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Artykuły w czasopismach na temat "Coumarin ring"
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Prahadeesh, N., Maheswaran Sithambaresan i Umaramani Mathiventhan. "A Study on Hydrogen Peroxide Scavenging Activity and Ferric Reducing Ability of Simple Coumarins". Emerging Science Journal 2, nr 6 (13.12.2018): 417. http://dx.doi.org/10.28991/esj-2018-01161.
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Coumarin compounds are δ-lactones where α-pyrone ring is fused with benzene ring. Coumarins are widely distributed in the plant kingdom as well as they are very important in synthetic organic chemistry. Coumarins have great interest because of their abundance in nature and diverse pharmacological activities including antibacterial, antiviral, antipyretic, and anticoagulant, antioxidant, anti-inflammatory and anticancer. This study focused on synthesizing different simple Coumarins and studying their antioxidant activity. Four simple Coumarins (Coumarin (C1), 4-hydroxy coumarin (C2), 7-hydroxy coumarin (C3) and 7-hydoxy-4-methyl coumarin (C4)) were synthesized by using standard methods and were characterized by using UV, IR, 1H and 13C NMR spectra. Antioxidant activity of the simple Coumarins was studied by using standard FRAP assay and Hydrogen peroxide assay and expressed as FRAP value (mmol Fe2+/g) and IC50 value (mg/dm-3) respectively. Ascorbic acid was used as standard. All synthesized simple Coumarins showed both antioxidant activities. Hydroxyl Coumarins (C2, C3 and C4) showed higher activities in both cases than C1. Among the hydroxyl Coumarins C3 showed highest hydrogen peroxide scavenging activity and Ferric reducing capacity too. Antioxidant power of the tested simple Coumarins in decreasing order was C3, C2, C4 and C1 in both cases. But the hydrogen peroxide scavenging activity and Ferric reducing capacity of the all synthesized simple Coumarins were lower when compared to standard ascorbic acid.
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Mohan, Resmi, M. Vidhyalakshmi i Venkatasubramanian Sivakumar. "Microwave Assisted Rapid Extraction and Characterization of Coumarin from Fig Plant (Ficus carica)". Asian Journal of Science and Applied Technology 8, nr 1 (5.05.2019): 1–4. http://dx.doi.org/10.51983/ajsat-2019.8.1.1043.
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Coumarins are fragrant natural bioactive organic compound find application as aroma, flavor and wide medicinal use. Fig plant (Ficus Carica) is a very good source of Coumarins. Coumarins are a member of the benzopyrone family and it has a benzene ring joined to a pyrone ring. There is a need for effective extraction and purification of Coumarins from plant materials. Different methods of extraction of Courmarin from Ficus Carica has been studied in this paper, among them, microwave extraction (180 W power) provided rapid extraction with 10 minutes time with extract yield of 0.67 g as compared to that of 1 hour of water bath extraction at 60C. Coumarin was isolated from the crude extract using NaOH and petroleum ether and their presence was characterized confirmed using UV spectroscopy, IR spectroscopy, TLC and fluorescence test. The antibacterial activity of coumarin was also evaluated using disc diffusion method and Minimum Inhibition Count (MIC). The present study analyzes and provides method of microwave assisted rapid extraction of Coumarin from Fig plant (Ficus Carica) and its characterization, which could be widely used as generic method from natural materials for different applications.
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Yoon, Jeong A., i Young Taek Han. "Efficient Synthesis of Pyrido[3,2-c]coumarins via Silver Nitrate Catalyzed Cycloisomerization and Application to the First Synthesis of Polyneomarline C". Synthesis 51, nr 24 (30.09.2019): 4611–18. http://dx.doi.org/10.1055/s-0037-1610730.
