/and NMR (nuclear magnetic resonance). The lipophilicity of resveratrol and its acylated derivatives was calculated using ALOGPS 2.1. Compared with related acylated products, resveratrol itself rendered higher antioxidant efficacy in all the antioxidant assays, namely DPPH, ABTS, FRAP, and ferrous chelation tests. Within various ester derivatives of resveratrol, short-chain fatty acid mono- and di-substituted resveratrols, especially the resveratrol monoacetate/diacetate, exhibited higher antioxidant efficacy in DPPH and ABTS assays than the rest of resveratrol derivatives, but the medium-chain monoesters of resveratrol, including caproate, caprylate, caprate, and laurate, showed a higher metal ion chelation ability compared to other acylated resveratrols. These results imply that resveratrol derivatives may be used in lipidic media as health-beneficial antioxidants. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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18 pages, 1017 KiB

Open AccessArticle

Metabolomic Profiling and Antioxidant Activities of Breonadia salicina Using ¹H-NMR and UPLC-QTOF-MS Analysis

by Dorcas B. Tlhapi, Isaiah D. I. Ramaite and Chinedu P. Anokwuru

Molecules 2021, 26(21), 6707; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26216707 - 05 Nov 2021

Cited by 5 | Viewed by 2149

Abstract

Breonadia salicina (Vahl) Hepper and J.R.I. Wood is widely used in South Africa and some other African countries for treatment of various infectious diseases such as diarrhea, fevers, cancer, diabetes and malaria. However, little is known about the active constituents associated with the biological activities. This study is aimed at exploring the metabolomics profile and antioxidant constituents of B. salicina. The chemical profiles of the leaf, stem bark and root of B. salicina were comprehensively characterized using proton nuclear magnetic resonance (¹H-NMR) spectroscopy and ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). The antioxidant activities of the crude extracts, fractions and pure compounds were determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging and reducing power assays. A total of 25 compounds were tentatively identified using the UPLC-QTOF-MS. Furthermore, the ¹H-NMR fingerprint revealed that the different parts of plant had differences and similarities among the different crude extracts and fractions. The crude extracts and fractions of the root, stem bark and leaf showed the presence of α-glucose, β-glucose, glucose and fructose. However, catechin was not found in the stem bark crude extracts but was found in the fractions of the stem bark. Lupeol was present only in the root crude extract and fractions of the stem bark. Furthermore, 5-O-caffeoylquinic acid was identified in the methanol leaf extract and its respective fractions, while the crude extracts and fractions from the root and dichloromethane leaf revealed the presence of hexadecane. Column chromatography and preparative thin-layer chromatography were used to isolate kaempferol 3-O-(2″-O-galloyl)-glucuronide, lupeol, d-galactopyranose, bodinioside Q, 5-O-caffeoylquinic acid, sucrose, hexadecane and palmitic acid. The crude methanol stem bark showed the highest antioxidant activity in the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity with an IC₅₀ value of 41.7263 ± 7.6401 μg/mL, whereas the root crude extract had the highest reducing power activity with an IC_0.5 value of 0.1481 ± 0.1441 μg/mL. Furthermore, the ¹H-NMR and UPLC-QTOF-MS profiles showed the presence of hydroxycinnamic acids, polyphenols and flavonoids. According to a literature survey, these phytochemicals have been reported to display antioxidant activities. Therefore, the identified hydroxycinnamic acid (caffeic acid), polyphenol (ellagic acid) and flavonoids (catechin and (epi) gallocatechin) significantly contribute to the antioxidant activity of the different parts of plant of B. salicina. The results obtained in this study provides information about the phytochemistry and phytochemical compositions of Breonadia salicina, confirming that the species is promising in obtaining constituents with medicinal potential primarily antioxidant potential. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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21 pages, 1945 KiB

