Identification of flavonoids using liquid chromatography with electrospray ionization and ion trap tandem mass spectrometry with an MS/MS library

Study of the release of gallic acid from (-)-epigallocatechin gallate in old oolong tea by mass spectrometry

Liquid chromatography combined with multiple-stage mass spectrometry (LC/MS(n)) was used to study the pathway of the release of gallic acid (GA) from epigallocatechin gallate (EGCG) in infusion of old oolong tea. The possibility of releasing GA from EGCG in old tea preparations was supported by an in vitro observation of GA degraded from EGCG under heating conditions mimicking the drying process. Negative electrospray ionization with the data-dependent mode of MS(n) was used to study the formation pathway of GA in old oolong tea. The MS(n) data show that GA was released from the dimer of EGCG, not directly degraded from EGCG.

Metabolomics revealed novel isoflavones and optimal cultivation time of Cordyceps militaris fermentation

Germinated soybean (GS) cultivated with Cordyceps militaris (GSC) might be a promising efficacious source of novel bioactive compounds. In this study, the metabolome changes between GS and GSC were investigated by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis coupled with a multivariate data set. Principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA) of GSC clearly showed higher levels of soyasaponin Bd, soyasaponin Bc(II), daidzein, genistein, four isoflavones (compounds 1-4), glycerol, proline, glutamine, pentitol, fructose, inositol, octadecanoic acid, and sucrose together with lower levels of pyroglutamic acid, citric acid, histidine, and palmitic acid in GSC than in GS. The structures of compounds 1-4 were analyzed by mass and NMR spectroscopy and were determined to be novel isoflavone methyl-glycosides (daidzein 7-O-beta-d-glucoside 4''-O-methylate (1), glycitein 7-O-beta-d-glucoside 4''-O-methylate (2), genistein 7-O-beta-d-glucoside 4''-O-methylate (3), and genistein 4'-O-beta-d-glucoside 4''-O-methylate (4)). Multivariate statistical models showed that metabolic changes of GSC were maximal within 1 week after the C. militaris inoculation, consistent with the strongest antioxidant activity of GSC cultivated for 1 week. This metabolomics study provides valuable information in regard to optimizing the cultivation process for bioactive compound production and describes an efficient way to screen for novel bioactive compounds from GSC.

Application of metabolomics in the analysis of manufacturing type of pu-erh tea and composition changes with different postfermentation year

Liquid chromatography-mass and multivariate analyses were employed to measure the composition of pu-erh teas and to determine the general changes in the compositional patterns of pu-erh teas during postfermentation. Principle component analysis of pu-erh teas indicated two large distinct clusters in the score plot: ripened pu-erh teas and raw pu-erh teas. The raw pu-erh teas contained more antioxidant compounds compared to ripened pu-erh teas. As a result, the raw pu-erh teas showed significantly higher antioxidant activities than the ripened pu-erh teas in the 1,1-diphenyl-2-picrylhydrazyl, Trolox equivalent antioxidant capacity, and ferric reducing antioxidant power assays. In addition, raw pu-erh teas showed significantly higher NO inhibitory and cell protective activities than the ripened pu-erh teas. Significant correlations between compounds and postfermentation year were observed in raw pu-erh teas; epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate, and quinic acid were decreased and gallic acid was increased in a year-dependent manner. The antioxidant activity was shown to decrease as the number of antioxidant compounds in raw pu-erh tea decreased. These findings indicate that a metabolomic approach is a useful tool for analyzing manufacturing type, postfermentation year, and antioxidant activity of pu-erh tea.

Metabolomics analysis reveals the compositional differences of shade grown tea (Camellia sinensis L.)

The different cultivation methods affect tea quality by altering the basic metabolite profiles. In this study, the metabolome changes were investigated in green tea and shade cultured green tea (tencha) by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) coupled with a multivariate data set. The principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA) of green tea clearly showed higher levels of galloylquinic acid, epigallocatechin, epicatechin, succinic acid, and fructose, together with lower levels of gallocatechin, strictinin, apigenin glucosyl arabinoside, quercetin p-coumaroylglucosyl-rhamnosylgalactoside, kaempferol p-coumaroylglucosylrhamnosylgalactoside, malic acid, and pyroglutamic acid than tencha. The effects of some seasonal variations were also observed in the primary metabolite concentrations such as amino acids and organic acids. In addition, green tea showed stronger antioxidant activity than tencha in both April and July. The antioxidant activity of green tea samples were significantly correlated with their total phenol and total flavonoid contents. This present study delineates the possibility to get high umami and less astringent green teas in shade culture. It highlights the metabolomic approaches to find out the effect of cultivation methods on chemical composition in plants and the relationship with antioxidant activity.

Induction of IL-8 expression by Cordyceps militaris grown on germinated soybeans through lipid rafts formation and signaling pathways via ERK and JNK in A549 cells

AIM OF THE STUDY

In order to elucidate immunoregulatory mechanisms of Cordyceps militaris, a methanol extract of Cordyceps militaris grown on germinated soybeans was prepared and its immunoregulatory effect in the human lung epithelial cells was investigated by examining its ability to induce IL-8 expression.

MATERIALS AND METHODS

Cordyceps militaris grown on germinated soybeans was extracted with 80% methanol (GSC4M) and used for stimulation of a human lung epithelial cell-line, A549. An enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction were performed to examine the production of IL-8 protein and its mRNA, respectively. For the analysis of transcription factors regulating IL-8 transcriptional activation, the nuclear fraction was extracted from GSC4M-treated A549 cells and subjected to electrophoretic mobility shift assay.

