Kinetics of the alkaline hydrolysis of flavonoid glycosides

Summary 1. In a study of the kinetics of the alkaline hydrolysis of flavone glycosides it has been found that derivatives of 3,3,4,5,7-pentahydroxyflavone hydrolyze faster than derivatives of 3,4,5,7-tetrahydroxyflavone and of 3,4,5,7-tetrahydroxy-3-methoxyflavone.2. In the hydrolysis of diglycosides of 3,3,4,5,7-pentahydroxyflavones the maximum amount of intermediate product is formed after 2 min (3,4,5,7-tetrahydroxyflavone glycoside), and in the case of 3,4,5,7-tetrahydroxy-3-methoxyflavone glycosides after 120–150 min.I. V. Kutateladze Institute of Pharmacochemistry, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 646–649, September–October, 1977.     

Identification of carbohydrate isomers in flavonoid glycosides after hydrolysis by hydrophilic interaction chromatography

A method for carbohydrate isomers (saccharide units) identification in flavonoid glycosides after hydrolysis by an HPLC system with two detectors (diode array UV-VIS detector and evaporative light scattering detector) was set up in this work. Experimental procedure was optimized with two types of model glycosides, namely rutin and hesperidin. The model glycosides were hydrolyzed to saccharide units and aglycone parts; the aglycone was characterized by its UV-VIS spectrum and the saccharide unit was identified by its retention time and elution profile (anomeric signals). Acidic and enzymatic hydrolyses were compared in the first step of the method; in acidic hydrolysis, trifluoracetic acid was used, while glucosidase, galactosidase, and hesperidinase were used in enzymatic hydrolysis. A complete enzymatic hydrolysis was achieved with hesperidin and neohesperidin, but not with 3-O-glycosides. The method was applied for the identification of a glycone from a glycoside isolated from Polygonum lapathifolium (Polygonaceae sp.).     

Investigation of flavonoid glycosides

Summary 1. The method of differential analysis in the IR region of the spectrum has been used in an investigation of the structure of the carbohydrate part of flavonoid glycosides. This method permits the pyranose and furanose forms of the carbohydrate substituents, the - and -anomers of the pyranosides and other structural features characterizing the nature of the sugars in the glycosides to be determined. The method can also be used to study other glycosides — for example, hydroxyanthraquinone glycosides, furocoumarin glycosides, and cardiac and other glycosides.2. A modified method of comparing molecular rotation has been proposed for determining the configuration of the glycosidic linkages and the size of the oxide rings in the carbohydrate part of the flavonoid glycosides.Khimiya Prirodnykh Soedinenii, Vol. 1, No. 4, pp. 233–241, 1965     

Acylated flavonoid glycosides from Barringtonia racemosa

Abstract

Using various chromatographic separations, three new acylated flavonoid glycosides, namely barringosides G–I (1–3), were isolated from the water-soluble extract of Barringtonia racemosa branches and leaves. The structure elucidation was performed by extensive analysis of the 1D and 2D NMR and HR-QTOF-MS data. Of the isolated compounds, barringoside I (3) showed moderate inhibitory effects on LPS-induced NO production in RAW264.7 cells with an IC₅₀ of 52.48?±?1.04?µM.     

The alkaline hydrolysis of 4-methoxycoumarin

The aqueous alkaline hydrolysis of 4-methoxycoumarin occurs in two stages. In the first, the lactone ring is opened at a rate directly proportional to the concentration of base. In the second, the methoxy group is replaced by an unusual route that depends upon the presence of an $\text{un}$ionised phenolic hydroxy group and is therefore inversely proportional to the concentration of base. Methanolysis by methoxide ion in methanol occurs primarily at position 4 and replaces the methoxy group before the ring is opened; the difference from the aqueous hydrolysis is ascribed to solvent effects.     

Hydrolysis of flavonoid glycosides by fungus enzymes

Chemistry of Natural Compounds -     

The alkaline hydrolysis of nylons and terylene

Summary The acid hydrolysis of nylons has been carried out quantitatively byHaslam ³ andSchroeder ⁴ using hydrochloric acid solutions. These methods require several hours for complete hydrolysis. The alkaline hydrolysis of nylon 6 has been carried out using barium hydroxide solutions in an autoclave for 24 hours⁵. Although the potassium hydroxide method described is not quantitative, the hydrolysis, isolation, and characterisation of the products can be carried out in 1 to 3 hours.

