Study of the characteristic fragmentation behavior of hydroquinone glycosides by electrospray ionization tandem mass spectrometry with optimization of collision energy

The fragmentation behavior of hydroquinone glycosides involving one or two sugar groups from Fraxinus sieboldiana and their analogue arbutin was investigated systematically by electrospray ionization tandem mass spectrometry in negative ion mode. The characteristic fragmentation reaction of these compounds was through the homolytic and heterolytic cleavage of the O‐glycosidic bond to produce radical aglycone ion ([Y₀ ? H]^??) and aglycone ion (Y₀^?), respectively. Unambiguous differentiation between the mono‐O‐glycoside isomers which differ in glycosylation position was achieved by comparing the relative abundance of [Y₀ ? H]^?? and Y₀^? ions with the optimized collision energy. In the fragmentation of 1, 4‐di‐O‐glycosides, only the Y₀^? ion was produced when the first glucosyl residue was expelled. However, both the [Y₀ ? H]^?? and Y₀^? ions were present when the second glucosyl residue was eliminated. In addition, an interesting [Y₀‐2H]^? ion was present in the product ion spectra of hydroquinone glycosides with methoxy group(s) substituted at C‐3 or/and C‐5 positions of the benzene ring. The results of this study can facilitate the rapid determination of hydroquinone glycosides in crude plant extracts and also reveal that the systematic investigation and optimization of collision energy play an important role in the differentiation of isomers which have subtle differences in structures. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural discrimination of isomeric tetrahydrofuran lignan glucosides by tandem mass spectrometry

Due to the possible role in human health, the number of analytical studies on lignans aimed at their quali‐ and quantitative analysis in plant extracts, biological fluids and foods is continuously increasing. However, helpful systematic mass spectrometric investigations on these compounds are few and rather limited to specific lignan sub‐classes. To increase the comprehension of the previously outlined picture of the gas‐phase properties of furofuran lignans, we extended the study to tetrahydrofuran lignans and here we reported the collision‐activated dissociation (CAD) fragmentation patterns of the alkali metal cation adducts, [M+Alk]⁺, and [M–H]^? ions of three isomeric tetrahydrofuran lignans, (+)‐8′‐hydroxylariciresinol 4′‐O‐β‐D ‐glucopyranoside (1), (+)‐7′‐hydroxylariciresinol 7′‐O‐β‐D ‐glucopyranoside (2) and 4‐O‐β‐D ‐glucopyranosyloxy‐3,3′‐dimethoxy‐7,9′‐epoxylignan‐5′,8′,9‐triol (3) investigated by electrospray ionization triple quadrupole mass spectrometry (ESI‐TQMS). Hydrogen/deuterium (H/D) solution exchange experiments, allowing the selective H/D exchange of all the acidic hydrogen atoms, proved to be a very effective tool to obtain information on the nature of fragments generated during TQ/CAD processes. The [M+Na]⁺ CAD mass spectra of the three isomeric tetrahydrofurans revealed four different pathways involving the loss of the glucose moiety, which allowed the assignment of the glycosylation site. In the negative ion mode, the main fragmentation channel of the [M–H]^? ions of O‐glucosylated lignans at the phenolic oxygen atoms is represented by the loss of 162 Da. When the sugar is bound to a benzylic OH group the loss of the sugar as a 180 Da unit occurs eventually following the loss of a water molecule involving both the C(9)H₂OH chain and the sugar. Copyright © 2010 John Wiley & Sons, Ltd.     

Two new acylated flavonoid glycosides from Morina nepalensis var. alba Hand.‐Mazz.

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 4^′‐O‐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.     

Two new complex triterpenoid saponins from Gledistsia dolavayi Franch.

