- REACTION OF CHROMOUS CHLORIDE WITH 3-NITROFLAVENES. A NOVEL SYNTHESIS OF FLAVONOLS
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Reaction of Chromium(II) chloride with 3-nitroflavene yields flavonol.
- Rao, T. Sudhakara,Mathur, H. H.,Trivedi, G. K.
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- An easy way for constructing hard-to-make epoxides employing HOF·CH3CN
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HOF·CH3CN, a very efficient oxygen transfer agent, was reacted with various types of difficult-to-epoxidize olefins. All products were obtained in a single-step, fast and high yield reaction.
- Golan, Elizabeth,Hagooly, Aviv,Rozen, Shlomo
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- Proton Transfer in Matrix-Isolated 3-Hydroxyflavone and 3-Hydroxyflavone Complexes
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The proton-transfer dynamics of 3-hydroxyflavone (3HF) and 3HF-solvent complexes have been studied in 10 K argon matrices.Both static and picosecond fluorescence spectroscopies were used.The results indicate that proton transfer in bare molecules occurs quite rapidly (10 ps).The 3HF-solvent complexes are formed by codeposition of argon:solvent mixtures (typically 2000:1) with 3HF followed by matrix annealing.Solvents include water, methanol, ethanol, and diethyl ether.The results show that proton transfer is very fast (10 ps) in alkohol and water monosolvates and can be interpreted in terms of cyclically hydrogen-bonded structures.The results also show that the diethyl ether monosolvate undergoes proton transfer in about 40 ps.Solvation with two or more waters or alkohols was found to inhibit proton transfer.
- Brucker, G. A.,Kelley, D. F.
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- Oxygenolysis of a series of copper(ii)-flavonolate adducts varying the electronic factors on supporting ligands as a mimic of quercetin 2,4-dioxygenase-like activity
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Four copper(ii)-flavonolate compounds of type [Cu(LR)(fla)] {where LR = 2-(p-R-benzyl(dipyridin-2-ylmethyl)amino)acetate; R = -OMe (1), -H (2), -Cl (3) and -NO2 (4)} have been developed as a structural and functional enzyme-substrate (ES) model of the Cu2+-containing quercetin 2,4-dioxygenase enzyme. The ES model complexes 1-4 are synthesized by reacting 3-hydroxyflavone in the presence of a base with the respective acetate-bound copper(ii) complexes, [Cu(LR)(OAc)]. In the presence of dioxygen the ES model complexes undergo enzyme-type oxygenolysis of flavonolate (dioxygenase type bond cleavage reaction) at 80 °C in DMF. The reactivity shows a substituent group dependent order as -OMe (1) > -H (2) > -Cl (3) > ?NO2 (4). Experimental and theoretical studies suggest a single-electron transfer (SET) from flavonolate to dioxygen, rather than valence tautomerism {[CuII(fla?)] ? [CuI(fla˙)]}, to generate the reactive flavonoxy radical (fla˙) that reacts further with the superoxide radical to bring about the oxygenative ring opening reaction. The SET pathway has been further verified by studying the dioxygenation reaction with a redox-inactive Zn2+ complex, [Zn(LOMe)(fla)] (5).
- Anoop, Anakuthil,Dey, Subhasis,Mandal, Sukanta,Podder, Nirmalya
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supporting information
p. 4338 - 4353
(2022/04/07)
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- Exploring 3-hydroxyflavone scaffolds as mushroom tyrosinase inhibitors: synthesis, X-ray crystallography, antimicrobial, fluorescence behaviour, structure-activity relationship and molecular modelling studies
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To explore new scaffolds as tyrosinase enzyme inhibitors remain an interesting goal in the drug discovery and development. In due course and our approach to synthesize bioactive compounds, a series of varyingly substituted 3-hydroxyflavone derivatives (1-23) were synthesized in one-pot reaction and screened for in?vitro against mushroom tyrosinase enzyme. The structures of newly synthesized compounds were unambiguously corroborated by usual spectroscopic techniques (FTIR, UV-Vis, 1H-, 13C-NMR) and mass spectrometry (EI-MS). The structure of compound 15 was also characterized by X-ray diffraction analysis. Furthermore, the synthesized compounds (1-23) were evaluated for their antimicrobial potential. Biological studies exhibit pretty good activity against most of the bacterial-fungal strains and their activity is comparable to those of commercially available antibiotics i.e. Cefixime and Clotrimazole. Amongst the series, the compounds 2, 4, 5, 6, 7, 10, 11, 14 and 22 exhibited excellent inhibitory activity against tyrosinase, even better than standard compound. Remarkably, the compound 2 (IC50 = 0.280 ± 0.010 μg/ml) was found almost sixfold and derivative 5 (IC50 = 0.230 ± 0.020 μg/ml) about sevenfold more active as compared to standard Kojic acid (IC50 =1.79 ± 0.6 μg/ml). Moreover, these synthetic compounds (1-23) displayed good to moderate activities against tested bacterial and fungal strains. Their emission behavior was also investigated in order to know their potential as fluorescent probes. The molecular modelling simulations were also performed to explore their binding interactions with active sites of the tyrosinase enzyme. Limited structure-activity relationship was established to design and develop new tyrosinase inhibitors by employing 2-arylchromone as a structural core in the future. Communicated by Ramaswamy H. Sarma.
- Ashraf, Jamshaid,Mughal, Ehsan Ullah,Sadiq, Amina,Bibi, Maryam,Naeem, Nafeesa,Ali, Anser,Massadaq, Anam,Fatima, Nighat,Javid, Asif,Zafar, Muhammad Naveed,Khan, Bilal Ahmad,Nazar, Muhammad Faizan,Mumtaz, Amara,Tahir, Muhammad Nawaz,Mirzaei, Masoud
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p. 7107 - 7122
(2020/08/21)
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- Synthesis, inverse docking-assisted identification and in vitro biological characterization of Flavonol-based analogs of fisetin as c-Kit, CDK2 and mTOR inhibitors against melanoma and non-melanoma skin cancers
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Due to hurdles, including resistance, adverse effects, and poor bioavailability, among others linked with existing therapies, there is an urgent unmet need to devise new, safe, and more effective treatment modalities for skin cancers. Herein, a series of flavonol-based derivatives of fisetin, a plant-based flavonoid identified as an anti-tumorigenic agent targeting the mammalian targets of rapamycin (mTOR)-regulated pathways, were synthesized and fully characterized. New potential inhibitors of receptor tyrosine kinases (c-KITs), cyclin-dependent kinase-2 (CDK2), and mTOR, representing attractive therapeutic targets for melanoma and non-melanoma skin cancers (NMSCs) treatment, were identified using inverse-docking, in vitro kinase activity and various cell-based anticancer screening assays. Eleven compounds exhibited significant inhibitory activities greater than the parent molecule against four human skin cancer cell lines, including melanoma (A375 and SK-Mel-28) and NMSCs (A431 and UWBCC1), with IC50 values ranging from 0.12 to 15 μM. Seven compounds were identified as potentially potent single, dual or multi-kinase c-KITs, CDK2, and mTOR kinase inhibitors after inverse-docking and screening against twelve known cancer targets, followed by kinase activity profiling. Moreover, the potent compound F20, and the multi-kinase F9 and F17 targeted compounds, markedly decreased scratch wound closure, colony formation, and heightened expression levels of key cancer-promoting pathway molecular targets c-Kit, CDK2, and mTOR. In addition, these compounds downregulated Bcl-2 levels and upregulated Bax and cleaved caspase-3/7/8 and PARP levels, thus inducing apoptosis of A375 and A431 cells in a dose-dependent manner. Overall, compounds F20, F9 and F17, were identified as promising c-Kit, CDK2 and mTOR inhibitors, worthy of further investigation as therapeutics, or as adjuvants to standard therapies for the control of melanoma and NMSCs.