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Herein, we report an efficient method for the synthesis of the pyrido[3,2-c]coumarin scaffold, one of the privileged heterocycle-fused coumarin scaffolds, via a AgNO3-catalyzed cycloisomerization of 4-(propynylamino)coumarins obtained from diverse 4-hydroxycoumarins. This concise method affords pyrido[3,2-c]coumarin analogues bearing diverse substituents on the benzene or pyridine ring in moderate to good yields. Moreover, this methodology was extended to the facile synthesis of polyneomarline C, a natural pyrido[3,2-c]coumarin derivative isolated from the Chinese herbal medicine Polyalthia nemoralis A. DC., in three steps and in 26% overall yield from the known 4-hydroxycoumarin.
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Kumari, Sumita, Amit Sharma i Sonia Yadav. "Pharmacological Potential of Coumarin-Based Derivatives: (A Comprehensive Brief Review)". Oriental Journal Of Chemistry 39, nr 3 (30.06.2023): 568–76. http://dx.doi.org/10.13005/ojc/390304.
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By combining of benzene nucleus and pyrone ring a class of heterocyclic compounds known as benzopyrone is generated. As a basic parent scaffold 1,2- benzopyrone ring system contains by coumarins. These compounds can be divided into two groups: 1. Benzo-α-pyrone 2. Benzo-γ-pyrone. Data on different coumarin derivatives are gathered in this review article as these compounds have a wide spectrum of pharmacological actions and can be further modified to make more potent and effective medications. Derivatives of coumarin play a significant role in industries and sectors of medicine. This can be linked to their variety of chemical characteristics and multiple biological activities. Coumarin based derivatives has a phenolic hydroxyl group which is generated as one of the most derivative functional groups. The focus of this systematic and comprehensive review on synthetic pathway of coumarin affiliates and their biological activities or potential. According to authors this review could help to medicinal chemists to choose appropriate functional group for development of novel therapeutic drugs.
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Medyouni, Rawdha, Olfa Naouali, Naceur HAMDI i Lassaad Baklouti. "Coumarin phthalonitriles: Synthesis and cation binding properties". JOURNAL OF ADVANCES IN CHEMISTRY 11, nr 4 (9.03.2015): 3512–18. http://dx.doi.org/10.24297/jac.v11i4.6695.
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Coumarin possess a number of biological activities like anticoagulant, antimicrobial, anti-inflammatory, analgesic,antioxidant, anticancer, antiviral, antimalarial etc. Coumarin belongs to a group as benzopyrones, which consists of a benzene ring joined to a pyrone nucleus. In this work, new coumarin phtalonitriles derivatives were synthesized and characterized via spectroscopic techniques IR, 1H NMR, 13C NMR, mass spectra and elemental analysis.The synthesis of coumarin phtalonitriles resulting from a nucleophilic aromatic substitution reaction between 4-nitrophtalonitrile and coumarins derivatives. The complexing properties of the coumarin derivatives toward alkali metal, alkaline earth metal, some transition metals and some heavy metal cations have been investigated in acetonitrile by means of UV spectrophotometry absorption and conductivity methods. Thus, the stoichiometry of the complexes formed and their stability constants were determined
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Cheke, Rameshwar S., Harun M. Patel, Vaishali M. Patil, Iqrar Ahmad Ansari, Jaya P. Ambhore, Sachin D. Shinde, Adel Kadri i in. "Molecular Insights into Coumarin Analogues as Antimicrobial Agents: Recent Developments in Drug Discovery". Antibiotics 11, nr 5 (24.04.2022): 566. http://dx.doi.org/10.3390/antibiotics11050566.
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A major global health risk has been witnessed with the development of drug-resistant bacteria and multidrug-resistant pathogens linked to significant mortality. Coumarins are heterocyclic compounds belonging to the benzophenone class enriched in different plants. Coumarins and their derivatives have a wide range of biological activity, including antibacterial, anticoagulant, antioxidant, anti-inflammatory, antiviral, antitumour, and enzyme inhibitory effects. In the past few years, attempts have been reported towards the optimization, synthesis, and evaluation of novel coumarin analogues as antimicrobial agents. Several coumarin-based antibiotic hybrids have been developed, and the majority of them were reported to exhibit potential antibacterial effects. In the present work, studies reported from 2016 to 2020 about antimicrobial coumarin analogues are the focus. The diverse biological spectrum of coumarins can be attributed to their free radical scavenging abilities. In addition to various synthetic strategies developed, some of the structural features include a heterocyclic ring with electron-withdrawing/donating groups conjugated with the coumarin nucleus. The suggested structure−activity relationship (SAR) can provide insight into how coumarin hybrids can be rationally improved against multidrug-resistant bacteria. The present work demonstrates molecular insights for coumarin derivatives having antimicrobial properties from the recent past. The detailed SAR outcomes will benefit towards leading optimization during the discovery and development of novel antimicrobial therapeutics.