Two new triterpenoid saponins, gledistside A ( 1 ) and gledistside B ( 2 ), isolated from the fruits of Gledistsia dolavayi Franch., were characterized as the 3,28‐O‐bisdesmoside of echinocystic acid acylated with monoterpene carboxylic acids. On the basis of spectroscopic and chemical evidence, their structures were elucidated as 3‐O‐β‐D ‐xylopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐glucopyranosyl‐28‐O‐β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐xylopyranosyl‐(1→4)‐[β‐D ‐galactopyranosyl‐(1→2)]‐α‐L ‐rhamnopyranosyl‐(1→2)‐{6‐O‐[2,6‐dimethyl‐6(S)‐hydroxy‐2‐trans‐2,7‐octadienoyl]}‐β‐D ‐glucopyranosylechinocystic acid ( 1 ) and 3‐O‐β‐D ‐xylopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐glucopyranosyl‐28‐O‐β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐xylopyranosyl‐(1→4)‐[β‐D ‐galactopyranosyl‐(1→2)]‐α‐L ‐rhamnopyranosyl‐(1→2)‐{6‐O‐[2‐hydroxymethyl‐6‐methyl‐6(S)‐hydroxy‐2‐trans‐2,7‐octadienoyl]}‐β‐D ‐glucopyranosylechinocystic acid ( 2 ). The complete ¹H and ¹³C assignments of saponins 1 and 2 were achieved on the basis of 2D NMR spectra including HMQC‐TOCSY, TOCSY, ¹H–¹H COSY, HMBC, ROESY and HMQC spectra. Copyright © 2002 John Wiley & Sons, Ltd.     

Structure elucidation and total assignment of 1H and 13C NMR data for a new bisdesmoside saponin from Cordia piauhiensis

Extensive 1D (¹H NMR, HBBD‐¹³C NMR, DEPT‐¹³C NMR) and 2D (COSY, TOCSY, NOESY, HMQC and HMBC) NMR analysis was used to characterize the structure of a new bisdesmoside saponin isolated from the methanol extract of stems of Cordia piauhiensis Fresen as 3β‐O‐[α‐L ‐rhamnopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl]ursolic acid 28‐O‐[β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranosyl] ester. Copyright © 2003 John Wiley & Sons, Ltd.     

Structure elucidation of a sodium salified anthraquinone from the seeds of Cassia obtusifolia by NMR technique assisted with acid–alkali titration

A new sodium salt of anthraquinone named sodium emodin‐1‐O‐β‐gentiobioside, together with nine known compounds, viz. rubrofusarin‐6‐O‐β‐D ‐gentiobioside, chrysophanol‐1‐O‐β‐D ‐glucopyranosyl‐(1–3)‐β‐D ‐glucopyranosyl‐(1–6)‐β‐D ‐glucopyranoside, obtusifolin‐2‐O‐β‐D ‐glucopyranoside, aurantio‐obtusin‐6‐O‐β‐D ‐glucopyranoside, physcion‐8‐O‐β‐D ‐glucopyranoside, 1‐hydroxyl‐2‐acetyl‐3,8‐dimethoxy‐6‐O‐β‐D ‐apiofuranosyl‐(1–2)‐β‐D ‐glucosylnaphthalene, toralactone‐9‐O‐β‐D ‐gentiobioside, aurantio‐obtusin, rubrofusarin‐6‐O‐β‐D ‐apiofuranosyl‐(1–6)‐O‐β‐D ‐glucopyranoside, was isolated from the seeds of Cassia obtusifolia and its structure was elucidated by ¹H and ¹³C NMR technique assisted with acid–alkali titration. The change of chemical shifts of sodium emodin‐1‐O‐β‐gentiobioside before and after acid–alkali titration was also characterized. Copyright © 2011 John Wiley & Sons, Ltd.     

New saponins from Sechium mexicanum

The chemical study of Sechium mexicanum roots led to the isolation of the two new saponins {3‐O‐β‐D ‐glucopyranosyl (1 → 3)‐β‐D ‐glucopyranosyl‐2β,3β,16α,23‐tetrahydroxyolean‐12‐en‐28‐oic acid 28‐O‐α‐L ‐rhamnopyranosyl‐(1 → 3)‐β‐D ‐xylopyranosyl‐(1 → 4)‐α‐L ‐rhamnopyranosyl‐(1 → 2)‐α‐L ‐arabinopyranoside} (1) and {3‐O‐β‐D ‐glucopyranosyl (1 → 3)‐β‐D ‐glucopyranosyl‐2β,3β,16α,23‐tetrahydroxyolean‐12‐en‐28‐oic acid 28‐O‐α‐L ‐rhamnopyranosyl‐(1 → 3)‐β‐D ‐xylopyranosyl‐(1 → 4)‐[β‐D ‐apiosyl‐(1 → 3)]‐α‐L ‐rhamnopyranosyl‐(1 → 2)‐α‐L ‐arabinopyranoside} (2), together with the known compounds {3‐O‐β‐D ‐glucopyranosyl‐(1 → 3)‐β‐D ‐glucopyranosyl‐2β,3β,6β,16α,23‐pentahydroxyolean‐12‐en‐28‐oic acid 28‐O‐α‐L ‐rhamnopyranosyl‐(1 → 3)‐β‐D ‐xylopyranosyl‐(1 → 4)‐α‐L ‐rhamnopyranosyl‐(1 → 2)‐α‐L ‐arabinopyranoside} (3), tacacosides A₁ (4) and B₃ (5). The structures of saponins 1 and 2 were elucidated using a combination of ¹H and ¹³C 1D‐NMR, COSY, TOCSY, gHMBC and gHSQC 2D‐NMR, and FABMS of the natural compounds and their peracetylated derivates, as well as by chemical degradation. Compounds 1–3 are the first examples of saponins containing polygalacic and 16‐hydroxyprotobasic acids found in the genus Sechium, while 4 and 5, which had been characterized partially by NMR, are now characterized in detail. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous quantification and rat pharmacokinetics of formononetin‐7‐O‐β‐d‐glucoside and its metabolite formononetin by high‐performance liquid chromatography–tandem mass spectrometry

