Determination of phenolic compounds in rose hip (Rosa canina) using liquid chromatography coupled to electrospray ionisation tandem mass spectrometry and diode-array detection

Liquid chromatography coupled with negative and positive electrospray ionisation (ESI) tandem mass spectrometry (MS/MS) and diode-array detection (DAD) was used for determination of phenols in rose hip (Rosa canina) extract. ESI mass spectra of the chromatographically separated phenols gave the molecular weight of the compounds through prominent [M - H](-) ions for most of the compounds and M(+) ions for the anthocyanins. Collision induced dissociation (CID) of the [M - H](-) (or M(+)) precursor ions yielded product ions which determined the molecular weight of the aglycones. In-source fragmentation followed by CID of the resulting deprotonated aglycone ([A - H](-)) provided product ions for the identification of the unconjugated phenols. The identification was based on comparison with product ion spectra of commercial standards. UV-diode-array spectra were used for identity confirmation. This combined approach allowed the identification in rose hip extract of an anthocyanin, i.e. cyanidin-3-O-glucoside, several glycosides of quercetin and glycosides of taxifolin and eriodictyol. Phloridzin was identified, and several conjugates of methyl gallate were also found, one of which was tentatively identified as methyl gallate-rutinoside. Catechin and quercetin were found as the aglycones in the extract.     

Electrospray tandem mass spectrometry for structural characterization of aporphine- benzylisoquinoline alkaloids

Electrospray mass spectrometry and tandem mass spectrometry techniques were utilized to elucidate the structures of ten aporphine-benzylisoquinoline alkaloids, consisting of monoether link between aporphine and benzyltetrahydroisoquinoline units, which were isolated and identified previously from a variety of Thalictrum sp. (Ranunculaceae family) based mainly on the UV, IR, CD, NMR, EI-MS, CI-MS, derivatization, and chemical degradation techniques. In this investigation, protonated molecules, [M+H]+ ions, for nine tertiary alkaloids, a molecular ion, [M+'] ion, for a quaternary alkaloid, and very intense doubly- protonated molecules, [M+2H]2+ ions (100% of relative abundance) in Q1 Scan MS spectra, and prominent as well as diagnostic product ions for structural information in the tandem MS/MS spectra were observed for all investigated alkaloids each in nanogram quantities. More than 10 microg quantities of each investigated alkaloid or other isoquinoline and aporphine analogs needed for the CI-MS, EI-MS and FAB-MS analysis from the previous studies.     

Screening for pregnane glycosides with immunological activities from the stems of Stephanotis mucronata by high-performance liquid chromatography/tandem mass spectrometry

The stems of the Chinese traditional medicine Stephanotis mucronata were screened for immunologically active pregnane glycosides using high-performance liquid chromatography (HPLC) coupled with electrospray ionization tandem mass spectrometry. In the mass spectra of pregnane glycosides, predominant [M+Na]+ ions were observed and used to determine the molecular masses, while fragmentation reactions of the [M+Na]+ ions were recorded to provide information on the primary sequences of oligosaccharide chains in terms of classes of monosaccharide. Fragment ions from the side-chain cleavage of aglycone portions can provide mass information about side-chain substitutions. To further confirm the fragment ion structures, Fourier transform ion cyclotron resonance tandem mass spectrometry (MSn) with low-energy collision-induced dissociation was performed using samples collected from HPLC fractions, which provided accurate elemental compositions of fragment ions. Based on fragmentation patterns and comparison with standards, ten pregnane glycosides were identified as stemucronatosides C, D, F, and G, mucronatosides A, B, and C, stephanoside E, and two glycosides that are identified in the S. mucronata extracts for the first time. The latter two pregnane glycosides are 12-O-cinnamoyldeacetylmetaplexigenin-3-O-6-deoxy-3-O-methyl-beta-D-allopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-beta-D-cymaropyranoside and 12-O-cinnamoyl-20-O-acetyl (20S)-pregn-6-ene-3beta,5alpha,8beta,12beta,14beta,17beta,20-heptaol 3-O-beta-D-thevetopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-beta-D-cymaropyranoside.     

