Phenolic Glycosides with antiproteasomal activity from Centaurea urvillei DC. subsp. urvillei

A new flavanone glycoside, naringenin-7-O-β-d-glucuronopyranoside, and a new flavonol glycoside, 6-hydroxykaempferol-7-O-β-d-glucuronopyranoside were isolated together with 12 known compounds, 5 flavone glycoside; hispidulin-7-O-β-d-glucuronopyranoside, apigenin-7-O-β-d-methylglucuronopyranoside, hispidulin-7-O-β-d-methylglucuronopyranoside, hispidulin-7-O-β-d-glucopyranoside, apigenin-7-O-β-d-glucopyranoside, a flavonol; kaempferol, two flavone; apigenin, and luteolin, a flavanone glycoside; eriodictyol-7-O-β-d-glucuronopyranoside, and three phenol glycoside; arbutin, salidroside, and 3,5-dihydroxyphenethyl alcohol-3-O-β-d-glucopyranoside from Centaurea urvillei subsp. urvillei. The structure elucidation of the new compounds was achieved by a combination of one- (¹H and ¹³C) and two-dimensional NMR techniques (G-COSY, G-HMQC, and G-HMBC) and LC-ESI-MS. The isolated compounds were tested for their antiproteasomal activity. The results indicated that kaempferol, a well known and widely distributed flavonoid in the plant kingdom, was the most active antiproteasomal agent, followed by apigenin, eriodictyol-7-O-β-d-glucuronopyranoside, 3,5-dihydroxyphenethyl alcohol-3-O-β-d-glucopyranoside, and salidroside, respectively.     

Covalent anthocyanin–flavonol complexes from the violet-blue flowers of Allium ‘Blue Perfume’

Three covalent anthocyanin–flavonol complexes (pigments 1–3) were extracted from the violet-blue flower of Allium ‘Blue Perfume’ with 5% acetic acid-MeOH solution, in which pigment 1 was the dominant pigment. These three pigments are based on delphinidin 3-glucoside as their deacylanthocyanin and were acylated with malonyl kaempferol 3-sophoroside-7-glucosiduronic acid or malonyl-kaempferol 3-p-coumaroyl-tetraglycoside-7-glucosiduronic acid in addition to acylation with acetic acid.By spectroscopic and chemical methods, the structures of these three pigments 1–3 were determined to be: pigment 1, (6^I-O-(delphinidin 3-O-(3^I-O-(acetyl)-β-glucopyranoside^I)))(2^VI-O-(kaempferol 3-O-(2^II-O-(3^III-O-(β-glucopyranosyl^V)-β-glucopyranosyl^III)-4^II-O-(trans-p-coumaroyl)-6^II-O-(β-glucopyranosyl^IV)-β-glucopyranoside^II)-7-O-(β-glucosiduronic acid^VI))) malonate; pigment 2, (6^I-O-(delphinidin 3-O-(3^I-O-(acetyl)-β-glucopyranoside^I)))(2^VI-O-(kaempferol 3-O-(2^II-O-β-glucopyranosyl^III)-β-glucopyranoside^II)-7-O-(β-glucosiduronic acid^VI))); and pigment 3, (6^I-O-(delphinidin 3-O-(3^I-O-(acetyl)-β-glucopyranoside^I)))(2^VI-O-(kaempferol 3-O-(2^II-O-(3^III-O-(β-glucopyranosyl^V)-β-glucopyranosyl^III)-4^II-O-(cis-p-coumaroyl)-6^II-O-(β-glucopyranosyl^IV)-β-glucopyranoside^II)-7-O-(β-glucosiduronic acid^VI))) malonate.The structure of pigment 2 was analogous to that of a covalent anthocyanin–flavonol complex isolated from Allium schoenoprasum where delphinidin was observed in place of cyanidin. The three covalent anthocyanin–flavonol complexes (pigment 1–3) had a stable violet-blue color with three characteristic absorption maxima at 540, 547 and 618 nm in pH 5–6 buffer solution. From circular dichroism measurement of pigment 1 in the pH 6.0 buffer solution, cotton effects were observed at 533 (+), 604 (−) and 638 (−) nm. Based on these results, these covalent anthocyanin–flavonol complexes were presumed to maintain a stable intramolecular association between delphinidin and kaempferol units closely related to that observed between anthocyanin and hydroxycinnamic acid residues in polyacylated anthocyanins. Additionally, an acylated kaempferol glycoside (pigment 4) was isolated from the same flower extract, and its structure was determined to be kaempferol 3-O-sophoroside-7-O-(3-O-(malonyl)-β-glucopyranosiduronic acid).     