Formononetin‐7‐O‐β‐d ‐glucoside has been proved to have significant anti‐inflammatory effect. To evaluate its rat pharmacokinetics, a rapid, sensitive, and specific liquid chromatography–tandem mass spectrometry method has been developed and validated for the quantification of formononetin‐7‐O‐β‐d ‐glucoside and its main metabolite formononetin in rat plasma. Samples were pretreated using a simple protein precipitation and the chromatographic separation was performed on a C₁₈ column by a gradient elution using a mobile phase consisting of water and acetonitrile both containing 0.1% formic acid. Both analytes were detected using a tandem mass spectrometer in positive multiple reaction monitoring mode. The assay showed wide linear dynamic ranges of both 0.10–100 ng/mL, with acceptable intra‐ and inter‐batch accuracy and precision. The lower limits of quantification were both 0.10 ng/mL using 50 μL of rat plasma for two analytes. The method has been successfully used to investigate the oral pharmacokinetic profiles of both analytes in rats. After oral administration of formononetin‐7‐O‐β‐d ‐glucoside at the dose of 50 mg/kg, it was rapidly absorbed in vivo and metabolized to its metabolite formononetin. The plasma concentration‐time profiles both showed double‐peak phenomena, which would be attributed to the strong enterohepatic circulation of formononetin‐7‐O‐β‐d ‐glucoside.     

Brauhenefloroside E and F; acylated flavonol glycosides from Stocksia brauhica Linn

Two new acylated flavonol glycosides, 3‐O‐{[2‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside and 3‐O‐{2‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside, trivially named as brauhenefloroside E (1) and F (2), respectively, were isolated from the fruits of Stocksia brauhica and their structures were elucidated using spectroscopic methods, including 2D NMR experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

Four new ursane‐type saponins from Morina nepalensis var. alba

Four new ursane‐type saponins, monepalosides C–F, together with a known saponin, mazusaponin II, were isolated from Morina nepalensis var. alba Hand.‐Mazz. Their structures were determined to be 3‐O‐α‐L ‐arabinopyranosyl‐(1 → 3)‐&[alpha;‐L ‐rhamnopyranosyl‐(1 → 2)]‐α‐L ‐arabinopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranoside (monepaloside C, 1 ), 3‐O‐α‐L ‐arabinopyranosyl‐(1 → 3)‐&[alpha;‐L ‐rhamnopyranosyl‐(1 → 2)]‐β‐D ‐xylopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranoside (monepaloside D, 2 ), 3‐O‐α‐L ‐arabinopyranosyl‐(1 → 3)‐&[beta;‐D ‐glucopyranosy‐(1 → 2)]‐α‐L ‐arabinopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranoside (monepaloside E, 3 ) and 3‐O‐β‐D ‐xylopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranoside (monepaloside F, 4 ) on the basis of chemical and spectroscopic evidence. 2D NMR techniques, including ¹H–¹H COSY, HMQC, 2D HMQC‐TOCSY, HMBC and ROESY, and selective excitation experiments, including SELTOCSY and SELNOESY, were utilized in the structure elucidation and complete assignments of ¹H and ¹³C NMR spectra. Copyright © 2002 John Wiley & Sons, Ltd.     