Analysis of tomato glycoalkaloids by liquid chromatography coupled with electrospray ionization tandem mass spectrometry

Steroidal glycoalkaloids (SGAs) extracted from tomato leaves and berries (Lycopersicon esculentum Mill.) were separated and identified using optimized reversed-phase liquid chromatography with electrospray ionization (ESI) and ion trap mass spectrometry (ITMS). The ESI source polarity and chromatographic conditions were evaluated. The ESI spectra contain valuable information, which includes the mass of SGAs, the mass of the aglycones, and several characteristic fragment ions. Cleavage at the interglycosidic bonds proximal to the aglycones is the most prominent process in the ESI process. A protonated molecule, [M+H]+, accompanied by a mixed adduct ion, [M+H+Na]2+, was observed for alpha-tomatine (i.e., m/z 1034.7 and 528.9) and dehydrotomatine (i.e., m/z 1032.6 and 527.9) in positive ion mode spectra. The structures of these tomato glycoalkaloids were confirmed using tandem mass spectrometry. The identification of a new alpha-tomatine isomer glycoalkaloid, named filotomatine (MW 1033), which shares a common tetrasaccharide structure (i.e., lycotretraose) with alpha-tomatine and dehydrotomatine, and soladulcidine as an aglycone, is described for the first time. It occurs in significant amounts in the extracts of wild tomato foliage. Multistage mass spectrometry both of the protonated molecules and of the doubly charged ions was used for detailed structural elucidation of SGAs. Key fragmentations and regularities in fragmentation pathways are described and the fragmentation mechanisms involved are proposed.     

Structural analysis of selected characteristic flavones by electrospray tandem mass spectrometry.

Seven structure analogical flavonoid aglycones have been analyzed using electrospray ionization tandem mass spectrometry (ESI-MSn) in the negative-ion mode. The spectra obtained ESI-MSn allowed us to propose plausible schemes for their fragmentation mechanism. By analyzing the product ions spectra of deprotonated molecule ions [M-H](-), some neutral diagnostic losses and specific retro Diels-Alder fragments were obtained. By using all of these characteristic fragment ions we can specially differentiate the flavone isomer.     

Electrospray ionization ion-trap time-of-flight tandem mass spectrometry of two furofurans: sesamin and gmelinol

High-resolution electrospray ionization multistage tandem mass spectrometry (MS(1-7)) in positive ion mode was used to determine the accurate masses and the fragmentation pathways of two furofurans, sesamin and gmelinol. The protonated molecules [M+H]+ were absent in the conventional mass spectra of both compounds, but two characteristic ions, [M+H-H(2)O]+ and [M+H-H(2)]+, were always observed. Successive losses of CH(2)O and CO are the common characteristic fragmentations. Based on the exact masses acquired from 21 different tandem mass spectra, two or three fragmentation pathways for each compound are proposed. The consecutive losses of two H(2)O molecules and one H(2) molecule readily take place from the furan rings for both sesamin and gmelinol, resulting in the absence of the protonated molecules in the single-stage experiments. HCHO loss is observed at least three times in the tandem mass spectra, mainly from methylenedioxy groups (OCH(2)O) for sesamin but only from tetrahydrofuran rings for gmelinol. Moreover, CO loss is found at least three times in the tandem mass spectra of both sesamin and gmelinol from the 3,4-methylenedioxyphenyl (ArOCH(2)O) moieties for sesamin and from both the dimethoxyphenyl and the tetrahydrofuran ring moieties for gmelinol. In addition, the disubstituted benzyl cation ArCH(2)+ at m/z 135 for sesamin and at m/z 151 for gmelinol was found in the MS(3) spectra of both sesamin and gmelinol, which is very helpful in the identification of the compositions of 3,4-disubstituted groups on the benzene rings of the furofurans.     

