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.     

Acetylated allose-containing flavonoid glucosides from Stachys anisochila

In continuation of our chemosystematic study of Stachys (Labiatae) we have isolated the previously reported isoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-β-D-glucopyranoside] (1) and 3′-hydroxy-4′-O-methylisoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-β-D-glucopyranoside] (4) and four new allose-containing flavonoid glycosides from S. anisochila. The new glycosides are hypolaetin 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-β-D-glucopyranside] (6) as well as the three corresponding diacetyl analogues of 1, 4 and 6, isoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-6″-O-acetyl-β-D-glucopyranoside], 3′-hydroxy-4′-O-methylisoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-6″-O-acetyl-β-D-glucopyranoside] and hypolaetin 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-6″-O-acetyl-β-D-glucopyranoside]. Extensive two-dimensional NMR studies (proton-carbon correlations, COSY experiments) allowed assignment of all ¹H NMR sugar signals and a correction of the ¹³C NMR signal assignments for C-2 and C-3 of the allose.     

Arvensoside A and B,triterpenoid saponins from Calendula arvensis

Two new triterpenoid glycosides from the aerial parts of Calendula arvensis were identified as oleanolic acid-28-O-β-D-glucopyranoside-3-β-O-(O-β-D-galactopyranosyl(1 → 3)-β-D-glucopyranoside) and oleanolic acid 3-β-O-(O-β-D-galactopyranosyl(1 → 3)-β-D-glucopyranoside) by FAB, FAB MIKE mass spectrometry and ¹³C NMR spectroscopy.     

Metabolomics-oriented isolation and structure elucidation of 37 compounds including two anthocyanins from Arabidopsis thaliana

In order to conduct metabolomic studies in a model plant for genome research, such as Arabidopsis thaliana (Arabidopsis), it is a prerequisite to obtain structural information for the isolated metabolites from the plant of interest. In this study, we isolated metabolites of Arabidopsis in a relatively non-targeted way, aiming at the construction of metabolite standards and chemotaxonomic comparison. Anthocyanins (5 and 7) called A8 and A10 were isolated and their structures were elucidated as cyanidin 3-O-[2-O-(β-d-xylopyranosyl)-6-O-(4-O-(β-d-glucopyranosyl)-E-p-coumaroyl)-β-d-glucopyranoside]-5-O-[6-O-(malonyl)-β-d-glucopyranoside] and cyanidin 3-O-[2-O-(2-O-(E-sinapoyl)-β-d-xylopyranosyl)-6-O-(4-O-(β-d-glucopyranosyl)-E-p-coumaroyl)-β-d-glucopyranoside]-5-O-[β-d-glucopyranoside] from analyses of 1D NMR, 2D NMR (¹H NMR, NOE, ¹³C NMR, HMBC and HMQC), HRFABMS, FT-ESI-MS and GC-TOF-MS data. In addition, 35 known compounds, including six anthocyanins, eight flavonols, one nucleoside, one indole glucosinolate, four phenylpropanoids and a derivative, together with three indoles, one carotenoid, one apocarotenoid, three galactolipids, two chlorophyll derivatives, one steroid, one hydrocarbon, and two dicarboxylic acids, were also isolated and identified from their spectroscopic data.     

Anthocyanins from red flowers of Camellia cultivar 'Dalicha'

Five anthocyanins, cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-(Z)-p-coumaroyl)-β-galactopyranoside (2), cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-(E)-p-coumaroyl)-β-galactopyranoside (3), cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-(E)-caffeoyl)-β-galactopyranoside (4), cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-acetyl)-β-galactopyranoside (5), and cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-acetyl)-β-glucopyranoside (6), together with the known cyanidin 3-O-(2-O-β-xylopyranosyl)-β-galactopyranoside (1), were isolated from red flowers of Camellia cultivar ‘Dalicha’ (Camellia reticulata) by chromatography using open columns. Their structures were subsequently determined on the basis of spectroscopic analyses, i.e., ¹H NMR, ¹³C NMR, HMQC, HMBC, HR ESI-MS and UV-vis.     

Methylated anthocyanidin glycosides from flowers of Canna indica

Methylated anthocyanin glycosides were isolated from red Canna indica flower and identified as malvidin 3-O-(6-O-acetyl-β-d-glucopyranoside)-5-O-β-d-glucopyranoside (1), malvidin 3,5-O-β-d-diglucopyranoside (2), cyanidin-3-O-(6″-O-α-rhamnopyranosyl-β-glucopyranoside (3), cyanidin-3-O-(6″-O-α-rhamnopyranosyl)-β-galactopyranoside (4), cyanidin-3-O-β-glucopyranoside (5) and cyanidin-O-β-galactopyranoside (6) by HPLC-PDA. Their structures were subsequently determined on the basis of spectroscopic analyses, that is, ¹H NMR, ¹³C NMR, HMQC, HMBC, ESI-MS, and UV-vis. Compounds (1-4) were found to be in major quantity while compounds (5-6) were in minor quantity.     