Open AccessArticle

Impact of Metallic Nanoparticles on In Vitro Culture, Phenolic Profile and Biological Activity of Two Mediterranean Lamiaceae Species: Lavandula viridis L’Hér and Thymus lotocephalus G. López and R. Morales

by Sandra Gonçalves, Inês Mansinhos, Raquel Rodríguez-Solana, Gema Pereira-Caro, José Manuel Moreno-Rojas and Anabela Romano

Molecules 2021, 26(21), 6427; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26216427 - 25 Oct 2021

Cited by 9 | Viewed by 1868

Abstract

Nanoparticles (NPs) recently emerged as new chemical elicitors acting as signaling agents affecting several processes in plant metabolism. The aim of this work was to investigate the impact of the addition of copper oxide (CuO), zinc oxide (ZnO) and iron oxide (Fe₃O₄) NPs (<100 nm) at different concentrations (1, 5 and 10 mg/L) to the culture media on several morphological, physiological and -biochemical parameters of in vitro shoot cultures of Lavandula viridis L’Hér and Thymus lotocephalus G. López and R. Morales (Lamiaceae), as well as on phenolic profile and bioactivity (antioxidant and enzyme inhibition capacities). Although some decreases in shoot number and length were observed in response to NPs, biomass production was not affected or was improved in both species. Most NPs treatments decreased total chlorophyll and carotenoid contents and increased malondialdehyde levels, an indicator of lipid peroxidation, in both species. HPLC-HR-MS analysis led to the identification of thirteen and twelve phenolic compounds, respectively, in L. viridis and T. lotocephalus extracts, being rosmarinic acid the major compound found in all the extracts. ZnO and Fe₃O₄ NPs induced an increase in total phenolic and rosmarinic acid contents in T. lotocephalus extracts. Additionally, some NPs treatments also increased antioxidant activity in extracts from this species and the opposite was observed for L. viridis. The capacity of the extracts to inhibit tyrosinase, acetylcholinesterase and butyrylcholinesterase enzymes was not considerably affected. Overall, NPs had a significant impact on different parameters of L. viridis and T. lotocephalus in vitro shoot cultures, although the results varied with the species and NPs type. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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12 pages, 440 KiB

Open AccessArticle

HPLC-DAD-qTOF Compositional Analysis of the Phenolic Compounds Present in Crude Tomato Protein Extracts Derived from Food Processing

by Ana Miklavčič Višnjevec, Paul W. Baker, Kelly Peeters, Matthew Schwarzkopf, Dominik Krienke and Adam Charlton

Molecules 2021, 26(21), 6403; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26216403 - 23 Oct 2021

Cited by 7 | Viewed by 2299

Abstract

The conversion of raw fruits and vegetables, including tomatoes into processed food products creates side streams of residues that can place a burden on the environment. However, these processed residues are still rich in bioactive compounds and in an effort to valorize these materials in tomato by-product streams, the main aim of this study is to extract proteins and identify the main phenolic compounds present in tomato pomace (TP), peel and skins (TPS) by HPLC-DAD-ESI-QTOF. Forty different phenolic compounds were identified in the different tomato extracts, encompassing different groups of phenolic compounds, including derivatives of simple phenolic acid derivatives, hydroxycinnamoylquinic acid, flavones, flavonones, flavonol, and dihydrochalcone. In the crude protein extract (TPE) derived from tomatoes, most of these compounds were still present, confirming that valuable phenolic compounds were not degraded during food processing of these co-product streams. Moreover, phenolic compounds present in the tomato protein crude extract could provide a valuable contribution to the required daily intake of phenolics that are usually supplied by consuming fresh vegetables and fruits. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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21 pages, 3205 KiB

Open AccessArticle

Phytochemical Profile, Free Radical Scavenging and Anti-Inflammatory Properties of Acalypha Indica Root Extract: Evidence from In Vitro and In Vivo Studies

by Ravi Sahukari, Jyothi Punabaka, Shanmugam Bhasha, Venkata Subbaiah Ganjikunta, Shanmugam Kondeti Ramudu, Sathyavelu Reddy Kesireddy, Weibing Ye and Mallikarjuna Korivi

