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Keywords = flavoalkaloids

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21 pages, 2593 KiB  
Article
Diverse Structures of Tea Polyphenols from Rougui Wuyi Rock Tea and Their Potential as Inhibitor of 3C-like Protease
by Qing Sun, Xiaojuan Chen, Jie Zhang, Juan Song, Lan Yao, Yang Zhao, Guang Yang, Xiu Wang, Haizhen Liang and Baiping Ma
Molecules 2025, 30(5), 1024; https://doi.org/10.3390/molecules30051024 - 23 Feb 2025
Viewed by 1385
Abstract
Tea polyphenols, the primary bioactive constituents responsible for the various health benefits of tea, can be categorized into different subgroups according to their structural characteristics. However, the distinctions in antiviral activity among the diverse types of polyphenolic compounds remain unexplored. In the present [...] Read more.
Tea polyphenols, the primary bioactive constituents responsible for the various health benefits of tea, can be categorized into different subgroups according to their structural characteristics. However, the distinctions in antiviral activity among the diverse types of polyphenolic compounds remain unexplored. In the present study, fifty-eight tea polyphenols with varied structures, including eleven undescribed compounds, were isolated from Rougui Wuyi rock tea. Their molecular structures were elucidated using comprehensive analytical approaches of NMR, HRMS, CD spectroscopic data and acid hydrolysis. The isolated polyphenol analogs could be structurally classified into two main categories: flavan-3-ols, which include catechins, flavoalkaloids, procyanidins and theasinensins, and flavones, encompassing kaempferol, quercetin, myricetin, and their respective glycosides. The inhibitory activities of fifty-eight tea polyphenols against 3CLpro were assessed in vitro, and eighteen phenolic compounds exhibited inhibitory effects on 3CLpro, with IC50 values ranging from 9.8 μM to 61.1 μM. Among them, two types of tea polyphenols, catechin and flavoalkaloid derivatives, demonstrated superior inhibitory effects compared to other categories. The structure-activity relationship was further explored, and molecular docking analysis revealed that the differing inhibitory effects of catechin and flavoalkaloid derivatives were attributed to the variations in the number and positions of the hydrogen bond interactions with 3CLpro. This study provides a valuable understanding of tea polyphenols and supplies potential lead compounds for antiviral drugs. Full article
(This article belongs to the Topic Natural Compounds in Plants, 2nd Volume)
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19 pages, 4938 KiB  
Article
Inula salicina L.: Insights into Its Polyphenolic Constituents and Biological Activity
by Viktoria Ivanova, Paraskev Nedialkov, Petya Dimitrova, Tsvetelina Paunova-Krasteva and Antoaneta Trendafilova
Pharmaceuticals 2024, 17(7), 844; https://doi.org/10.3390/ph17070844 - 27 Jun 2024
Cited by 4 | Viewed by 2628
Abstract
In this study, UHPLC-HRMS analysis of the defatted methanol extract obtained from Inula salicina L. led to the identification of 58 compounds—hydroxycinnamic and hydroxybenzoic acids and their glycosides, acylquinic and caffeoylhexaric acids, and flavonoids and their glycosides. In addition, a new natural compound, [...] Read more.
In this study, UHPLC-HRMS analysis of the defatted methanol extract obtained from Inula salicina L. led to the identification of 58 compounds—hydroxycinnamic and hydroxybenzoic acids and their glycosides, acylquinic and caffeoylhexaric acids, and flavonoids and their glycosides. In addition, a new natural compound, N-(8-methylnepetin)-3-hydroxypiperidin-2-one was isolated and its structure was elucidated by NMR spectroscopy. The presence of a flavoalkaloid in genus Inula is described now for the first time. Chlorogenic acid was the main compound followed by 3,5-, 1,5- and 4,5-dicaffeoylquinic acids. The methanol extract was studied for its antioxidant potential by DPPH, ABTS, and FRAP assays and sun protective properties. In addition, a study was conducted to assess the effectiveness of the tested extract in inhibiting biofilm formation by Gram-positive and Gram-negative strains. Results from crystal violet tests revealed a notable decrease in biofilm mass due to the extract. The anti-biofilm efficacy was confirmed through the observation of the biofilm viability by live/dead staining. The obtained results showed that this plant extract could be used in the development of cosmetic products with antibacterial and sun protection properties. Full article
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27 pages, 5378 KiB  
Article
An Integrated—Omics/Chemistry Approach Unravels Enzymatic and Spontaneous Steps to Form Flavoalkaloidal Nudicaulin Pigments in Flowers of Papaver nudicaule L.
