Of -flavanone

Dduzorme has reported a simple synthesis of flavanones by radical denitratiQn and dehalo-genadon of 3-chlQrQ-2,3-dihydrQ-3-nitrQ-2-aryl-4//-l-ben2Qpyran-4-ones, which are readily prepared by the reacdon of salicylaldehydes with l-chlQrQ-l-nltrQ-2-arylethenes fEq. 7.73. ... 

Treatment of dibromides 2 with sodium azide in N,N-dimethylformamide (DMF) at room temperature resulted in the formation of two products, 3-(a-azidobenzyOchromones 2a-c,g or -1-thiochromones 2d-f and the 3-arylidenechromanones la-c,g,h or -1-thiochromanones Id-f, respectively (eqn. 2). As shown by yield data given in Table 2, the substituent at position 2 plays decisive role in the product ratio. Dibromides unsubstituted at position 2 tended to give almost exclusively azides 3a-f and only a small amount of 1 was obtained. On the contrary, the reaction of flavanone derivatives 2gjh gave 3-arylideneflavanones... 

Ibrahim A-R S, YJ Abul-Hajj (1990b) Microbiological transformation of (+/—)-flavanone and (J-/-)-isoflava-none. J Nat Prod 53 644-656. 

The basic structures of flavanones, flavones, and isoflavones together with coumestrol, an intermediate in the phenylpropane metabolism, are given in Fig. 2. The 3,5,7,3 -tetrahydroxy-4 -methoxyflavanone is a nod gene inducer in Rhizo-bium leguminosarum bv. viciae the 3, 4, 5,7-tetrahydroxyflavone, in Rhizobium ineliloti and 4,7-dihydroxyisoflavone, in Bradyrhizobium japonicum. Coumestrol, an intermediate in phenylpropane metabolism, is only a weak inducer (7). 

Root flavonoids that may act as signals for the initiation and development of endomycorrhizal and ectomycorrhizal symbio.ses have been identified (see Chap. 7). Metabolites of the phenylpropanoid pathways apparently act as signaling molecules in endo- and ectomycorrhizal interactions (14). The role of flavonoids is still controversial, but a variety of flavanones, flavones, and isoflavones... 

M. T. Drexler, M. D. and Amiridis, Heterogeneous Synthesis of Flavanone over MgO, Chemical Industries (Dekker) Catal. Org. React.) 451-457 (2000). 

Flavanonols Flavanonols can be considered as flavanones with a hydroxyl group on position 3. They are sometimes referred to as dihydroflavonols. Similar to the situation of flavanones, flavanonols are no longer a minor subgroup of flavonoids, and they are a structurally highly diverse and multisubstituted subgroup (Grayer and Veitch 2006). A well-known flavanonol is taxifolin from citrus fruits (Kawaii and others 1999) (see Table 5.1 and Fig. 5.2). 

An improved version of the Knoevenagel reaction between acetophenones and aldehydes allows direct access to trarcr-2,3-disubstituted chroman-4-ones, examples of which show high anti-estrogenic activity <00T1811>. Reduction of flavanones by NaBUi leads to the 2,4-cis-flavan-4-ols from which 4-methoxyflavans can readily be obtained detailed H and 13C NMR data are provided <00T6047>. 

PELLETIER, M.K., SHIRLEY, B.W., Analysis of flavanone 3-hydroxylase in Arabidopsis seedlings Coordinate regulation with chalcone synthase and chalcone isomerase, Plant Physiol., 1996, 111, 339-345. 

KREUZALER, F., HAHLBROCK, K., Enzymic synthesis of an aromatic ring from acetate units partial purification and some properties of flavanone synthase from cell-suspension cultures of Petroselinum hortense, Eur. J. Biochem., 1975, 56, 205-213. 

Microcrystallin cellulose triacetate (MCTA) has also been employed in the TLC analysis of flavanones. Plates were home-made by mixing 3 g of silica with 9 g of MCTA in 35 ml of ethanol and the suspension was spread on to 20 X 10 cm plates. A considerable number... 

Britsch L, Heller W, Grisebach. H (1981) Conversion of flavanone to flavone, dihy-droflavonol and flavonol with an enzyme system from cell cultures of parsley. Z Naturforsch... 

