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15 pages, 2734 KiB

Open AccessArticle

Catechins and Selenium Species—How They React with Each Other

by Aleksandra Sentkowska and Krystyna Pyrzynska

Molecules 2023, 28(15), 5897; https://doi.org/10.3390/molecules28155897 - 05 Aug 2023

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The combination of selenium and tea infusion, both with antioxidant properties, has potentially complementary mechanisms of action. Se-enriched tea has been considered as a possible Se supplement and a functional beverage to reduce the health risk of Se deficiency. This work investigated the [...] Read more.

The combination of selenium and tea infusion, both with antioxidant properties, has potentially complementary mechanisms of action. Se-enriched tea has been considered as a possible Se supplement and a functional beverage to reduce the health risk of Se deficiency. This work investigated the interactions between plant catechins present in tea infusions and selenium species based on changes in the concentration of both reagents, their stability in aqueous solutions, and the possibilities of selenonanoparticles (SeNPs) formation. Selenium species exhibited instability both alone in their standard solutions and in the presence of studied catechins; selenocystine appeared as the most unstable. The recorded UV–Vis absorption spectra indicated the formation of SeNPs in the binary mixtures of catechins and selenite. SeNPs have also formed with diameters smaller than 100 nm when selenite and selenomethionine were added to tea infusions. This is an advantage from the point of view of potential medical applications. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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13 pages, 1807 KiB

Open AccessArticle

Antioxidant Guided Fractionation of Blackberry Polyphenols Show Synergistic Role of Catechins and Ellagitannins

by Katerina Tzima, Gontorn Putsakum and Dilip K. Rai

Molecules 2023, 28(4), 1933; https://doi.org/10.3390/molecules28041933 - 17 Feb 2023

Viewed by 1269

Abstract

In the present study, blackberry extract was prepared using a previously optimized solid–liquid extraction method in 70% aqueous acetone aimed at the recovery of its principal phenolics. Subsequently, 0.5 g of freeze-dried extract was subjected to flash chromatography fractionation, which was conducted on [...] Read more.

In the present study, blackberry extract was prepared using a previously optimized solid–liquid extraction method in 70% aqueous acetone aimed at the recovery of its principal phenolics. Subsequently, 0.5 g of freeze-dried extract was subjected to flash chromatography fractionation, which was conducted on a C18 column using a binary solvent system of water and methanol at 10 mL/min. The total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) activities of the obtained 42 flash fractions were determined, and a strong positive correlation (r ≥ 0.986) was exhibited among them. Furthermore, the graph of the antioxidant indices of the flash fractions resembled the flash chromatogram, suggesting a good correlation among the compounds within the chromatographic peaks and the antioxidant indices. LC-MS/MS identified as many 28 phenolics, including cinnamtannin A2 reported for the first time in blackberries. This study further established the role of dominant anthocyanins (cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside), but uniquely those of ellagitannins and catechins on the antioxidant capacity of blackberries. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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17 pages, 3061 KiB

Open AccessArticle

NMR-Based Metabolomics: A New Paradigm to Unravel Defense-Related Metabolites in Insect-Resistant Cotton Variety through Different Multivariate Data Analysis Approaches

by Anam Amin Shami, Muhammad Tayyab Akhtar, Muhammad Waseem Mumtaz, Hamid Mukhtar, Amna Tahir, Syed Shahzad-ul-Hussan, Safee Ullah Chaudhary, Bushra Muneer, Hafsa Iftikhar and Marios Neophytou

Molecules 2023, 28(4), 1763; https://doi.org/10.3390/molecules28041763 - 13 Feb 2023

Cited by 1 | Viewed by 1761

Abstract

Cotton (Gossypium hirsutum) is an economically important crop and is widely cultivated around the globe. However, the major problem of cotton is its high vulnerability to biotic and abiotic stresses. It has been around three decades since the cotton plant was [...] Read more.

Cotton (Gossypium hirsutum) is an economically important crop and is widely cultivated around the globe. However, the major problem of cotton is its high vulnerability to biotic and abiotic stresses. It has been around three decades since the cotton plant was genetically engineered with genes encoding insecticidal proteins (mainly Cry proteins) with an aim to protect it against insect attack. Several studies have been reported on the impact of these genes on cotton production and fiber quality. However, the metabolites responsible for conferring resistance in genetically modified cotton need to be explored. The current work aims to unveil the key metabolites responsible for insect resistance in Bt cotton and also compare the conventional multivariate analysis methods with deep learning approaches to perform clustering analysis. We aim to unveil the marker compounds which are responsible for inducing insect resistance in cotton plants. For this purpose, we employed 1H-NMR spectroscopy to perform metabolite profiling of Bt and non-Bt cotton varieties, and a total of 42 different metabolites were identified in cotton plants. In cluster analysis, deep learning approaches (linear discriminant analysis (LDA) and neural networks) showed better separation among cotton varieties compared to conventional methods (principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLSDA)). The key metabolites responsible for inter-class separation were terpinolene, α-ketoglutaric acid, aspartic acid, stigmasterol, fructose, maltose, arabinose, xylulose, cinnamic acid, malic acid, valine, nonanoic acid, citrulline, and shikimic acid. The metabolites which regulated differently with the level of significance p < 0.001 amongst different cotton varieties belonged to the tricarboxylic acid cycle (TCA), Shikimic acid, and phenylpropanoid pathways. Our analyses underscore a biosignature of metabolites that might involve in inducing insect resistance in Bt cotton. Moreover, novel evidence from our study could be used in the metabolic engineering of these biological pathways to improve the resilience of Bt cotton against insect/pest attacks. Lastly, our findings are also in complete support of employing deep machine learning algorithms as a useful tool in metabolomics studies. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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17 pages, 2037 KiB