Profiling isoflavone conjugates in root extracts of lupine species with LC/ESI/MSn systems

Extracts obtained from roots of three lupine species (Lupinus albus, L. angustifolius, L. luteus) were analysed using LC/UV and LC/ESI/MS(n). The experiments were performed using two mass spectrometric systems, equipped with the triple quadrupole or ion trap analysers. Thirteen to twenty isomeric isoflavone conjugates were identified in roots of the investigated lupine species. These were di- and monoglycosides of genistein and 2'-hydroxygenistein with different patterns of glycosylation, both at oxygen and carbon atoms; some glycosides were acylated with malonic acid. It was not possible to establish the glycosylation sites of the aglycone only on the basis of the registered mass spectra; however, it was possible to differentiate C- and O-glucosides of isoflavones. Only comparison of retention times with those of standard compounds permitted to indicate the correct glycosylation pattern. In the case of diglycosides, the glycosylation pattern (O-diglucoside or O-glucosylglucoside) was distinguishable on the basis of the relative intensities of daughter ions in the mass spectra of protonated molecular ions. It was not possible to elucidate the site of malonylation on the sugar moiety from mass spectra, however, protonated molecules [M + H](+) of isoflavone glucosides with different placement of the malonyl group on the sugar ring were recognized in the extracts. In addition to the isoflavone glycosides, some flavone or flavonol glycosides were identified in the samples on the basis of collision-induced daughter ion spectra of the aglycone ions. A comparison of results obtained with the triple quadrupole and ion trap analysers was done in the course of the investigations.     

High-performance liquid chromatography–tandem mass spectrometry for identification of isoflavones and description of the biotransformation of kudzu root

High-performance liquid chromatography-tandem mass spectrometry has been used to identify isoflavone aglycones and glycosides in kudzu root. Fourteen isoflavones were detected. Among these, six were identified by comparison with authentic standards. Tentative identifications of the other isoflavones are based on UV spectra, mass spectra of protonated and deprotonated molecules, and MS-MS data. Several are reported for the first time in kudzu root. The bioactivity and bioavailability of isoflavone aglycones are usually greater than those of their glycosides. To improve the bioavailability of kudzu root isoflavones, crude beta-glycosidases prepared from microbes were used to hydrolyze the isoflavone glycosides. Several MS modes are combined not only to identify the isoflavones in kudzu root, but also to describe the biotransformation of kudzu root isoflavone glycosides. It is also proved that crude beta-glycosidases have high selectivity toward the O-glycosides of isoflavones.     

Liquid chromatographic/electrospray ionization tandem mass spectrometric study of the phenolic composition of cocoa (Theobroma cacao)

Liquid chromatography coupled with ionspray mass spectrometry in the tandem mode (LC/MS/MS) with negative ion detection was used for the identification of a variety of phenolic compounds in a cocoa sample. Gradient elution with water and acetonitrile, both containing 0.1% HCOOH, was used. Standard solutions of 31 phenolic compounds, including benzoic and cinnamic acids and flavonoid compounds, were studied in the negative ion mode using MS/MS product ion scans. At low collisional activation, the deprotonated molecule [M - H](-) was observed for all the compounds studied. For cinnamic and benzoic acids, losses of CO(2) or formation of [M - CH(3)](-*) in the case of methoxylated compounds were observed. However, for flavonol and flavone glycosides, the spectra present both the deprotonated molecule [M - H](-) of the glycoside and the ion corresponding to the deprotonated aglycone [A - H](-). The latter ion is formed by loss of the rhamnose, glucose, galactose or arabinose residue from the glycosides. Different fragmentation patterns were observed in MS/MS experiments for flavone-C-glycosides which showed fragmentation in the sugar part. Fragmentation of aglycones provided characteristic ions for each family of flavonoids. The optimum LC/MS/MS conditions were applied to the characterization of a cocoa sample that had been subjected to an extraction/clean-up procedure which involved chromatography on Sephadex LH20 and thin-layer chromatographic monitoring. In addition to compounds described in the literature, such as epicatechin and catechin, quercetin, isoquercitrin (quercetin-3-O-glucoside) and quercetin-3-O-arabinose, other compounds were identified for the first time in cocoa samples, such as hyperoside (quercetin-3-O-galactoside), naringenin, luteolin, apigenin and some O-glucosides and C-glucosides of these compounds.     