- Roy, Tithi,Boateng, Samuel T.,Banang-Mbeumi, Sergette,Singh, Pankaj K.,Basnet, Pratik,Chamcheu, Roxane-Cherille N.,Ladu, Federico,Chauvin, Isabel,Spiegelman, Vladimir S.,Hill, Ronald A.,Kousoulas, Konstantin G.,Nagalo, Bolni Marius,Walker, Anthony L.,Fotie, Jean,Murru, Siva,Sechi, Mario,Chamcheu, Jean Christopher
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supporting information
(2021/01/14)
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- Simultaneous Two-Color Visualization of Lipid Droplets and Endoplasmic Reticulum and Their Interplay by Single Fluorescent Probes in Lambda Mode
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In living systems, subcellular organelles mutually cooperate and closely contact to form organelle interaction networks. Thus, the simultaneous and discriminative visualization of different organelles is extremely valuable for elucidating their distribution and interplay. However, such meaningful investigations remain a great challenge due to the lack of advanced single fluorescent probes (SF-probes) capable of simultaneous and two-color imaging of two targets. Herein, for the first time, we present two excited-state intramolecular proton transfer (ESIPT) based SF-probes (PPC and EPC) for simultaneous two-color fluorescence imaging of lipid droplets (LDs) and the endoplasmic reticulum (ER) under single-wavelength excitation. Due to the strong electron-donating ability of the side substituents, the fluorescence spectra and colors of these ESIPT probes are highly sensitive to the nuance of water contents between LDs and ER, leading to orange and green fluorescence in LDs and ER, respectively, in the Lambda imaging mode. Using the probe PPC or EPC, the morphology, size, and distribution of LDs and ER have been investigated in live cells and tissues. With the aid of in situ and real-time fluorescence imaging in Lambda mode, we observed the generation of newborn LDs near the ER regions and their close apposition and shared identical fluorescence colors, probably providing a valuable proof for the mainstream hypothesis that LDs originate from the ER. The remarkable imaging performances render these SF-probes as powerful tools to decipher LD-ER related biological processes.
- Guo, Lifang,Tian, Minggang,Zhang, Zhiyun,Lu, Qing,Liu, Zhiqiang,Niu, Guangle,Yu, Xiaoqiang
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supporting information
p. 3169 - 3179
(2021/03/01)
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- Exploring 3-Benzyloxyflavones as new lead cholinesterase inhibitors: synthesis, structure–activity relationship and molecular modelling simulations
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In this protocol, a series of 3-benzyloxyflavone derivatives have been designed, synthesized, characterized and investigated in?vitro as cholinesterase inhibitors. The findings showed that all the synthesized target compounds (1–10) are potent dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes with varying IC50 values. In comparison, they are more active against AChE than BChE. Remarkably, amongst the series, the compound 2 was identified as the most active inhibitor of both AChE (IC50 = 0.05 ± 0.01 μM) and BChE (IC50 = 0.09 ± 0.02 μM) relative to the standard Donepezil (IC50 = 0.09 ± 0.01 for AChE and 0.13 ± 0.04 μM for BChE). Moreover, the derivatives 5 (IC50 = 0.07 ± 0.02 μM) and 10 (0.08 ± 0.02 μM) exhibited the highest selective inhibition against AChE as compared to the standard. Preliminary structure-activity relationship was established and thus found that cholinesterase inhibitory activities of these compounds are highly dependent on the nature and position of various substituents on Ring-B of the 3-Benzyloxyflavone scaffolds. In order to find out the nature of binding interactions of the compounds and active sites of the enzymes, molecular docking studies were carried out. (Figure presented.) HIGHLIGHTS 3-benzyloxyflavone analogues were designed, synthesized and characterized. The target molecules (1–10) were evaluated for their inhibitory potential against AChE and BChE inhibitory activities. Limited structure-activity relationship was developed based on the different substituent patterns on aryl part. Molecular docking studies were conducted to correlate the in?vitro results and to identify possible mode of interactions at the active pocket site of the enzyme. Communicated by Ramaswamy H. Sarma.
- Mughal, Ehsan Ullah,Sadiq, Amina,Ayub, Momna,Naeem, Nafeesa,Javid, Asif,Sumrra, Sajjad Hussain,Zafar, Muhammad Naveed,Khan, Bilal Ahmad,Malik, Fouzia Perveen,Ahmed, Ishtiaq
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p. 6154 - 6167
(2020/08/10)
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- COMPOSITION FOR IMPROVING RESPIRATORY HEALTH CONTINUOUSLY EXPOSED TO PARTICULATE MATTER ATMOSPHERE
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An aspect of the present disclosure relates to a composition for improving respiratory health exposed to particulate matter, which contains a green tea extract, a green tea polysaccharide and a green tea flavonol as active ingredients. The composition provided in an aspect of the present disclosure can improve respiratory health damaged by exposure to particulate matter by enhancing the effect of preventing adsorption of particulate matter to bronchial epithelial cells and activating the cilia of bronchial epithelial cells. The composition provided in an aspect of the present disclosure may decrease blood heavy metal level.
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- Bismuth(III) Flavonolates: The Impact of Structural Diversity on Antibacterial Activity, Mammalian Cell Viability and Cellular Uptake
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A series of homoleptic and heteroleptic bismuth(III) flavonolate complexes derived from six flavonols of varying substitution have been synthesised and structurally characterised. The complexes were evaluated for antibacterial activity towards several problematic Gram-positive (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE)) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. The cell viability of COS-7 (monkey kidney) cells treated with the bismuth flavonolates was also studied to determine the effect of the complexes on mammalian cells. The heteroleptic complexes [BiPh(L)2] (in which L=flavonolate) showed good antibacterial activity towards all of the bacteria but reduced COS-7 cell viability in a concentration-dependent manner. The homoleptic complexes [Bi(L)3] exhibited activity towards the Gram-positive bacteria and showed low toxicity towards the mammalian cell line. Bismuth uptake studies in VRE and COS-7 cells treated with the bismuth flavonolate complexes indicated that Bi accumulation is influenced by both the substitution of the flavonolate ligands and the degree of substitution at the bismuth centre.
