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1.
Ten 8‐(3,3‐dimethylallyl)‐substituted flavonoid glycosides, including the four new flavonol glycosides 1 and 3 – 5 and the new flavanonol glycoside 2 , besides five known flavonol glycosides, were isolated from the aerial parts of Epimedium koreanum Nakai . Their structures were determined by spectroscopic methods, including UV, IR, 1D‐ and 2D‐NMR, ESI‐MSn, HR‐ESI‐MS, and circular dichroism (CD) experiments.  相似文献   

2.
We report the synthesis of a modified 8mer RNA sequence, (C‐C‐C‐C‐A‐C‐C‐(2′‐thio)A)‐RNA 5′‐(dihydrogen phosphate) ( 9 ) containing a 3′‐terminal 2′‐thioadenosine (Schemes 2 and 3), and its spontaneous and site‐specific aminoacylation with the weakly activated amino acid thioester H Phe SPh ( 12 ). This reaction, designed in analogy to the ‘native chemical ligation’ of oligopeptides, occurs efficiently in buffered aqueous solutions and under a wide range of conditions (Table). At pH values between 5.0 and 7.4, two products, the 3′‐O‐monoacylated and the 3′‐O,2′‐S‐diacylated RNA sequences 10 and 11 are formed fast and quantitatively (Scheme 4). At pH 7.4 and 37°, the 3′‐O‐monoacylated product 10 is formed as major product in situ by selective hydrolysis of the O,S‐diacylated precursor 11 . Additionally, the preparation and isolation of the relevant 3′‐O‐monoacylated product 10 was optimized at pH 5. The here presented concept could be employed for a straightforward aminoacylation of analogously modified tRNAs.  相似文献   

3.
Three new flavonol glycosides, namely, isorhamnetin 3‐O‐(6″‐O‐(Z)‐p‐coumaroyl)‐β‐D ‐glucopyranoside ( 1 ), quercetin 3‐O‐α‐L ‐rhamnopyranosyl(1 → 2)‐α‐L ‐arabinopyranosyl(1 → 2)‐α‐L ‐rhamnopyranoside ( 2 ), and quercetin 3‐O‐α‐L ‐arabinopyranosyl(1 → 2)‐α‐L ‐rhamnopyranoside ( 3 ), were isolated from the stems of Alphitonia philippinensis. Their structures were established by spectral analysis. In addition, NMR data were assigned for ceanothenic acid ( 11 ). Some of the isolated triterpenoids and flavonoid glycosides showed cytotoxicity against human PC‐3 cells and hepatoma HA22T cells, and inhibition of replication on herpes simplex virus type‐1.  相似文献   

4.
A comprehensive characterization of C‐glycosyl flavones in wheat germ has been conducted using multi‐stage high resolution mass spectrometry (HRMSn) in combination with a mass defect filtering (MDF) technique. MDF performed the initial search of raw data with defined C‐glycosyl flavone mass windows and mass defect windows to generate the noise‐reduced data focusing on targeted flavonoids. The high specificity of the exact mass measurement permits the unambiguous discrimination of acyl groups (nominal masses of 146, 162 and 176.) from sugar moieties (rhamnose, glucose or galactose and glucuronic acid). A total of 72 flavone C‐glycosyl derivatives, including 2 mono‐C‐glycosides, 34 di‐C‐glycosides, 15 tri‐glycosides, 14 acyl di‐C‐glycosides and 7 acyl tri‐glycosides, were characterized in wheat germ, some of which were considered to be important marker compounds for differentiation of whole grain and refined wheat products. The 7 acylated mono‐O‐glycosyl‐di‐C‐glycosyl flavones and some acylated di‐C‐glycosyl flavones are reported in wheat for the first time. The frequent occurrence of numerous isomers is a remarkable feature of wheat germ flavones. Both UV and mass spectra are needed to maximize the structure information obtained for data interpretation. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