Open AccessArticle

Using HPLC with In-Column Derivatization to Authenticate Coffee Samples

by Corey W. Manwaring, Jake A. Cravino, Margi Patel, Jonathan G. H. Stathakis, Arianne Soliven, Thirada Suktham and Ross Andrew Shalliker

Molecules 2023, 28(4), 1651; https://doi.org/10.3390/molecules28041651 - 08 Feb 2023

Cited by 3 | Viewed by 1821

Abstract

Coffee is one of the world’s most popular beverages, with the global coffee capsule market worth over USD 4 billion and growing. The incidence of coffee fraud is estimated to be up to one in five coffees being contaminated with cheaper blends of [...] Read more.

Coffee is one of the world’s most popular beverages, with the global coffee capsule market worth over USD 4 billion and growing. The incidence of coffee fraud is estimated to be up to one in five coffees being contaminated with cheaper blends of coffee. Given the worsening extent of climate change, coffee crop yields are harder to maintain, while demand is increasing. The 2021 Brazil frost delaying or destroying many coffee crops is an example. Hence, the incidence of coffee fraud is expected to increase, and as the market becomes more complex, there needs to be faster, easier, and more robust means of real-time coffee authentication. In this study, we propose the use of novel approaches to postcolumn derivatization (termed herein as in-column derivatization) to visualize the antioxidant profiles of coffee samples, to be later used as indicators for authentication purposes. We propose three simple mathematical similarity metrics for the real-time identification of unknown coffee samples from a sample library. Using the CUPRAC assay, and these metrics, we demonstrate the capabilities of the technique to identify unknown coffee samples from within our library of thirty. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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11 pages, 1692 KiB

Open AccessArticle

Identification of Unstable Ellagitannin Metabolites in the Leaves of Quercus dentata by Chemical Derivatization

by Zhang-Bin Liu, Yosuke Matsuo, Yoshinori Saito, Yong-Lin Huang, Dian-Peng Li and Takashi Tanaka

Molecules 2023, 28(3), 1246; https://doi.org/10.3390/molecules28031246 - 27 Jan 2023

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Abstract

The identification of unstable metabolites of ellagitannins having ortho-quinone structures or reactive carbonyl groups is important to clarify the biosynthesis and degradation of ellagitannins. Our previous studies on the degradation of vescalagin, a major ellagitannin of oak young leaves, suggested that the initial [...] Read more.

The identification of unstable metabolites of ellagitannins having ortho-quinone structures or reactive carbonyl groups is important to clarify the biosynthesis and degradation of ellagitannins. Our previous studies on the degradation of vescalagin, a major ellagitannin of oak young leaves, suggested that the initial step of the degradation is regioselective oxidation to generate a putative quinone intermediate. However, this intermediate has not been identified yet. In this study, young leaves of Quercus dentata were extracted with 80% acetonitrile containing 1,2-phenylenediamine to trap unstable ortho-quinone metabolites, and subsequent chromatographic separation afforded a phenazine derivative of the elusive quinone intermediate of vescalagin. In addition, phenylenediamine adducts of liquidambin and dehydroascorbic acid were obtained, which is significant because liquidambin is a possible biogenetic precursor of C-glycosidic ellagitannins and ascorbic acid participates in the production of another C-glycosidic ellagitannin in matured oak leaves. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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15 pages, 4057 KiB

Open AccessArticle

Neuroprotective Effect of Polyphenol Extracts from Terminalia chebula Retz. against Cerebral Ischemia-Reperfusion Injury

by Kuan Lin, Mei Zhou, Changlong Leng, Xiaoqing Tao, Rong Zhou, Youwei Li, Binlian Sun, Xiji Shu and Wei Liu

Molecules 2022, 27(19), 6449; https://doi.org/10.3390/molecules27196449 - 30 Sep 2022

Cited by 6 | Viewed by 1740

Abstract

Current therapies for ischemic stroke are insufficient due to the lack of specific drugs. This study aimed to investigate the protective activity of polyphenol extracts from Terminalia chebula against cerebral ischemia-reperfusion induced damage. Polyphenols of ethyl acetate and n-butanol fractions were extracted from [...] Read more.