- Burke, Kirralee J.,Stephens, Liam J.,Werrett, Melissa V.,Andrews, Philip C.
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supporting information
p. 7657 - 7671
(2020/06/02)
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- Synthesis of Flavonols via Pyrrolidine Catalysis: Origins of the Selectivity for Flavonol versus Aurone
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A novel synthetic method for flavonol from 2′-hydroxyl acetophenone and benzaldehyde promoted by pyrrolidine under an aerobic condition in water is established. This protocol was supported by efficient synthesis of 44 common examples and three natural products. The α, β-unsaturated iminium ion (enimine ion E) was proved to be the key intermediate in the reaction. H218O and 18O2 isotope tracking experiments demonstrated that both water and the aerobic atmosphere were necessary to ensure the transformation. The selectivity for flavonol or aurone was originated from solvent-triggered intermediates, which were determined by UV-visible spectra from isolated enimine. The phenol-iminium E-A is dominant in water and the ketoenamine intermediate E-B is prevalent in acetonitrile. In the presence of pyrrolidine and oxygen, E-A leads to flavonol through E-I, a zwitterionic-like phenoloxyl-iminium ion, following the key steps of cyclization and a [2 + 2] oxidation; E-B proceeds through path II, a radical process induced by photolysis of E-B with both pyrrolidine and oxygen, to afford aurone. Preliminary mechanistic studies are reported.
- Xiong, Wei,Wang, Xiaohong,Shen, Xianyan,Hu, Cuifang,Wang, Xin,Wang, Fei,Zhang, Guolin,Wang, Chun
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supporting information
p. 13160 - 13176
(2020/11/23)
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- Flavonol dyes with different substituents in photopolymerization
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To further expand the applications of flavonol dyes (3HFs) in photopolymerization, six flavonol dyes with different substituents were prepared by using the Algar–Flynn–Oyamada method. The steady-state photolysis and fluorescence quenching of 3HFs under the 385 nm LED light source showed that the proton transfer reaction preceded the charge transfer reaction between 3HFs and triethanolamine (TEOA) or iodonium salts (ONI), and groups with different electron properties could affect the photochemistry of 3HFs. The influence of substituents on the free radical polymerization efficiencies of 3HFs/TEOA and 3HFs/ONI was evaluated. Results showed that charge transfer occurred in the oxidation or reduction processes between 3HFs and TEOA or ONI. The possible mechanism was speculated, and the thermal feasibility of charge transfer between 3HFs and TEOA or ONI was calculated on the basis of the free energy changes of photoinduced electron transfer.
- You, Jian,Fu, Hongyuan,Zhao, Di,Hu, Tianyu,Nie, Jun,Wang, Tao
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- Faster and More Specific: Excited-State Intramolecular Proton Transfer-Based Dyes for High-Fidelity Dynamic Imaging of Lipid Droplets within Cells and Tissues
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Lipid droplets (LDs), a type of dynamic organelle residing at the center of cellular lipid storage, have been identified to play important roles in multiple biological processes, metabolic disorders, and diseases. The highly dynamic characters of LDs were found to correspond to their physiological and pathological functions. Hence, the fluorescent probes which enable dynamic tracking of LDs should be very helpful for better understanding the mechanisms of LDs involved biological processes and diseases. Herein we present, to the best of our knowledge, the first class of excited-state intramolecular proton transfer (ESIPT) fluorescence dyes (Flp-(11-13, 19)) for dynamic imaging of LDs based on 3-hydroxyflavone (3HF) derivatives. Flp-(11-13, 19) display strong fluorescence from yellow to NIR in lipid but exhibit almost nonfluorescence in aqueous solution. Besides, they also show large Stokes shifts (>150 nm), narrow absorption and emission peaks, and good oil-water separation efficiency, which makes them specifically target and stain LDs with very low background noisy in both living cells and fixed cells. They stain intracellular LDs quite quickly (within 30 s) with very low dosage (as low as 500 nM). Benefitting from these advantages, Flp-(11-13, 19) are applied successfully in tracking the dynamic nature of LDs and accumulation of LDs in both aqueous solution and living cells, 3D imaging of LDs for visualization of their repartition within the cells, and visualizing LDs in tissues of diseases mice models including adipose, skeletal muscle, and fatty liver tissues, underscoring the potential utility of these dyes in both LDs biology research and medical diagnosis of LDs involved diseases.
- Jiang, Gangwei,Jin, Yi,Li, Man,Liu, Changlin,Liu, Chunrong,Ren, Zhuqing,Wang, Huiling,Xiong, Mengyao,Yuan, Hong,Zeng, Weili
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p. 10342 - 10349
(2020/09/18)
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- Discovery of a Prenylated Flavonol Derivative as a Pin1 Inhibitor to Suppress Hepatocellular Carcinoma by Modulating MicroRNA Biogenesis
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Peptidyl-prolyl cis-trans isomerase Pin1 plays a crucial role in the development of human cancers. Recently, we have disclosed that Pin1 regulates the biogenesis of miRNA, which is aberrantly expressed in HCC and promotes HCC progression, indicating the therapeutic role of Pin1 in HCC therapy. Here, 7-(benzyloxy)-3,5-dihydroxy-2-(4-methoxyphenyl)-8-(3-methylbut-2-en-1-yl)-4H-chromen-4-one (AF-39) was identified as a novel Pin1 inhibitor. Biochemical tests indicate that AF-39 potently inhibits Pin1 activity with an IC50 values of 1.008 μm, and also displays high selectivity for Pin1 among peptidyl prolyl isomerases. Furthermore, AF-39 significantly suppresses cell proliferation of HCC cells in a dose- and time-dependent manner. Mechanistically, AF-39 regulates the subcellular distribution of XPO5 and increases miRNAs biogenesis in HCC cells. This work provides a promising lead compound for HCC treatment, highlighting the therapeutic potential of miRNA-based therapy against human cancer.