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Thakur, Abhinay, Rohit Sharma, Vivek Sheel Jaswal, Eugenie Nepovimova, Ashun Chaudhary i Kamil Kuca. "Psoralen: A Biologically Important Coumarin with Emerging Applications". Mini-Reviews in Medicinal Chemistry 20, nr 18 (7.12.2020): 1838–45. http://dx.doi.org/10.2174/1389557520666200429101053.
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Coumarin belongs to a class of lactones that are fundamentally comprised of a benzene ring fused to an α-pyrone ring; these lactones are known as benzopyrones. Similarly, coumarin has a conjugated electron-rich framework and good charge-transport properties. Plants produce coumarin as a chemical response to protect themselves from predation. Coumarins are used in different products, such as cosmetics, additives, perfumes, aroma enhancers in various tobaccos and some alcoholic drinks, and they play a relevant role in natural products and in organic and medicinal chemistry. In addition, as candidate drugs, many coumarin compounds have strong pharmacological activity, low toxicity, high bioavailability and better curative effects and have been used to treat various types of diseases. Various endeavors were made to create coumarin-based anticoagulant, antimicrobial, antioxidant, anticancer, antidiabetic, antineurodegenerative, analgesic and anti-inflammatory agents. A class of chemical compounds called furocoumarins has phototoxic properties and is naturally synthesized via the fusion of coumarin to a furan ring in different plant species. Psoralens belong to the furocoumarin class and occur naturally in various plants, e.g., lemons, limes, and parsnips. Angelicin is an isomer of psoralens, and most furocoumarins, e.g., xanthotoxin, bergapten, and nodekenetin, are derivatives of psoralens or angelicin. The present work demonstrated that psoralen molecules exhibit anti-tumoral activity against breast cancer and influence different intracellular signals to maintain the high survival of breast cancer cells. Psoralens perform different functions, e.g., antagonize metabolic pathways, protease enzymes, and cell cycle progression and even interfere in the crosslinking between receptors and growth factor mitogenic signaling.
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Jalhan, Sunny. "Review Article: Various Biological Activities of Coumarin and Oxadiazole Derivatives." Asian Journal of Pharmaceutical and Clinical Research 10, nr 7 (1.07.2017): 38. http://dx.doi.org/10.22159/ajpcr.2017.v10i7.18461.
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In this review article data is collected regarding the various derivatives of coumarin and oxadiazole as both these have wide range of biological activities and they can be further modified to synthesize more effective and potent drugs. Coumarin class of organic compounds consists of 1,2-benzopyrone ring system as a basic parent scaffold. These benzopyrones are subdivided into alpha-benzopyrones and gamma benzopyrones; with coumarin class of compounds belonging to alpha-benzopyrones. Since the last few years, coumarins were synthesized in many of their derivative forms. Their pharmacological, therapeutic and biochemical properties depend upon their pattern of substitution. Coumarins exhibit a wide range of pharmacological activities, which includes anti-diabetic, anti-viral, anti-microbial, anticancer, anti-oxidant, anti-parasitic, anti-helminthic, anti-proliferative, anti-convulsant, anti-inflammatory and antihypertensive activities. 1,3,4-Oxadiazole is a heterocyclic compound containing an oxygen atom and two nitrogen atoms in a five-membered ring. It is derived from furan by substitution of two methylene groups (=CH) with two pyridine type nitrogens (-N=). There are three known isomers: 1,2,4-oxadiazole, 1,2,3-oxadiazole and 1,2,5- oxadiazole. Oxadiazole moiety shows antimicrobial, anticancer and anti-inflammatory activity and suitably substituted 1,3,4-oxadiazole having biological activities like antimicrobial, anticancer and other biological activities.