Die flavonolglykoside von Equisetum telmateja

Nine kaempferol glycosides, including the hitherto unkown 3-β-d-(6-O-acetylglucoside)-7-β-d-glucoside and 3-β-d-(6-O-acetylglucoside)-7-α-l-rhamnoside, have been isolated from Equisetum telmateja of European origin.     

Flavonoid constituents of Ephedra alata

Two new flavonol glucosides have been identified in Ephedra alata, namely, herbacetin 8-methyl ether 3-O- glucoside-7-O-rutinoside and herbacetin 7-O-(6″-quinylglucoside). The known flavonoids vicenin II, lucenin III, kaempferol 3-rhamnoside, quercetin 3-rhamnoside and herbacetin 7-glucoside were also found. The structure of the isolated compounds was determined mostly by FABMS and ¹H NMR spectroscopy. The final structure of the new compounds and of herbacetin 7-glucoside was confirmed by ¹³C NMR spectroscopy.     

Acylated flavonol glycosides from Delphinium staphisagria

An ethanolic extract of the aerial parts of Delphinium staphisagria L. from Tenerife yielded four new flavonol glycosides 2″-acetylastragalin, 2″-acetylpaeonoside, quercetin 3-O-(2-acetyl-β-glucopyranoside)-7-O-β-glucopyranoside and 2″-acetylpetiolaroside in addition to astragalin, isoquercitrin, paeonoside, kaempferol 3-O-β-glucopyranoside-7-O-α-rhamnopyranoside, petiolaroside and rutin.     

Isolation and purification of flavonoid glucosides from Radix Astragali by high-speed counter-current chromatography

High-speed counter-current chromatography methods, combined with resin chromatography were applied to the separation and purification of flavonoid glycosides from the Chinese medicinal herb, Radix Astragali. Five flavonoid glycosides, namely calycosin-7-O-β-d-glucoside, ononin, (6aR, 11aR)-9,10-dimethoxypterocarpan-3-O-β-d-glucoside, (3R)-2′-hydroxy-3′,4′-dimethoxyisoflavan-7-O-β-d-glucoside and calycosin-7-O-β-d-glucoside-6′′-O-acetate, were obtained. Among them, calycosin-7-O-β-d-glucoside-6′′-O-acetate was preparatively separated from Radix Astragali for the first time. Their structures were identified by ESI–MS, ¹H NMR, ¹³C NMR, and 2D NMR.     

Flavonol glycosides from Anthyllis onobrychioides

A new flavonol glycoside, rhamnocitrin 3-O-β-D-galactopyranoside, has been isolated from aerial parts of Anthyllis onobrychioides, together with the known 3-O-β-D-galactopyranosides of quercetin, isorhamnetin and kaempferol.     

Studies on cellulolytic enzymes I: The use of 3,4-dinitrophenyl glycosides as substrates

The syntheses of 3,4-dinitrophenyl β-d-glucoside, β-cellobioside, β-cellotrioside, and β-cellotetraoside and their use to monitor the purification of two enzymes from a crude commercial cellulase preparation from Trichoderma viride are described. The enzymes isolated are an endo-β-1,4-d-glucan glucanohydrolase (EI) of molecular weight ca. 12 000 which catalysed the release of 3,4-dinitrophenol from 3,4-dinitrophenol-β-cellotetraoside, and an enzyme of molecular weight about 76 000 which catalysed the hydrolysis of 3,4-dinitrophenyl β-d-glucoside (EII) and is probably a cellobiase or exo-β-1,4-d-glucan glucohydrolase. Kinetic parameters are reported for the hydrolyses of 3,4-dinitrophenyl β-cellobioside, β-cellotrioside, and β-cellotetraoside catalysed by enzyme EI. In the presence of cellotriose, cellotetraose, or cellopentaose 3,4-dinitrophenyl β-d-glucoside underwent induced hydrolyses by EI. Similar but faster induced hydrolyses were shown by 3,4-dinitrophenyl β-d-xyloside and 3,4-dinitrophenyl β-d-6-deoxyglucoside; 3,4-dinitrophenyl 6-chloro-6-deoxy-β-d-glucoside and 3,4-dinitrophenyl 6-O-methyl-β-d-glucoside underwent slower induced hydrolyses than the glucoside. p-Nitrophenyl β-d-glucoside also underwent an induced hydrolysis in the presence of cellopentaose and the enzyme EI, but p-nitrophenyl 2-deoxy-β-d-glucoside did not. These results are discussed and compared with the results obtained previously on induced hydrolyses found with lysozyme. Kinetic parameters are reported for the hydrolysis of 3,4-dinitrophenyl and p-nitrophenyl β-d-glucosides catalysed by the enzyme EII. 3,4-Dinitrophenyl 6-deoxy-β-d-glucoside, β-d-xyloside, 6-chloro-6-deoxy-β-d-glucoside, 6-O-methyl-β-d-glucoside and p-nitrophenyl-β-d-galactopyranoside and 2-deoxy-β-d-glucopyranoside were hydrolysed 10² to 10³ times slower by EII than the corresponding glucosides, but 3,4-dinitrophenyl 2-acetamido-2-deoxy-β-d-glucoside was only hydrolysed about 25 times slower than 3,4-dinitrophenyl β-d-glucoside. The significance of these results is discussed. EII catalysed the release of 3,4-dinitrophenol from 3,4-dinitrophenyl β-cellobioside, β-cellobioside, and β-cellotetraoside, but these reactions showed induction periods which are consistent with stepwise removal of glucose residues from the oligosaccharide chains before release of the phenol.     

