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Showing papers on "Flavanone published in 1997"


Journal ArticleDOI
TL;DR: The bioavailability and pharmacokinetics of tea polyphenols are being studied in animals and humans to provide a basis for more quantitative analyses on the effect of tea on carcinogenesis and to understand the effects of tea consumption on human carcinogenesis.
Abstract: Many polyphenolic compounds have demonstrated anticarcinogenic activities in animal models. These compounds include flavanone, flavonols, isoflavone, and catechins. In this article, tea catechins w...

143 citations


Journal ArticleDOI
TL;DR: Sequence alignment analysis of various 2-oxoglutarate-dependent dioxygenases and related enzymes revealed eight amino acid residues that seem to be strictly conserved within this group of enzymes, and concludes that His220, His278 and Asp222 constitute three of the possible ligands for iron binding in the active site of flavanone 3beta-hydroxylase.
Abstract: Flavanone 3β-hydroxylase, involved in the biosynthesis of flavonoids, catechins, and anthocyanidins, is a non-heme iron enzyme, dependent on Fe2+, molecular oxygen, 2-oxoglutarate, and ascorbate, the typical cofactors of the class of 2-oxoglutarate-dependent dioxygenases. Sequence alignment analysis of various 2-oxoglutarate-dependent dioxygenases and related enzymes revealed eight amino acid residues that seem to be strictly conserved within this group of enzymes. Among these residues, two histidines (His220 and His278) and one aspartic acid (Asp222) were identified as part of the putative iron-binding site and an arginine residue (Arg288) as part of the 2-oxoglutarate binding site, by site-directed mutagenesis and functional analysis of the mutated recombinant enzyme. The mutant genes were expressed in Escherichia coli to give soluble proteins whose molecular masses were in excellent agreement with the wild-type enzyme. Four out of nine mutant enzymes, [Gln78]FHT, [Gln121]FHT, [Gln264]FHT and [Gln266]FHT, were enzymatically active with activities reduced to 26–57%, implying that the mutated amino acid residues are not essential for catalysis. Replacement of His220 by glutamine and Asp222 by asparagine remarkably reduced the catalytic activity to about 0.15% and 0.4%, respectively. The [Gln220]FHT and [Asn222]FHT enzymes showed a slightly increased Km value with respect to iron binding, as compared to the wild-type enzyme. The most drastic effect on the reaction rate of flavanone 3β-hydroxylase was achieved by mutating His278 to glutamine. The mutant had no detectable enzyme activity, indicating that His278 was essential for the catalytic reaction. The observed protection of purified enzyme from inactivation by diethylpyrocarbonate after the addition of cofactors provided further independent confirmation for the involvement of histidine residues in the active site. The substitution of Arg288 by lysine or glutamine induced a precipitous decrease in catalytic activity and a fivefold and 160-fold increase in the Michaelis constants for 2-oxoglutarate, respectively. In addition, the enzymatic activities of the latter two mutant enzymes showed a strong pH dependence in the weakly acidic as well as in the neutral pH range, unlike the wild-type enzyme. These results clearly indicate that Arg288 probably contributes to the specific binding of 2-oxoglutarate at the active site of the enzyme, most likely by providing a positive charge, properly located in order to interact with the (5-carboxyl function of 2-oxoglutarate. Furthermore, we conclude that His220, His278 and Asp222 constitute three of the possible ligands for iron binding in the active site of flavanone 3β-hydroxylase.

138 citations


Journal ArticleDOI
TL;DR: The activation of aflatoxin B1 and benzo[a]pyrene in hepatic microsomes was inhibited by the antibodies against these isozymes, which suggested that the enhanced activation of the mutagens by the co-administration might be mediated by the induction of theseIsozymes.

135 citations


Journal ArticleDOI
TL;DR: When 56 flavonoids, 32 coumarins, five naphthoquinones, 12 anthraquinones and five structurally-related compounds were tested for their antimutagenic potencies with respect to mutagenicities induced by Salmonella typhimurium TA98 distinct structure-activity relationships were detected.