by Bettina Dudek, Anne-Christin Warskulat, Heiko Vogel, Natalie Wielsch, Riya Christina Menezes, Yvonne Hupfer, Christian Paetz, Steffi Gebauer-Jung, Aleš Svatoš and Bernd Schneider
Int. J. Mol. Sci. 2021, 22(8), 4129; https://doi.org/10.3390/ijms22084129 - 16 Apr 2021
Cited by 4 | Viewed by 3808
Abstract
Flower colour is an important trait for plants to attract pollinators and ensure their reproductive success. Among yellow flower pigments, the nudicaulins in Papaver nudicaule L. (Iceland poppy) are unique due to their rarity and unparalleled flavoalkaloid structure. Nudicaulins are derived from pelargonidin [...] Read more.
Flower colour is an important trait for plants to attract pollinators and ensure their reproductive success. Among yellow flower pigments, the nudicaulins in Papaver nudicaule L. (Iceland poppy) are unique due to their rarity and unparalleled flavoalkaloid structure. Nudicaulins are derived from pelargonidin glycoside and indole, products of the flavonoid and indole/tryptophan biosynthetic pathway, respectively. To gain insight into the molecular and chemical basis of nudicaulin biosynthesis, we combined transcriptome, differential gel electrophoresis (DIGE)-based proteome, and ultra-performance liquid chromatography–high resolution mass spectrometry (UPLC-HRMS)-based metabolome data of P. nudicaule petals with chemical investigations. We identified candidate genes and proteins for all biosynthetic steps as well as some key metabolites across five stages of petal development. Candidate genes of amino acid biosynthesis showed a relatively stable expression throughout petal development, whereas most candidate genes of flavonoid biosynthesis showed increasing expression during development followed by downregulation in the final stage. Notably, gene candidates of indole-3-glycerol-phosphate lyase (IGL), sharing characteristic sequence motifs with known plant IGL genes, were co-expressed with flavonoid biosynthesis genes, and are probably providing free indole. The fusion of indole with pelargonidin glycosides was retraced synthetically and promoted by high precursor concentrations, an excess of indole, and a specific glycosylation pattern of pelargonidin. Thus, nudicaulin biosynthesis combines the enzymatic steps of two different pathways with a spontaneous fusion of indole and pelargonidin glycoside under precisely tuned reaction conditions. Full article
(This article belongs to the Special Issue Pigments and Volatiles in Flowers)
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11 pages, 1225 KiB  
Article
Corynanthean-Epicatechin Flavoalkaloids from Corynanthe pachyceras
by Tapé Kouamé, Aboua Timothée Okpekon, Nicaise F. Bony, Amon Diane N’Tamon, Jean-François Gallard, Somia Rharrabti, Karine Leblanc, Elisabeth Mouray, Philippe Grellier, Pierre Champy, Mehdi A. Beniddir and Pierre Le Pogam
Molecules 2020, 25(11), 2654; https://doi.org/10.3390/molecules25112654 - 7 Jun 2020
Cited by 9 | Viewed by 3848
Abstract
Epicatechocorynantheines A and B, and epicatechocorynantheidine were isolated from the stem bark of Corynanthe pachyceras. These molecules were pinpointed, and their isolation streamlined, by a molecular networking strategy. The structural elucidation was unambiguously accomplished from HRMS and 1D/2D NMR data. These compounds [...] Read more.
Epicatechocorynantheines A and B, and epicatechocorynantheidine were isolated from the stem bark of Corynanthe pachyceras. These molecules were pinpointed, and their isolation streamlined, by a molecular networking strategy. The structural elucidation was unambiguously accomplished from HRMS and 1D/2D NMR data. These compounds represent the first examples of corynanthean-type alkaloids tethered with a flavonoid. Epicatechocorynantheidine notably instigated two connections between the monoterpene indole alkaloid and the flavonoid, yielding an unprecedented octacyclic appendage. These flavoalkaloids exerted moderate antiplasmodial activities. Full article
(This article belongs to the Section Natural Products Chemistry)
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