- Zheng, Yuanyuan,Pu, Wenchen,Li, Jiao,Shen, Xianyan,Zhou, Qiang,Fan, Xin,Yang, Sheng-Yong,Yu, Yamei,Chen, Qiang,Wang, Chun,Wu, Xin,Peng, Yong
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supporting information
p. 130 - 134
(2018/11/30)
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- The detection of the precursors of the photorearranged products of 3-hydroxyflavones in selected solvents from UV-visible spectra: In situ
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Mechanistic studies relating to the photochemistry of 3-hydroxy-2-phenyl-4H-chromen-4-one (3HF) and 6-chloro-3-hydroxy-2-phenyl-4H-chromen-4-one (Cl-3HF) have been reinvestigated in selected solvents. The UV-visible spectra of the photoproduct(s) of 3HF and Cl-3HF have been computed in situ via subtracting the spectra of unreacted substrates, with acetonitrile (ACN) and methanol (MeOH) as solvents. These spectra turn out to be different from the spectra of the corresponding isolated photoproducts: 3-hydroxy-3-phenyl-indan-1,2-dione and 6-chloro-3-hydroxy-3-phenyl-indan-1,2-dione (referred to as dione). Analyses of the photoproduct(s) via GC-MS show the formation of a single detectable product, i.e., the corresponding dione. On the basis of some experimental observations, it is proposed that the primary photoproduct in situ is 2,3-epoxy-2-hydroxy-1-indanone (referred to as epoxide) instead of dione as reported in previous years. Earlier, epoxide has been proposed to be the intermediate in the mechanism for the formation of dione. This is the first report where the formation of epoxide has been directly detected in the selected solvents. On the other hand, both dione and epoxide (2?:?1) are shown to be formed with MeOH as solvent. The second important finding is that epoxide and dione interconvert in the dark, depending upon the environment. With ACN as solvent, pure dione in the dark is kinetically and partially converted to epoxide. With MeOH as solvent, epoxide is instantly and partially converted to dione until both are in equilibrium. However, a solution of dione in MeOH remains stable in the dark. The photoformation of epoxide is quantitative with ACN as solvent and it is sufficiently stable. It has been further observed that epoxide solutions of 3HF and Cl-3HF in ACN are quantitatively converted into 3-phenylisobenzofuran-1(3H)-one and 6-chloro-3-phenylisobenzofuran-1(3H)-one, i.e., the corresponding phthalides, through the loss of CO when kept in the dark for some days. A mechanism has been proposed where epoxide has been shown to give dione and/or phthalide via selective C-O or C-C bond cleavage in the oxiranyl ring, respectively. The selection of this cleavage depends mainly on the solvent system and the substituents in the parent flavones.
- Tomar, Jyoti,Kaur, Kulvir,Bansal, Manisha
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p. 2912 - 2920
(2019/12/24)
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- Alkynyl Gold(I) complexes derived from 3-hydroxyflavones as multi-targeted drugs against colon cancer
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The design of multi-targeted drugs has gained considerable interest in the last decade thanks to their advantages in the treatment of different diseases, including cancer. The simultaneous inhibition of selected targets from cancerous cells to induce their death represents an attractive objective for the medicinal chemist in order to enhance the efficiency of chemotherapy. In the present work, several alkynyl gold(I) phosphane complexes derived from 3-hydroxyflavones active against three human cancer cell lines, colorectal adenocarcinoma Caco-2/TC7, breast adenocarcinoma MCF-7 and hepatocellular carcinoma HepG2, have been synthesized and characterized. Moreover, these compounds display high selective index values towards differentiated Caco-2 cells, which are considered as a model of non-cancerous cells. The antiproliferative effect of the most active complexes [Au(L2b)PPh3] (3b) and [Au(L2c)PTA] (4c) on Caco-2 cells, seems to be mediated by the inhibition of the enzyme cyclooxygenase-1/2 and alteration of the activities of the redox enzymes thioredoxin reductase and glutathione reductase. Both complexes triggered cell death by apoptosis, alterations in cell cycle progression and increased of ROS production. These results provide support for the suggestion that multi-targeting approach involving the interaction with cyclooxygenase-1/2 and the redox enzymes that increases ROS production, enhances cell death in vitro. All these results indicate that complexes [Au(L2b)PPh3] and [Au(L2c)PTA] are promising antiproliferative agents for further anticancer drug development.
- Mármol, Inés,Castellnou, Pilar,Alvarez, Raquel,Gimeno, M. Concepción,Rodríguez-Yoldi, M. Jesús,Cerrada, Elena
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- Design, synthesis, and biological evaluation of Helicobacter pylori inosine 5′-monophosphate dehydrogenase (HpIMPDH) inhibitors
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Inosine 5′-monophosphate dehydrogenase (IMPDH) catalyzes a crucial step in the biosynthesis of guanine nucleotides. Being a validated target for immunosuppressive, antiviral, and anticancer drug development, lately it has been exploited as a promising target for antimicrobial therapy. Extending our previous work on Mycobacterium tuberculosis IMPDH, GuaB2, inhibitor development, we screened a set of 23 new chemical entities (NCEs) with substituted flavone (Series 1) and 1,2,3-triazole (Series 2) core structures for their in vitro Helicobacter pylori IMPDH (HpIMPDH) and human IMPDH2 (hIMPDH2) inhibitory activities. All the NCEs possessed acceptable molecular, physicochemical, and toxicity property profiles. The ranges for HpIMPDH and hIMPDH2 inhibition were 9–99.9% and 16–57%, respectively, at 10 μM concentration. The most potent HpIMPDH inhibitor, 25c, exhibited IC50 value of 1.27 μM with no hIMPDH2 inhibitory activity. The moderately potent, structurally novel hit molecule, 25c, may serve as a lead for further design and development of highly potent HpIMPDH inhibitors.
- Sahu, Niteshkumar U.,Purushothaman, Gayathri,Thiruvenkatam, Vijay,Kharkar, Prashant S.
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p. 125 - 132
(2018/11/06)
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- An ESIPT Probe for the Ratiometric Imaging of Peroxynitrite Facilitated by Binding to Aβ-Aggregates
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A series of 3-hydroxyflavone (3-HF) ESIPT (excited-state intramolecular proton transfer) boronate-based fluorescent probes have been developed for the detection of peroxynitrite (ONOO-). The dyes are environmentally sensitive, and each probe exhibited a ratiometric response toward ONOO-in a micellar environment. The probes were used to image different aggregation states of amyloid-β (Aβ) in the presence of ONOO-. The3-HF-OMeprobe was found to produce a ratiometric response toward ONOO-when bound to Aβ aggregates, resulting in a novel host-guest ensemble, which adds insight into the development of other ESIPT-based probes for the simultaneous sensing of fibrous proteins/peptides and environmental ROS/RNS.
- Sedgwick, Adam C.,Dou, Wei-Tao,Jiao, Jin-Biao,Wu, Luling,Williams, George T.,Jenkins, A. Toby A.,Bull, Steven D.,Sessler, Jonathan L.,He, Xiao-Peng,James, Tony D.
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p. 14267 - 14271
(2018/10/25)
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- Chalcone and flavonol copper(II) complexes containing schiff base co-ligand: Synthesis, crystal structures and catecholase-like activity
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Four new heteroleptic copper(II) complexes having chalcone or flavonol ligands and Schiff base (N-phenyl-5-chlorosalicylideneimine) as co-ligand were prepared, chemically and structurally characterized and investigated as functional biomimetic catecholase models. The complexes were prepared by the solution synthesis and crystal and molecular structures were determined by X-ray diffraction. Complexes were chemically characterized by elemental analysis, infrared and electronic absorption spectroscopy as well as by electrochemical measurements. Copper(II) chalcone complexes, with square-pyramidal CuO4N core, are binuclear, featuring phenolate oxygen from the Schiff base as a bridging atom, while copper(II) flavonol complexes are mononuclear, and reveal a square planar CuO3N coordination core. Catalytic activity of the complexes in 3,5-di-tert-butylcatechol oxidation was confirmed by spectrophotometric and electrochemical measurements. Kinetic measurements revealed that the binuclear (chalcone-containing) complexes have enhanced catalytic activity as compared to the mononuclear Cu(II) flavonol complexes. Relatively high kcat values (300 – 750 h–1) confirmed their respectable biomimetic catecholase-like activity.