118 citations


Journal ArticleDOI
TL;DR: Results clearly indicate that N,N‐DEAEFo are acting as promising antioxidants and radioprotectors comparable to rutin activities: they should prove to be useful under acute oxidative stress conditions for which both properties were required.
Abstract: The antiradical and antioxidant activities of four biologically active N,N-diethyloaminoethyl ethers of flavanone oximes (N,N-DEAEFo) were investigated in vitro and compared with these of polyphenolic flavonoid (rutin). Four experimental models were used: iron- and ascorbate driven Fenton systems, gamma-radiolysis, xanthine/xanthine oxidase system and diphenylpicrylhydrazyl (DPPH) radical scavenging. The results clearly indicate that N,N-DEAEFo are acting as promising antioxidants and radioprotectors comparable to rutin activities: they should prove to be useful under acute oxidative stress conditions for which both properties were required.

113 citations


Journal ArticleDOI
TL;DR: It could be shown that further mechanisms of flavonoid interaction with the overall mutagenic process may exist, such as interactions with biological membranes (luteolin, fisetin) and effects on fixation and expression ofDNA damage.
Abstract: The mutagenicity of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in Salmonella typhimurium TA98 is inhibited by flavonoids with distinct structure-antimutagenicity relationships (Edenharder, R., I. von Petersdorff I. and R. Rauscher (1993). Antimutagenic effects of flavonoids, chalcones and structurally related compounds on the activity of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and other heterocyclic amine mutagens from cooked food, Mutation Res., 287, 261-274). With respect to the mechanism(s) of antimutagenicity, the following results were obtained here. (1) 7-Methoxy- and 7-ethoxyresorufin-O-dealkylase activities in rat liver microsomes, linked to cytochrome P-450-dependent 1A1 and 1A2 monooxygenases catalyzing oxidation of IQ to N-hydroxy-IQ (N-OH-IQ), were effectively inhibited by 16 flavonoids (IC50: 0.4-9.8 microM). Flavones and flavonols are in general more potent enzyme inhibitors than flavanones, isoflavones, and chalcones. Among flavones the presence of hydroxyl or methoxyl groups resulted in minor changes only. However, among flavonols and flavanones the parent compounds exerted the strongest inhibitory effects, which decreased in dependence on number and position of hydroxyl functions. Contrary to the results obtained in the Salmonella assay in the tests with alkoxyresorufins no extraordinary counteracting effects of isoflavones, of hydroxyl groups at carbons 6 or 2' or of the elimination of ring B (benzylideneacetone) were detected. (2) No effects of flavonoids on NADPH-dependent cytochrome P-450 reductase activity could be detected. (3) The effects of 30 flavonoids on mutagenicity induced by N-OH-IQ in S. typhimurium TA98NR were again structure dependent. The most striking feature was the, in principle, reverse structure-antimutagenicity pattern as compared to IQ: non-polar compounds were inactive and a 50% inhibition was achieved only by some flavones and flavonols (IC50: 15.0-148 nmol/ml top agar). Within the flavone and flavonol subgroups inhibitory effects increased in dependence on number and position of hydroxyl functions. Isoflavones and flavanones, however, as well as glycosides, were inactive. Hydroxyl groups at carbons 7, 3', 4', and 5' generated antimutagenic compounds, a hydroxyl function at C5 was ineffective, but hydroxyls at C3 and 6 as well as methoxyl groups at C3' (isorhamnetin) or 4' (diosmetin) generated comutagenic compounds. 4. Cytosolic activation of IQ to mutagenic metabolites as determined by experiments with the hepatic S105 fraction comprises about 10% of the mutagenicity after activation by the combined microsomal and cytosolic fractions (S9). The pattern of inhibition as produced by 20 flavonoids was closely similar to that observed with the S9 fraction. 5. In various experiments designed for modulation of the mutagenic response, it could be shown that further mechanisms of flavonoid interaction with the overall mutagenic process may exist, such as interactions with biological membranes (luteolin, fisetin) and effects on fixation and expression of.DNA damage (flavone, fisetin).

