- Glucuronidation of Methylated Quercetin Derivatives: Chemical and Biochemical Approaches
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Botanical supplements derived from grapes are functional in animal model systems for the amelioration of neurological conditions, including cognitive impairment. Rats fed with grape extracts accumulate 3′-O-methyl-quercetin-3-O-β-d-glucuronide (3) in their brains, suggesting 3 as a potential therapeutic agent. To develop methods for the synthesis of 3 and the related 4′-O-methyl-quercetin-7-O-β-d-glucuronide (4), 3-O-methyl-quercetin-3′-O-β-d-glucuronide (5), and 4′-O-methyl-quercetin-3′-O-β-d-glucuronide (6), which are not found in the brain, we have evaluated both enzymatic semisynthesis and full chemical synthetic approaches. Biocatalysis by mammalian UDP-glucuronosyltransferases generated multiple glucuronidated products from 4′-O-methylquercetin, and is not cost-effective. Chemical synthetic methods, on the other hand, provided good results; 3, 5, and 6 were obtained in six steps at 12, 18, and 30% overall yield, respectively, while 4 was synthesized in five steps at 34% overall yield. A mechanistic study on the unexpected regioselectivity observed in the quercetin glucuronide synthetic steps is also presented.
- Docampo-Palacios, Maite L.,Alvarez-Hernández, Anislay,Adiji, Olubu,Gamiotea-Turro, Daylin,Valerino-Diaz, Alexander B.,Viegas, Luís P.,Ndukwe, Ikenna E.,De Fátima, ?ngelo,Heiss, Christian,Azadi, Parastoo,Pasinetti, Giulio M.,Dixon, Richard A.
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p. 14790 - 14807
(2020/12/23)
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- Correlation study on methoxylation pattern of flavonoids and their heme-targeted antiplasmodial activity
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A library of 33 polymethoxylated flavones (PMF) was evaluated for heme-binding affinity by biomimetic MS assay and in vitro antiplasmodial activity on two strains of P. falciparum. Stability of heme adducts was discussed using the dissociation voltage at 50% (DV50). No correlation was observed between the methoxylation pattern and the antiparasitic activity, either for the 3D7 chloroquine-sensitive or for the W2 chloroquine-resistant P. falciparum strains. However, in each PMF family an increased DV50 was observed for the derivatives methoxylated in position 5. Measurement of intra-erythrocytic hemozoin formation of selected derivatives was performed and hemozoin concentration was inversely correlated with heme-binding affinity. Kaempferol showed no influence on hemozoin formation, reinforcing the hypothesis that this compound may exert in vitro antiplasmodial activity mostly through other pathways. Pentamethoxyquercetin has simultaneously demonstrated a significant biological activity and a strong interaction with heme, suggesting that inhibition of hemozoin formation is totally or partially responsible for its antiparasitic effect.
- Boutefnouchet, Sabrina,Bouzidi, Chouaha,Cojean, Sandrine,Figadère, Bruno,Grougnet, Rapha?l,Maciuk, Alexandre,Michel, Sylvie,Ortiz, Sergio,Vásquez-Ocmín, Pedro G.
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- Quercetin analogs with high fetal hemoglobin-inducing activity
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β-Thalassemia is the major health problems in developing countries, when affected patients and healthy carriers are numerous, resulting a total absence or severe decrease in the production of β-globin chains. The use of chemical agents for increasing the production of fetal hemoglobin (HbF) by reactivating γ-globin gene to balance excess α-globin chains is an alternative therapeutic approach. Therefore, the search for molecules exhibiting the property of inducing γ-globin gene expression is of great interest. In this report, we discovered that quercetin (1), the major flavonoid isolated from the heartwoods of the medicinal plant Anaxagorea luzonensis promoted the expression of γ-globin gene. Chemical modification of 1 to fourteen methyl ether analogs (2?15) was conducted. The structures of these compounds were established on the basis of their spectroscopic data and by comparison with those of the reported values. The parent flavonoid and its chemically modified analogs were investigated for their γ-globin gene induction for the first time. The parent compound 1 exhibited less induced γ-globin gene expression than cisplatin and hemin, the positive controls. 3,4′-Di-O-methylquercetin (7), the modified analog, significantly enhanced γ-globin gene expression with 2.6-fold change at 8 μM, which was slightly higher than cisplatin and hemin. Moreover, compounds 1 and 7 displayed less cytotoxic activity against K562::ΔGγAγEGFP cells than cisplatin. Structure-activity relationship (SAR) study revealed that the methoxyl groups at the 3- and 4?-positions and the free hydroxyl group at the 7-position are required for strong HbF-inducing activity.