Molecules 2021, 26(20), 6251; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26206251 - 15 Oct 2021

Cited by 6 | Viewed by 3152

Abstract

In our in vitro and in vivo studies, we used Acalypha indica root methanolic extract (AIRME), and investigated their free radical scavenging/antioxidant and anti-inflammatory properties. Primarily, phytochemical analysis showed rich content of phenols (70.92 mg of gallic acid/g) and flavonoids (16.01 mg of rutin/g) in AIRME. We then performed HR-LC-MS and GC-MS analyses, and identified 101 and 14 phytochemical compounds, respectively. Among them, ramipril glucuronide (1.563%), antimycin A (1.324%), swietenine (1.134%), quinone (1.152%), oxprenolol (1.118%), choline (0.847%), bumetanide (0.847%) and fenofibrate (0.711%) are the predominant phytomolecules. Evidence from in vitro studies revealed that AIRME scavenges DPPH and hydroxyl radicals in a concentration dependent manner (10–50 μg/mL). Similarly, hydrogen peroxide and lipid peroxidation were also remarkably inhibited by AIRME as concentration increases (20–100 μg/mL). In vitro antioxidant activity of AIRME was comparable to ascorbic acid treatment. For in vivo studies, carrageenan (1%, sub-plantar) was injected to rats to induce localized inflammation. Acute inflammation was represented by paw-edema, and significantly elevated (p < 0.05) WBC, platelets and C-reactive protein (CRP). However, AIRME pretreatment (150/300 mg/kg bodyweight) significantly (p < 0.05) decreased edema volume. This was accompanied by a significant (p < 0.05) reduction of WBC, platelets and CRP with both doses of AIRME. The decreased activities of superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase in paw tissue were restored (p < 0.05 / p < 0.01) with AIRME in a dose-dependent manner. Furthermore, AIRME attenuated carrageenan-induced neutrophil infiltrations and vascular dilation in paw tissue. For the first time, our findings demonstrated the potent antioxidant and anti-inflammatory properties of AIRME, which could be considered to develop novel anti-inflammatory drugs. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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14 pages, 1184 KiB

Open AccessArticle

Identification of a Sesquiterpene Lactone from Arctium lappa Leaves with Antioxidant Activity in Primary Human Muscle Cells

by Nour El Khatib, Sylvie Morel, Gérald Hugon, Sylvie Rapior, Gilles Carnac and Nathalie Saint

Molecules 2021, 26(5), 1328; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26051328 - 02 Mar 2021

Cited by 8 | Viewed by 2309

Abstract

Many pathologies affecting muscles (muscular dystrophies, sarcopenia, cachexia, renal insufficiency, obesity, diabetes type 2, etc.) are now clearly linked to mechanisms involving oxidative stress. In this context, there is a growing interest in exploring plants to find new natural antioxidants to prevent the appearance and the development of these muscle disorders. In this study, we investigated the antioxidant properties of Arctium lappa leaves in a model of primary human muscle cells exposed to H₂O₂ oxidative stress. We identified using bioassay-guided purification, onopordopicrin, a sesquiterpene lactone as the main molecule responsible for the antioxidant activity of A. lappa leaf extract. According to our findings, onopordopicrin inhibited the H₂O₂-mediated loss of muscle cell viability, by limiting the production of free radicals and abolishing DNA cellular damages. Moreover, we showed that onopordopicrin promoted the expression of the nuclear factor-erythroid-2-related factor 2 (Nrf2) downstream target protein heme oxygenase-1 (HO-1) in muscle cells. By using siRNA, we demonstrated that the inhibition of the expression of Nrf2 reduced the protective effect of onopordopicrin, indicating that the activation of the Nrf2/HO-1 signaling pathway mediates the antioxidant effect of onopordopicrin in primary human muscle cells. Therefore, our results suggest that onopordopicrin may be a potential therapeutic molecule to fight against oxidative stress in pathological specific muscle disorders. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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11 pages, 662 KiB