67 citations


Journal ArticleDOI
TL;DR: The flavonoids rutin and 3',5,7-trihydroxy-4' methoxyflavone-7-rutinoside, which have a sugar moiety (O-rha-glu), had no significant effect on the ileum, indicating that the presence of sugar substitution reduces the biological activity of the flavonoid.
Abstract: 1. Eleven selected flavonoids were studied to evaluate their effects on the rat isolated ileum and to determine their structure-activity relationships. 2. The flavonoids rutin and 3',5,7-trihydroxy-4' methoxyflavone-7-rutinoside, which have a sugar moiety (O-rha-glu), had no significant effect on the ileum, indicating that the presence of sugar substitution reduces the biological activity of the flavonoids. 3. Nine other flavonoids caused inhibition of tonic and phasic contractions of the ileum with the following order of potency from highest to lowest: galangin, quercetin, chrysin, xanthomicrol, flavone, naringenin, fisetin, morin, and flavanone. 4. Flavones were more potent than flavanones, indicating that the double bond at carbon 2-3 increases the potency of the flavonoid. 5. Galangin, quercetin, chrysin, and xanthomicrol, which have hydroxyl substituents on carbon 3 and/or 5, showed higher potency than flavone, indicating that such hydroxyl groups are essential for the activity. 6. Galangin was more potent than quercetin, morin, and fisetin, suggesting that the hydroxyl substituents on ring B attenuate the potency. 7. Quercetin caused more potent relaxation of the ileum than morin, suggesting that the presence of a hydroxyl group at C-2' of ring B attenuates the myolytic activity.

60 citations


Journal ArticleDOI
TL;DR: From the leaves of Monotes engleri, five prenylated flavanones were isolated as constituents that displayed cytotoxic activity against several human cancer cell lines and the structures of the new compounds were determined by spectral analysis 1D- and 2D-NMR experiments.

57 citations


Journal ArticleDOI
TL;DR: A phenyl propanoid glycoside, cinnamoyl-β-d-glucopyranoside (CIN), characteristic of blood oranges, was isolated by column and thin layer chromatographies as discussed by the authors.
Abstract: A phenyl propanoid glycoside, cinnamoyl-β-d-glucopyranoside (CIN), characteristic of blood oranges, was isolated by column and thin layer chromatographies The structure of this compound was established using 1H and 13C NMR spectral data and by analysis of its components upon hydrolysis Flavanone glycosides (FGs) [narirutin (NAT), hesperidin (HES), and didymin (DID)] and cinnamic derivatives [CIN and trans-cinnamic acid (TCA)] of four blood orange varieties (47 samples) were analyzed by HPLC Differences in the polyphenol profiles clearly showed variety differentiation Keywords: Fruit juice; Citrus sinensis; blood orange varieties; cinnamoyl-β-d-glucopyranoside; flavanone glycoside; NMR; liquid chromatography

54 citations


Journal ArticleDOI
TL;DR: In this article, Eucalyptus camaldulensis, E. rudis and E. globulus have been studied and the phenolic acids gallic, protocatechuic and ellagic acids, some flavonol glycosides, one flavanone (naringenin) and two flavones (luteolin and apigenin) were recognized.
Abstract: Ether soluble polyphenols from leaves of Eucalyptus camaldulensis, E. globulusand E. rudis have been studied. The phenolic aldehyde vanillin, the phenolic acids gallic, protocatechuic and ellagic acids, some flavonol glycosides (rutin, quercetin-3-arabinoside, quercetin-3,7-dirhamnoside, quercitrin, kaempferol-3-arabinoside and their aglycones), one flavanone (naringenin) and two flavones (luteolin and apigenin) were identified and quantified. Some ellagitannins, flavonols and flavanones were recognized according to their ultra-violet spectra. E. camaldulensis and E. rudis showed the highest concentrations and varieties of flavonol glycosides, whilst E. globulus was characterized by high concentrations of ellagitannins. © 1997 John Wiley & Sons, Ltd.