Development of a high‐performance liquid chromatography procedure to identify known and detect novel C‐13 oligosaccharide moieties in diterpene glycosides from Stevia rebaudiana (Bertoni) Bertoni (Asteraceae): Structure elucidation of rebaudiosides V and W

As an aid for structure elucidation of new steviol glycosides, reversed‐phase C18 high‐performance liquid chromatography method was developed with several previously characterized diterpene glycosides, to identify known and detect novel aglycone‐C13 oligosaccharide moieties and indirectly identify C‐19 interlinkages. Elution order of several diterpene glycosides and their aglycone‐C13 oligosaccharide substituted with different sugar arrangements were also summarized. Comparison of the retention time of a product obtained after alkaline hydrolysis with the aglycone‐C‐13 portions of known compounds reported herein allowed us to deduce the exact positions of the sugars in the C‐13 oligosaccharide portion. The elution position of several steviol glycosides with an ent‐kaurene skeleton was helpful to describe an identification key. Two previously uncharacterized diterpene glycosides together with two known compounds were isolated from a commercial Stevia rebaudiana leaf extract. One was found to be 13‐[(2‐O‐β‐d ‐xylopyranosyl‐ 3‐O‐β‐d ‐glucopyranosyl‐β‐d ‐glucopyranosyl)oxy]ent‐kaur‐16‐en‐19‐oic acid‐(2‐O‐β‐d ‐glucopyranosyl‐β‐d ‐glucopyranosyl) ester (rebaudioside V), whereas the other was determined to be 13‐[(2‐O‐β‐d ‐xylopyranosyl‐ 3‐O‐β‐d ‐glucopyranosyl‐β‐d‐ glucopyranosyl)oxy]ent‐kaur‐16‐en‐19‐oic acid‐(2‐O‐α‐l ‐rhamnopyranosyl‐3‐O‐β‐d ‐glucopyranosyl‐β‐d ‐glucopyranosyl) ester (rebaudioside W). Previously reported compounds were isolated in gram quantities and identified as rebaudioside J and rebaudioside H. In addition, a C‐19 sugar‐free derivative was also prepared from rebaudioside H to afford rebaudioside H₁. Chemical structures were partially determined by the high‐performance liquid chromatography method and unambiguously characterized by using one‐dimensional and two‐dimensional nuclear magnetic resonance experiments.     

Structure elucidation of new acacic acid‐type saponins from Albizia coriaria

Three new acacic acid derivatives, named coriariosides C, D, and E ( 1–3 ) were isolated from the roots of Albizia coriaria. Their structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR studies and mass spectrometry as 3‐O‐[β‐D ‐xylopyranosyl‐(1 → 2)‐β‐D ‐fucopyranosyl‐(1 → 6)‐2‐(acetamido)‐2‐deoxy‐β‐D ‐glucopyranosyl]‐21‐O‐{(2E,6S)‐6‐O‐{4‐O‐[(2E,6S)‐2,6‐dimethyl‐ 6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐β‐D ‐quinovopyranosyl}‐2,6‐dimethylocta‐2,7‐dienoyl}acacic acid 28‐O‐β‐D ‐xylopyranosyl‐(1 → 4)‐α‐L ‐rhamnopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl ester ( 1 ), 3‐O‐{β‐D ‐fucopyranosyl‐(1 → 6)‐[β‐D ‐glucopyranosyl‐(1 → 2)]‐β‐D ‐glucopyranosyl}‐21‐O‐{(2E,6S)‐6‐O‐{4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐β‐D ‐quinovopyranosyl}‐2,6‐dimethylocta‐2,7‐dienoyl}acacic acid 28‐O‐α‐L ‐rhamno pyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl ester ( 2 ), and 3‐O‐[β‐D ‐fucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranosyl]‐21‐O‐{(2E,6S)‐6‐O‐{4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl)‐β‐D ‐quinovopyranosyl]octa‐2,7‐dienoyl}acacic acid 28‐O‐β‐D ‐glucopyranosyl ester ( 3 ). Copyright © 2010 John Wiley & Sons, Ltd.     

Target‐guided isolation of polar antioxidants from Abelmoschus esculentus (L). Moench by high‐speed counter‐current chromatography method coupled with wavelength switching and extrusion elution mode

An off‐line two‐dimensional high‐speed counter‐current chromatography strategy combined with the wavelength switching technique and extrusion elution mode was successfully developed and applied to the isolation of polar antioxidants from Abelmoschus esculentus (L).Moench. Target‐guided by the result of 2,2‐diphenyl‐1‐picrylhydrazyl screening assay, four antioxidants were obtained with purities over 90% through orthogonal high‐speed counter‐current chromatography separation. UV spectroscopy, mass spectrometry and ¹H NMR spectroscopy were employed to identify their structures, which were assigned as l ‐tryptophan, quercetin‐3‐O‐sophoroside, 5,7,3′,4′‐tetrahydroxyflavonol‐3‐O‐[β‐d ‐rhamnopyranosil‐(1→2)]‐β‐d ‐glucopyranoside, and quercetin‐3‐O‐glucoside. Each monomer exhibited significant antioxidant activity. The results demonstrated that proposed method could be an effective approach to isolate bioactive compounds from complex natural products.     