5.
This article describes detailed structure‐property relationships of 5 regioselectively methylated celluloses and 10 diblock cellulose derivatives with regioselective functionalization patterns: methyl 2,3,6‐tri‐O‐ ( 1 , 236MC), methyl 2,3‐di‐O‐ ( 2 , 23MC), methyl 2,6‐di‐O‐ ( 3 , 26MC), methyl 3‐O‐ ( 4 , 3MC), methyl 6‐O‐methyl‐cellulosides ( 5 , 6MC), methyl β‐D‐glucopyranosyl‐(1→4)‐2,3,6‐tri‐O‐methyl‐ ( 6 , G‐236MC), methyl β‐D‐glucopyranosyl‐(1→4)‐2,3‐di‐O‐methyl‐ ( 7 , G‐23MC), methyl β‐D‐glucopyranosyl‐(1→4)‐2,6‐di‐O‐methyl‐ ( 8 , G‐26MC), methyl β‐D‐glucopyranosyl‐(1→4)‐3‐O‐methyl‐ ( 9 , G‐3MC), methyl β‐D‐glucopyranosyl‐(1→4)‐6‐O‐methyl‐ ( 10 , G‐6MC), methyl β‐D‐glucopyranosyl‐(1→4)‐β‐D‐glucopyranosyl‐(1→4)‐2,3,6‐tri‐O‐methyl‐ ( 11 , GG‐236MC), methyl β‐D‐glucopyranosyl‐(1→4)‐β‐D‐glucopyranosyl‐(1→4)‐2,3‐di‐O‐methyl‐ ( 12 , GG‐23MC), methyl β‐D‐glucopy‐ranosyl‐(1→4)‐β‐D‐glucopyranosyl‐(1→4)‐2,6‐di‐O‐methyl‐ ( 13 , GG‐26MC), methyl β‐D‐glucopyranosyl‐(1→4)‐β‐D‐glucopyranosyl‐(1→4)‐3‐O‐methyl‐ ( 14 , GG‐3MC), and methyl β‐D‐glucopyranosyl‐(1→4)‐β‐D‐glucopyranosyl‐(1→4)‐6‐O‐methyl‐cellulosides ( 15 , GG‐6MC). Surface tension, differential scanning calorimetry, fluorescence, and dynamic light scattering measurements of aqueous solutions of compounds 1 – 15 revealed that there was no relationship between aggregation behaviors and gel formation, gelation occurred only when the hydrophobic environments formed by hydrophobic interactions between the sequences of 2,3,6‐tri‐O‐methyl‐glucopyranosyl units upon heating. The diblock structure consisting of cellobiosyl block and approx. ten 2,3,6‐tri‐O‐methyl‐glucopyranosyl units was of crucial importance for thermoreversible gelation of methylcellulose. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1539–1546, 2011  相似文献   

6.
Flavonoids present in the extracts from leaves of Pseudotsuga menziesii (Pinaceae), Ginkgo biloba (Ginkgoaceae) and Podocarpus dacrydioides (Podocarpaceae) were separated by use of the reversed phase HPLC method. The analysed compounds belong to different groups of flavonoids – biflavones (amentoflavone, bilobetin, 5–methoxybilobetin, podocarpusflavone A, sequoiaflavone, podocarpusflavone B, ginkgetin, isoginkgetin, sciadopitysin, kayaflavone, hinokiflavone, 2,3–dihydrosciadopitysin, 2,3–dihydroisoginkgetin), O–acylated flavonol glycosides (daglesiosides I, II, III, IV, trans–tiliroside, trans–ditiliroside), flavonol O–glycosides (astragalin, isoquercetin) and flavonol aglycones (kaempferol, quercetin, isorhamnetin). The conditions for flavonoid separation were optimized using various RP–18 columns. The chromatographic resolution was performed with isocratic or gradient elution – optimized by Drylab program or by traditional trial-and-error method, depending on the composition of flavonoid complex.  相似文献   

7.
A preparative high‐speed counter‐current chromatography method for isolation and purification of flavonoid compounds from Oroxylum indicum was successfully established by using ionic liquids as the modifier of the two‐phase solvent system. Two flavonoid compounds including baicalein‐7‐O‐diglucoside and baicalein‐7‐O‐glucoside were purified from the crude extract of O. indicum by using ethyl acetate–water–[C4mim][PF6] (5:5:0.2, v/v) as two‐phase solvent system. 36.4 mg of baicalein‐7‐O‐diglucoside and 60.5 mg of baicalein‐7‐O‐glucoside were obtained from 120 mg of the crude extract. Their purities were 98.7 and 99.1%, respectively, as determined by HPLC area normalization method. The chemical structures of the isolated compounds were identified by 1H‐NMR and 13C‐NMR.  相似文献   