51 citations


Journal ArticleDOI
Abstract: In some European countries there is a legal barrier against the marketing of some citrus juice mixtures under the denomination “orange juice”, as allowed under certain conditions by the FDA for pasteurized and canned orange juice and for frozen concentrated orange juice. For this reason methods have to be developed to determine a juice addition of up to 10% Citrus reticulata and hybrids thereof and up to 5% Citrus aurantium. Using HPLC equipped with a photodiode array (PDA) detector we could establish that a combination of the flavanone glycoside (FG) and polymethoxylated flavone (PMF) pattern offers possibilities. For the flavanone glycosides the method is based on the presence of some specific compounds, on the didymin content, on a divergent ratio of hesperidin on narirutin, and/or on an unidentified component. In other cases, however, an F test applied on the relative PMF pattern offers a better solution calculating the % adulteration probability. We could conclude that, for all examined citrus sample...

Journal ArticleDOI
TL;DR: A preliminary study indicated that the high flavanone contents of some lesser known citrus cultivars grown in Cuba resulted from the genetic characteristics of the cultivars, rather than from climatic effects.

Journal ArticleDOI
TL;DR: In this article, six diarylheptanoids bearing chalcone or flavanone moiety (1, 6) were isolated from the seeds of Alpinia blepharocalyx K. Schum.

Journal ArticleDOI
TL;DR: The antifungal activity of flavone and flavanone was tested in three different concentrations, 0.5, 2 and 8 × 10 -4 M, against 34 fungi, and flavone was the substance with the higher activity, and could at 2 × 10-4 M completely inhibit several fungi.

Journal ArticleDOI
TL;DR: From the stem and root bark of Erythrina sigmoidea and E. eriotricha, one new prenylated flavanone, named sigmoidin L, and two new esters of ferulic and isoferulic acid, erythrinassinates C and D, were isolated together with eight known compounds.

Patent
25 Jul 1997
TL;DR: In this article, the authors present an invention related to novel flavone/flavanone compounds or their pharmaceutically acceptable salts and process for preparation thereof for protecting gastrointestinal tracts against gastritis, ulcers and inflammatory bowel disease.
Abstract: The present invention relates to novel flavone/flavanone compounds or their pharmaceutically acceptable salts and process for preparation thereof for protecting gastrointestinal tracts against gastritis, ulcers and inflammatory bowel disease.

Journal ArticleDOI
TL;DR: The structure of the new flavonol was elucidated as 3-hydroxy-5,7,3,4,4′,5,5′-pentamethoxyflavone on the basis of spectroscopic studies.

Journal ArticleDOI
TL;DR: In this article, the underground part of Iris tenuifolia has been isolated and several new flavonoids have been characterized by high resolution mass spectrometry (HR-MS), and 1H and 13C NMR as 5,2′,3′-trihydroxy-6,7-methylenedioxyflavanone, 5, 2′-dihydroxy-7,2-dimethoxyflanone, 3,5,2.

Journal ArticleDOI
TL;DR: In this article, the hexane extract from the stems of N. magnifica has been used to identify two new flavonoids: 2′-hydroxy-3,4,4′,5-tetramethoxy-5′,6′-(2″,2″-dimethylpyran)chalcone and 5,6,7,3′,4-4-5-hexamethoxyflavanone, the sterols sitosterol and stigmasterol were also identified.