Current therapies for ischemic stroke are insufficient due to the lack of specific drugs. This study aimed to investigate the protective activity of polyphenol extracts from Terminalia chebula against cerebral ischemia-reperfusion induced damage. Polyphenols of ethyl acetate and n-butanol fractions were extracted from T. chebula. BV2 microglial cells exposed to oxygen-glucose deprivation/reoxygenation and mice subjected to middle cerebral artery occlusion/reperfusion were treated by TPE and TPB. Cell viability, cell morphology, apoptosis, mitochondrial membrane potential, enzyme activity and signaling pathway related to oxidative stress were observed. We found that TPE and TPB showed strong antioxidant activity in vitro. The protective effects of TPE and TPB on cerebral ischemia-reperfusion injury were demonstrated by enhanced antioxidant enzyme activities, elevated level of the nucleus transportation of nuclear factor erythroid 2-related factor 2 and expressions of antioxidant proteins, with a simultaneous reduction in cell apoptosis and reactive oxygen species level. In conclusion, TPE and TPB exert neuroprotective effects by stimulating the Nrf2 signaling pathway, thereby inhibiting apoptosis. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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14 pages, 674 KiB

Open AccessArticle

Pitahaya Peel: A By-Product with Great Phytochemical Potential, Biological Activity, and Functional Application

by Sandra N. Jimenez-Garcia, Lina Garcia-Mier, Xóchitl S. Ramirez-Gomez, Humberto Aguirre-Becerra, Alexandro Escobar-Ortiz, Luis M. Contreras-Medina, Juan F. Garcia-Trejo and Ana A. Feregrino-Perez

Molecules 2022, 27(16), 5339; https://doi.org/10.3390/molecules27165339 - 22 Aug 2022

Cited by 6 | Viewed by 2283

Abstract

Hylocereus spp. present two varieties of commercial interest due to their color, organoleptic characteristics, and nutritional contribution, such as Hylocerous polyrhizus and Selenicerus undatus. The fruit recognized as dragon fruit or Pitahaya is an exotic fruit whose pulp is consumed, while the [...] Read more.

Hylocereus spp. present two varieties of commercial interest due to their color, organoleptic characteristics, and nutritional contribution, such as Hylocerous polyrhizus and Selenicerus undatus. The fruit recognized as dragon fruit or Pitahaya is an exotic fruit whose pulp is consumed, while the peel is discarded during the process. Studies indicate that the pulp has vitamin C and betalains, and seeds are rich in essential fatty acids, compounds that can contribute to the prevention of chronic non-communicable diseases (cancer, hypertension, and diabetes). In the present study, polyphenolic compounds, biological activity, and fatty acids present in the peel of the two varieties of pitahaya peel were evaluated, showing as a result that the variety S. undatus had higher antioxidant activity with 51% related to the presence of flavonoids 357 mgRE/g sample and fatty acids (hexadecanoic acid and linoleate) with 0.310 and 0.248 mg AG/g sample, respectively. On the other hand, H. polyrhizuun showed a significant difference in the inhibitory activity of amylase and glucosidase enzymes with 68% and 67%, respectively. We conclude that pitahaya peel has potential health effects and demonstrate that methylated fatty acids could be precursors to betalain formation, as well as showing effects against senescence and as a biological control against insects; in the same way, the peel can be reused as a by-product for the extraction of important enzymes in the pharmaceutical and food industry. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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Review

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42 pages, 9534 KiB

Open AccessReview

Spiro-Flavonoids in Nature: A Critical Review of Structural Diversity and Bioactivity

by Łukasz Pecio, Solomiia Pecio, Tomasz Mroczek and Wiesław Oleszek

Molecules 2023, 28(14), 5420; https://doi.org/10.3390/molecules28145420 - 14 Jul 2023

Viewed by 1260

Abstract

Based on the literature data from 1973 to 2022, this work summarizes reports on spiro-flavonoids with a spiro-carbon at the center of their structure and how this affects their isolation methods, stereochemistry, and biological activity. The review collects 65 unique structures, including spiro-biflavonoids, [...] Read more.

Based on the literature data from 1973 to 2022, this work summarizes reports on spiro-flavonoids with a spiro-carbon at the center of their structure and how this affects their isolation methods, stereochemistry, and biological activity. The review collects 65 unique structures, including spiro-biflavonoids, spiro-triflavonoids, spiro-tetraflavonoids, spiro-flavostilbenoids, and scillascillin-type homoisoflavonoids. Scillascillin-type homoisoflavonoids comprise spiro[bicyclo[4.2.0]octane-7,3′-chromane]-1(6),2,4-trien-4′-one, while the other spiro-flavonoids contain either 2H,2′H-3,3′-spirobi[benzofuran]-2-one or 2′H,3H-2,3′-spirobi[benzofuran]-3-one in the core of their structures. Spiro-flavonoids have been described in more than 40 species of eight families, including Asparagaceae, Cistaceae, Cupressaceae, Fabaceae, Pentaphylacaceae, Pinaceae, Thymelaeaceae, and Vitaceae. The possible biosynthetic pathways for each group of spiro-flavonoids are summarized in detail. Anti-inflammatory and anticancer activities are the most important biological activities of spiro-flavonoids, both in vitro and in vivo. Our work identifies the most promising natural sources, the existing challenges in assigning the stereochemistry of these compounds, and future research perspectives. Full article

(This article belongs to the Special Issue Natural Polyphenols: Isolation, Characterization and Health Benefits)

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