- Unraveling the anti-influenza effect of flavonoids: Experimental validation of luteolin and its congeners as potent influenza endonuclease inhibitors
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The biological effects of flavonoids on mammal cells are diverse, ranging from scavenging free radicals and anti-cancer activity to anti-influenza activity. Despite appreciable effort to understand the anti-influenza activity of flavonoids, there is no clear consensus about their precise mode-of-action at a cellular level. Here, we report the development and validation of a screening assay based on AlphaScreen technology and illustrate its application for determination of the inhibitory potency of a large set of polyols against PA N-terminal domain (PA-Nter) of influenza RNA-dependent RNA polymerase featuring endonuclease activity. The most potent inhibitors we identified were luteolin with an IC50 of 72 ± 2 nM and its 8-C-glucoside orientin with an IC50 of 43 ± 2 nM. Submicromolar inhibitors were also evaluated by an in vitro endonuclease activity assay using single-stranded DNA, and the results were in full agreement with data from the competitive AlphaScreen assay. Using X-ray crystallography, we analyzed structures of the PA-Nter in complex with luteolin at 2.0 ? resolution and quambalarine B at 2.5 ? resolution, which clearly revealed the binding pose of these polyols coordinated to two manganese ions in the endonuclease active site. Using two distinct assays along with the structural work, we have presumably identified and characterized the molecular mode-of-action of flavonoids in influenza-infected cells.
- Albi?ana, Carlos Berenguer,Brynda, Ji?í,Fanfrlík, Jind?ich,Flieger, Miroslav,Hodek, Jan,Karlukova, Elena,Ko?í?ek, Milan,Konvalinka, Jan,Machara, Ale?,Majer, Pavel,Radilová, Kate?ina,Weber, Jan,Zima, Václav
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- Preparation method and application of tricetin
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The invention belongs to the field of medicine synthesis, and in particular relates to a preparation method and application of tricetin. The method comprises the following steps: performing hydroxy protection to form a compound 3 by using 2,4,6-trihydroxyacetophenone as a starting material, performing an acylation reaction on the compound 3 and 3,4,5-trimethoxybenzoyl chloride to form a compound 4, performing Baker-Venkataranan rearrangement on the compound 4 to form a compound 5, performing cyclization on the compound 5 under catalysis of H2SO4/HOAc to form a compound 6, and finally performing pyridine hydrochloride deprotection on the compound 6 to form the tricetin, wherein in the step of synthesizing the compound 5, when NaOH is selected as a base and pyridine is selected as a solvent,the yield is greatly improved, and the reaction is relatively stable. According to the method provided by the invention, pharmacological activity experiments show that the compound synthesized by themethod has anti-nerve damage activity, so that the compound has better application prospects in treating nerve damage-related diseases.
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- A new synthesis for acacetin, chrysoeriol, diosmetin, tricin and other hydroxylated flavones by modified Baker-Venkataraman transformation
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Baker-Venkataraman (BV) rearrangement is the method of choice for the synthesis of flavones. The major limitation of BV is that it requires extensive protections and deprotections of hydroxyl groups which make the process lengthy and cumbersome. In the present study, a three step efficient method has been developed using simple protecting groups and easily available starting materials. New syntheses for acacetin, chrysoeriol, diosmetin, tricin and other hydroxylated flavones are described.
- Pandurangan
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p. 225 - 229
(2014/05/20)
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- Inhibitory effects of 5,6,7-trihydroxyflavones on tyrosinase
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Baicalein (1), 6-hydroxyapigenin (6), 6-hydroxygalangin (13) and 6-hydroxykaempferol (14), which are naturally occurring flavonoids from a set of 14 hydroxyflavones tested, exhibited high inhibitory effects on tyrosinase with respect to L-DOPA, while each of the 5,6,7-trihydroxyflavones 1, 6, 13 or 14 acted as a cofactor to monophenolase. Moreover, 6-hydroxykaempferol (14) showed the highest activity and was a competitive inhibitor of tyrosinase compared to L-DOPA. 5,6,7-Trihydroxyflavones 1, 6, 13 or 14 showed also high antioxidant activities. Hence, we conclude that the 5,6,7-trihydroxy-flavones are useful as good depigmentation agents with inhibitory effects in addition to their antioxidant properties.
- Gao, Hong,Nishida, Jun,Saito, Shizuka,Kawabata, Jun
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