Showing papers on "Flavanone published in 1992"
TL;DR: It is shown that hyphal growth of the VAM fungus, Gigaspora margarita Becker & Hall, is affected by both stimulatory and inhibitory flavonoids, when applied at 10 μ together with an optimal carbon dioxide enrichment.
Abstract: summary
Plant phenolic compounds are known to be inducers of virulence genes in plant-pathogen interactions such as those involving Agrobacterium, and flavonoids are known to be inducers or inhibitors of Nod genes in Rhizobium-legume symbiosis. More recent studies suggest that some of these compounds act as molecular signals in the development of vesicular-arbuscular mycorrhizas (VAM). The present study has shown that hyphal growth of the VAM fungus, Gigaspora margarita Becker & Hall, is affected by both stimulatory and inhibitory flavonoids, when applied at 10 μ together with an optimal carbon dioxide enrichment. Stimulatory compounds were all flavonols (kaempferol, quercetin and morin) and possessed at least one hydroxyl group on the B ring. Conversely, two isoflavones (biochanin A, and genistein), a single flavanone (hesperetin) and two compounds without any hydroxyl group on the B ring, galangin (flavonol) and chrysin (flavone), were all inhibitors of hyphal growth.
176 citations
TL;DR: Activity-based fractionation of Eriodictyon californicum resulted in the isolation of 12 flavonoids that inhibit the metabolism of the carcinogen benzo[a]pyrene by hamster embryo cells in tissue culture, indicating that these flavones warrant further investigation in vivo as potential chemopreventive agents.
Abstract: Activity-based fractionation of Eriodictyon californicum resulted in the isolation of 12 flavonoids that inhibit the metabolism of the carcinogen benzo[a]pyrene by hamster embryo cells in tissue culture. One was identified as a new flavanone, 3'-methyl-4'-isobutyryleriodictoyol [1], on the basis of spectroscopic analysis and alkaline hydrolysis. The seven other active flavanones were identified as eriodictyol [2], homoeriodictyol [3], 5,4'-dihydroxy-6,7-dimethoxyflavanone [4], pinocembrin [5], sakuranetin [6], 5,7,4'-trihydroxy-6,3'-dimethoxyflavanone [7], and naringenin 4'-methyl ether [8]. Four active flavones were also isolated: cirsimaritin [9], chrysoeriol [10], hispidulin [11], and chrysin [12]. The high inhibition of benzo[a]pyrene metabolism and the activation of benzo[a]pyrene to ultimate carcinogenic DNA-binding metabolites by cirsimaritin and chrysoeriol at a concentration of only 10 micrograms/ml indicates that these flavones warrant further investigation in vivo as potential chemopreventive agents.
140 citations
TL;DR: Genomic Southern blot analysis showed the presence of only one gene for flavanone 3 beta-hydroxylase in P. hybrida, and computer-aided sequence analysis revealed high similarity (73.5%) to flavan one 3 Beta-hydrogenase from barley.
131 citations
TL;DR: In this article, two novel flavanones with a lavandulyl residue, exiguaflavanones A and B, were isolated from the roots of Sophora exigua in addition to a known flavanone (sophoraflavone G) by means of 2D NMR spectral analysis.
46 citations
TL;DR: Isomerization equilibria of the flavanone/2′-hydroxychalcone, 7hydroxyflavanone/ 2′,4′-dihydroxy-chalcone and 4′,5,7-trihydroxy flavanone (naringenin) systems have been studied in dilute and saturated solutions as discussed by the authors, the latter in equilibrium with the solid precipitated form.
Abstract: Isomerisation equilibria of the flavanone/2′-hydroxychalcone, 7-hydroxyflavanone/2′,4′-dihydroxychalcone and 4′,5,7-trihydroxyflavanone (naringenin)/2′,4′,6′,4-tetrahydroxychalcone systems have been studied in dilute and saturated solutions – the latter in equilibrium with the solid precipitated form. Seemingly inconsistent results found in the literature are rationalized in terms of proton transfer reactions and solubility effects. The results indicate that at least two different isomerisation mechanisms operate, one in the acidic and weakly alkaline region, the second in strongly alkaline solutions. Practical conclusions may ease the preparation of pure chalcones or flavanones in which contamination with the other isomer is minimized.