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Sanaryh Mohammed Al-awad, Leaqaa Abdalredha raheem i Ausama Ayob Jaccob. "Synthesis and Pharmacological Evaluation of Novel Coumarin Derivatives". International Journal of Research in Pharmaceutical Sciences 11, nr 1 (27.01.2020): 865–74. http://dx.doi.org/10.26452/ijrps.v11i1.1908.
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The current work focuses on new architecture, synthesis of coumarin-oxadiazole hybrid derivative products as both these (coumarin ring and oxadiazole) have a wide variety of biological behavior, Compounds containing the nucleus of coumarin (2H-1-benzopyran-2-one) are an interesting class of hetero cycles which hold an important role in the field of natural ingredients and synthetic organic chemistry. It has been exciting medicinal chemists to study native coumarins or synthetic analogs for their application for decades. And they can be further modified to synthesize more effective and potent drugs. Compounds have been characterized by spectrophotometry of physicochemical properties and their structures verified by infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H-NMR) Such new derivatives of coumarinyl-oxadiazole was qualified to estimate the lethal dose, anticancer, anticoagulant and antioxidant activity. Their pharmacological properties depend on their pattern of substitution, compound S4F proved significant anticoagulant activity in concentration (50, 100, 200 mg/ml) similar for heparin, and monitor the coagulation effect on plasma, while compound S4CO give significant anticancer activity against MCF-7 a breast cancer cell. Specific compounds have strong antioxidants with the effective action of radical scavengers; the S4Cl compound with IC50 1.49 is the most potent antioxidant activity note. Basically, all the formulations tested reported satisfactory behavior. The review shows that varieties of coumarin derivatives have synthesized and shown anti-cancer, antioxidant and anti-coagulant potentials. These derivatives synthesis and its biological assay can be further modified in the future to improve the anti-cancer, anti-oxidant and anticoagulant potentials of the versatile coumarin nucleus.
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Zeydi, Masoud Mohammadi, Seyed Jafar Kalantarian i Zahra Kazeminejad. "Overview on developed synthesis procedures of coumarin heterocycles". Journal of the Iranian Chemical Society 17, nr 12 (27.06.2020): 3031–94. http://dx.doi.org/10.1007/s13738-020-01984-1.
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Abstract Considering highly valuable biological and pharmaceutical properties of coumarins, the synthesis of these heterocycles has been considered for many organic and pharmaceutical chemists. This review includes the recent research in synthesis methods of coumarin systems, investigating their biological properties and describing the literature reports for the period of 2016 to the middle of 2020. In this review, we have classified the contents based on co-groups of coumarin ring. These reported methods are carried out in the classical and non-classical conditions particularly under green condition such as using green solvent, catalyst and other procedures.
Rozprawy doktorskie na temat "Coumarin ring"
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Trécourt, François. "Elaboration de dérivés carbonylés orthosubstitués de la pyridine : application d'une nouvelle méthode de synthèse de pyridines, synthèse d'hétérocycles du type coumarine et xanthone". Rouen, 1987. http://www.theses.fr/1987ROUES021.
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A partir de bromo-3 pyridines orthosubstituées par un fluor, un chlore, un méthoxy, un méthylthio, une première méthode de synthèse a permis d'élaborer des dérivés carbonylés (aldéhydes, cétones) orthosubstitués de la pyridine en utilisant la réaction d'échange halogène-métal. Cette méthode donne de bons résultats mais comporte en général un nombre important d'étapes. Une deuxième méthode de synthèse des dérivés carbonylés orthosubstitués de la pyridine a été mise en oeuvre. Cette méthode, basée sur la réaction de métallation régiosélective de dérivés monosubstitués de la pyridine (fluoro, chloro, méthoxy pyridines) est facile a mettre en oeuvre et permet d'accéder en une ou deux étapes à des formylpyridines , des pyridyléthanones et des pyridylméthanones orthosubstituées. Les dérivés carbonylés ainsi préparés nous ont permis de synthétiser des polyhétérocycles comportant au moins un cycle pyridinique : azacoumarines, azathiocoumarines, azaxanthones, diazathioxanthones. Lors de ces synthèses, le chlorure de pyridinium s'est révélé être un excellent agent de cyclisation
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SAKELLARIOU, FARGUES REINE. "Reactivite chimique et photochimique d'alpha -enones dans les milieux organises". Toulouse 3, 1986. http://www.theses.fr/1986TOU30044.