Open AccessArticle

Effect of Enzymatic, Ultrasound, and Reflux Extraction Pretreatments on the Yield and Chemical Composition of Essential Oils

by Anđela Miljanović, Ana Bielen, Dorotea Grbin, Zvonimir Marijanović, Martina Andlar, Tonči Rezić, Sunčica Roca, Igor Jerković, Dražen Vikić-Topić and Maja Dent

Molecules 2020, 25(20), 4818; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25204818 - 20 Oct 2020

Cited by 18 | Viewed by 3321

Abstract

The effect of different hydrodistillation pretreatments, namely, reflux extraction, reflux extraction with the addition of cell wall-degrading enzymes, and ultrasound, on the yield and chemical composition of essential oils of sage, bay laurel, and rosemary was examined. All pretreatments improved essential oil yield compared to no-pretreatment control (40–64% yield increase), while the oil quality remained mostly unchanged (as shown by statistical analysis of GC-MS results). However, enzyme-assisted reflux extraction pretreatment did not significantly outperform reflux extraction (no-enzyme control), suggesting that the observed yield increase was mostly a consequence of reflux extraction and enzymatic activity had only a minute effect. Thus, we show that ultrasound and reflux extraction pretreatments are beneficial in the production of essential oils of selected Mediterranean plants, but the application of enzymes has to be carefully re-evaluated. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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13 pages, 2582 KiB

Open AccessArticle

Preparation, Characterization and Antioxidant Activities of Kelp Phlorotannin Nanoparticles

by Ying Bai, Yihan Sun, Yue Gu, Jie Zheng, Chenxu Yu and Hang Qi

Molecules 2020, 25(19), 4550; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25194550 - 05 Oct 2020

Cited by 18 | Viewed by 2651

Abstract

Phlorotannins are a group of major polyphenol secondary metabolites found only in brown algae and are known for their bioactivities and multiple health benefits. However, they can be oxidized due to external factors and their bioavailability is low due to their low water solubility. In this study, the potential of utilizing nanoencapsulation with polyvinylpyrrolidone (PVP) to improve various activities of phlorotannins was explored. Phlorotannins encapsulated by PVP nanoparticles (PPNPS) with different loading ratios were prepared for characterization. Then, the PPNPS were evaluated for in vitro controlled release of phlorotannin, toxicity and antioxidant activities at the ratio of phlorotannin to PVP 1:8. The results indicated that the PPNPS showed a slow and sustained kinetic release of phlorotannin in simulated gastrointestinal fluids, they were non-toxic to HaCaT keratinocytes and they could reduce the generation of endogenous reactive oxygen species (ROS). Therefore, PPNPS have the potential to be a useful platform for the utilization of phlorotannin in both pharmaceutical and cosmetics industries. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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23 pages, 3918 KiB

Open AccessArticle

Accumulation of Phenolic Compounds and Antioxidant Capacity during Berry Development in Black ‘Isabel’ Grape (Vitis vinifera L. x Vitis labrusca L.)

by Aynur Kurt-Celebi, Nesrin Colak, Sema Hayirlioglu-Ayaz, Sanja Kostadinović Veličkovska, Fidanka Ilieva, Tuba Esatbeyoglu and Faik Ahmet Ayaz

Molecules 2020, 25(17), 3845; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25173845 - 24 Aug 2020