Systematic screening and characterization of glycosides in tobacco leaves by liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry using neutral loss scan and product ion scan

Glycosides in tobacco leaves are highly important aromatic precursors. It is necessary to reveal glycosides in tobacco leaves to improve tobacco planting and processing. This study describes a method for the systematic screening of glycosides in tobacco leaves by liquid chromatography with tandem mass spectrometry. Although glycosides contain numerous aglycones, the number of glycans is limited. Based on a screening table of glycans designed for neutral loss scan, glycosides with different aglycones were systematically screened out. Then, the MS² fragment spectra of scanned glycosides were further obtained using product ion scan. By comparison with the spectra in online tandem mass spectral databases, reported references, and verification by commercial standards, 64 glycosides were detected, including 39 glycosides linked with monosaccharides, 18 glycosides linked with disaccharides and 7 glycosides linked with trisaccharides. It is noteworthy that glycosides linked with trisaccharides have previously been rarely reported in tobacco. This method appears to be a useful tool for the systematic screening and characterization of glycosides in tobacco and can potentially be applied to other plants.     

Identification of flavonoids and their glycosides by high-performance liquid chromatography with electrospray ionization mass spectrometry and with diode array ultraviolet detection

Identification of flavonoids and flavonoid glycosides was carried out on Psidium guajava Linn leaves by means of high-performance liquid chromatography ultraviolet (HPLC-UV) analysis and HPLC mass spectrometry. By using HPLC-UV, two known phenolics (gallic acid and quercetin) and five newly reported ones (procatechuic acid, chlorogenic acid, caffeic acid, kaempferol and ferulic acid) were identified in alcohol guava leaf extract. Structural information about the compounds was obtained from the retention times, the UV spectra and mass spectra without the need to isolate the individual compounds. Two flavonoids (quercetin and kaempferol) and four flavonoid glycosides (three known components, quercetin 3-O-alpha-L-arabinoside, quercetin 3-O-beta-D-glucoside and quercetin 3-O-beta-D-galactoside, along with one novel compound, kaempferol-glycoside) and three other unknown compounds have been identified in the fractions.     

Plasma chromatography of heroin and cocaine with mass-identified mobility spectra.

Plasma chromatography detects and identifies compounds in trace quantities at atmospheric pressure through characteristic positive and negative mobility spectra. To facilitate use of the technique to detect gas chromatographic effluents, a number of reference mobility spectra for different classes of compounds have been reported. Reference spectra for two more compounds, heroin and cocaine, are presented in this study. The primary ions found in these mobility spectra were determined to be M+, (M - H2)+, and (M - CH3CO2)+ for heroin and M+, (M - C6H5CO2)+ and (M - C6H5CO2 - CO2CH3)+ for cocaine using a directly interfaced plasma chromatograph-mass spectrometer. The identified ions agree closely with those predicted in the ion mobility spectra using mass-mobility correlation data coupled with chemical ionization mass spectrometry data. Also, an independent check demonstrating the reliability of reduced mobility values reported in earlier reference spectra was made.     

