Showing papers on "Flavanone published in 1975"
TL;DR: Flavanone synthase was isolated and purified about 300-fold from fermenter-grown, light-induced cell suspension cultures of Petroselinum hortense as discussed by the authors.
Abstract: Flavanone synthase was isolated and purified about 300-fold from fermenter-grown, light-induced cell suspension cultures of Petroselinum hortense. The enzyme catalyzed the formation of the flavanone naringenin from p-coumaroyl-CoA and malonyl-CoA. Trapping experiments with an enzyme preparation, which was free of chalcone isomerase activity, revealed that in fact the flavanone and not the isomeric chalcone was the immediate product of the synthase reaction. Thus the enzyme is not a chalcone synthase as previously assumed.
No cofactors were required for flavanone synthase activity. The enzyme was strongly inhibited by the two reaction products naringenin and CoASH, by the antibiotic cerulenin, by acetyl-CoA, and by several compounds reacting with sulfhydryl groups. Optimal enzyme activity was found at pH 8.0, at 30°C, and at an ionic strength of 0.1–0.3 M potassium phosphate. EDTA, Mg2+, Ca2+, or Fe2+ at concentrations of about 0.7 μM did not affect the enzyme activity. Apparent molecular weights of approx. 120000, 50000, and 70000, respectively, were determined for flavanone synthase and two metabolically related enzymes, chalcone isomerase and malonyl-CoA : flavonoid glycoside malonyl transferase.
The partially purified flavanone synthase efficiently catalyzed the formation of malonyl pantetheine from malonyl-CoA and pantetheine. This malonyl transferase activity, and a general similarity with the condensation steps involved in the mechanisms of fatty acid and 6-methyl-salicylic acid synthesis from “acetate units”, are the basis for a hypothetical scheme which is proposed for the sequence of reactions catalyzed by the multifunctional flavanone synthase.
168 citations
TL;DR: The present results suggest that the styrylpyrone derivative formed in vitro is an artificial product of the first enzyme of the flavonoid pathway, flavanone synthetase, and supports earlier conclusions from experiments in vivo favoring a mechanism of synthesis for the pyrone ring of bisnoryangonin according to the “acetate rule.”
74 citations
TL;DR: The chalcone-flavanone isomerase from soya bean seed has been purified 8300-fold and a number of flavonoid compounds competitively inhibit the reaction, suggesting a possible regulatory role for this enzyme in flavonoids biosynthesis.
Abstract: The chalcone-flavanone isomerase from soya bean seed has been purified 8300-fold. A molecular weight of 15,600 plus or minus 1000 has been determined for the enzyme. Effects of iodoacetamide and sodium tetrathionate on the enzyme, and pH dependence of the catalytic step, indicate that a sulphydryl group is not involved in the reaction mechanism and the catalytic group is probably an imidazole side chain in the basic form. The kinetics of the isomerisation of isoliquiritigenin to liquiritigenin have been examined and show that at pH 7.6 the reaction is reversible with an equilibrium constant of 37 in favour of flavanone. A number of flavonoid compounds competitively inhibit the reaction, suggesting a possible regulatory role for this enzyme in flavonoid biosynthesis.
62 citations
TL;DR: Cell-free extracts from very young primary leaves of parsley plants catalyse the oxidation of naringenin (5,7,4′-trihydroxyflavanone) to apigenin (4,2′, 4′-Trihydroxychalcone), which is not H 2 O 2 -dependent and is not inhibited by catalase, cyanide, or 1.4·10 −2 m mercaptoethanol.
31 citations
16 citations
TL;DR: The root wood of Zanthoxylum dipetalum contained the alkaloids canthin-6-one, chelerythrine, nitidine and tembetarine, the pyranocoumarins avicennol and xanthoxyletin, the triterpene lupeol and the flavanoid hesperidin this article.
15 citations
TL;DR: In this article, the authors consider cyclization of 2′-hydroxychalcones and their α-oxygenated counterparts (α-alkoxy- and peltogynoid chalcones) following a logical sequence of α- or β-addition directed by the nature of the α-substituent and the pH or the reaction medium.