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Zusammenfassung Die saure Hydrolyse von Nylon wurde vonHaslam ³ undSchroeder ⁴ mit Salzsäurelösungen quantitativ durchgeführt. Diese Verfahren beanspruchen für die vollständige Hydrolyse mehrere Stunden. Die alkalische Hydrolyse von Nylon 6 wurde mit Bariumhydroxidlösung in einem Autoklaven in 24 Stunden durchgeführt⁵. Obwohl das beschriebene Verfahren mit Kalilauge nicht quantitativ ist, kann man die Hydrolyse sowie die Isolierung und Charakterisierung der dabei erhaltenen Produkte in 1 bis 3 Stunden ausführen.

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Résumé Haslam ³ etSchroeder ⁴ ont effectué l'hydrolyse acide quantitative des nylons en utilisant des solutions d'acide chlorhydrique. Ces méthodes exigent plusieurs heures pour l'hydrolyse complète. On a réalisé l'hydrolyse alcaline du nylon 6 en utilisant des solutions d'hydroxyde de baryum, pendant 24 heures dans une autoclave. Bien que la méthode à l'hydroxyde de potassium décrite ne soit pas quantitative, l'hydrolyse, l'isolement et la caractérisation des produits peuvent s'effectuer en 1 à 3 heures.

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The author wishes to express his gratitude to Dr.J. Haslam for helpful discussions and to I. C. I., Ltd., Courtaulds, Ltd., and G. Slack, Ltd., for the gift of samples.     

Three new flavonoid glycosides isolated from Elsholtzia bodinieri

Three new flavonoid glycosides, eriodictyol 7-O-(6'-feruloyl)-beta-D-glucopyranoside (1), eriodictyol 7-O-[6'-(3'-hydroxy-4'-methoxy cinnamoyl)]-beta-D-glucopyranoside (2), and luteolin 7-O-[6'-(3'-hydroxy-4'-methoxy cinnamoyl)]-beta-D-glucopyranoside (3), and eight known flavonoids were isolated from the whole plants of Elsholtzia bodinieri. The structures of the 3 new compounds were elucidated on the basis of extensive spectroscopic analysis.     

Efficient strategies for preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa

Efficient strategies for the preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa using preparative high-performance liquid chromatography combined with appropriate pretreatment technologies were developed. Four fractions (Fr.1-1, Fr.1-2, Fr.1-3, and Fr.2-1) were firstly isolated from the crude extract of Hedyotis diffusa by column chromatography with C18, resin, and silica gel materials, respectively. Then, corresponding separation strategies were developed according to the polarity and chemical constituents. High-polar compounds of Fr.1-1 were purified by hydrophilic reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography mode. The combination of C18 and phenyl columns realized the complementary separation of iridoid glycosides in Fr.1-2. Meanwhile, the improved selectivity caused by the change of organic solvent in the mobile phase was utilized to realize the purification of flavonoid glycosides in Fr.1-3 and Fr. 2-1. Finally, 27 compounds (purity > 95%) mainly involving nine iridoid glycosides and five flavonoid glycosides were obtained. A complete strategy was established for the separation of a complex sample with a wide polarity range, to jointly solve the problems of enrichment of target components and separation of structural analogs.     

New flavonoid glycosides from the leaves of Solidago altissima

Two new flavonoid glycosides kaempferol 3-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside (1), and quercetin 3-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside (2), together with six known flavonoid glycosides were isolated from the leaves of Solidago altissima L. grown in Kochi of Japan. The structure elucidation of the isolated compounds was performed by acid hydrolysis and spectroscopic methods including UV, IR, ESI-MS, 1D- and 2D-NMR experiments.     

HPLC determination of the flavonoid glycosides fromBetulae folium extracts

Summary The main flavonoid glycosides ofBetulae folium extracts (quercetin-3-glucuronide, myricetin-3-galactoside, hyperosid, quercetin-3-arabinoside and quercetin-3-rhamnoside) have been separated by isocratic elution on a C₁₈ Aquapore RP-300 column. Elution was performed with 17% isopropanol at pH 6.2 confirming the validity of this eluent for the analysis of the flavonoid glycosides.