- Pabuprapap, Wachirachai,Wassanatip, Yanisa,Khetkam, Pichit,Chaichompoo, Waraluck,Kunkaewom, Sukanya,Senabud, Pongpan,Hata, Janejira,Chokchaisiri, Ratchanaporn,Svasti, Saovaros,Suksamrarn, Apichart
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p. 1755 - 1765
(2019/08/02)
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- The first synthesis of 3-O-methylcyanidin and the effect of 3-O-substitution on stability under acidic conditions
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The simplest and most common anthocyanin in nature is 3-O-glucosylcyanidin (1), and 3-O-glucosylation is believed to stabilize the chromophore. To clarify the effect of the glucose residue we compared the stability of 1 with its aglycone, cyanidin (2), an
- El-Meligy, Asmaa B.,Ishihara, Takehiro,Oyama, Kin-Ichi,El-Nahas, Ahmed M.,Yoshida, Kumi
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p. 946 - 959
(2019/04/26)
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- Natural and Synthetic Flavonoids as Potent Mycobacterium tuberculosis UGM Inhibitors
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This study reports a novel class of inhibitors of uridine 5′-diphosphate (UDP) galactopyranose mutase (UGM) derived from a screening of natural products. This enzyme is an essential biocatalyst involved in the cell wall biosynthesis of Mycobacterium tuberculosis. Flavonoids are potent inhibitors of UGM. The synthesis of novel methylated flavonoids allowed a structure–activity relationship analysis to be performed and which functional groups and structural elements were required for UGM inhibition could be determined. The binding mode of one of the best inhibitors was found to be noncompetitive. Docking simulations indicated that this molecule was likely to bind UGM in its open conformation, in a cavity recently identified as a “druggable” pocket. Importantly, two of the best inhibitors of the M. tuberculosis UGM displayed moderate activity against whole M. tuberculosis cells. This study reports the first natural products that act as inhibitor of UGM. Given the importance of natural products in medicinal chemistry, these results create new opportunities for the discovery of new antitubercular agents.
- Villaume, Sydney A.,Fu, Jian,N'Go, Inès,Liang, Hui,Lou, Huayong,Kremer, Laurent,Pan, Weidong,Vincent, Stéphane P.
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p. 10423 - 10429
(2017/08/07)
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- Effects of Functional Groups and Sugar Composition of Quercetin Derivatives on Their Radical Scavenging Properties
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Quercetin derivatives are widespread in the plant kingdom and exhibit various biological actions. The aim of this study was to investigate the structure-activity relationships of quercetin derivatives, with a focus on the influence of functional groups and sugar composition on their antioxidant capacity. A series of quercetin derivatives were therefore prepared and assessed for their DPPH radical scavenging properties. Isoquercetin O-gallates were more potent radical scavengers than quercetin. The systematic analysis highlights the importance of the distribution of hydroxy substituents in isoquercetin O-gallates to their potency.
- Kato, Komei,Ninomiya, Masayuki,Tanaka, Kaori,Koketsu, Mamoru
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p. 1808 - 1814
(2016/08/02)
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- Flavone glycoside derivatives, and preparation method and application thereof
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The invention discloses flavone glycoside derivatives which are compounds with a general structural formula I shown in the description, and pharmaceutically acceptable salts or hydrates thereof, including racemates, optical isomers and epimers of the deri
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- Discovery of metal ions chelator quercetin derivatives with potent anti-HCV activities
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Analogues or isosteres of α,γ-diketoacid (DKA) 1a show potent inhibition of hepatitis C virus (HCV) NS5B polymerase through chelation of the two magnesium ions at the active site. The anti-HCV activity of the flavonoid quercetin ( 2) could partly be attri
- Zhong, Dongwei,Liu, Mingming,Cao, Yang,Zhu, Yelin,Bian, Shihui,Zhou, Jiayi,Wu, Fengjie,Ryu, Kum-Chol,Zhou, Lu,Ye, Deyong
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p. 6978 - 6999
(2015/05/13)
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- Biological evaluation and SAR analysis of O-methylated analogs of quercetin as inhibitors of cancer cell proliferation
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Preclinical Research Using a high-throughout screening approach, the anticancer activities of 16 O-methylated (OMe) analogs of quercetin were assessed. The structure-activity relationships showed that OMe moieties at the 4′ and/or 7 positions were important for maintaining inhibitory activities against the 16 cancer cell lines. Furthermore, when the OH groups at the 3′ and 4′ positions were both replaced by OMe moieties, anticancer activity was enhanced.
