- Dimethylallyl diphosphate: Kaempferol 8-dimethylallyl transferase in Epimedium diphyllum cell suspension cultures
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The enzymatic formation of des-O-methylanhydroicaritin from dimethylallyl diphosphate and kaempferol was investigated in the cell-free extract of Epimedium diphyllum cell suspension cultures. The enzyme catalysing the dimethylallyl group transfer to C-8 position of kaempferol (EC 2.5.1.) was membrane-bound and required divalent cations such as Mg2+ and Mn2+. Mg2+ was the most effective for the reaction. The enzyme showed a very broad pH optimum in the alkaline region, pH 7.5-11.0. It required dimethylallyl diphosphate as a sole prenyl donor, but had a rather broad substrate specificity for the prenyl acceptor. Not only kaempferol, but also quercetin (39%), apigenin (60%) and luteolin (34%) were prenylated, whereas kaempferol glycosides, naringenin and genistein were not prenylated. These results suggested that the prenylation reaction of kaempferol precedes the glycosylation step in epimedoside A biosynthesis. The apparent K(m) values for dimethylallyl diphosphate and kaempferol were 0.58 and 0.13 mM, respectively.
- Yamamoto, Hirobumi,Kimata, Junko,Senda, Masayuki,Inoue, Kenichiro
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- Method for preparing dewatered icaritin through total-synthesis
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The invention provides a method for preparing dewatered icaritin through total-synthesis. The method includes the steps of connecting an isopentene group to 8th-position carbon through ortho-positionrearrangement with methoxybenzoyl chloride, isoprenyl bromide and the like as the raw materials by means of trihydroxyacetophenone, and conducting the forming series reaction of a flavone framework toobtain the dewatered icaritin. The defects that in a traditional method of introducing an isopentene group, the yield is low, catalysts are expensive and lots of byproducts are produced are overcome,and the method is low in cost, simple in operation, good in yield and suitable for industrial production.
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- The first total synthesis of sophoflavescenol, flavenochromane C, and citrusinol
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The first total syntheses of sophoflavescenol (1), flavenochromane C (2), and citrusinol (3) were achieved. These three naturally occurring prenylated or prenyl-cyclized flavonoids have important biological activities such as cytotoxicity against some can
- Nguyen, Van-Son,Dong, Lin-Pei,Wang, Sheng-Chun,Wang, Qiuan
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p. 2297 - 2302
(2015/04/14)
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- 1H-NMR CHEMICAL SHIFT OF THE FLAVONOL 5-HYDROXY PROTON AS A CHARACTERIZATION OF 6- OR 8-ISOPRENOID SUBSTITUTION
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1H Nmr examination of 6- or 8-isoprenoid substituted flavonols has shown that the location of isoprenoid side chain on A ring can be deduced from the chemical shift of the 5-hydroxy proton.The application of this 1H nmr technique to identification of the
- Fukai, Toshio,Nomura, Taro
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p. 1213 - 1225
(2007/10/02)
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- A 2,2-DIMETHYLPYRANOFLAVONOL FROM CITRUS NOBILIS
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An investigation of the root bark constituents of Citrus nobilis var. sunki has afforded a sesquiterpene , six coumarins , and four acridone alkaloids together with p-hidroquinone.A new 2,2-dimethylpyranoflavonol was also isolated, identified and named citrusinol. Key Word Index - Citrus nobilis var. sunki; Rutaceae; citrusinol; flavonoids; coumarins; sesquiterpene; acridone alkaloids; homoacridone alkaloids.
- Wu, Tian-Shung
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p. 3094 - 3095
(2007/10/02)
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