8.
Flavonoid O‐glycosides are a ubiquitous and important group of plant natural products in which a wide variety of sugars are O‐linked to an aglycone. Determining the identity of the sugars, and the manner in which they are linked, by mass spectrometry alone is challenging. To improve the identification of common O‐linked di‐ and trisaccharides when analysing mixtures of flavonoid O‐glycosides by liquid chromatography/mass spectrometry (LC/MS), the fragmentation of electrosprayed sodium adducts in an ion trap mass spectrometer was investigated. The sodium adducts [M + Na]+ of kaempferol 3‐O‐glycosides generated sodiated glycosyl groups by the neutral loss of kaempferol. The product ion spectra of these sodiated glycosyl groups differed between four isomeric kaempferol 3‐O‐rhamnosylhexosides and four isomeric kaempferol 3‐O‐glucosylhexosides in which the primary hexose was either glucose or galactose and bore the terminal glucose or rhamnose at either C‐2 or C‐6. Fragmentation of sodiated glycosyl groups from linear O‐triglucosides and branched O‐glucosyl‐(1 → 2)‐[rhamnosyl‐(1 → 6)]‐hexosides produced sodiated disaccharide residues, and the product ion spectra of these ions assisted the identification of the complete sugar. The product ion spectra of the sodiated glycosyl groups were consistent among flavonoid O‐glycosides differing in the position at which the sugar was O‐linked to the aglycone, and the nature of the aglycone. The abundance of sodiated species was enhanced by application of a pre‐trap collision voltage, without the need to dope with salt, allowing automated LC/MS methods to be used to identify the glycosyl groups of common flavonoid O‐glycosides, such as rutinosides, robinobiosides, neohesperidosides, gentiobiosides and sophorosides. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

9.
An efficient ultra high‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry method was developed for separation and profiling of phytochemical constituents of Chinese wild mandarin Mangshanju (Citrus reticulata Blanco). All constituents were well separated within 16 min. Based on retention times, accurate mass, MSE fragments, and/or reference standards as well as databases, a total of 81 compounds were unambiguously identified or tentatively assigned including flavonoid glycosides, acylated flavonoid glycosides, flavones, polymethoxylated flavonoids, and limonoids as well as four other compounds. Among them, 22 polymethoxylated flavones and ten polymethoxylated flavanones/chalcones were identified in Mangshanju, more types than other citrus reported before. A basic procedure for identifying flavonoid‐O‐glycosides and the aglycones including polymethoxylated flavonoids was proposed. In addition, this method was successfully used to analyze another four mandarin germplasms, Cenxi suan ju, Xipi gousi gan, Nanfeng miju, and Or, showing that Mangshanju contained two characteristic compounds distinct from the other four citrus species. This study systematically profiled phytochemical constituents of Mangshanju, which was helpful for further utilization of Mangshanju owing to its abundant bioactive compounds.  相似文献   

10.
Efficient syntheses of 2‐C‐trifluoromethyl D‐ and L‐ribose and some O‐glycosides via trifluoromethylation of D‐ and L‐3,4‐O‐isopropylidene‐β‐erythro‐pentopyranosid‐2‐ulose with Ruppert's reagent are described.  相似文献   

11.
From the whole plant of Morina nepalensis var. alba Hand.‐Mazz., two new acylated flavonoid glycosides ( 1 and 2 ), together with four known flavonoid glycosides ( 3–6 ), were isolated. Their structures were determined to be quercetin 3‐O‐[2″′‐O‐(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐galactopyranoside (monepalin A, 1 ), quercetin 3‐O‐[2″′‐O‐(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐glucopyranoside (monepalin B, 2 ), quercetin 3‐O‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐galactopyranoside (rumarin, 3 ), quercetin 3‐O‐β‐D ‐galactopyranoside ( 4 ), quercetin 3‐O‐β‐D ‐glucopyranoside ( 5 ) and apigenin 4O‐β‐D ‐glucopyranoside ( 6 ). Their structures were determined on the basis of chemical and spectroscopic evidence. Complete assignments of the 1H and 13C NMR spectra of all compounds were achieved from the 2D NMR spectra, including H–H COSY, HMQC, HMBC and 2D HMQC‐TOCSY spectra. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

12.
A new and rare type of iridoid glycoside, agnusoside ( 1 ), a new caffeoylquinic acid derivative, castusic acid ( 2 ), and a new sugar ester, 1,2‐di‐(4‐hydroxybenzoyl)‐β‐glucopyranose ( 3 ), along with ten known compounds belonging to iridoid glycosides (agnuside, trans‐eurostoside), caffeoylquinic acid derivatives (chlorogenic acid and isochlorogenic acid A), flavonoids (isoorientin, isovitexin, kaempferol 3‐O‐sophoroside, luteolin 6‐C‐(2′′‐Otrans‐caffeoyl)glucopyranoside, and simple phenolic acids (4‐hydroxybenzoic acid, 3,4‐dihydroxybenzoic acid), chemical classes were isolated from the flowers of Vitex agnus‐castus. The structures of the isolates were established by extensive 1D‐ and 2D‐NMR spectroscopic analysis as well as HR‐ESI‐MS. Agnusoside ( 1 ) represents an unusual type of iridoid glycoside with its 6‐keto C(4) nonsubstituted aglycone.  相似文献   