Acylated flavonol glucosides of Pinus contorta needles

From fresh Pinus contorta Doug (Coastal) needles four flavonol acylated glucosides and 6-methyl-kaempferol 3-β-D-glucoside were isolated. The three monoacylated glucosides were kaempferol-3-β-D(6-O-p- coumaryl)glucoside, isorhamnetin-3-β-D-(6-O-acetyl)glucoside, quercetin-3-β-D-(p-coumaryl)glucoside and the diacyl compound was kaempferol-3-β-D-(di-p-coumaryl)glucoside.     

Two new flavonol glycosides from the leaves of Cleome viscosa L.

From the leaves of Cleome viscosa L., two new flavonol glycosides, named visconoside A (1) and visconoside B (2), together with six known flavonol glycosides, vincetoxicoside A (3), vincetoxicoside B (4), kaempferitrin (5), kaempferide 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (6), kaempferol 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (7), and isorhamnetin 3-O-β-d-glucopyranoside (8) were isolated by various chromatography methods. Its chemical structure was elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and compared with literatures.     

Temporal lag between gene expression and metabolite accumulation in flavonol biosynthesis of Arabidopsis roots

The temporal lag between gene expression and metabolite accumulation has been estimated in flavonol biosynthesis, but the time difference between these events is unclear. In the present study, we investigated the expression of flavonol biosynthetic genes ELONGATED HYPOCOTYL5, MYELOBLASTOSIS PROYEIN12/PRODUCTION OF FLAVONOL GLYCOSYDES1, CHALCONE SYNTHASE, CHALCONE ISOMERASE, FLAVANONE 3-HYDROXYLASE, and FLAVONOL SYNTHASE1, and the accumulation of flavonol glycosides (kaempferol and quercetin glycosides) in time-series samples of Arabidopsis thaliana roots. All genes started to be expressed within 3 h after sequential light irradiation (HAS) and reached their maximum expression levels at 12 HAS, and the accumulation of the flavonol glycosides started at 6 HAS. Metabolome analysis using liquid chromatography-mass spectrometry showed that the accumulation of kaempferol 3-O-glucoside-7-O-rhamnoside and kaempferol 3-O-rhamnosyl (1 → 2) glucoside-7-O-rhamnoside reached their maximum levels at 48 HAS, whereas other flavonol glycosides, such as kaempferol/quercetin 3-O-rhamnoside-7-O-rhamnoside, quercetin 3-O-glucoside-7-O-rhamnoside and quercetin 3-O-rhamnosyl (1 → 2) glucoside-7-O-rhamnoside, increased gradually until 96 HAS. These results show that the expression of the flavonol genes is an early response against light exposure, and that the accumulation of the flavonol glycosides is a late response.     

New spermidine alkaloids from Capparis spinosa roots

Three new spermidine alkaloids capparispine (1), capparispine 26-O-β-d-glucoside (2) and cadabicine 26-O-β-d-glucoside hydrochloride (3) were isolated from the roots of Capparis spinosa. Their structures were established on the basis of spectroscopic analysis, including 1D and 2D NMR experiments (¹H–¹H COSY, HSQC, HMBC).     

Flavonol glycosides of Phlomis spectabilis

Four flavonol glucosides, one new, have been isolated from a methanolic extract of Phlomis spectabilis. Their structures were established as the 3-glucosides and 3-(6″-(E)-p-coumaroyl)glucosides of kaempferol and of kaempferol 7,4′-dimethyl ether.     

