- Synthesis and Biological Evaluation of 4-Substituted Kaempfer-3-ols
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The synthesis of two series of five kaempfer-3-ols was described. The first set all have a C-3 hydroxyl group and the second has a carboxymethoxy ether at the C-3 position. Both series have variable substitution at the C-4 position (i.e., OH, Cl, F, H, OMe). Both kaempferols and carboxymethoxy ethers were evaluated for their ability to inhibit ribosomal s6 kinase (RSK) activity and cancer cell proliferation.
- Kim, Sugyeom,Lannigan, Deborah A.,Li, Yu,Lin, Lin,O'Doherty, George A.,Sayasith, Peyton R.,Tarr, Ariel T.,Wright, Eric B.,Yasmin, Sharia
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p. 4279 - 4288
(2020/04/09)
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- 7-O-Arylmethylgalangin as a novel scaffold for anti-HCV agents
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In spite of potent antiviral activity, suboptimal physicochemical properties of aryl diketo acids (ADKs) necessitates modification of the core 1,3-diketo acid functionality into a novel scaffold. As the metal-binding affinity of the diketo acid is the key to the antiviral activity of ADKs, we anticipated 3,5-dihydroxy-4-oxo arrangement of galangin scaffold would serve as an excellent mimic for the diketo acid functionality. In this study, through synthesis and biological evaluation of various galangin derivatives, we have shown that the diketo acid functionality can be successfully replaced with the galangin scaffold by specific combination of the substituents to result in identification of a novel galangin derivative (3s) with anti-HCV activity (EC50 = 0.9 μM) comparable to the ADK counterpart.
- Lee, Hyo Seon,Park, Kwang-Su,Lee, Chaewoon,Lee, Bokhui,Kim, Dong-Eun,Chong, Youhoon
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scheme or table
p. 5709 - 5712
(2010/11/04)
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- Tannins, flavonol sulfonates, and a norlignan from Phyllanthus virgatus
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Investigation of the constituents of Phyllanthus virgatus has led to the isolation of five new compounds, including a norlignan, 2-(3,4- methylenedioxybenzyl)-4-(3,4-methylenedioxyphenyl)-3-butyne-1,2-diol named virgatyne (1); a hydrolyzable tannin, virganin (2); and three flavonoid sulfonates, galangin-8-sulfonate (4), galangin-3-O-β-D-glucoside-8- sulfonate (5), and kaempferol-8-sulfonate (6). Their structures were established by spectral and chemical methods.
- Huang, Yu-Lin,Chen, Chien-Chih,Hsu, Feng-Lin,Chen, Chieh-Fu
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p. 1194 - 1197
(2007/10/03)
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- Reduction potentials of flavonoid and model phenoxyl radicals. Which ring in flavonoids is responsible for antioxidant activity?
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Model phenoxyl and more complex flavonoid radicals were generated by azide radical induced one-electron oxidation in aqueous solutions. Spectral, acid-base and redox properties of the radicals were investigated by the pulse radiolysis technique. The physicochemical characteristics of the flavonoid radicals closely match those of the ring with the lower reduction potential. In flavonoids which have a 3,5-dihydroxyanisole (catechins), or a 2,4-dihydroxyacetophenone (hesperidin, rutin, quercetin)-like A ring and a catechol- or 2-methoxyphenol-like B ring, the antioxidant active moiety is clearly the B ring [reduction potential difference between the model phenoxyls is ΔE(A-B ring models) > 0.1 V]. In galangin, where the B ring is unsubstituted phenyl, the antioxidant active moiety is the A ring. Even though the A ring is not a good electron donor, E7, > 0.8/NHE V, it can still scavenge alkyl peroxyl radicals, E7, = 1.06 V, and the Superoxide radical, E7 > 1.06 V. Quercetin is the best electron donor of all investigated flavonoids (measured E10.8 = 0.09 V, and calculated E7 = 0.33 V). The favourable electron-donating properties originate from the electron donating O-3 hydroxy group in the C ring, which is conjugated to the catechol (B ring) radical through the 2,3-double bond. The conjugation of the A and B rings is apparently minimal, amounting to less than 2.5% of the substituent effect in either direction. Thus, neglecting the acid-base equilibria of the A ring, and using those of the B ring and the measured values of the reduction potentials at pH 3,7 and 13.5, the pH dependence of the reduction potentials of the flavonoid radicals can be calculated. In neutral and slightly alkaline media (pH 7-9), all investigated flavonoids are inferior electron donors to ascorbate. Quercetin, E7 = 0.33 V, and gallocatechins, E7 = 0.43 V, can reduce vitamin E radicals (assuming the same reduction potential as Trolox C radicals, E7 = 0.48 V). Since all investigated flavonoid radicals have reduction potentials lower than E7 = 1.06 V of alkyl peroxyl radicals, the parent flavonoids qualify as chain-breaking antioxidants in any oxidation process mediated by these radicals.
- Jovanovic, Slobodan V.,Steenken, Steen,Hara, Yukihiko,Simic, Michael G.
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p. 2497 - 2504
(2007/10/03)
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- Dye-sensitized Photo-oxygenation of Chalcones
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The dye-sensitized photo-oxygenation of several chalcones has been examined.Some of the chalcones give rise to degradation products while others lead to flavonol formation.A rational explanation for the observations has been proposed.The study may have a significance in the biogenesis of naturally occurring plant polyphenolics.
- Chawla, H. Mohindra,Chakrabarty, Kakoli
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p. 1511 - 1513
(2007/10/02)
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