Gas‐phase hydration of Mg2+ complexes with deprotonated uracil,thymine, uridine,and thymidine

The gas‐phase hydration of Mg²⁺ complexes with deprotonated uracil ( U ), thymine ( T ), uridine ( U _r , uracil riboside), and thymidine ( T _dr , thymine deoxyriboside) was studied. The aim of the work was to analyze the hydration of product ions (eg, [2 U ‐H+Mg]⁺) formed as a result of the collision induced dissociation of the respective parent ion (eg, [3 U _r ‐H+Mg]⁺). The efficiency of gas‐phase hydration of the ions [2 U ‐H+Mg]⁺ and [2 T ‐H+Mg]⁺ was similar. However, the efficiency of gas‐phase hydration of the ion [ U + U _r ‐H+Mg]⁺ was much higher than that of gas‐phase hydration of the ion [ T + T _dr ‐H+Mg]⁺. On the basis of the mass spectra obtained and the performed molecular modelling, it was concluded that in the ion [ T + T _dr ‐H+Mg]⁺, we deal with a steric hindrance due to the presence of a sugar moiety, which affects water attachment. In the ion [ U + U _r ‐H+Mg]⁺, the position of the sugar moiety does not affect water attachment.     

Tetrapterosides A and B,two new oleanane‐type saponins from Tetrapleura tetraptera

From the stem bark of Tetrapleura tetraptera, two new oleanane‐type saponins, tetrapteroside A 3‐O‐{6‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐hydroxyocta‐2,7‐dienoyl]‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl‐(1 → 3)‐β‐D ‐glucopyranosyl‐(1 → 4)‐[β‐D ‐glucopyranosyl‐(1 → 2)]‐β‐D ‐glucopyranosyl}‐3,27‐dihydroxyoleanolic acid (1), and tetrapteroside B 3‐O‐{ β‐D ‐glucopyranosyl‐(1 → 2)‐6‐O‐[(E)‐feruloyl]‐β‐D ‐glucopyranosyl‐(1 → 3)‐β‐D ‐glucopyranosyl‐(1 → 4)‐[β‐D ‐glucopyranosyl‐(1 → 2)]‐β‐D ‐glucopyranosyl}‐3,27‐dihydroxyoleanolic acid (2), were isolated. Further extractions from the roots led to the isolation of four known oleanane‐type saponins. Their structures were elucidated by the combination of mass spectrometry (MS), one and two‐dimensional NMR experiments. Copyright © 2009 John Wiley & Sons, Ltd.     

NMR analysis of mono‐ and difructosyllactosucrose synthesized by 1F‐fructosyltransferase purified from roots of asparagus (Asparagus officinalis L.)

Two novel oligosaccharides, mono‐ and difructosyllactosucrose {[O‐β‐D ‐fructofuranosyl‐(2 → 1)]_n‐β‐D ‐fructofuranosyl‐O‐[β‐D ‐galactopyranosyl‐(1 → 4)]‐α‐D ‐glucopyranoside, n = 1 and 2} were synthesized using 1^F‐fructosyltransferase purified form roots of asparagus (Asparagus officinalis L.). Their ¹H and ¹³C NMR spectra were assigned using several NMR techniques. The spectral analysis was started from two anomeric methines of aldose units, galactose and glucose, since they showed separate characteristic signals in their ¹H and ¹³C NMR spectra. After assignments of all the ¹H and ¹³C signals of two units of aldose, they were discriminated as galactose and glucose using proton–proton coupling constants. The HMBC spectrum revealed the galactose residue attached to C‐4 of glucose, fructose residue attached to the C‐1 of glucose, and further fructosyl fructose linkage extended from the glucosyl fructose residues. Copyright © 2002 John Wiley & Sons, Ltd.     