- Shi, Zhi-Hao,Li, Nian-Guang,Tang, Yu-Ping,Shi, Qian-Ping,Tang, Hao,Li, Wei,Zhang, Xu,Fu, Hai-An,Duan, Jin-Ao
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p. 455 - 462
(2015/04/14)
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- Synthesized quercetin derivatives stimulate melanogenesis in B16 melanoma cells by influencing the expression of melanin biosynthesis proteins MITF and p38 MAPK
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In order to understand the effect of structure-activity relationships on melanogenesis using B16 melanoma cells, 19 quercetin derivatives were synthesized. Among the synthesized compounds, 3-O-methylquercetin (11) and 3′,4′,7-O-trimethylquercetin (14) increased melanin content more potently than the positive control theophylline, while exhibiting low cytotoxicity. Compound 11 exhibited less melanogenesis-stimulating activity than compound 14. However, 11 increased the expression of tyrosinase and tyrosinase-related protein 1 (TRP-1) to a greater extent than 14, thereby suggesting that melanogenesis in melanoma cells does not depend solely on the expression of the enzymes catalyzing melanin biosynthesis. Furthermore, 14 also stimulated the expression of the microphthalmia-associated transcription factor (MITF) and p-p38 mitogen activated protein kinase (MAPK), while they were not increased by 11. These results suggest that 11 may enhance the expression of tyrosinase and TRP-1 by regulating the proteasomal degradation of melanogenic enzymes and/or by activating other transcriptional factors regulating enzyme expression.
- Yamauchi, Kosei,Mitsunaga, Tohru,Inagaki, Mizuho,Suzuki, Tohru
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p. 3331 - 3340
(2014/06/23)
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- Metabolism-based synthesis, biologic evaluation and SARs analysis of O-methylated analogs of quercetin as thrombin inhibitors
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In blood, quercetin is mainly found in metabolized forms. In order to study the activities of these quercetin metabolites in cardiovascular disease, 17 methylquercetin derivatives were synthesized based on metabolism in vivo, their thrombin inhibition activity were evaluated through the analyzation of prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen (FIB). The results showed that 6 methylquercetin derivatives had stronger inhibitory activities than that of quercetin. Preliminary SARs analysis showed that hydroxyl groups at C-3′ and C-4′ position in the B-ring and hydroxyl group at C-3 position in the C-ring played key roles in the thrombin inhibitory activity. The findings of this study would provide information for the exploitation and utilization of quercetin as thrombin inhibitor for thrombotic disease treatment.
- Shi, Zhi-Hao,Li, Nian-Guang,Tang, Yu-Ping,Wei-Li,Lian-Yin,Yang, Jian-Ping,Hao-Tang,Duan, Jin-Ao
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p. 210 - 222
(2012/09/07)
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- Hemisynthesis of all the O-monomethylated analogues of quercetin including the major metabolites, through selective protection of phenolic functions
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A new methodology for the hemisynthesis of all the five O-monomethylated analogues of quercetin (3′-O-methylquercetin (isorhamnetin), 4′-O-methylquercetin (tamarixetin), 3-O-methylquercetin, 5-O-methylquercetin (azaleatin) and 7-O-methylquercetin (rhamnetin)) through sequential protection of the different phenolic functions of quercetin is reported.
- Bouktaib, Mohamed,Lebrun, Stéphane,Atmani, Aziz,Rolando, Christian
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p. 10001 - 10009
(2007/10/03)
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- An improved synthesis of the anti-picornavirus flavone 3-O-methylquercetin
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Two optimised procedures to synthesise 3-O-methylquercetin (1), an important antivirally active flavone, are presented: one is based on an Allan-Robinson condensation, the other one on a modified phase transfer catalysed Baker-Venkataraman transformation.
- Boers, Frank,Deng, Bo-Liang,Lemiere, Guy,Lepoivre, Jozef,De Groot, Alex,Dommisse, Roger,Vlietinck, Arnold J.
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p. 313 - 316
(2007/10/03)
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- UNIQUE FLAVONOID GLYCOSIDES FROM THE NEW ZEALAND WHITE PINE, DACRYCARPUS DACRYDIOIDES
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A number of new flavonoid glycosides have been isolated from foliage of the New Zealand white pine, Dacrycarpus dacrydioides.These include tricetin 3',5'-di-O-β-glucopyranoside; the 3'-O-β-xylopiranoside, 7-O-α-rhamnopyranoside and 7-O-α-rhamnopyranoside-
- Markham, Kenneth R.,Whitehouse, Lynley A.
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p. 1931 - 1936
(2007/10/02)
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- O-methylation of flavonoids by cell-free extracts of calamondin orange
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Cell-free extracts of calamondin orange (Citrus mitis) catalysed the O-methylation of almost all hydroxyls of a number of flavonoids, indicating the existence in citrus tissues of ortho, meta, para and 3-O-methyltransferases. The latter, hitherto unreported enzyme, catalysed the formation of 3-O-methyl ethers of galangin and quercetin. The stepwise O-methylation of a number of compounds, especially quercetin and quercetagetin, tends to suggest a coordinated sequence of O-methylations on the surface of a multienzyme complex. The methyl acceptor abilities of the flavonoid substrates used are discussed in relation to their hydroxyl substitution patterns and their negative electron density distribution.
- Brunet, Gunter,Ibrahim, Ragai K.
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p. 741 - 746
(2007/10/02)
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