Poliumoside,a caffeic glycoside ester from Teucrium belion

A new caffeic glycoside ester, poliumoside, has been isolated from the aerial parts of Teucrium belion. Its structure, [β-(3′,4′-dihydroxyphenyl)-ethyl]-(3,6-O-α-L-dirhamnopyranosyl)-(4-O-caffeoyl)-β-D-glucopyranoside, was established mainly by high-resolution ¹H NMR and ¹³C NMR spectroscopy.     

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.     

Steroidal saponins from the leaves of Cordyline fruticosa (L.) A. Chev. and their cytotoxic and antimicrobial activity

Three new steroidal saponins, spirosta-5,25(27)-diene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-β-d-fucopyranoside (fruticoside H) 1, 5α-spirost-25(27)-ene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-(4-O-sulfo)-β-d-fucopyranoside (fruticoside I) 2, and (22S)-cholest-5-ene-1β,3β,16β,22-tetrol 1-O-β-galactopyranosyl-16-O-α-l-rhamnopyranoside (fruticoside J) 3, together with the known quercetin 3-O-β-d-glucopyranoside, quercetin 3-O-[6-trans-p-coumaroyl]-β-d-glucopyranoside, quercetin 3-rutinoside, apigenin 8-C-β-d-glucopyranoside and farrerol, were isolated from the leaves of Cordyline fruticosa. Their structures were elucidated by spectroscopic techniques (¹H NMR, ¹³C NMR, HSQC, ¹H–¹H COSY, HMBC, TOCSY, NOESY), mass spectrometry (HRESIMS, Tandem MS–MS), chemical methods and by comparison with published data. Compounds 1 and 2 showed moderate cytotoxic activity against MDA-MB 231 human breast adenocarcinoma cell line, HCT 116 human colon carcinoma cell line, and A375 human malignant melanoma cell line, while compound 3 was not active. Compound 2 also showed a moderate antibacterial activity against the Gram-positive Enterococcus faecalis.     

Three flavonoid glycosides containing acetylated allose from stachys recta

By means of ¹³C and ¹H NMR spectroscopy three flavone glycosides, obtained from Stachys recta, were identified as 7-O-(2″-O-6″′-O-acetyl-β-D-allopyranosyl-β-D-glucopyranosides) of 4′-O-methylisoscutellarein, isoscutellarein and 3′-hydroxy-4′-O-methylisoscutellarein. The latter two compounds are isolated for the first time. Only mannose and glucose have been reported previously as sugar components of flavonoids of the genus Stachys.     

Two further acylated flavone glucosides from Anisomeles ovata

The structures of two new acylated apigenin glucosides are reported from the aerial parts of Anisomeles ovata. They were separated as their acetates and identified as apigenin 7-O-β-d-(2″,6″-di-O-p-coumaroyl)glucoside and apigenin 7-O-β-d-(4″,6′-di-O-p-coumaroyl)glucoside by ¹H NMR study of the acetates and by chemical degradative methods. The allocation of the p-coumaroyl moieties is also supported by a study of the ¹³C NMR spectrum of the inseparable mixture of glucosides.     

Flavanol glucosides from rhubarb and Rhaphiolepis umbellata

Investigations of rhubarb and the bark of Rhaphiolepis umbellata led to the isolation of new flavan-3-ol glucosides. Their structures were elucidated on the basis of ¹H and ¹³C NMR analysis hydrolytic studies as (+)-catechin 5-O-β-d-glucopyranoside and (?)-catechin 7-O-β-d-glucopyranoside.     

A new complex triterpenoid saponin from Samanea saman with haemolytic activity and adjuvant effect

A new complex triterpenoid saponin was isolated from the stem bark of Samanea saman by using chromatographic methods. Its structure was established as 3-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]-2,23-dihydroxy-(2β,3β,4α)-olean-12-en-28-oic acid O-β-d-glucopyranosyl-(1 → 3)-O-[O-β-d-glucopyranosyl-(1 → 4)]-O-6-deoxy-α-l-mannopyranosyl-(1 → 2)-6-O-[4-O-[(2E,6S)-2,6-dimethyl-1-oxo-2,7-octadienyl]-6-deoxy-α-l-mannopyranosyl)oxy]-β-d-glucopyranosyl ester (1). Structural elucidation was performed using detailed analyses of ¹H and ¹³C NMR spectra including 2D NMR spectroscopic techniques and chemical conversions. The haemolytic activity of the saponin was evaluated using in vitro assays, and its adjuvant potential on the cellular immune response against ovalbumin antigen was investigated using in vivo models.     