- Kahrovi?, Emira,Zahirovi?, Adnan,Vi?njevac, Aleksandar,Osmankovi?, Irnesa,Turku?i?, Emir,Kurtagi?, Harun
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p. 195 - 207
(2018/08/06)
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- Ruthenium(II)-Catalyzed Synthesis of Spirobenzofuranones by a Decarbonylative Annulation Reaction
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The first decarbonylative insertion of an alkyne through C?H/C?C activation of six-membered compounds is reported. The Ru-catalyzed reaction of 3-hydroxy-2-phenyl-chromones with alkynes works most efficiently in the presence of the ligand PPh3 to provide spiro-indenebenzofuranones. Unlike previously reported metal-catalyzed decarbonylative annulation reactions, in the present decarbonylative annulation reaction, the annulation occurs before extrusion of carbon monoxide.
- Kaishap, Partha P.,Duarah, Gauri,Sarma, Bipul,Chetia, Dipak,Gogoi, Sanjib
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supporting information
p. 456 - 460
(2018/02/21)
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- Synthesis, structure-activity relationship and molecular docking studies of 3-O-flavonol glycosides as cholinesterase inhibitors
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The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, 1H, 13C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (21–30) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC50 values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior with the active pocket of AChE and BChE enzymes. The experimental and theoretical results are in parallel with one another.
- Mughal, Ehsan Ullah,Javid, Asif,Sadiq, Amina,Murtaza, Shahzad,Zafar, Muhammad Naveed,Khan, Bilal Ahmad,Sumra, Sajjad Hussain,Tahir, Muhammad Nawaz,Kanwal,Khan, Khalid Mohammed
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p. 3696 - 3706
(2018/06/19)
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- Synthesis of 5-subsituted flavonols via the Algar-Flynn-Oyamada (AFO) reaction: The mechanistic implication
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Herein, we report a synthetic method with improved selectivity for 5-substituted flavonols via the Algar-Flynn-Oyamada reaction (AFO), by using of sodium carbonate/hydrogen peroxide A series of 5-substituted flavonols was obtained with moderate to high yields. The mechanism of the AFO reaction was elucidated. LCMS analysis and in situ 1H NMR analysis indicated that the epoxide was involved in the transformation from chalcone to flavonol and/or aurone under alkaline base/peroxide conditions.
- Shen, Xianyan,Zhou, Qiang,Xiong, Wei,Pu, Wenchen,Zhang, Wei,Zhang, Guolin,Wang, Chun
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p. 4822 - 4829
(2017/07/17)
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- Exploring the anti-breast cancer potential of flavonoid analogs
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In the course of our search for new antitumor agents for breast cancer, novel flavone derivatives were synthesized, characterized and examined for their antitumor activities against breast cancer cell lines. In initial screening, analogs 7a [3-(5-amino-1,3,4-thiadiazol-2-yl)methoxy-2-phenyl-4H-chromen-4-one] and 7b [3-(5-amino-1,3,4-thiadiazol-2-yl)methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one] were found to be effective against the estrogen receptor negative cell line (MDA-MB 453), which was followed by their evaluation in five dose assays. In addition, mechanistic studies of 7a and 7b were performed by cytometric analysis and electrophoretic studies and it was observed that apoptosis is a mechanism of cell death, confirmed morphologically by acridine orange/ethidium bromide double staining and TUNEL analysis. Further in vivo evaluation of the anti-tumor activity of compound 7a and 7b by Ehrlich Ascites Carcinoma (EAC) model and related studies confirms the anti-breast cancer potential of flavonoid analogs.
- Thakor, Vanrajsinh,Poddar, Mayur,Dey, Sumit,Manjula,Madhunapantula, Subbarao V.,Pawara, Rahul,Patel, Harun M.,Noolvi, Malleshappa N.
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p. 79166 - 79179
(2016/09/09)
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- A highly selective and sensitive 3-hydroxyflavone-based colorimetric and fluorescent probe for hydrogen sulfide with a large Stokes shift
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A 3-hydroxyflavone-based colorimetric and fluorescence probe for hydrogen sulfide (H2S) has been developed with high sensitivity and excellent selectivity. This probe was designed based on the mechanism that H2S selectively cleaved the NBD (7-nitro-2,1,3-benzoxadiazole) ether moiety in this probe and therefore release the fluorophore, 3-hydroxyflavone. The addition of H2S to the solution of probe 1 resulted in a green fluorescence and an obvious color change from colorless to pink, indicating that this probe can serve as a colorimetric and fluorescent dual probe for H2S. Furthermore, this probe displays a rapid response and reaches to a plateau within 5 min. It also exhibits a 146 nm Stokes shift and a low detection limit (20 nM, based on S/N=3) in detecting H2S. Importantly, practical utility of this probe for the selective detection of H2S in living cells has been successfully demonstrated.
- Hou, Peng,Li, Hongmei,Chen, Song
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p. 3531 - 3534
(2016/06/06)
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- A facile microwave-assisted synthesis of 3-hydroxy-2-phenyl-4H-chromen-4-one and its derivatives via a novel approach
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The presented research work demonstrates a new methodology for generating a petite library of novel flavonol derivatives via Algar-Flynn-Oyamada reaction. Amongst oxygen-containing heterocycles, flavonoids are versatile scaffolds due to their manifestation as crucial components in various natural products and encompassing massive biological activities. Thus, in view of the immense significance of flavonols and the pronounced effect of microwave-assisted protocol, a systematic and efficient scheme is put together for constructing the target motive and its derivatives by both classical and novel method. Initially, 2-hydroxy chalcones are assembled through an innovative conventional technique, later followed by the formation of flavonols. This methodical protocol results in enhanced yield with reduced reaction times under benign and environmental friendly conditions. (Chemical Equation Presented).
- Ehsan, Shahana,Faisal, Saniya,Akbar, Wajiha
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p. 1190 - 1195
(2017/01/25)
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- Absorption and fluorescent studies of 3-hydroxychromones
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The synthesis and spectral studies of variously substituted 3-hydroxychromones have been carried out. A key relationship between the structural motif of synthesized 3-hydroxychromones (3-HCs) and their fluorescent properties was found. The chromones substituted with electron-donating group at 4′-position expressed the red shift of the N and T band and also exhibited the increased fluorescent intensity ratio while the chromones with electron-withdrawing group showed the blue shift of the N and T band. Therefore, these 3-HCs may behave as the possible fluorescent probes.