Journal ArticleDOI
TL;DR: The Japanese morning glory carrying the recessive mutable speckled allele with the dominant Speckled-activator bears colorless flowers with fine and round colored spots distributed over the corolla whereas the plant without the speckles produces pale yellow flowers, indicating that the specking allele is neither the F3H gene nor a regulatory gene acting on the F 3H gene expression.
Abstract: The Japanese morning glory carrying the recessive mutable speckled allele with the dominant speckled-activator bears colorless flowers with fine and round colored spots distributed over the corolla whereas the plant without the speckled-activator produces pale yellow flowers. Previous chemical analysis has indicated that a mutation in the gene for flavanone 3-hydroxylase (F3H) is a likely candidate for the speckled allele. However, the F3H mRNA without sequence alteration accumulates normally in the pale yellow flowers, indicating that the speckled allele is neither the F3H gene nor a regulatory gene acting on the F3H gene expression.

Journal ArticleDOI
TL;DR: O-Glycosyltransferase(s) extracted from apple fruit skin showed activity towards a range of flavonols and anthocyanins, but no glycosylating activity was shown towards a dihyroflavonol (dihydroquercetin), a flavanone (eriodictyol) or a flavone (luteolin).
Abstract: O-Glycosyltransferase(s) extracted from apple (Malus pumila Mill) fruit skin showed activity towards a range of flavonols and anthocyanins. However, no glycosylating activity was shown towards a dihyroflavonol (dihydroquercetin), a flavanone (eriodictyol) or a flavone (luteolin). The enzyme preparation glycosylated those flavonoids normally present in apple skins (quercetin and cyanidin) and in addition several other related compounds (delphinidin, fisetin, isorhamnetin, kaempferol, myricetin and pelargonidin). This enzyme(s) specifically transferred the glycosyl moiety from sugar nucleotide donors to the 3-position of the flavonoid nucleus. Only flavonoid 3-glycosides occur naturally in apple skin. Activity with different sugar donors was in the order galactose>glucose>xylose, which reflected the ratios of cyanidin and quercetin glycosides found in apple fruit skin. There were slight differences in the relative UFGT activity with quercetin and the three different sugar donors between ‘Granny Smith’ and ‘Splendour’, and this was reflected by similar differences in the ratios of endogenous quercetin glycosides. ©1997 SCI

Journal ArticleDOI
TL;DR: Experiments using a strain of Ascochyta rabiei pathogenic to chickpea, which can metabolize non-planar isoflavonoid pterocarpans revealed that 6-prenylnaringenin gave only a minute amount of metabolites, whilst the prenylated is oflavone luteone was slowly converted into the corresponding dihydrofuranoisoflavone.


Journal ArticleDOI
TL;DR: By means of nanosecond laser photolysis and steady-state photo-lysis at room temperature, it was concluded as follows: (1) Both the lowest excited triplet states of flavanone and flavone with mixed n£ ∗ -£ £ ∗ character abstract a hydrogen atom from ethanol generating the solute and solvent radicals as discussed by the authors.
Abstract: By means of nanosecond laser photolysis and steady-state photolysis at room temperature, it is concluded as follows: (1) Both the lowest excited triplet states of flavanone and flavone with mixed n£ ∗ -££ ∗ character abstract a hydrogen atom from ethanol generating the solute and solvent radicals. (2) The radical species of flavanone is undoubtedly its ketyl yielding the pinacol-type isomers and the solvent adduct. (3) The ketyl radical of flavone is indistinguishable from the enol-benzyl-type radical but the photoproducts formed from the latter radical (or from the corresponding keto-benzyl-type radical) are obtained.