Characterization of inositol phosphorylceramides from <Emphasis Type="Italic">Leishmania major</Emphasis> by tandem mass spectrometry with electrospray ionization

We describe tandem mass spectrometric approaches, including multiple stage ion-trap and source collisionally activated dissociation (CAD) tandem mass spectrometry with electrospray ionization (ESI) to characterize inositol phosphorylceramide (IPC) species seen as [M - H](-) and [M - 2H + Li](-) ions in the negative-ion mode as well as [M + H](+), [M + Li](+), and [M - H + 2Li](+) ions in the positive-ion mode. Following CAD in an ion-trap or a triple-stage quadrupole instrument, the [M - H](-) ions of IPC yielded fragment ions reflecting only the inositol and the fatty acyl substituent of the molecule. In contrast, the mass spectra from MS(3) of [M - H - Inositol](-) ions contained abundant ions that are readily applicable for assignment of the fatty acid and long-chain base (LCB) moieties. Both the product-ion spectra from MS(2) and MS(3) of the [M - 2H + Alk](-), [M + H](+), [M + Alk](+), and [M - H + 2Alk](+) ions also contained rich fragment ions informative for unambiguous assignment of the fatty acyl substituent and the LCB. However, the sensitivity of the ions observed in the forms of [M - 2H + Alk](-), [M + H](+), [M + Alk](+), and [M - H + 2Alk](+) (Alk = Li, Na) is nearly 10 times less than that observed in the [M - H](-) form. In addition to the major fragmentation pathways leading to elimination of the inositol or inositol monophosphate moiety, several structurally informative ions resulting from rearrangement processes were observed. The fragmentation processes are similar to those previously reported for ceramides. While the tandem mass spectrometric approach using MS(n) (n = 2, 3) permits the structures of the Leishmania major IPCs consisting of two isomeric structures to be unveiled in detail, tandem mass spectra from constant neutral loss scans may provide a simple method for detecting IPC in mixtures.     

Approach to the study of flavone di‐C‐glycosides by high performance liquid chromatography‐tandem ion trap mass spectrometry and its application to characterization of flavonoid composition in Viola yedoensis

The mass spectrometric (MS) analysis of flavone di‐C‐glycosides has been a difficult task due to pure standards being unavailable commercially and to that the reported relative intensities of some diagnostic ions varied with MS instruments. In this study, five flavone di‐C‐glycoside standards from Viola yedoensis have been systematically studied by high performance liquid chromatography‐electrospray ionization‐tandem ion trap mass spectrometry (HPLC‐ESI‐IT‐MSⁿ) in the negative ion mode to analyze their fragmentation patterns. A new MS² and MS³ hierarchical fragmentation for the identification of the sugar nature (hexoses or pentoses) at C‐6 and C‐8 is presented based on previously established rules of fragmentation. Here, for the first time, we report that the MS² and MS³ structure‐diagnostic fragments about the glycosylation types and positions are highly dependent on the configuration of the sugars at C‐6 and C‐8. The base peak (^0,2X₁^0,2X₂^? ion) in MS³ spectra of di‐C‐glycosides could be used as a diagnostic ion for flavone aglycones. These newly proposed fragmentation behaviors have been successfully applied to the characterization of flavone di‐C‐glycosides found in V. yedoensis. A total of 35 flavonoid glycosides, including 1 flavone mono‐C‐hexoside, 2 flavone 6,8‐di‐C‐hexosides, 11 flavone 6,8‐di‐C‐pentosides, 13 flavone 6,8‐C‐hexosyl‐C‐pentosides, 5 acetylated flavone C‐glycosides and 3 flavonol O‐glycosides, were identified or tentatively identified on the base of their UV profiles, MS and MSⁿ (n = 5) data, or by comparing with reference substances. Among these, the acetylated flavone C‐glycosides were reported from V. yedoensis for the first time. Copyright © 2014 John Wiley & Sons, Ltd.     