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Dans une premiere partie on determine les zones monophasiques des diagrammes des phases pseudoternaires de plusieurs microemulsions. Dans l'une d'elles l'isophorone remplace l'huile. Ensuite les chapitres ii et iii sont consacres aux reactions de photocycloaddition (a+a, a+b) d'alpha -enones (isophorone, coumarine, dimethylthymine). On montre que les phenomenes observes sont lies aux differentes localisations possibles des substrats, aux mecanismes de reaction et aux structures des milieux. En conclusion, la localisation des reactifs a l'interface permet la combinaison des effets de concentration, d'organisation et de proximite et conduit a des rendements, des regio et des stereoselectivite eleves
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Lin, Li, i 林立. "Synthesis and Biological Evaluation of Coumarin-3-Carboxamide Derivatives via Ring-Opening Reaction of Coumarin-3-Activated Aziridines". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/51699927764062756603.
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碩士臺北醫學大學
藥學系
94
Coumarin is important structure of organic chemistry and belongs to the benzopyrones. Coumarins are widely distributed in plants and have a variety of bioactivities including anticoagulation, estrogenic, dermal photosensitizing, antimicrobial, antioxidation, vasodilation, antithelmintic, sedative and hypnotic, analgesic and hypothermic activities. Aziridine is a class of compound important both in chemical synthesis and in chemotherapy of cancer. Ring opening of 2-methyl-N-acylaziridine by various nucleophiles has been reported. Nucleophilic attack at the unsubstituted carbon atom of the aziridine ring is called ” normal“ ring cleavage (in the SN2). Nucleophilic attack at tertiary or secondary carbon atom of aziridine ring is called “Abnormal” ring cleavage. We used the regioselectivity of ring opening of aziridines to synthesize a series of Coumarin-3- carboxamides. Four series of coumarin derivatives were synthesized from N-(coumarin-3-carboxyl) aziridines in this study. First, we used coumarin-3-carboxyl chloride (20) and a series of azirides with 4N NaOH to synthesize a class of N-(coumarin-3-caboxyl) aziridines (21, 22). Reactions of N-acylazirides with the radical anion of naphthalene had previusly been studied by Stamm, Mall, Falkenstein, Werry and Pen-Yuan Lin. Second, we used N-(coumarin-3-carboxyl) aziridines (21, 22) and activated thiols with the radical anion of naphthalene to synthesize Coumarin-3- carboxamide derivatives (27-40). Third, we used N-(coumarin-3- carboxyl) aziridines and 4-hydroxycoumarins to synthesize coumarin dimmer (41-50). Fourth, we used N-(coumarin-3-carboxyl) aziridines and 7-hydroxycoumarins to synthesize coumarin dimmer (51-54). The physical and chemical characteristics of the synthesized compound 1-35 were measured by 1H-NMR, IR, HRMS, and melting point determination. The cytotoxicities of all synthesized compounds to cancer cell lines (Colon 205, K-562, MCF7) are also examined in this study.
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Chen, Yun, i 陳筠. "Aluminum Complexes Bearing [N,O]-Coumarin-Based Ligands : Synthesis, Characterization and Applicationin Ring-Opening Polymerization of Cyclic Ester". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/20417976002348155562.