- Khanna, Radhika,Kumar, Ramesh,Dalal, Aarti,Kamboj, Ramesh C.
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p. 1159 - 1163
(2015/10/20)
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- The rearrangement of tosylated flavones to 1′-(alkylamino)aurones with primary amines
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A rearrangement of 3-tosylflavone to the corresponding 1′-(alkylamino)aurone proceeds under mild conditions in the presence of primary amines in high yields. The reaction is applicable to different substituted 3-tosylflavones and alkyl amines and the respective aurones were isolated as a mixture of E/Z isomers. Further conversion of 1′-(methylamino)aurone to the corresponding thionated compound was performed by reaction with Lawesson's reagent and only the E isomer was obtained. This observation can be explained by the weaker exocyclic double bond, which facilitates rotation and the formation of the thermodynamically preferred E form. The characterization, preliminary biological investigations of the synthesized compounds and lipophilicity studies are discussed.
- Kandioller, Wolfgang,Kubanik, Mario,Bytzek, Anna K.,Jakupec, Michael A.,Roller, Alexander,Keppler, Bernhard K.,Hartinger, Christian G.
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p. 8953 - 8959
(2015/11/02)
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- Quantum-chemical analysis of the Algar-Flynn-Oyamada reaction mechanism
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This work is devoted to improving the understanding of Algar-Flynn-Oyamada reaction mechanism and the analysis of factors that affect the formation of flavonols. The calculation of thermodynamic parameters for the key reaction steps pointed to a mechanism involving chalcone epoxides as intermediates. A correlation was identified between the nucleophilicity of oxygen atom at position 2' of epoxide anions and the yields of flavonols. An increased charge at the nucleophilic center was shown to reduce the effectiveness of β-cyclization of epoxide anions.
- Serdiuk,Roshal,B?a?ejowski
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p. 396 - 403
(2014/08/05)
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- Series of structural and functional models for the ES (enzyme-substrate) complex of the Co(II)-containing quercetin 2,3-dioxygenase
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A series of mononuclear CoII-flavonolate complexes [Co IILR(fla)] (LRH = 2-{[bis(pyridin-2-ylmethyl) amino]methyl}-p/m-R-benzoic acid; R = p-OMe (1), p-Me (2), m-Br (4), and m-NO2 (5); fla = flavonolate) were designed and synthesized as structural and functional models for the ES (enzyme-substrate) complexes to mimic the active site of the Co(II)-containing quercetin 2,3-dioxygenase (Co-2,3-QD). The metal center Co(II) ion in each complex shows a similar distorted octahedral geometry. The model complexes display high enzyme-type dioxygenation reactivity (oxidative O-heterocyclic ring opening of the coordinated substrate flavonolate) at low temperature, presumably due to the attached carboxylate group in the ligands. The reactivity exhibits a substituent group dependent order of -OMe (1) > -Me (2) > -H (3)14b > -Br (4) > -NO2 (5), and the Hammett plot is linear (ρ = -0.78). This can be explained as the electronic nature of the substituent group in the ligands may influence the conformation and redox potential of the bound flavonolate and finally bring different reactivity. The structures, properties, and reactivity of the model complexes show some dependence on the substituent group in the supporting model ligands, and there is some relationship among them. This study is the first example of a series of structural and functional ES models of Co-2,3-QD, with focus on the effects of the electronic nature of substituted groups and the carboxylate group of the ligands to the dioxygenation reactivity, that will provide important insights into the structure-property-reactivity relationship and the catalytic role of Co-2,3-QD.
- Sun, Ying-Ji,Huang, Qian-Qian,Zhang, Jian-Jun
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supporting information
p. 2932 - 2942
(2014/04/03)
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- Boron difluoride complexes of 3-hydroxyflavone derivatives: Efficient bioinspired dyes for solution and solid-state emission
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A series of six boron difluoride complexes of 3-hydroxyflavone derivatives is described. These dyes were synthesized very simply and exhibited bright visible emission in solution (up to unity) as well as emission in the solid state. Complexation to boron difluoride was shown to impart donor-acceptor character to the excited state of these dyes, which further shifted the emission towards the visible part of the spectrum. Furthermore, differences were noticed following the strength of the donor and the acceptor. Light emission from the π-stacked molecules was quenched relative to the solution behaviour which was interpreted in terms of both packing and electronic properties of the molecular dyes. The packing arrangement was found to be a function of the substituent on the 3-hydroxyflavone derivatives.
- D'Aleo, Anthony,Fages, Frederic
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p. 500 - 510
(2013/06/05)
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- An expeditious synthesis of flavonols promoted by montmorillonite KSF clay and assisted by microwave irradiation under solvent-free conditions
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A simple, efficient, rapid, and ecofriendly synthesis of flavonols in >90% yield from 2′-(mesyloxy)epoxychalcones (=2-(3-aryl-2,3- epoxypropanoyl)phenyl methanesulfonates) promoted by montmorillonite KSF clay and assisted by microwave irradiation has been described. Copyright
- Babu, Mariappan,Pitchumani, Kasi,Ramesh, Penugonda
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p. 1269 - 1272
(2013/08/23)
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- Synthesis and biological evaluation of flavones and benzoflavones as inhibitors of BCRP/ABCG2
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Multidrug resistance (MDR) often leads to a failure of cancer chemotherapy. Breast Cancer Resistance Protein (BCRP/ABCG2), a member of the superfamily of ATP binding cassette proteins has been found to confer MDR in cancer cells by transporting molecules with amphiphilic character out of the cells using energy from ATP hydrolysis. Inhibiting BCRP can be a solution to overcome MDR.We synthesized a series of flavones, 7,8-benzofl avones and 5,6-benzo flavones with varying substituents at positions 3, 3′ and 4′ of the (benzo)fl avone structure. All synthesized compounds were tested for BCRP inhibition in Hoechst 33342 and pheophorbide A accumulation assays using MDCK cells expressing BCRP. All the compounds were further screened for their P-glycoprotein (P-gp) and Multidrug resistance-associated protein 1 (MRP1) inhibitory activity by calcein AM accumulation assay to check the selectivity towards BCRP. In addition most active compounds were investigated for their cytotoxicity. It was observed that in most cases 7,8-benzoflavones are more potent in comparison to the 5,6-benzoflavones. In general it was found that presence of a 3-OCH3 substituent leads to increase in activity in comparison to presence of OH or no substitution at position 3. Also, it was found that presence of 3′,4′-OCH3 on phenyl ring lead to increase in activity as compared to other substituents. Compound 24, a 7,8-benzoflavone derivative was found to be most potent being 50 times selective for BCRP and showing very low cytotoxicity at higher concentrations.
- Juvale, Kapil,Stefan, Katja,Wiese, Michael
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p. 115 - 126
(2013/10/01)
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- Metal-catalyzed cascade rearrangements of 3-alkynyl flavone ethers
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Metal-mediated rearrangements of 3-alkynyl flavone ethers are reported. The overall process involves 5-endo enyne cyclization to a platinum-containing spiro-oxocarbenium intermediate which may be trapped with methanol to produce spirodihydrofurans or further rearranged to afford either allenyl chromanediones or benzofuranones.