Britsch L, Dedio J, Saedler H, Forkmann G (1993) Molecular characterization of flavanone 3 beta-hydroxylases. Consensus sequence, comparison with related enzymes and the role of conserved histidine residues. Eur J Biochem 217(2) 745-754... 

Sutter A, Poulton J, Grisebach H (1975) Oxidation of flavanone to flavone with cell-free extracts from young parsley leaves. Arch Biochem Biophys 170(2) 547-556... 

Stotz G, Forkmann G (1981) Oxidation of flavanones to flavones with flower extracts of Antirrhinum majus (snapdragon). Z Naturforsch 36C 737-741... 

Tanner DC (2000) Structural elucidation of flavanone 7-O-glucosyltransferase in grapefruit (Citrusparadisi) seedlings. M.A. Thesis, East Tennessee State University... 

Reports on the antiviral activity of flavanones isolated from medicinal plants have also been found in the literature. Two new antiviral flavanone derivatives were isolated from a methanol extract of leaves of Pithecellobium clypearia (Jack.) Benth (Fabaceae), guided by antiviral assays.The structures were characterized as 7-0-galloyltricetifavan (Fig. 14) and 7,4 -di-0-galloyltricetifavan. CPE reduction assay showed that both compounds possess antiviral activity against respiratory syncytial virus, influenza A HlNl virus, CVB3 and HSV-1. Examples of other... 

Utility of Cmc/iona-alkaloid derived chiral thionreas were nsed in Scheidt s gronp [82] for the enantioselective syntheses of flavanones. The qninoline-tethered thionrea catalyst 140 displayed better stereodirecting properties than the corresponding thionrea that is tethered to a chiral cyclohexadiamine (139). Under optimized reaction conditions, flavanone 142 was obtained in 92% yield and 97 3 er the best er nsing catalyst 139 was 90 10 nnder similar conditions (Scheme 32). 

This enzyme, a P-450 monooxygenase, catalyzes the NADPH-dependent conversion of flavanones to fla-vones. 

Briggs, L. and Colebrook, L., Infrared spectra of flavanones and flavones. Carbonyl and hydroxyl stretching and CH out-of-plane bending absorption, Spectrochim. Acta, 18, 939, 1962. 

The Citrus enzyme catalyzes 2"-0-rhamnosylation of the 7-O-glucoside of flavanones and flavones but not flavonols. 

Akashi, T. et al.. Molecular cloning and biochemical characterization of a novel cytochrome P450, flavone synthase II, that catalyzes direct conversion of flavanones to flavones. Plant Cell Physiol, 40, 1182, 1999. 

Hashim, M.F. et al.. Reaction mechanism of oxidative rearrangement of flavanone in isofiavone biosynthesis. FEBS Lett., 271, 219, 1990. 

Flavones and flavanones were less frequently consumed during the 4-day collection period. Flavones were not consumed at all by 38 participants, while 29 people did not consume any citrus flavonoids — flavanones. The interquartile range of intake of flavones was relatively limited, ranging from 0.0 to 2.0 mg/day. Flavone consumption was not normally distributed and was negatively skewed toward a lack of consumption of foods rich in flavones such as olives and lettuce. Likewise, flavanone intake was also not normally distributed with a mean flavanone intake of 1 mg/day compared to the median intake of 1.2 mg/day. This is accounted for by the fact that the range of flavanone intakes was very wide (0 to 239 mg/day), 36%i of participants not consuming any flavanone-rich foods. The main dietary... 

Mouly, P.P. et ak, Differentiation of citrus juices by factorial discriminant analysis using liquid chromatography of flavanone glycosides, J. Agric. Food Chem., 42, 70, 1994. 

Marini, D. and Balestrieri, F., Multivariate analysis of flavanone glycosides in citrus juices, Ital. J. Food Sci., 1, 255, 1995. 

Biogenetically, chalcones are the immediate precursors of flavanones, and some flavanones isomerize by ring opening into chalcones during isolation from plants or after chemical treatment with alkali. In turn, flavanones are intermediates in the biosynthesis of most other flavonoid groups, including flavones, flavonols, and isoflavonoids. For more information on the biosynthesis of flavonoids and flavanones in particular, the reader is referred to Chapter 3 and reviews by Heller and Forkmann. ... 

No. O-Substitution of Flavanone Mol. Formula Trivial Name Plant Source Family Organ" Ref. 

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