40 citations
TL;DR: In this article, three new flavonoids have been isolated from the leaves of Petiveria alliacea and assigned the structures 6-formyl-8-methyl-7-O-methylpinocembrin, 6-hydroxymethyl-8 -methyl-5,7-di-O -methylpINOcemBrin, respectively.
39 citations
TL;DR: It is concluded that the threshold effect depends on the chemical structure of the flavonoid and the enzyme activity, and low threshold doses for conjugating enzymes may be important for the anticarcinogenicity properties of these compounds.
Abstract: The induction of drug-metabolizing enzymes for different dietary flavonoids has been shown previously. The purpose of this study was to determine the threshold effect of these components. Rats were fed diets containing flavone, flavanone, or tangeretin at different levels (20, 50, 200, 500, and 200 ppm). Flavone induced ethoxyresorufin and pentoxyresorufin dealkylase activities at 500 ppm and arylhydrocarbon hydroxylase at 200 ppm. Epoxide hydrolase and glutathion transferase were increased at 200 ppm. UDP-glucuronyl transferases were enhanced at 20 ppm. Flavanone induced pentoxyresorufin dealkylase and arylhydrocarbon hydroxylase at the greatest level. In contrast, epoxide hydrolase and conjugating enzymes were increased at the lowest dose. Significant induction was seen only for ethoxyresorufin deethylase and UDP-glucuronyl transferase with diets containing 2000 ppm tangeretin. We conclude that the threshold effect depends on the chemical structure of the flavonoid and the enzyme activity. Low threshold doses for conjugating enzymes may be important for the anticarcinogenicity properties of these compounds.
39 citations
TL;DR: It is confirmed that flavonoids, in vitro, are potent inhibitors of carcinogen-DNA binding and the influence of flavonoid pretreatment on hepatic microsomal enzymes involved in BaP metabolism has been examined.
23 citations
TL;DR: The isolation and characterization of a new chalcone, spinochalcone C, and two new flavanones, spinoflavanones A and B, from various parts of Tephrosia spinosa are reported in this paper.
20 citations
TL;DR: A new scheme for the P 450 enzymic conversion of flavanones, which surmounts known experimental constraints, is proposed and is shown to surmount some of the experimental constraints.
19 citations
TL;DR: In this article, two new flavanones, leachianones D and E, were isolated from the roots of Sophora leachiana together with maackiain and a caffeic acid ester.
TL;DR: In this article, 5,7-Dihydroxy-6,5′-dimethoxy-3′,4′-methylenedioxyflavanone has been isolated for the first time from Agave americana.
TL;DR: The first report of butin in sorghum tissues was reported in this paper, where the authors found negative correlations between HPLC peaks and in-vitro digestibility, i.e., true dry matter and neutral-detergent fibre digestibility.
Abstract: Soluble phenolics in leaf blades and sheaths from the crop residues of 24 sorghum varieties were studied. Apigenin, luteolin, apigenin and luteolin 7-O-glucosides, p-coumaric acid, butin and apigeninidin were identified. This is the first report of butin in sorghum tissues. Derivatives of the following compounds were also detected but not characterised further: apigeninidin, luteolinidin, chalcone, flavanone and/or dihydroflavonol, cinnamic acid, apigenin and luteolin. The composition of phenolics was clearly different between leaf blades (LB) and sheaths (LS), and also between leaf sheaths of bird-resistant (BR) and non-bird-resistant (NBR) varieties. Routes of flavonoid biosynthesis in BR and NBR varieties appear to diverge at the flavanone/dihydroflavonol level. Several negative correlations were found between HPLC peaks and in-vitro digestibilities, ie true dry matter and neutral-detergent fibre digestibility. These were highly significant with butin and significant with several luteolin derivatives but only with one apigenin derivative. Butin in turn was highly negatively correlated with colorimetric measurements of 3-desoxyanthocyanidins. This may suggest that butin—rather than the 3-desoxyanthocyanidins as previously reported—is implicated in reducing dry matter digestibility. Selecting varieties low in luteolin derivatives and butin and rich in apigenin should enhance the digestibilities of sorghum crop residues.
TL;DR: The roots of Tephrosia polyphylla afforded a new isoflavonoid, 4′-demethyltoxicarol is oflavone, together with the known compounds toxicarol and 7-methylglabranin this article.
TL;DR: The microbial, asymmetric reduction of flavanone with fermenting bakers′ yeast led to the formation of (2S,4S)-(+)-cis-4-hydroxyflavan and (2R)-( +)-flavanone.