5-Methyl ether flavone glucosides from the leaves of Bruguiera gymnorrhiza

Two new 5-methyl ether flavone glucosides (7,4′,5′-trihydroxy-5,3′-dimethoxyflavone 7-O-β-D-glucopyranoside and 7,4′-dihydroxy-5-methoxyflavone 7-O-β-D-glucopyranoside) were isolated from the leaves of Thai mangrove Bruguiera gymnorrhiza together with 7,3′,4′,5′-tetrahydroxy-5-methoxyflavone, 7,4′,5′-trihydroxy-5,3′-dimethoxyflavone, luteolin 5-methyl ether 7-O-β-D-glucopyranoside, 7,4′-dihydroxy-5,3′-dimethoxyflavone 7-O-β-D-glucopyranoside, quercetin 3-O-β-D-glucopyranoside, rutin, kaempferol 3-O-rutinoside, myricetin 3-O-rutinoside and an aryl-tetralin lignan rhamnoside. The structure of a lignan rhamnoside was found to be related to racemiside, an isolated compound from Cotoneaster racemiflora, and also discussed. Structure determinations were based on analyses of physical and spectroscopic data including 1D- and 2D-NMR.     

Flavonol glycoside gallates from Tellima grandiflora

Quercetin 3-O-(6″-O-galloyl)-β-d-glucoside has been identified as a constituent of Tellima grandiflora (Saxifragaceae). In all, twelve gallates were encountered: two isomeric gallates of quercetin 3-O-glucoside and two of quercetin 3-O-galactoside, a similar set involving kaempferol, and a similar set involving myricetin.     

Differences in the floral anthocyanin content of violet–blue flowers of Vinca minor L. and V. major L. (Apocynaceae)

Two novel delphinidin 3-(tri or di)-glycoside-7-glycosides were isolated from the violet–blue flowers of Vinca minor L. and V. major L. (Family: Apocynaceae), and determined to be delphinidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-(2^G-xylosylrobinobioside)-7-rhamnoside] as major floral anthocyanin of V. minor and delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-robinobioside-7-rhamnoside] as major floral anthocyanin of V. major by chemical and spectroscopic methods. In addition, chlorogenic acid and kaempferol 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= kaempferol 3-robinobioside-7-rhamnoside (robinin)] were identified in these flowers. In this paper, the relation between the structure of floral anthocyanins and classification of Vinca species was discussed.     

Kaempferol and its glycosides from Equisetum silvaticum L. from the Khanty-Mansi autonomous area

Three flavonoids were isolated from the aerial part of the wood horsetail (Equisetum silvaticum L.); two of them were found for the first time. The compounds were identified as kaempferol, kaempferol 3-O-β-D-galactopyranosyl-7-O-α-L-rhamnopyranoside and kaempferol 3-O-rutinosyl-7-O-L-rhamnopyranoside on the basis of the chemical transformations and IR, UV, ¹H-NMR and mass spectra.     

Two new xanthone glycosides from Tripterospermum lanceolatum

Oleanolic acid, mangiferin, and two new xanthone glucosides, named lanceoside (1,8-dihydroxy-3,7- dimethoxyxanthone- 4-O-β-d-glucoside) and lancerin (C-4-β-d-glucosyl-1,3,7-trihydroxyxanthone), respectively, were isolated from the aerial parts of Tripterospermum lanceolatum.     

Flavonoid glycosides from the leaves of Aphananthe aspera (Thunb.) Planch. (Cannabaceae) and their chemotaxonomic significance

From the leaves of Aphananthe aspera (Thunb.) Planch. (Family: Cannabaceae), six flavonol glycosides, such as quercetin 3-O-β-glucopyranoside (1), kaempferol 3-O-β-glucopyranoside (2), quercetin 3-O-rutinoside (3), kaempferol 3-O-rutinoside (4), quercetin 3-O-neohesperidoside (5) and kaempferol 3-O-neohesperidoside (6) were isolated and identified. Structure elucidation of these compounds was performed on the basis of NMR spectral data. All these compounds were isolated for the first time from the genus Aphananthe. Chemotaxonomic significance and distribution of these flavonoid derivatives among the genera of Cannabaceae are explained in detail.     

Purification and some properties of steryl β-d-glucoside hydrolase from Sinapis alba seedlings

Homogenates of 7-day-old S. alba seedlings hydrolysed cholesteryl[4-H¹⁴C] β-d-glucoside or sitosteryl β-d-glucoside-[6-³H]. Activity was located predominantly in the cell membrane structures sedimenting at 1000–15 000 g and was solubilized by acetone treatment. Partially purified enzyme preparation, with an about 1500 times higher specific activity with respect to the crude homogenate, was obtained by repeated acetone precipitation and subsequent chromatography on DEAE-Sephadex and Sephadex G-100. During this procedure a considerable separation from other enzymes with β-glucosidase activity was achieved. The enzyme had MW 65 000 daltons, pH optimum at 5.2–5.6. Two observations suggested that the enzyme was a specific steryl β-d-glucoside hydrolase. Firstly, there was no substrate competition between steryl glucosides and several other β-d-glucosides. Secondly, enzyme activity wasstrongly inhibited by low concentrations of various 3β-OH sterols with a planar ring system and an intact side chain.