- Xiong, Yuan,Schaus, Scott E.,Porco Jr., John A.
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supporting information
p. 1962 - 1965
(2013/06/04)
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- Superior anticancer activity of halogenated chalcones and flavonols over the natural flavonol quercetin
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A series of chalcone and flavonol derivatives were synthesized in good yield by an eco-friendly approach. A pharmacological evaluation was performed with the human colorectal carcinoma cell line HCT116 and revealed that the anticancer activity of flavonols was higher when compared with that of the respective chalcone precursors. The antiproliferative activity of halogenated derivatives increases as the substituent in the 3- or 4-positon of the B-ring goes from F to Cl and to Br. In addition, halogens in position 3 enhance anticancer activity in chalcones whereas for flavonol derivatives the best performance was registered for the 4-substituted derivatives. Flow cytometry analysis showed that compounds 3p and 4o induced cell cycle arrest and apoptosis as demonstrated by increased S, G2/M and sub-G1 phases. These data were corroborated by western blot and fluorescence microscopy analysis. In summary, halogenated chalcones and flavonols were successfully prepared and presented high anticancer activity as shown by their cell growth and cell cycle inhibitory potential against HCT116 cells, superior to that of quercetin, used as a positive control.
- Dias, Tatiana A.,Duarte, Cecília L.,Lima, Cristovao F.,Proen?a, M. Fernanda,Pereira-Wilson, Cristina
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p. 500 - 510
(2013/10/01)
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- A new ratiometric ESIPT sensor for detection of palladium species in aqueous solution
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An aqueous ratiometric ESIPT sensor with a 87 nM (15.4 ppb) detection limit was successfully synthesized and applied for detection of all oxidation states of palladium species. The Royal Society of Chemistry 2012.
- Liu, Bin,Wang, Hu,Wang, Taisheng,Bao, Yinyin,Du, Fanfan,Tian, Jiao,Li, Qianbiao,Bai, Ruke
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supporting information; body text
p. 2867 - 2869
(2012/04/10)
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- Targeting the DNA-topoisomerase complex in a double-strike approach with a topoisomerase inhibiting moiety and covalent DNA binder
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RuII(arene)-flavonoids with high in vitro antitumour activity were synthesised. These compounds are capable of inhibiting human topoisomerase IIα and binding covalently to DNA.
- Kurzwernhart, Andrea,Kandioller, Wolfgang,Bartel, Caroline,Baechler, Simone,Trondl, Robert,Muehlgassner, Gerhard,Jakupec, Michael A.,Arion, Vladimir B.,Marko, Doris,Keppler, Bernhard K.,Hartinger, Christian G.
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supporting information; experimental part
p. 4839 - 4841
(2012/06/30)
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- Structure-Activity relationships of targeted RuII(η 6- P -Cymene) anticancer complexes with flavonol-Derived ligands
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RuII(arene) complexes have been shown to be promising anticancer agents, capable of overcoming major drawbacks of currently used chemotherapeutics. We have synthesized RuII(η6-arene) compounds carrying bioactive flavonol ligands with the aim to obtain multitargeted anticancer agents. To validate this concept, studies on the mode of action of the complexes were conducted which indicated that they form covalent bonds to DNA, have only minor impact on the cell cycle, but inhibit CDK2 and topoisomerase IIα in vitro. The cytotoxic activity was determined in human cancer cell lines, resulting in very low IC50 values as compared to other RuII(arene) complexes and showing a structure-activity relationship dependent on the substitution pattern of the flavonol ligand. Furthermore, the inhibition of cell growth correlates well with the topoisomerase inhibitory activity. Compared to the flavonol ligands, the RuII(η6-p-cymene) complexes are more potent antiproliferative agents, which can be explained by potential multitargeted properties.
- Kurzwernhart, Andrea,Kandioller, Wolfgang,B?chler, Simone,Bartel, Caroline,Martic, Sanela,Buczkowska, Magdalena,Mühlgassner, Gerhard,Jakupec, Michael A.,Kraatz, Heinz-Bernhard,Bednarski, Patrick J.,Arion, Vladimir B.,Marko, Doris,Keppler, Bernhard K.,Hartinger, Christian G.
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p. 10512 - 10522
(2013/02/22)
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- Facile syntheses of 3-hydroxyflavones
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Modification of the present synthetic methods led to the syntheses of 3-hydroxyflavones in a shorter reaction time, with simple purification and higher yields. Application of the method provided the syntheses of 3HFs having a hydroxyl group on the phenyl ring (ring B) in one step, which is an improvement compared to the four steps, long reaction time, and low yield using the current method available in the literature.
- Gunduz, Simay,Goren, Ahmet C.,Ozturk, Turan
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supporting information; experimental part
p. 1576 - 1579
(2012/05/20)
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- A mild and efficient protocol for the protection of 3-hydroxychromones under phase-transfer catalysis
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A mild and efficient protocol for the introduction of different protecting groups on 3-hydroxychromones (3-HCs) under phase-transfer catalysis conditions in toluene or dichloromethane/aqueous potassium hydroxide system in the presence of crown ether has been developed. The method is useful for the protection of base-sensitive chromone derivatives. Protected chromones are easier to handle and to purify, and therefore suitable for further chemical transformations. The protecting groups were cleaved cleanly using standard conditions. Georg Thieme Verlag Stuttgart ? New York.
- Dziuba, Dmytro,Benhida, Rachid,Burger, Alain
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body text
p. 2159 - 2164
(2011/08/05)
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- Synthesis and molecular docking studies of novel 2-chloro-pyridine derivatives containing flavone moieties as potential antitumor agents
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A series of novel 2-chloro-pyridine derivatives containing flavone, chrome or dihydropyrazole moieties as potential telomerase inhibitors were synthesized. The bioassay tests showed that compounds 6e and 6f exhibited some effect against gastric cancer cell SGC-7901 with IC50 values of 22.28 ± 6.26 and 18.45 ± 2.79 μg/mL, respectively. All title compounds were assayed for telomerase inhibition by a modified TRAP assay, the results showed that compound 6e can strongly inhibit telomerase with IC50 value of 0.8 ± 0.07 μM. Docking simulation was performed to position compound 6e into the active site of telomerase (3DU6) to determine the probable binding model.