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碩士國立中興大學
化學系所
103
The coumarin-derived ligand precursors L1H-L8H have been prepared. Reactions of L1H-L8H with 1.2 equiv. of AlMe3 afford aluminum complexes 48-55. All compounds were characterized by NMR spectroscopy and elemental analysis. Molecular structures of 49, 51, and 52 were determined by X-ray crystallography. The catalytic activities of these complexes towards the ring-opening polymerization of cyclic esters in the presence of alcohols were also examined. Based on the homonuclear decoupled 1H NMR spectra, the atactic polylactides (Pm values ranged from 0.44 to 0.57) were produced using 48-55 as catalysts. Kenetics studies showed that the polymerization reaction is first-order for the complex 48.
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cheng, chai-yi, i 鄭佳怡. "A new synthetic strategy in the preparation of aromatic ring-fused coumarins". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/82676749915719283545.
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碩士國立中正大學
化學所
95
The addition of propargyl tetrahydropyranyl ether to the aromatic ring-fused cyclohexanone followed by dehydration and deprotection gives the corresponding cyclohexenyl-substituted propargl alcohol. This alcohol was oxidized to the aldehyde followed by sequentially partial reduction of the triple bond and eletrocyclization to give the corresponding dihydropyran. After treated with DDQ, the dihydropyran can be converted to benzocoumarin derivative. The aforementioned cyclohexenyl-substituted propargl alcohol could also be prepared from the corresponding cyclohexenyl triflate and the propargyl tetrahydropyranyl ether by Sonogashira coupling. Besides benzocoumarin, we can also synthesize a variety of heteroaromalic ring-fused coumarin. In summary, we have developed a new and versatile synthetic strategy to prepare the aromatic (or heteroaromatic) ring-fused coumarins.
Części książek na temat "Coumarin ring"
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"Shikimic Acid Pathway: Phenols". W Chemical Diversity of Plant Specialized Metabolites, 163–217. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781837671472-00163.
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Plant metabolites having one or more hydroxyl groups attached to an aromatic ring are known as phenols. Phenols are a heterogeneous group of compounds. One of the most important functions of phenols is in plant communication e.g., allelopathy, attracting pollinating and disseminating agents, attracting symbiotic bacteria, and inhibiting pathogens and predators. Some phenolic compounds (e.g., lignin) are structural components of plant cell wall. Phenols also protect the plant from oxidants and ultraviolet radiation. Due to the free radical scavenging properties, phenolics present in the human diet help to prevent chronic stress related diseases. Most of the phenolic compounds, such as hydroxycinnamic acids, hydroxybenzoic acids, monolignols, lignins, lignans, phenylpropenes, tannins, betalains, and many of the naphthoquinones are produced by the shikimic acid pathway. Some phenolic compounds follow mixed biogenetic pathways. Flavonoids, phlobaphene, curcuminoids, stilbenes and xanthones are produced through formation of polyketides by addition of malonyl-CoA to the phenolic acids. Anthraquinones, some naphthoquinones, benzoquinones and coumarin structures are formed after addition of MVA/MEP pathway derived isopentenyl diphosphate, dimethylallyl diphosphate, geranyl diphosphate or farnesyl diphosphate.
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Kamal Kant Arya, Rajeshwar, Arun Kumar, Anchala Guglani, Dheeraj Bisht i Deepak Kumar. "Chromene as Antioxidants". W The Role of Chromenes in Drug Discovery and Development, 215–24. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815124330123010012.
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Chromene is a heterocyclic compound that contains oxygen in its ring. It is widely obtained naturally from both animals and plants, and it is an integral part of alkaloids, tocopherol, anthocyanins, and flavonoids. The 2-oxo-2H-chromene is called coumarins, and coumarins have excellent antioxidant potential due to the presence of the phenol group, more than 1300 coumarins have been identified to date. The chromene scaffold in coumarins has the structural modification ability that makes it the structure of choice for medicinal purposes. Various medicines can be synthesized by using a chromene scaffold e.g. asthma, hypertension, antifungal, and antimicrobial. Chromene shows a good antioxidant potential that depends on its hydrogen ion.releasing capacity and stabilizes hydrogen with the help of a high resonating structure. The bond length between bonds also enhances the free radical scavenging function. In this chapter, we have discussed some chromene derivatives and their antioxidant potential, and the effect of cyclic structure on the antioxidant’s function.