Cited by 9 | Viewed by 3688

Abstract

Grapes are one of the most economically important fruits in the world and are of considerable benefit to human health due to their phenolic compounds. The black ‘Isabel’ grape (V. vinifera L. xV. labrusca L.) is widely grown in the Black Sea region of Turkey, where it is attracting increasing interest. The aim of this study was to investigate phenolic compounds and antioxidant capacity (DPPH (2,2-diphenyl-1-picrylhydrazyl) and CUPRAC (CUPric Reducing Antioxidant Capacity)) in the grape during berry development, which has been not reported yet from the region. A trend towards an increase in total phenolic compounds, flavonoid, and anthocyanin contents and antioxidant capacity values was observed from un-ripened to overly ripened berries. In addition, anthocyanins in berries and proanthocyanidins seeds were characterized during berry development. Accordingly, malvidin-3-O-glucoside was the major anthocyanin in skin (1.05–1729 mg/kg fresh weight (fw)) and whole berry (0.23–895 mg/kg fw), followed by the content of peonidin-3-O-glucoside (0.98–799 mg/kg fw and 0.15–202 mg/kg fw, respectively). After veraison (onset of ripening or change of color in the grape berries), all proanthocyanidins showed a gradual decrease through ripening. The results showed that anthocyanins and proanthocyanidins in the grape showed significant stage-dependent changes with positive or negative strong correlations. Considering the phenolic compounds, an optimum harvest date of the grape might be suggested between mid-September and mid-October (263 and 293 DAFBs). Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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18 pages, 3433 KiB

Open AccessArticle

Physicochemical Properties, Antioxidant and Antidiabetic Activities of Polysaccharides from Quinoa (Chenopodium quinoa Willd.) Seeds

by Minghui Tan, Senlin Chang, Jianing Liu, Hang Li, Pengwei Xu, Peidong Wang, Xiaodong Wang, Mingxia Zhao, Bing Zhao, Liwei Wang and Qingsheng Zhao

Molecules 2020, 25(17), 3840; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25173840 - 24 Aug 2020

Cited by 36 | Viewed by 3369

Abstract

Quinoa is known for its rich nutrients and bioactive compounds. In order to elucidate the preliminary structural characteristics and biological activity of polysaccharides from quinoa (QPs), five crude polysaccharides (QPE50, QPE60, QPE70, QPE80 and QPE90) were successively fractionated by gradient ethanol, and their physicochemical properties, antioxidant and antidiabetic activities were analyzed. The results implied that their total sugar contents were 52.82%, 63.69%, 67.15%, 44.56%, and 41.01%, and their weight-average molecular weights were 13,785 Da, 6489 Da, 4732 Da, 3318 Da, and 1960 Da, respectively. Glucose was a predominantly monosaccharide in these QPs, which together in QPE50, QPE60, QPE70, QPE80, and QPE90, respectively, made up 94.37%, 87.92%, 92.21%, 100%, and 100% of the total polysaccharide. Congo red test showed that all five QPs contained triple-helix structure. The Fourier transform-infrared spectroscopy (FT-IR) and X-ray diffractometry (XRD) results suggest that the QPs form a semi-crystalline polymer constituted typical functional groups of polysaccharide including CO, CH and OH. The thermogravimetric analysis (TGA) of QPs showed that weight loss was at about 200 °C and 320 °C. The observation from scanning electron microscope (SEM) and atomic force microscope (AFM) image indicated that the morphology of QPs exhibited spherical shape. Antioxidant and antidiabetic assay exhibited that all five QPs samples had certain antioxidant and antidiabetic activities, and QPE90 showed the best antioxidant and antidiabetic activity. Overall, QPs present a promising natural source of food antioxidants and antidiabetic agents. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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Review

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30 pages, 8251 KiB

Open AccessReview

Free and Esterified Tocopherols, Tocotrienols and Other Extractable and Non-Extractable Tocochromanol-Related Molecules: Compendium of Knowledge, Future Perspectives and Recommendations for Chromatographic Techniques, Tools, and Approaches Used for Tocochromanol Determination

by Paweł Górnaś, Georgijs Baškirovs and Aleksander Siger

Molecules 2022, 27(19), 6560; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27196560 - 04 Oct 2022