Flavonoid profile in soybeans by high-performance liquid chromatography/tandem mass spectrometry

Flavonoid profiling of a soybean sample has been performed by liquid chromatography/positive electrospray tandem mass spectrometry (LC/ESI(+)-MS/MS) using a quadrupole-linear ion trap (QLIT) instrument with an information-dependent data acquisition (IDA) protocol that looped, in a single run, an enhanced MS scan and an enhanced product ion scan. As compromise between time and obtainable information, spectra acquisition was split into two distinct runs: 220-450 Th and 400-800 Th, respectively. The isoflavones daidzein and genistein were identified as aglycones, monoglycosides, diglycosides, triglycosides, acetylglycosides, malonylglycosides, malonyl diglycosides, and dimalonyl diglycosides, whereas glycitein triglycosides, acetylglycosides, and dimalonyl diglycosides were not detected. Also kaempferol di- and triglycosides, malonylglycosides and malonyl diglycosides, previously reported in soy leaves and pods, and four naringenin malonylglycosides were identified.     

Structural characterization of flavonoid glycosides from leaves of wheat (Triticum aestivum L.) using LC/MS/MS profiling of the target compounds

The aim of this study was to present integrated mass spectrometric methods for the structural characterization and identification of flavonoid glycoconjugates. During the liquid chromatography/mass spectrometry analyses, TriVersa NanoMate chip‐based system with nanoelectrospray ionization and fraction collection was combined to a quadrupole time‐of‐flight mass spectrometer. In the extract samples prepared from green leaves of wheat plantlets, 41 flavonoid derivatives were recognized. Part of the target natural products had the full structure being characterized after the registration of mass spectra, where m/z values for protonated [M + H]⁺ and deprotonated molecules [M ? H]^? were annotated. MS² and pseudo‐MS³ experiments were performed for [M + H]⁺ or [M ? H]^? and aglycone ions (Y₀^+/?‐type), respectively. It should be underlined that pseudo‐MS³ mass spectra were registered for aglycone product ions in the mass spectra of O‐glycosides present in the extract samples. In many cases, only tentative structural identification of aglycones was possible, mainly because of the presence of numerous C‐monoglycoside or C‐diglycoside in the samples. Acylation of the sugar moiety and/or methylation of the aglycone in the flavonoid glycosides under study was observed. The existence of isobaric and/or isomeric compounds was demonstrated in the extract studied. The collision‐induced dissociation mass spectra registered for C,O‐diglycosides and C,C‐diglycosides did not permit to draw complete structural conclusions about the compounds studied. For the investigated class of natural products, unambiguous classification of sugar moieties linked to the aglycones from the recorded mass spectra was not possible. Registration of the positive and negative ion mass spectra did not lead to the precise conclusion about the glycosylation position at C‐6 or C‐8, and O‐4′ or O‐7 atoms. It was possible, on the basis of the collected MS² spectra, to differentiate between O‐glycosides and C‐glycosides present in the samples analyzed. Copyright © 2013 John Wiley & Sons, Ltd.     

Fragmentation study of iridoid glucosides through positive and negative electrospray ionization, collision-induced dissociation and tandem mass spectrometry

Mass spectrometric methodology based on the combined use of positive and negative electrospray ionization, collision-induced dissociation (CID) and tandem mass spectrometry (MS/MS) has been applied to the mass spectral study of a series of six naturally occurring iridoids through in-source fragmentation of the protonated [M+H]+, deprotonated [M--H]- and sodiated [M+Na]+ ions. This led to the unambiguous determination of the molecular masses of the studied compounds and allowed CID spectra of the molecular ions to be obtained. Valuable structural information regarding the nature of both the glycoside and the aglycone moiety was thus obtained. Glycosidic cleavage and ring cleavages of both aglycone and sugar moieties were the major fragmentation pathways observed during CID, where the losses of small molecules, the cinnamoyl and the cinnamate parts were also observed. The formation of the ionized aglycones, sugars and their product ions was thus obtained giving information on their basic skeleton. The protonated, i.e. [M+H]+ and deprotonated [M--H]-, ions were found to fragment mainly by glycosidic cleavages. MS/MS spectra of the [M+Na]+ ions gave complementary information for the structural characterization of the studied compounds. Unlike the dissociation of protonated molecular ions, that of sodiated molecules also provided sodiated sugar fragments where the C0+ fragment corresponding to the glucose ion was obtained as base peak for all the studied compounds.     

