Dihydroxy-chalcone

Fig. 2.73. HPLC-MS-MS analysis of a methanolic extract of hops, peaks 1 = isoxanthohumol 2 = xanthohumol 3 = 2, 4-dihydroxy- chalcone (internal standard) 4 = 8-prenylnaringenin 5 = desmethylxanthohumol 6 = 6-prenylnaringenin 7 = 3 geranylchalconaringenin 8 = 6-geranylnaringenin. Prenylflavomoids were detected in a single HPLC run by multiple-reaction ion monitoring vertical lines in the panels indicate start of a new scanning period. For other details see text. Reprinted with permission from. J. F. Stevens, et al. [191].

B. Meric, K. Kerman, D. Ozkan, P. Kara, A. Erdem, 0. Kucukoglu, E. Erciyas, and M. Ozsoz, Electrochemical biosensor for the interaction of DNA with the alkylating agent 4,4-dihydroxy chalcone based on guanine and adenine signals,/. Pharm. Biomed. Anal 30(4), 1339-1346 (2002). 

The stereoselective epoxidation of chalcones, followed by acid-catalysed ring closure and concomitant cleavage of the epoxide ring, provides a very efficient route to chiral flavon-3-ols and, subsequently, by borohydride reduction to produce flavan-3,4-diols [13, 14], It has been shown that diastereoselective reduction of the chiral flavon-3-ols by sodium borohydride in methanol yields the trans-2,3-dihydroxy compounds, whereas borohydride reduction in dioxan produces the cis-isomers [14] the synthetic procedure confirms the cis configuration of the 2,3-hydroxy groups of naturally occurring leucodelphinidins [14]. 

Dihydroxy-6 -methoxy-3 -(8,17-epoxy-16-0X0-12, 14-labdadien-15-yl)chalcone C36H42O6 Alpinia katsumadai Zingiberaceae 198... 

Out of a series of 42 compounds isolated and characterized in our investigation on B. papyrifera [41], comprising benzofurans, coumarins, and various types of flavonoids (biphenylpropanes, chalcones, flavans, flavanones, and flavones), only certain representatives of the latter class of compounds showed potent aromatase inhibition activity (Table 2). Flavanone 39 (2S)-2, 4 -dihydroxy-2"-(l -hydroxy- 1-methylethyl)-... 

The triketo ester (602) undergoes a Claisen condensation in aqueous potassium hydroxide yielding the chalcone (603). On heating, cyclization to the flavanone, pinocembrin (604), occurred (67JA6734). Methanolic potassium hydroxide effects an alternative cyclization to methyl 2,4-dihydroxy-6-styrylbenzoate. 

The main flavonoid skeleton derives from the stepwise condensation of three molecules of malonyl CoA with one molecule of 4-coumaroyl CoA, a reaction catalyzed by chalcone synthase (CHS) to form naringenin (2, 4,4 ,6,-tetrahydroxy) chalcone, the common intermediate in the formation of all flavonoids with 5,7-dihydroxy (flavone numbering) A-ring substitution. In some plants, however, an NADP-dependent chalcone-ketide reductase coacts with CHS to form 6 -deoxychalcone, the precursor of 5-deoxyflavonoids. The resulting chalcones undergoe a stereospecific cyclization to the corresponding (2S) flavanones, the... 

The polymethylated flavonoids 5-hydroxy-3,6,7,8,4 -pentamethoxyflavone (353), 5-hydroxy-3,6,7,8,-tetramethoxyflavone (354), and 5,6-dihydroxy-3,7-dimethoxyflavone (355) and a chalcone, 4,4, 6 -trihydroxy-2 -methoxychalcone 356, have all been isolated from cudweed, Gnaphalium affine Compositae).153 Although the flavonoids were present in small amount in the plant, they all exhibit high antifeedant activity against the common cutworm (S. litura) with ED50 values of 1.1 x 10-7 mol cm-2 for 353, 2.0 x 10-8 mol cm-2 for 354, and 2.5 x 10 8 mol cm-2 for 355. The chalcone 356 was present in higher amounts, but had less activity (3.8 x 10 7 mol cm-2).153... 

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