Journal ArticleDOI
TL;DR: The butanol extract of the flowers of Ononis vaginalis Vahl as mentioned in this paper provided two new norphenylpropanoid glucosides, 1-b-D-glucopyranosyl-2-(4-hydroxyphenyl) (E)-ethene (trans-vaginoside), 1-d-glocopyrano-2-4-hexyl (2S) naringenin (hemipholin), as well as the known flavanone Cglucoside, (+)-6-C-b
Abstract: The butanol extract of the flowers of Ononis vaginalis Vahl. Symb. afforded two new norphenylpropanoid glucosides, 1-b-D-glucopyranosyl-2-(4-hydroxyphenyl) (E)-ethene (trans-vaginoside), 1-b-D-glucopyranosyl-2-(4-hydroxyphenyl) (Z)-ethene (cis-vaginoside) as well as the known flavanone C-glucoside, (+)-6-C-b-D-glucopyranosyl (2S) naringenin (hemipholin). The structures of the isolated compounds were established utilizing chemical and spectroscopic methods.

Patent
Franz Staeb1, Reza Keyhani1, Uwe Schoenrock1, Heiner Max1, Oliver Bleck1 
24 Sep 1997
TL;DR: The use of cosmetically or pharmaceutically acceptable flavone or flavanone derivatives (especially flavonoids) to combat undesirable pigmentation of the skin is claimed.
Abstract: The use of cosmetically or pharmaceutically acceptable flavone or flavanone derivatives (especially flavonoids) to combat undesirable pigmentation of the skin is claimed.- MECHANISM OF ACTION - Tyrosinase inhibitor (see e.g. EP357042; JP06321759).TF - TECHNOLOGY FOCUS - PHARMACEUTICALS - The flavone or flavanone derivatives are preferably alpha-glucosylrutin, naringin, hesperidin, rutin, troxerutin, monoxerutin, dihydrorobinetin, taxifoline, eriodictyol-7-glucoside and/or flavanomarein (i.e. 3',4',7,8-tetrahydroxyflavanone-7-glucoside)

Journal ArticleDOI
TL;DR: In this article, optically active (R)- and (S)-flavanones were prepared by an enzymatically enantioselective hydrolysis of O-acylates employing lipases.

Journal ArticleDOI
TL;DR: Dihydrooroxylin A was isolated and characterized from human urine collected after oral administration of traditional Chinese medicines, Daisaiko-to and Shosaikoto as mentioned in this paper.
Abstract: Dihydrooroxylin A was isolated and characterized from human urine collected after oral administration of traditional Chinese medicines, Daisaiko-to and Shosaiko-to ( Dachaihu-tang and Xiaochaihu-tang in Chinese, respectively). Spectroscopic data (UV, CD, 1 H NMR and MS) and chiral HPLC analysis revealed that this compound had the S -configuration (80% ee). This is the first example of stereoselective hydrogenation of a substituted flavone into its corresponding flavanone in the human body.

Journal ArticleDOI
TL;DR: In this article, the synthesis of (R,S)-dioclein, a bioactive flavanone isolated from the root bark of Dioclea grandiflora Mart. ex Benth, is described.
Abstract: Synthesis of (R,S)-dioclein, a bioactive flavanone isolated from the root bark of Dioclea grandiflora Mart. ex Benth., is described.

Patent
08 Jul 1997
TL;DR: In this article, the authors proposed a composition for topical application, containing a specific flavanone mixture and an excipient, effective for promoting the differentiation of keratinocyte to keep the skin in fresh state and useful for decreasing the wrinkles.
Abstract: PROBLEM TO BE SOLVED: To provide a composition for topical application, containing a specific flavanone mixture and an excipient, effective for promoting the differentiation of keratinocyte to keep the skin in fresh state and useful for decreasing the wrinkles, imparting the skin with moistness and treating light-damaged skin, etc. SOLUTION: This composition contains (A) 0.001-5.0% flavanone consisting of eriodictyol, taxifolin or their mixture, (B) 0.001-5.0% flavanone consisting of hesperetin, naringenin or their mixture, (C) an excipient for the components A and B and, as necessary, (D) a ceramide selected from a short-chain ceramide, pseudoceramide and neoceramide. The weight/mol ratio of B/A in the composition is 1:5 to 5:1 and the amount of the component D in the composition is 0.001-50%.