Rapid characterization of triterpene saponins from Conyza blinii by liquid chromatography coupled with mass spectrometry

Conyza blinii Le'vl is a medicinal herb used for the treatment of inflammation in Chinese folk medicine. Its major bioactive constituents are triterpene saponins, most of which contain 6–8 sugar residues. In this report, electrospray ionization tandem mass spectrometry fragmentation behaviors of bisdesmosidic triterpene saponins (conyzasaponin A, B, and C) were studied in both positive and negative ion modes with an ion‐trap mass spectrometer. In full scan mass spectrometry, these saponins gave predominant [M–H]^? and [M+Na]⁺ ions, which determined the molecular weights. In tandem mass spectrometry (MSⁿ, n = 2–4), the [M–H]^? and [M+Na]⁺ ions yielded fragments [Y_0α–H]^? and [B_α+Na]⁺, which were diagnostic for the structures of the triterpene skeleton and sugar chains. The structural elucidation was approved by accurate mass data using IT‐TOF‐MS. An interpretation guideline based on MSⁿ (n = 2–4) diagnostic ions was proposed in order to elucidate the chemical structures of unknown triterpene saponins in C. blinii extract. The saponins in C. blinii were separated by liquid chromatography with a methanol/acetonitrile/water solvent system, and then analyzed by ion‐trap and IT‐TOF mass spectrometers. Based on the interpretation guideline, a total of 35 triterpenoid saponins were tentatively identified. Among them, 15 saponins had been previously reported, and the other 20 saponins were reported from Conyza species for the first time. This study indicates that LC/MS is a powerful technology for the rapid characterization of complicated saponins in herbal extracts. Copyright © 2010 John Wiley & Sons, Ltd.     

HPLC–UV–ESI MS/MS identification of the color constituents of sawwort (Serratula tinctoria L.)

Extracts from wool dyed with sawwort (Serratula tinctoria L.) obtained with methanol/formic acid and methanol/hydrochloric acid solutions were examined by high-performance liquid chromatography with UV detection coupled with electrospray ionization tandem mass spectrometry. Chromatograms and mass spectra were registered in the negative ion mode under various orifice voltages and collision energies, which enabled us to observe signals corresponding to [M???H]^? ions and also Y^? and/or Y^?? ions, which were further subjected to fragmentation. The results obtained allowed us to define previously unknown constituents of sawwort, which are proposed as specific markers for its identification: chlorogenic acid and its isomers, luteolin-O-glucuronides, eriodictyol-O-glucuronides, and diosmetin-O-glucuronides. Moreover, it was found that during extraction, flavonoid O-glucuronides react with methanol in the presence of hydrochloric acid, forming stable O-methylated derivatives.     

Rapid characterization and determination of multiple components in Bu‐Shen‐Yi‐Qi‐Fang by high‐performance liquid chromatography coupled to electrospray ionization and quadrupole time‐of‐flight mass spectrometry

In this study, a qualitative and quantitative analysis using high‐performance liquid chromatography coupled to electrospray ionization and quadrupole time‐of‐flight mass spectrometry was performed for the quality control of Bu‐Shen‐Yi‐Qi‐Fang, a traditional Chinese formula used for asthma. Thirty‐four compounds, including flavonoids, isoflavonoids, triterpenoid saponins, and iridoid glycosides were identified or tentatively characterized by comparing their retention times and mass spectra with those of authentic standards or literature data. Sixteen components were considered as the main bioactive constituents of Bu‐Shen‐Yi‐Qi‐Fang and they were chosen as the chemical markers in quantitative analysis, including catalpol, leonuride, calycosin‐7‐O‐β‐d ‐glucoside, hyperoside, acteoside, formononetin‐7‐O‐β‐d ‐glucoside, epimedin A, calycosin, icariin, epimedin B, epimedin C, formononetin, astragaloside IV, astragaloside II, baohuoside‐I, and astragaloside I. The total run time was 20 min. It was found that the calibration curves for all analytes showed good linearity (R² > 0.99) within the test ranges. The relative standard deviations for intra‐ and inter‐day precisions were below 3.9 and 11.7%, respectively. The accuracy was evaluated by the recovery test within the range of 89.20–110.71% with the relative standard deviation < 4.8%. The sample was stable for at least 48 h at 4°C. The results showed that the new approach was effective for the quality control of Bu‐Shen‐Yi‐Qi‐Fang.     

Structural determination and complete NMR spectral assignments of a new bufadienolide glycoside

The structure of a new bufadienolide glycoside, cinobufagin 3‐O‐β‐D ‐glucoside, was determined by extensive 1D and 2D NMR techniques (¹H, ¹³C, DEPT, COSY, HSQC, g‐HMBC and NOESY). The complete assignments of the ¹³C and ¹H spectral data were also carried out. Copyright © 2002 John Wiley & Sons, Ltd.