Abstract: The microbial, asymmetric reduction of flavanone with fermenting bakers′ yeast led to the formation of (2S,4S)-(+)-cis-4-hydroxyflavan and (2R)-(+)-flavanone. The kinetic resolution of racemic cis-4-acetoxyflavan with lipase PS yields (2R, 4R)-(–)-cis-4-hydroxyflavan, and the (2S,4S)-(+)-enantiomer remains as the acetate.
TL;DR: In this paper, a rapid and sensitive capillary column gas chromatographic method for the separation and identification of trimethylsilyl derivatives of flavonoid aglycones is reported.
Abstract: A rapid and sensitive capillary column gas chromatographic method for the separation and identification of trimethylsilyl derivatives of flavonoid aglycones is reported. Well-resolved, sharp and symmetrical peaks were obtained for a wide range of flavone, flavonol, isoflavone and flavanone aglycones with a variety of substitution patterns. Chromatographic behaviour and the effects of the number, position and type of the substituents on the retention times of these compounds have been defined.
TL;DR: In this article, the genesis of the [M − H + ion in flavanone and 2'-hydroxychalcone was studied with the aid of metastable decompositions and deuterium labeling.
Abstract: Studies of the genesis of the [M − H] + ion in flavanone and 2'-hydroxychalcone, performed with the aid of metastable decompositions and deuterium labelling, allow new structural notations to be Dostulated for the [M − H] + ions, which in turn provide evidence for the pathways in the [M − H − ketene] + fragmentation routes for these compounds
TL;DR: One-step chemical conversion of flavanones into isoflavones by use of thallium trinitrate (TIN) is reported in this paper, and the mechanism of a 2,3-aryl migration in this reaction is discussed in relation to in vivo rearrangement process of precursors in the is oflavone biosynthesis.
Abstract: One-step chemical conversion of flavanones into isoflavones by use of thallium trinitrate (TIN) is reported, and the mechanism of a 2,3-aryl migration in this reaction is discussed in relation to in vivo rearrangement process of flavanone precursors in the isoflavone biosynthesis.
Journal Article•
TL;DR: In this paper, 17 compounds were separated from the whole dried part of Arteisia subdigitata Mattf. and their structures were identified by spectrometry and four of them are new flavanoids; 5,8,3',5'-tetrahydroxy flavanone (1), 5, 8,2'-trihydroxy-5'-methoxyflavanone(2),5,7,4'-tri-hydroxyl tri-hydroxy (3,5'-dimethoxy)phenoxy-2-propenal
TL;DR: Some 1,3-benzodioxan analogs of chalcones and their epoxides have been obtained, and used to prepare pyrazolines and novel flavone and flavanone analogues of flavolignan as discussed by the authors.
Abstract: Some 1,3-benzodioxan analogs of chalcones and their epoxides have been obtained, and used to prepare pyrazolines and novel flavone and flavanone analogs of flavolignan (sylibin). The PMR spectra of novel compounds are shown and discussed, together with the results of preliminary biological tests.
30 Jun 1992
TL;DR: In this article, a callus cultures of Sophora favescens var. angustifolia established on Murashige-Skoog medium containing 1 μм 2,4-dichlorophenoxyacetic acid and 1μм kinetin produced the prenylated flavanones (2S)-5,7,2,2′,4′, 4′-tetrahydroxy-8-lavandulylflavanone (sophoraflavone G) and (25)-7, 2.4-
Abstract: Callus cultures of Sophora favescens var. angustifolia established on Murashige-Skoog medium containing 1 μм 2,4-dichlorophenoxyacetic acid and 1 μм kinetin produced the prenylated flavanones (2S)-5,7,2′,4′-tetrahydroxy-8-lavandulylflavanone (sophoraflavanone G) and (25)-7,2′,4′-trihydroxy-8-lavandulylflavanone (lehmannin). In addition, maackiain and its 3-O-β-glucoside (trifolirhizin) were also produced in the callus. Up on transfer to White’s medium or M9 medium, the content of prenylated flavanones, in particular lehmannin, was increased, whereas that of pterocarpans was decreased. Time-course experiments indicated that the production of pterocarpans was closely related with cell growth. On the other hand, an inverse relationship existed between cell growth and the production of prenylated flavanones.