Cited by 13 | Viewed by 2138

Abstract

Free and esterified (bound) tocopherols, tocotrienols and other tocochromanol-related compounds, often referred to “tocols”, are lipophilic antioxidants of great importance for health. For instance, α-tocopherol is the only tocochromanol with vitamin E activity, while tocotrienols have a positive impact on health and are proposed in the prevention and therapy of so-called modern diseases. Tocopherols, tocotrienols and plastochromanol-8 are the most well-known tocochromanols; in turn, knowledge about tocodienols, tocomonoenols, and other rare tocochromanol-related compounds is limited due to several challenges in analytical chemistry and/or low concentration in plant material. The presence of free, esterified, and non-extractable tocochromanols in plant material as well as their biological function, which may be of great scientific, agricultural and medicinal importance, is also poorly studied. Due to the lack of modern protocols as well as equipment and tools, for instance, techniques suitable for the efficient and simultaneous chromatographical separation of major and minor tocochromanols, the topic requires attention and new solutions, and/or standardization, and proper terminology. This review discusses the advantages and disadvantages of different chromatographic techniques, tools and approaches used for the separation and detection of different tocochromanols in plant material and foodstuffs. Sources of tocochromanols and procedures for obtaining different tocochromanol analytical standards are also described. Finally, future challenges are discussed and perspective green techniques for tocochromanol determination are proposed along with best practice recommendations. The present manuscript aims to present key aspects and protocols related to tocochromanol determination, correct identification, and the interpretation of obtained results. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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40 pages, 5799 KiB

Open AccessReview

Six Common Herbs with Distinctive Bioactive, Antioxidant Components. A Review of Their Separation Techniques

by Antigoni Oreopoulou, Evanthia Choulitoudi, Dimitrios Tsimogiannis and Vassiliki Oreopoulou

Molecules 2021, 26(10), 2920; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26102920 - 14 May 2021

Cited by 13 | Viewed by 4336

Abstract

Rosemary, oregano, pink savory, lemon balm, St. John’s wort, and saffron are common herbs wildly grown and easily cultivated in many countries. All of them are rich in antioxidant compounds that exhibit several biological and health activities. They are commercialized as spices, traditional medicines, or raw materials for the production of essential oils. The whole herbs or the residues of their current use are potential sources for the recovery of natural antioxidant extracts. Finding effective and feasible extraction and purification methods is a major challenge for the industrial production of natural antioxidant extracts. In this respect, the present paper is an extensive literature review of the solvents and extraction methods that have been tested on these herbs. Green solvents and novel extraction methods that can be easily scaled up for industrial application are critically discussed. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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20 pages, 3938 KiB

Open AccessReview

Environmentally Friendly Techniques and Their Comparison in the Extraction of Natural Antioxidants from Green Tea, Rosemary, Clove, and Oregano

by Mariel Calderón-Oliver and Edith Ponce-Alquicira

Molecules 2021, 26(7), 1869; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26071869 - 26 Mar 2021

Cited by 34 | Viewed by 3762

Abstract

Many current food and health trends demand the use of more ecological, sustainable, and environmentally friendly techniques for the extraction of bioactive compounds, including antioxidants. However, extraction yields and final antioxidant activities vary between sources and are highly influenced by the given extraction method and nature and ratio of the employed solvent, especially for total polyphenols, flavonoids, and anthocyanins, which are well recognized as natural antioxidants with food applications. This review focused on the most common extraction techniques and potential antioxidant activity in the food industry for various natural antioxidant sources, such as green tea, rosemary, clove, and oregano. Green extraction techniques have been proven to be far more efficient, environmentally friendly, and economical. In general, these techniques include the use of microwaves, ultrasound, high hydrostatic pressure, pulsed electric fields, enzymes, and deep eutectic solvents, among others. These extraction methods are described here, including their advantages, disadvantages, and applications. Full article

(This article belongs to the Special Issue Antioxidants from Natural Sources: Separation and Characterization)

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Antioxidants from Natural Sources: Separation and Characterization

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