- 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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- Rhamnetin Glycosides from the Genus Spiraea
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Rhamnetin (7-O-methylquercetin,1) and its glycosides were found for the first time in the genus Spiraea (Rosaceae) during chromatographic studies of representatives from the subgenus Protospiraea. Leaves of S. salicifolia yielded1, rhamnetin-3-O-β-D-glucopyranoside (2), and two new flavonoids3and4that were identified by UV, IR, and NMR spectroscopy and mass spectrometry as rhamnetin-3-O-(6″-O-p-coumaroyl)-β-D-glucopyranoside (spiraearhamnin A,3) and rhamnetin-3-O-(6″-O-caffeoyl)-β-D-glucopyranoside (spiraearhamnin B,4). Leaves of S. betulifolia and S. betulifolia var. aemiliana afforded1and2and glycosides of kaempferol, quercetin, and isorhamnetin. Species of the subgenus Metaspiraea (S. alpina, S. chamaedryfolia, S. dahurica, S. hypericifolia, and S. media) did not contain1or its derivatives.
- Olennikov,Chirikova
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- New Flavonol Glucuronides from the Flower Buds of Syzygium aromaticum (Clove)
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Repeated chromatography of the EtOAc-soluble fraction from the 70% EtOH extract of the flower buds of Syzygium aromaticum (clove) led to the isolation and characterization of four new flavonol glucuronides, rhamnetin-3-O-β-d-glucuronide (1), rhamnazin-3-O-β-d-glucuronide (2), rhamnazin-3-O-β-d-glucuronide-6″-methyl ester (3), and rhamnocitrin-3-O-β-d-glucuronide-6″-methyl ester (4), together with 15 flavonoids (5-19) having previously known chemical structures. The structures of the new compounds 1-4 were determined by interpretation of spectroscopic data, particularly by 1D- and 2D-NMR studies. Six flavonoids (6, 7, 9, 14, 18, and 19) were isolated from the flower buds of S. aromaticum for the first time in this study. The flavonoids were examined for their cytotoxicity against human ovarian cancer cells (A2780) using MTT assays. Among the isolates, pachypodol (19) showed the most potent cytotoxicity on A2780 cells with an IC50 value of 8.02 μM.
- Ryu, Byeol,Kim, Hye Mi,Lee, Jin Su,Lee, Chan Kyu,Sezirahiga, Jurdas,Woo, Jeong-Hwa,Choi, Jung-Hye,Jang, Dae Sik
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p. 3048 - 3053
(2016/05/19)
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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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- Selective monomethylation of quercetin
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Quercetin was monomethylated under mild conditions in moderate yields through selective deprotection. The combined effects of the protecting group and the heating mode on the reactivity were investigated. The presence of borax and the use of microwave irradiation significantly improved the yield and selectivity of alkylation. Georg Thieme Verlag Stuttgart - New York.
- Zhou, Zhong-Hua,Fang, Zhuan,Jin, Hui,Chen, Yue,He, Ling
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experimental part
p. 3980 - 3986
(2011/02/22)
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- Regioselective O-derivatization of quercetin via ester intermediates. An improved synthesis of rhamnetin and development of a new mitochondriotropic derivative
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The regioselective synthesis of several quercetin (3,3',4',5,7-pentahydroxy flavone) tetraesters bearing a single free OH on 5-C was achieved in good yield by proper choice of reaction conditions using common esterification procedures. Tetracetylated quercetin with the free OH on 7-C was selectively obtained instead via imidazole-promoted deacylation of the corresponding pentaester. Unambiguous structural characterization of the two isomeric tetraacetyl quercetin derivatives was obtained by combined HSQC and HMBC 2D-NMR analysis. These molecules can be used as starting materials for the regioselective synthesis of other derivatives. High yield syntheses of the natural polyphenol rhamnetin (7-O-methylquercetin) and of the new mitochondriotropic compound 7-(4-triphenylphosphoniumbutyl) quercetin iodide are reported as examples.
- Mattarei, Andrea,Biasutto, Lucia,Rastrelli, Federico,Garbisa, Spiridione,Marotta, Ester,Zoratti, Mario,Paradisi, Cristina
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experimental part
p. 4722 - 4736
(2010/10/20)
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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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- Structural requirements of flavonoids and related compounds for aldose reductase inhibitory activity
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The methanolic extracts of several natural medicines and medicinal foodstuffs were found to show an inhibitory effect on rat lens aldose reductase. In most cases, flavonoids were isolated as the active constituents by bioassay-guided separation, and among them, quercitrin (IC50=0.15 μM), guaijaverin (0.18 μM), and desmanthin-1 (0.082 μM) exhibited potent inhibitory activity. Desmanthin-1 showed the most potent activity, which was equivalent to that of a commercial synthetic aldose reductase inhibitor, epalrestat (0.072 μM). In order to clarify the structural requirements of flavonoids for aldose reductase inhibitory activity, various flavonoids and related compounds were examined. The results suggested the following structural requirements of flavonoid: 1) the flavones and flavonols having the 7-hydroxyl and/or catechol moiety at the B ring (the 3′,4′-dihydroxyl moiety) exhibit the strong activity; 2) the 5-hydroxyl moiety does not affect the activity; 3) the 3-hydroxyl and 7-O-glucosyl moieties reduce the activity; 4) the 2-3 double bond enhances the activity; 5) the flavones and flavonols having the catechol moiety at the B ring exhibit stronger activity than those having the pyrogallol moiety (the 3′,4′,5′-trihydroxyl moiety).
- Matsuda, Hisashi,Morikawa, Toshio,Toguchida, Iwao,Yoshikawa, Masayuki
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p. 788 - 795
(2007/10/03)
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- Chemical Studies on the Constituents of Hyphear Tanakae HOSOKAWA from Different Host Trees
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The chemical constituents of Hyphear Tanakae HOSOKAWA epiphyting to four different host trees were examined.A new triterpene fatty acid ester (III) and four known flavonoid glycosides, rhamnocitrin-3-O-rhamnoside (V), kaempferol-3-O-rhamnoside (VI), rhamnetin-3-O-rhamnoside (VII), and quercetin-3-O-rhamnoside (VIII) have been isolated from the leaves and twigs of this plant epiphyting to Castanea crenata SIEB., together with fatty acids (I), phytosterol (II), and phytosterol-glucoside (IV).The present investigation has revealed that compounds II-V, VII, and VIII are contained in this plant irrespective of the host, among the four host trees, examined.Keywords - Hyphear Tanakae; misletoe; Loranthaceae; triterpene; lup-20(29)-ene-3β,7β,15α-triol; flavonoid; rhamnocitrin-3-O-rhamnoside; kaempferol-3-O-rhamnoside; rhamnetin-3-O-rhamnoside; quercetin-3-O-rhamnoside
- Fukunaga, Takehiko,Nishiya, Koichi,Kajikawa, Ikuko,Watanabe, Yoshikuni,Suzuki, Nobuo,et al.
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p. 1180 - 1184
(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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