On-line identification of sugarcane (Saccharum officinarum L.) methoxyflavones by liquid chromatography-UV detection using post-column derivatization and liquid chromatography-mass spectrometry

Sugarcane (Saccharum officinarum L., Gramineae) bagasse and leaves were investigated for their flavonoid content and transgenic sugarcane ("Bowman-Birk" and "Kunitz") was compared with non-modified ("control") plants. Analyses were carried out by high-performance liquid chromatography coupled to diode array UV detection (LC/UV), also using post-column addition of shift reagents, and tandem MS (atmospheric pressure chemical ionization-MS/MS and collision-induced dissociation-MS). On-line UV and MS data demonstrated the presence of methoxyflavone glycosides and aglycones in a total of seven compounds. Three naturally occurring flavones glycosides and two unusual erythro- and threo-diastereoisomeric flavolignan 7-O-glucosides were identified together with their aglycones.     

Identification and structural characterization of steroidal glycosides in Hoodia gordonii by ion-trap tandem mass spectrometry and liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry

Electrospray ion-trap tandem mass spectrometry (ESI-MS/MS) and high-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOFMS) were used to identify and characterize eight C-21 steroidal glycosides in Hoodia gordonii. A generalized fragmentation pathway was proposed by comparing the spectra acquired for eight C-21 steroidal glycosides. The steroidal glycosides in Hoodia gordonii have been classified into two major core groups: hoodigenin A and calogenin. Using the ESI-TOF method, the major core peak ions generated by hoodigenin A glycosides are m/z 313 and 295 and by calogenin glycosides are m/z 479, 461, 299 and 281, respectively. In the MS/MS spectra, fragmentation reactions of the [M+Na](+) ion were recorded to provide structural information about the glycosyl and aglycone moieties. The data illustrates the ability of positive mode ESI for the identification of hoodigenin A and calogenin glycosides, including the nature of the hoodigenin A and calogenin core, the number of sugar residues and the type of saccharide moiety.     

Analysis of triterpenoids in <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> using liquid chromatography coupled with electrospray ionization mass spectrometry

Triterpenoids extracted from Ganoderma lucidum (Leyss. ex Fr.) Karst were separated and characterized using optimized reversed-phase liquid chromatography with diode array detection and electrospray ion trap tandem mass spectrometry (HPLC-DAD-ESI-MS(n)). They could be classified into five types depending on the fragmentation behavior. All triterpenoids gave [M - H](-) and [2M - H](-) ions by electrospray ionization monitored in the negative ion mode; in addition, compounds of types III and IV gave prominent [M - H - H(2)O](-) ions and the unsaturated bond at C-20, 22 would reduce the abundance of [M - H - H(2)O](-) ion. The key fragmentation information was cleavage at C- and D-rings despite the predominant losses of H(2)O and CO(2). Compounds with hydroxyls at C-7 and C-15 would produce a list of b, b - 1, b - 2, and b - 16 ions attributed to cleavage of D-ring; if the second alcohol at C-15 were oxidized to ketone, the prominent cleavage would occur at C-ring and produce a group of ions of a; if C-7 were oxidized to ketone, transference of two hydrogen atoms would occur during the cleavage of rings and a list of ions about a + 2 and/or b + 2 would appear instead. The above fragmentations and regularities in fragmentation pathways were reported for the first time, and were implemented for the analysis of triterpenoids in G. lucidum. The chloroform extract was separated on a Zorbax SB-C(18) column, eluting with an acetonitrile-0.2% acetic acid gradient. A total of 32 triterpenoids, including six new ones, were identified or tentatively characterized based on the tandem mass spectra of the HPLC peaks.