13.
The photoinitiated thiol?ene addition reaction is a highly stereo‐ and regioselective, and environmentally friendly reaction proceeding under mild conditions, hence it is ideally suited for the synthesis of carbohydrate mimetics. A comprehensive study on UV‐light‐induced reactions of 2,3‐unsaturated O‐, C‐, S‐ and N‐glycosides with various thiols was performed. The effect of experimental parameters and structural variations of the alkenes and thiols on the efficacy and regio‐ and stereoselectivity of the reactions was systematically studied and optimized. The type of anomeric heteroatom was found to profoundly affect the reactivity of 2,3‐unsaturated sugars in the thiol?ene couplings. Hydrothiolation of 2,3‐dideoxy O‐glycosyl enosides efficiently produced the axially C2‐S‐substituted addition products with high to complete regioselectivity. Moderate efficacy and varying regio‐ and stereoselectivity were observed with 2,3‐unsaturated N‐glycosides and no addition occurred onto the endocyclic double bond of C‐glycosides. Upon hydrothiolation of 2,3‐unsaturated S‐glycosides, the addition of thiyl radicals was followed by elimination of the thiyl aglycone resulting in 3‐S‐substituted glycals.  相似文献   

14.
Flavonoids are the main components of Meconopsis integrifolia (Maxim.) Franch, which is a traditional Tibetan medicine. However, traditional chromatography separation requires a large quantity of raw M. integrifolia and is very time consuming. Herein, we applied high‐speed counter‐current chromatography in the separation and purification of flavonoids from the ethanol extracts of M. integrifolia flower. Ethyl acetate/n‐butanol/water (2:3:5, v/v/v) was selected as the optimum solvent system to purify the four components, namely quercetin‐3‐O‐β‐d‐ glucopyrannosy‐(1→6)‐β‐d‐ glucopyranoside (compound 1 , 60 mg), quercetin 3‐O‐[2’’’‐O‐acetyl‐β‐d‐ glucopyranosyl‐(1→6)‐β‐d‐ glucopyranoside (compound 2 , 40 mg), quercetin 3‐O‐[3’’’‐O‐acetyl‐β‐d‐ glucopyranosyl‐(1→6)‐β‐d‐ glucopyranoside (compound 3 , 11 mg), and quercetin 3‐O‐[6’’’‐O‐acetyl‐β‐d‐ glucopyranosyl‐(1→6)‐β‐d‐ glucopyranoside (compound 4 , 16 mg). Among the four compounds, 3 and 4 were new acetylated flavonol diglucosides. After the high‐speed counter‐current chromatography separation, the purities of the four flavonol diglucosides were 98, 95, 90, and 92%, respectively. The structures of these compounds were identified by mass spectrometry and NMR spectroscopy.  相似文献   

15.
Anthraquinone glycosides, such as chrysophanol 1‐O‐β‐d‐ glucoside, chrysophanol 8‐O‐β‐d‐ glucoside, and physion 8‐O‐β‐d‐ glucoside, are the accepted important active components of Rheum tanguticum Maxim. ex Balf. due to their pharmacological properties: antifungal, antimicrobial, cytotoxic, and antioxidant activities. However, an effective method for the separation of the above‐mentioned anthraquinone glycosides from this herb is not currently available. Especially, greater difficulty existed in the separation of the two isomers chrysophanol 1‐O‐β‐d‐ glucoside and chrysophanol 8‐O‐β‐d‐ glucoside. This study demonstrated an efficient strategy based on preparative high‐performance liquid chromatography and high‐speed countercurrent chromatography for the separation of the above‐mentioned anthraquinone glycosides from Rheum tanguticum Maxim.ex Balf.  相似文献   

16.
In this study, an on‐line two‐dimensional high‐speed counter‐current chromatography system based on a six‐port valve was developed. Target‐guided by ultrafiltration with high‐performance liquid chromatography, the one‐step isolation of three potential α‐amylase inhibitors from Abelmoschus esculentus (L).Moench was achieved by employing the developed orthogonal system and extrusion elution mode. The purities of three potential α‐amylase inhibitors were all over 95% as determined by high‐performance liquid chromatography. Furthermore, UV, mass spectrometry and 1H NMR spectroscopy were applied to the structural identification of the isolated three target compounds, their structures were assigned as quercetin‐3‐O‐sophoroside (i), 5,7,3′,4′‐tetrahydroxy flavonol‐3‐O‐[β‐d ‐rhamnopyranosil‐(1→2)]‐β‐d ‐glucopyranoside (ii ) and isoquercitrin (iii), respectively. The Results demonstrated that the proposed method was highly efficient to screen and isolate enzyme inhibitors from complex natural products extracts, and on‐line two‐dimensional high‐speed counter‐current chromatography can effectively increase the peak resolution of target compounds.  相似文献   