Structures of verbascoside and orobanchoside,caffeic acid sugar esters from Orobanche rapum-genistae

The complete structural elucidation of the two caffeic acid sugar esters verbascoside and orobanchoside, has been realized by ¹H and ¹³C NMR studies. It has been demonstrated that verbascoside is β-(3′,4′-dihydroxyphenyl)ethyl-O-α-L-rhamnopyranosyl(1→3)-β-D-(4-O-caffeoyl)-glucopyranoside, and orobanchoside is β-hydroxy-β-(3′,4′-dihydroxyphenyl)-ethyl-O-α-L-rhamnopyranosyl(1→2)-β-D-(4-O-caffeoyl)-glucopyranoside.     

An acylated allose-containing 8-hydroxyflavone glycoside from Veronica filiformis

A novel flavone glycoside has been obtained from the whole plant of Veronica filiformis and identified by means of ¹³C NMR spectroscopy as isoscutellarein 4′-methyl ether 7-O-β-(6?-O-acetyl-2″-O-allosylglucoside). The related isoscutellarein glycoside is also present. This is the first report of 2-allosylglucose as a disaccharide unit of flavonoids. ¹³`C NMR data on some A-ring trioxygenated flavonoids are also presented.     

Canna indica flower: New source of anthocyanins

In this study the red flowers of Canna indica (Cannaceae) were extracted by using sonicator and isolation of anthocyanins have been carried out. Four anthocyanin pigments have been isolated apart from quercetin and lycopene. They are Cyanidin-3-O-(6′′-O-α-rhamnopyranosyl)-β-glucopyranoside (1), Cyanidin-3-O-(6′′-O-α-rhamnopyranosyl)-β-galactopyranoside (2), Cyanidin-3-O-β-glucopyranoside (3) and Cyanidin-O-β-galactopyranoside (4). These compounds were isolated by using HPLC and their structures were subsequently determined on the basis of spectroscopic analyses, i.e., ¹H NMR, ¹³C NMR, HMQC, HMBC, ESI-MS, FTIR, UV–Visible etc. The isolated compounds showed good antioxidant activity thus makes it suitable for use in food coloration and as a nutraceutical. Thus it is a promising pigment source for food applications.     

Flavonoids of the flowers of tamarix nilotica

The ethyl ester of kaempferol 3-O-β-D-glucuronide, the methyl and ethyl esters of quercetin 3-O-β-D-glucuronide have been isolated from an aqueous acetone extract of the flowers of Tamarix nilotica. In addition kaempferol 3-O-sulphate-7,4′-dimethyl ether and the free aglycones were isolated. The structures were established by routine methods, by FAB-MS and by ¹³C NMR spectral measurements.     

Phenolic glycosides from Cucumis melo var. inodorus seeds

A new phenolic glycoside (E)-4-hydroxycinnamyl alcohol 4-O-(2′-O-β-d-apiofuranosyl)(1″ → 2′)-β-d-glucopyranoside (1) was isolated and identified from Cucumis melo seeds together with benzyl O-β-d-glucopyranoside (2), 3,29-O-dibenzoylmultiflor-8-en-3α,7β,29-triol (3) and 3-O-p-amino-benzoyl-29-O-benzoylmultiflor-8-en-3α,7β,29-triol (4). Their structures were elucidated by extensive NMR experiments including ¹H–¹H (COSY, TOCSY, ROESY) and ¹H–¹³C (HSQC and HMBC) spectroscopy and chemical evidence. The multiflorane triterpene esters were identified as new melon constituents.     

Three flavone glycosides from citrus sudachi

Three flavone glycosides, sudachiins B, C and D, were isolated from the green peel of Citrus sudachi. On the basis of UV, ¹H NMR and ¹³C NMR spectral data sudachiins B and C were identified as sudachiin A 6″- (3-hydroxy-3-methyl)glutarateand 7-O-β-D-glucosyl sudachitin 6″-(3-hydroxy-3-methyl)glutarate, respectively. Sudachiin D was found to be a unique glycoside in which sudachiin A and 7-O-β-D-glucosylsudachitin were esterified at their 6″-positions with 3-hydroxy-3-methylglutaric acid.     

Allelopathic activity of luteolin 7-O-β-glucuronide isolated from Chrysanthemum morifolium L.

Two flavones, luteolin 7-O-β-glucuronide and diosmetin 7-O-β-glucuronide, were isolated and identified from Chrysanthemum morifolium L. v. Ramat leaves. Identification techniques included HPLC DAD, MS, ¹H and ¹³C NMR spectroscopy. At concentrations of 0.2 and 2.0 mM, luteolin 7-O-β-glucuronide significantly reduced the frond number and chlorophyll content of Lemna gibba plants, but did not significantly affect dry weight. At a concentration of 0.2 mM diosmetin 7-O-β-glucuronide had no significant effect on frond number, dry weight or chlorophyll concentration of L. gibba. These results indicate that an ortho-3′,4′-dihydroxy arrangement of the B-flavonoid ring in the luteolin compound is probably responsible for allelopathic activity.