- Liu, Xin-Hua,Liu, Hui-Feng,Shen, Xu,Song, Bao-An,Bhadury, Pinaki S.,Zhu, Hai-Liang,Liu, Jin-Xing,Qi, Xing-Bao
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scheme or table
p. 4163 - 4167
(2010/08/20)
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- Synthesis of novel flavone acyl esters and correlation of log P value with antioxidant and antimicrobial activity
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Three series of flavones namely 6-hydroxy flavone, 6-chloro-3-hydroxy flavone, 3,6-dihydroxy flavone were synthesized. They were further benzoylated with different aromatic acid chlorides in the presence of pyridine gave three of acyl esters series (SCF 1 to 8, SHF 1 to 8 and SDF 1 to 8). The yields of all the substituted flavones were found satisfactory. These compounds were purified, characterized by their spectral data. log P and pKa value. They were screened for in vitro radical (DPP?) scavenging activity, showed appreciable activity. 7 compounds showed antimicrobial activity against Gram-positive bacteria. Further, the MIC values of these 7 compounds were also determined. All the compounds showing antioxidant activity also showed antibacterial activity. The relationship between log P, antioxidant and antibacterial activity was established.
- Jayashree,Thejaswini,Nayak, Yogendra,Kumar, D. Vijay
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experimental part
p. 1055 - 1066
(2012/03/26)
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- An efficient oxyfunctionalisation by dimethyldioxirane of the benzylethereal carbon of flavonoids; a general and useful way to anthocyanidins
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Compounds with flavonoid structure were selectively oxyfunctionalised at the C-2 carbon atom by DMD. The reaction permitted a new route to flavylium salts.
- Bernini, Roberta,Mincione, Enrico,Sanetti, Anna,Bovicelli, Paolo,Lupattelli, Paolo
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p. 4651 - 4654
(2007/10/03)
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- Flavonoid epoxides. Part 20. Some unusual reactions of dimethyldioxirane (DMD) with flavonoid compounds
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Dimethyldioxirane (DMD), generally as a solution in acetone, has proved itself to be an excellent epoxidising agent. It was observed that either the 2'-hydroxychalcone epoxide or the tans-2,3-dihydroflavonol could be obtained depending on the pH of the reaction mixture and the type of β-arene ring present in the substrate. Using this methodology trans-2,3-dihydroflavonols can be synthesised in far better yields than by the most commonly used method for their synthesis, that of the Algar-Flynn-Oyamada reaction. Treatment of both flavonol 14 and the novel isoaurone 21 with DMD gave unusual products instead of the expected epoxides, but nonetheless, an epoxide was assumed to have formed during the reaction.
- Burke, Anthony J.,O'Sullivan, W. Ivo
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p. 8491 - 8500
(2007/10/03)
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- Synthesis and cyclization of 1-(2-hydroxyphenyl)-2-propen-1-one epoxides: 3-Hydroxychromanones and -flavanones versus 2-(1-hydroxyalkyl)-3-coumaranones
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Competitive α and β cyclization of 2'-hydroxychalcone epoxides affords 2-(α-hydroxybenzyl)-3-coumaranone and/or 3-hydroxyflavanones, which depends on the conditions employed. Epoxidation of 2'-hydroxychalcones by dimethyldioxirane followed by either base- or acid-catalyzed ring closure provides a novel, general, and efficient method for the synthesis of trans-3-hydroxyflavanones, which includes also the naturally occurring derivatives. Extension of this two-step procedure to 1-(2-hydroxyphenyl)-2-alken-1-ones was also accomplished. A strong preference for α cyclization was observed in the case of β-unsubstituted or -monoalkylated α,β-enones, while both 2,2-dimethyl-3-hydroxychromanones and 2-(1-hydroxy-1-methylethyl)-3-coumaranones were obtained from the β,β-dimethylated substrates.
- Patonay, Tamas,Levai, Albert,Nemes, Csaba,Timar, Tibor,Toth, Gabor,Adam, Waldemar
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p. 5375 - 5383
(2007/10/03)
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- Flavonoids. 43. Deprotonation-initiated Aryl Migration with Sulfur Dioxide Extrusion: A Route to 2,3-Dihydro-2,3-diaryl-3-hydroxy-4H-1-benzopyran-4-ones
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Treatment of trans-2,3-dihydro-2-aryl-3-nosyloxy-4H-1-benzopyran-4-ones with various bases afforded 2,3-dihydro-r-2-aryl-t-3-hydroxy-c-3-(4-nitrophenyl)-4H-1-benzopyran-4-ones in a deprotonation-initiated aryl migration followed by sulfur dioxide extrusion.In the presence of hydroxide and methoxide ions a secondary ring cleavage has also been observed.However, the reaction of trans-2,3-dihydro-2-aryl-3-nosyloxy-4H-1-benzopyran-4-ones with cyanide ions gave 2,3-dihydro-r-2-aryl-t-4-cyano-c-3,c-4-epoxy-4H-1-benzopyrans in a carbonyl attack of cyanide followed by an internal substitution reaction.
- Patonay, Tamas,Hegedues, Laszlo,Patonay-Peli, Erzsebet
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p. 145 - 151
(2007/10/02)
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- A convenient and general synthesis of trans-3-hydroxyflavanones from chalcones by dimethyldioxirane epoxidation and subsequent base-catalyzed cyclization
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2'-Hydroxychalcone epoxides were found to give trans-3-hydroxyflavanone and 2-(α-hydroxybenzyl)-3-coumaranone under basic conditions. Epoxidation of 2'-hydroxychalcones with dimethyldioxirane followed by treatment of tetrabutylammonium hydroxide provides a convenient and general method for the synthesis of trans-3-hydroxyflavanones.
- Patonay,Toth,Adam
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p. 5055 - 5058
(2007/10/02)
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- Use of Nitrile Oxides in Synthesis. A Novel Synthesis of Chalcones, Flavanones, Flavones and Isoflavones
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Novel methodology is developed for a three-step synthesis of chalcones, flavanones, flavones and isoflavones. 1.Salicylaldoxime is chlorinated to the corresponding hydroxamoyl chloride in the presence of pyridine, and cycloadded to styrene and phenylacetylene. 2.The isoxazole derivatives formed are reductively cleaved over Raney-Ni to β-hydroxyketones or 1,3 diketones. 3.Acid-catalyzed cyclization gives the flavonoids.Use of ω-methoxy- or ω-dialkylamino-substituted styrenes (enamines) leads regioselectively to 4-aryl-substituted isoxazoles and derived isoflavones.
- Thomsen, Ib,Torssell, Kurt B. G.
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p. 303 - 308
(2007/10/02)
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- REACTION OF POTASSIUM SUPEROXIDE WITH 3-NITRO-2-PHENYL-2H-1-BENZOPYRANS AND THEIR DIHYDRO DERIVATIVES
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3-Nitro-2-phenyl-2H-1-benzopyrans on treatment with potassium superoxide in dimethyl sulphoxide are degraded mainly to the corresponding salicylic acids and benzoic acids. Formation of flavonols, as a minor product are also observed. The dihydro derivatives of 3-nitro-2-phenyl-2H-1-benzopyrans are converted to the corresponding flavonols by potassium superoxide in benzene containing 18-crown-6 ether.
- Rao, Takkellapati Sudhakar,Trivedi, Girish Kumar
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p. 2117 - 2124
(2007/10/02)
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