Abstract: Cyclizations of 2′-hydroxychalcones and their α-oxygenated counterparts (α-alkoxy- and peltogynoid chalcones) follow a logical sequence of α- or β-addition directed by the nature of the α-substituent and the pH or the reaction medium. For β-addition the reaction equilibrium and hence its course depends on the thermodynamic stability of, the presence of a 5-hydroxy function in, and the acidity of the 3-protons of the resulting flavanone. Cyclization of the chalcone is independent of possible α-directing steric effects iontroduced by 6′-methoxylation.The latter reflects on similar cyclizations under oxidative conditions [alkaline ferricyanide, acidic lead tetraacetate, and alkaline peroxide (Algar–Flynn–Oyamada reaction)], where the directing effects of free radical and ionic mechanisms are invoked to rationalize their variable course.
13 citations
01 Jan 1975
TL;DR: In this paper, the authors discuss the properties of dihydroflavonols and their relation to the closely related flavanones and dihydronols, and the absolute configuration of a number of these compounds has also been established.
Abstract: This chapter is concerned with the closely related flavanones and dihydroflavonols. Flavanones are based upon structure (1), 2-phenylbenzopyran-4-one, which is flavanone itself. The parent compound is not known to be naturally occurring; the simplest plant flavanone has a hydroxy 1 group at position 7. The numbering system of the flavanone nucleus is similar to that in most other flavonoid series. Flavanones are isomeric with chalcones from which they can be obtained synthetically and from which they arise biosynthetically. Flavanones have a centre of asymmetry at C-2 so that naturally occurring members are often optically active. The absolute configuration of a number of these compounds has also been established. It is of historical interest that the isolation of optically active flavanones provided a strong argument that these compounds were natural and not simply artifacts resulting from overzealous treatment of natural chalcones.
10 citations
TL;DR: Data obtained by feeding 14 C-labeled amino acids, a flavanone, flavones, and a C -glycosyl-flavone to axenically cultured Spirodela polyrhiza indicated that the B-ring oxidation pattern of flavone- O - Glycosides was determined at the flavone level of biosynthesis and was essentially irreversible.
10 citations
Journal Article•
TL;DR: In this paper, the structures of the above mentioned chalcones were established through the examination and comparison of spectral data (U.V., I.R., N.M., M.S.) and of the chemical behaviour.
Abstract: The isolation of eight prenylated chalcones (cordoin, isocordoin, psi-isocordoin, derricin, lonchocarpin, 4-hydroxyderricin, 4-hydroxylonchocarpin, 4-hydroxyisocordoin) and of the flavanone and dihydrochalcone corresponding to cordoin is described. These substances are biogenetically correlated. The structures of the above mentioned substances were established through the examination and comparison of spectral data (U.V., I.R., N.M.R., M.S.) and of the chemical behaviour. Particular interest is shown by psi-isocordoin and 4-hydroxy derivatives. The latter and 4-hydroxyderricin in particular show also a marked inhibition on the growth of gram-positive bacteria.
10 citations
TL;DR: In this article, the chalcones and dihydrochalcones of the flavanone glycosides naringin, neohesperidin and hesperidine were separated and identified by thin-layer chromatography; a similar procedure was utilized to perform preparative TLC for purification of these compounds.
Abstract: The chalcones and dihydrochalcones of the flavanone glycosides naringin, neohesperidin and hesperidin were separated and identified by thin-layer chromatography; a similar procedure was utilized to perform preparative TLC for purification of these compounds. A new spectrophotometric method for the quantitative determination of dihydrochalcones in the concentration range from 0.005 to 0.100% in aqueous or alcoholic solution is described as well as a detection method of these compounds in agar media for microbiological studies.
TL;DR: A mixture of 2,5,7,3′,4′-pentahydroxy-flavanone-5-glucoside and its tautomers has been isolated from the seed of Galega officinalis L.
Abstract: Abstract A mixture of 2,5,7,3′,4′-pentahydroxy-flavanone-5-glucoside and its tautomers has been isolated from the seed of Galega officinalis L.; its constitution is prooved by conversion to luteoline-5-glucoside.