17.
Systematic phytochemical investigation on heat‐processed Epimedium koreanum led to the isolation of 13 flavonoids, including five new prenyl‐flavonol glycosides, koreanosides A–E ( 1 – 5 , resp.). Their structures were elucidated on the basis of detailed analysis of the 1D‐ and 2D‐NMR spectroscopic data and chemical reactions. Apigenin ( 11 ) exhibited moderate anti‐HIV‐1 activity with an EC50 value of 12.8±3.27 μg/ml.  相似文献   

18.
Structural analysis via HPLC‐ESI‐MSn, UPLC‐HESI‐MS/MS and NMR reported 152 phenolic secondary metabolites in spring barley seedlings (Hordeum vulgare L.). Flavonoids with various patterns of glycosylation and acylation, as well as hydroxycinnamic acid glycosides, esters and amides, were identified in methanolic extracts from leaves of nine varieties of barley originating from different regions of the world. Hordatines derivatives, flavones acylated directly on the aglycone, and hydroxyferulic acid derivatives deserve special attention. Preparative chromatography enabled characterization of a number of compounds at trace levels with the 6‐C‐[6″‐O‐glycosyl]‐glycosides and the 6‐C‐[2″,6″‐di‐O‐glycosides]‐glucoside structure of flavones. Derivatives of flavonols, quercetin and isorhamnetin were observed only in Syrian varieties. The ultra performance liquid chromatography profiles of UV‐absorbing secondary metabolites were used for chemotaxonomic comparison between nine varieties of barley from different climatic conditions. The hierarchical clustering of bred lines from the Fertile Crescent and European and American varieties indicates a great diversity of chemical phenotypes within barley species. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

19.
An offline preparative two‐dimensional reversed‐phase liquid chromatography/hydrophilic interaction liquid chromatography coupled with hydrophilic interaction solid‐phase extraction method was developed for the preparative isolation of flavonoid glycosides from a crude sample of Sphaerophysa salsula . First, the non‐flavonoids were removed using an XAmide solid‐phase extraction cartridge. Based on the separation results of three different chromatographic stationary phases, the first‐dimensional preparation was performed on an XAqua C18 prep column, and 15 fractions were obtained from the 5.2 g target sample. Then, three representative fractions were selected for additional purification on an XAmide preparative column to further isolate the flavonoid glycosides. In all, eight flavonoid glycosides were isolated in purities over 97%. The results demonstrated that the two‐dimensional liquid chromatography method used in this study was effective for the preparative separation of flavonoid glycosides from Sphaerophysa salsula . Additionally, this method showed great potential for the separation of flavonoid glycosides from other plant materials.  相似文献   

20.
Glycosides including triterpenoid saponins and flavonoid glycosides are the main constituents of Glycyrrhiza uralensis Fisch (licorice) and exhibit prominent pharmacological activities. However, conventional methods for the separation of glycosides always cause irreversible adsorption and unavoidable loss of sample due to their high hydrophilicities. The present paper describes a convenient method for the simultaneous separation of triterpenoid saponins and flavonoid glycosides from licorice by pH‐zone‐refining counter‐current chromatography. Ethyl acetate/n‐butanol/water (2:3:5, v/v) with 10 mM TFA in the upper organic stationary phase and 10 mM ammonia in the lower aqueous mobile phase was used as the biphasic solvent system. Three triterpenoid saponins and two flavonoid glycosides including licorice‐saponin A3 (63.3 mg), glycyrrhizic acid (342.2 mg), 3‐O‐[β‐d ‐glucuronopyranosyl‐(1 → 2)‐β‐d ‐galactopyranosyl]glycyrrhetic acid (56.0 mg), liquiritin apioside (232.6 mg), and liquiritin (386.5 mg) were successfully obtained from licorice ethanol extract (2 g) in one step. This method subtly takes advantage of the common acidic properties of triterpenoid saponins and flavonoid glycosides, and obviously is much more efficient and convenient than the previous methods. It is also the first time that the separation of acidic triterpenoid saponins by using pH‐zone‐refining counter‐current chromatography has been reported.  相似文献   

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