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Supuran, Claudiu T. "Coumarins as Carbonic Anhydrase Inhibitors". W Flavonoids and Phenolics, 298–329. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815079098122010013.
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Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes and relevant drug targets with many medicinal chemistry applications. Their classes of inhibitors are in clinical use as diuretics, or drugs for the management of glaucoma, epilepsy, obesity, tumors and infectious diseases. Among the inhibitors discovered so far, coumarins constitute an interesting class. They undergo CA-catalyzed hydrolysis and act as “prodrug inhibitors”, forming 2-hydroxy-cinnamic acids, which bind at the entrance of the enzyme active site, which has a relevant variability of amino acid residues among the different CA isoforms present in mammals, humans included. Coumarins act as isoform-selective CA inhibitors against pharmacologically relevant enzymes, such as the tumor-associated CA IX and XII. Coumarins present as metabolites in many species of bacteria, fungi, plants and ascidians showed relevant CA inhibitory properties and were used as leads for obtaining synthetic derivatives with enhanced enzyme inhibitory action belonging to a variety of classes, such as polysubstituted coumarins on both rings, thiocoumarins, thioxocoumarins, sulfocoumarins, etc.<br>
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Dell, C. P. "By Ring Contraction of 4-(Halomethyl)coumarins". W Fused Five-Membered Hetarenes with One Heteroatom, 1. Georg Thieme Verlag KG, 2001. http://dx.doi.org/10.1055/sos-sd-010-00092.
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V. Vastrad, Jyoti, Pratikhya Badanayak i Giridhar Goudar. "Phenolic Compounds in Tea: Phytochemical, Biological, and Therapeutic Applications". W Phenolic Compounds - Chemistry, Synthesis, Diversity, Non-Conventional Industrial, Pharmaceutical and Therapeutic Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.98715.
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Phenolic compounds are one of the major and most complex groups of phytochemicals found among plant kingdom. Structurally they comprise of aromatic ring along with one or more hydroxyl groups. Based on the structure they are divided into subgroups such as phenolic acids, flavonoids, tannins, coumarins, lignans, quinones, stilbenes and carotenoids. Plant polyphenols are gaining popularity as a result of their potent antioxidant properties and notable effects in the prevention of oxidative stress-related diseases. Extraction, identification and characterisation of phenolic compounds from various plant sources has become a major area of health and medical research in the recent years. The major bioactive compounds responsible for tea’s health benefits are thought to be phenolics. Catechin derivatives make up the majority of the phenolic compounds found in tea, and though flavonols and phenolic acids are also present in smaller amounts. The bioactivity of the compounds has been linked to a lower risk of serious illnesses like cancer, cardiovascular disease, and neurodegenerative disease. This chapter covers phenolic extraction, purification, analysis and quantification, as well as their antioxidant properties in different varieties of tea leaves.
Streszczenia konferencji na temat "Coumarin ring"
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Nagasawa, Yutaka, Arkadiy P. Yartsev, Keisuke Tominaga i Keitaro Yoshihara. "Chemical Substitution and Deuterium Isotope Effects on Ultrafast Intermolecular Electron Transfer: Possible Role of Molecular Vibrations". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.fa.3.
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We have observed ultrafast non-exponential fluorescence quenching of 7-aminocoumarin dyes in electron donating solvents by means of femtosecond fluorescence up-conversion technique [1]. We regarded this fluorescence quenching as an ultrafast intermolecular electron transfer (ET) from the solvent to the excited dye. When the carbon chain on the amino group becomes longer, the rate of ET becomes slower, and when the amino group is fixed by hexagonal carbon ring, it becomes the slowest. Some of the fast reactions occur much faster than the diffusive solvent relaxation process. The fastest reaction with a time constant of ~200 fs was observed for coumarin 151 (C151) in N,N-dimethylaniline (DMA). In such a case, some dynamics faster than diffusive orientational polarization of the solvent is required to induce the reaction.