- Miscrowave-assisted efficient synthesis of polymethoxyacetophenones and natural polymethoxyflavones, and thier inhibitory effects on melanogenesis
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Microwave, assisted Friedel-Crafts acetylation of polymethoxybenzenes with acetic anhydride in the presence of In(CF3SO3)3 under solvent-free conditions was achieved rapidly to give polymethoxyacetophenones in high yields. Microwave-assisted benzoylation of 2'-hydroxypolymethoxyacetophenones with polymethoxybenzoyl chlorides, followed by the rearrangement of the resulting benzoates and the final formation of natural polymethoxyflavones was achieved rapidly and efficiently. The polymethoxyflavones showed inhibitory effects on melanogenesis in human melanoma cells.
- Tsukayama, Masao,Kusunoki, Eiji,Hossain, Mohammad M.,Kawamura, Yasuhiko,Hayashi, Shinji
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p. 1589 - 1600
(2008/09/17)
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- Regioselective hydroxylation of 2-hydroxychalcones by dimethyldioxirane towards polymethoxylated flavonoids
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The flavone nucleus is part of a large number of natural products and medicinal compounds. In this presentation the novel regioselective hydroxylation of hydroxyarenes with DMD is described. The results showed further that flavonoids with 5-hydroxy group were selectively oxyfunctionalized at the para-position C8 carbon atom by DMD. Finally, according to this methodology, the naturally occurring isosinensetin, tangeretin, sinensetin, nobiletin, natsudaidain, gardenin B, 3,3′,4′,5,6,7,8- heptamethoxyflavone, quercetin and its derivatives were synthesized.
- Chu, Han-Wei,Wu, Huan-Ting,Lee, Yean-Jang
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p. 2647 - 2655
(2007/10/03)
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- Taste modifier and a method of modifying taste
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Taste modifier comprising a flavone derivative as an active ingredient of the general formula (I): STR1 wherein R1, R3, R4, R6 and R8 are independently a methoxy group or an hydrogen atom, R2 and R7 are methoxy groups, and R5 is a methoxy group or an hydroxy group, and a method of modifying taste, comprising adding a taste-modifying effective amount of the flavone derivative (I) to a product used in a mouth or an orally ingestible product. Various factors associated with taste can be modified, for example, the derivative can enhance sourness, reduce saltiness, inhibit unpleasant lasting of sweetness, enhance refreshing flavor and its continuity, reduce flavor associated with acetic acid, and enhance body, deliciousness and savor associated with the combination of these tastes.
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- Syntheses of 6-Hydroxyluteolin and Sinensetin by Wessely - Moser Rearrangement
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Syntheses of 6-hydroxyluteolin (1) and sinensetin (2) are described.The compounds 6 and 7 afford 1 on Wessely - Moser rearrangement.The synthetic samples 1 and 2 are identical (m.m.p. and co-ir) with the authentic samples.
- Shaw, S. C.,Azad, R.,Mandal, S. P.,Gandhi, R. S.
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p. 107 - 109
(2007/10/02)
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- Flavanoids from Leaves of Callitris glauca R.Br. (Cupressaceae)
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From the leaf extracts of Callitris glauca R.Br., a new glycoside, kaempferol-5-O-rhamnoside (I) has been isolated along with 3',4',5,7,8-pentahydroxyflavone (hypoletin), amentoflavone and sequoiaflavone.Di-O-methylamentoflavone and hinokiflavone have only been detected by TLC.
- Ansari, F. R.,Ansari, W. H.,Rahman, W.,Okigawa, M.,Kawano, N.
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p. 724 - 725
(2007/10/02)
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