Flavone 3-hydroxy

Diphenylboric acid-2-aminoethyl ester reacts to form complexes with 3-hydroxy-flavones with bathochromic shift of their absorption maximum. 

McMorrow D, Kasha M (1984) Intramolecular excited-state proton transfer in 3-hydroxy-flavone. Hydrogen-bonding solvent perturbations. J Phys Chem 88 2235-2243... 

Kelley and co-workers [70, 71] measured the dynamics of the excited-state intramolecular proton transfer in 3-hydroxyflavone and a series of its derivatives as a function of solvent (Scheme 2.9). The energy changes associated with the processes examined are of the order of 3 kcal/mol or less. The model they employed in the analysis of the reaction dynamics was based upon a tunneling reaction path. Interestingly, they find little or no deuterium kinetic isotope effect, which would appear to be inconsistent with tunneling theories. For 3-hydroxy-flavone, they suggest the lack of an isotope effect is due to a very large... 

Cornard, J.-P., Vrielynck, L., and Merlin, J.-C., Structural and vibrational study of 3-hydroxy-flavone and 3-methoxyfiavone, Spectrochim. Acta A, 51, 913, 1995. 

Flavonoids, especially flavones and flavonols, also directly bind to several CYP isoforms (lAl, 1A2, IBl, 3A4) involved in xenobiotics metabolism and inhibit enzyme activity. Structure-activity relationships show rather high isoform selectivities depending on the flavonoid substitution pattern and contrasted inhibition mechanisms. For instance, inhibition by flavonoids of 7-methoxyresorufin O-demethylation in microsomes enriched in CYP lAl and 1A2 reveals that galangin (3,5,7-trihydroxyflavone) is a mixed inhibitor of CYP 1A2 (.ST = 8 nM) and a five times less potent inhibitor of CYP 1A1. By contrast, 7-hydroxy flavone is a competitive inhibitor of CYP lAl (Aii = 15 nM) and a six times less potent inhibitor of CYP 1A2. In addition, fairly selective inhibition of CYP IBl (specifically detected in cancer cells) by some flavonoids has been reported. For example, 5,7-dihydroxy-4 -methoxyflavone inhibits IBl, 1 Al, and 1A2 with IC50 values of 7, 80, and 80 nM, respectively. ... 

Petroselinin (Graveolbioside A) luteolin 3, 4, 5,7-tetra- hydroxy- flavone Petroselinum crispum (parsley)25 and Apium graveolens (celery)27- 5... 

Kaempferol-3 (3- glucoapioside kaempferol 4, 3,5,7-tetra- hydroxy- flavone Cicer arietinum (chick pea)37... 

The conversion of androstenedione to estrone is catalyzed by aromatase. Inhibition of aromatase (human estrogen synthetase) by several naturally occurring flavonoids, including quercetin, chrysin, and apigenin, has been described. The synthetic flavone 7,8-benzoflavone was most active. Aromatization of androstenedione was affected by several flavonoids, of which 7-hydroxy-flavone and 7,4-dihydroxyflavone were the most potent. 

Anthraquinones, coumarins, flavonoids, and terpenoids alizarin, anthraflavic acid, bomeol, chrysin, emodin, eugenol, 4-ethylphenol, galangin, 7-hydroxy flavone, menthol (low), 4-methylumbelliferone (low), 1-naphthol, naringen (low),... 

Research in our laboratory has focused on cancer prevention in colon and skin by phytochemicals. We have recently studied apigenin, a tri-hydroxy flavone that is widely distributed in plants and resveratrol, a phytoalexin that is found in grapes, wine, peanuts, and Asian herbs. We initially found that topical apigenin inhibited chemically and ultraviolet (UV)-light induced skin cancer and that it was most effective in preventing cancer promotion. 

Flavonol isomers, which differ only in the position of hydroxyl group on their chemical structures, showed different chromatographic behaviors. Liu et al. separated three flavonol isomers (3-hydroxyflavone, 6-hydroxy-flavone, and 7-hydroxyflavone) by a lab-constmcted packed column SFC system with carbon dioxide modified with ethanol containing 0.5% (V/V) phosphoric acid as the mobile phase. The effects of temperature, pressure, composition of mobile phase, and packed-column type on... 

A wide variety of flavonoid compounds have been isolated from hardwoods, including flavones, flavanols, flavanones, isoflavones, and chalcones, most of whieh are highly hydroxylated, and which vary in hydroxylation pattern. Two of the many compounds present are shown in Figure 2.17 robinetin is the 3-hydroxy-flavone extracted from Robinia and Intsia sp. while the chalcone, okanin, is found in Cyclodiscus sp. 

Flavones and isoflavones (3-aryl-chromones) are quantitatively converted into 2,3-epoxides by exposure to dimethyl dioxirane flavone oxides are quantitatively converted by acid into 3-hydroxy-flavones, which are naturally occurring. ... 

An entirely similar obligatory intermediate appears to be required to account for the quercetinase-mimetic dioxygenation of 3-hydroxy-flavones (15) to the acid (17), which is induced by Go(II)salen (Scheme 14) 11, 56). Here again a preliminary redox cycle is necessary to produce the appropriately reactive Co(III) enolate (16). The intermediacy of the enoxy radical (18) is ruled out by the behavior of the latter when independently generated from (15) by manganese dioxide in the presence of oxygen. The result is dimerization to (19) rather than oxygenation 11). 

Sengupta, P.K. and Kasha, M., Excited-state proton-transfer spectroscopy of 3-hydroxy-flavone and quercetin, Chem. Phys. Lett., 68, 382, 1979. 

The flavone, isoflavone, and flavonol-type dyes owe their importance to the presence of an o-hydroxy carbonyl stmcture within the molecule. Positions 4 and 5 can chelate with different metallic salts to give colored, insoluble complexes. In other words, these dyes require a mordant in order to fix them onto the fiber. Perkin was able to predict the stmcture of unknown flavones by comparing the color of their complexes with the color of known complexes (70). For example, ferric chloride gives a green color with 5-hydroxyflavones and a brown one with 3-hydroxyflavones (71). 

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