RESULTS

GSC4M induced IL-8 protein secretion and its mRNA expression from A549 cells in a dose- and time-dependent manner. GSC4M-induced IL-8 expression was inhibited by an inhibitor for lipid rafts formation but not by that for clathrin-coated pits. In addition, signaling pathways for GSC4M-induced IL-8 expression were mediated through ERK and JNK but hardly through p38 kinase. Furthermore, GSC4M augmented the DNA-binding activity of the transcription factors AP-1, NF-IL6, and NF-kappaB, all of which are involved in the transcriptional activation of the IL-8 gene.

CONCLUSION

Cordyceps militaris grown on germinated soybeans stimulates lung epithelial cells to produce IL-8 through lipid rafts formation and signaling pathways via ERK and JNK.

Assigning glucose or galactose as the primary glycosidic sugar in 3-O-mono-, di- and triglycosides of kaempferol using negative ion electrospray and serial mass spectrometry

Kaempferol 3-O-beta-glucopyranoside, kaempferol 3-O-beta-galactopyranoside and higher glycosides of these two flavonoids with alpha-rhamnose at C-2 and/or C-6 of the primary sugar were studied by negative ion electrospray ionisation and serial mass spectrometry in a three-dimensional (3D) ion trap mass spectrometer. Kaempferol 3-O-beta-glucopyranoside and kaempferol 3-O-alpha-rhamnopyranosyl(1-->6)-beta-glucopyranoside could be distinguished from their respective galactose analogues by differences in the ratio of the radical aglycone ion [Y(0) - H](*-) to the rearrangement aglycone ion Y(0) (-) following MS/MS of the deprotonated molecules. Kaempferol 3-O-rhamnopyranosyl(1-->2)-beta-glucopyranoside and kaempferol 3-O-alpha-rhamnopyranosyl(1-->2)[alpha-rhamnopyranosyl(1-->6)]-beta-glucopyranoside could be distinguished from their respective galactose analogues by differences in the product ion spectra of the [(M - H) - rhamnose](-) ion following serial mass spectrometry. In the triglycoside, it was deduced that this ion resulted from the loss of the rhamnose substituted at 2-OH of the primary sugar by observing that MS/MS of deprotonated kaempferol 3-O-beta-glucopyranosyl(1-->2)[alpha-rhamnopyranosyl(1-->6)]-beta-glucopyranoside showed the loss of glucose and not rhamnose. Thus the class of sugar (hexose, deoxyhexose, pentose) at C-2 and C-6 of the primary sugar can be determined. These observations aid the assignment of kaempferol 3-O-glycosides, having glucose or galactose as the primary glycosidic sugar, in LC/MS analyses of plant extracts, and this can be done with reference to only a few standards.

A promising approach for understanding the mechanism of Traditional Chinese Medicine by the aggregation morphology

OBJECTIVE

Previous work has found that the Traditional Chinese Medicine (TCM) form aggregates in the aqueous solution, and the activities of two Chinese herbal formulae against three cardiovascular targets were aggregates-related. This paper further studied the molecular morphology composed of aggregation and single active molecule in TCM.

METHODS

We take Pueraria lobata (Willd.) Ohwi (PUE) as an example. By means of dynamic light scattering (DLS), transmission electron microscopy (TEM), and high performance liquid chromatography-mass spectrometry (HPLC-MS), the mechanism and active components of the aggregates in PUE have been studies. Besides the relationship between aggregation and therapeutic activities in the vivo level has been studied by hemorheological method.

RESULTS

Puerarin, daidzein, daidzin, genistein, these cardiovascular bioactive compounds existed in the aggregates. Three kinds of aggregation processes by the bioactive molecules in the solution were elucidated: (1) the aggregation of single molecule oneself; (2) the aggregation between different single molecules; (3) the aggregation between different single molecules and the primary metabolites. Furthermore, the therapeutic activity of PUE solution was aggregates-related in vivo level.

CONCLUSIONS

The aggregation morphology of molecules in TCM might be a promising way to study the mechanism of TCM, even to develop an approach of new nanomedicine of TCM.

Characterization of fifty-one flavonoids in a Chinese herbal prescription Longdan Xiegan Decoction by high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry and photodiode array detection

High-performance liquid chromatography coupled to electrospray ionization (ESI) tandem mass spectrometry and photodiode array detection (HPLC-DAD-ESI-MS(n)) was developed to identify and characterize the flavonoids in a Chinese formulated preparation, Longdan Xiegan Decoction (LXD). In total, fifty-one flavonoids (27 flavones, 10 flavanones, 7 chalcones, 5 flavonols and 2 isoflavones) were characterized. Eighteen compounds among them including a newly detected flavonoid, naringin, from the ingredient herbs, were unambiguously determined by comparing the retention times (t(R)), UV spectral data and mass fragmentation behaviors with those of the reference compounds. Another thirty-three compounds were tentatively identified by referencing to the reported data of their UV and MS spectra. The ESI-MS/MS fragmentation behavior of flavones (OMe-substituted, O-glycosides, C-glycosides), chalcones, flavonols and their appropriate characteristic pathways were proposed. In negative ion ESI-MS all the flavonoids yielded prominent [M--H](-) ions in the first order mass spectra. Fragmentation with a loss of mass of 15 Da (CH(3)), 18 Da (H(2)O), 28 Da (CO), 44 Da (CO(2)), 56 Da (2CO) and the residues of glucose and glucuronic acid observed in the MS/MS spectra were useful for aiding the structural identification of the flavonoids investigated.

Evaluation of glycosylation and malonylation patterns in flavonoid glycosides during LC/MS/MS metabolite profiling

Flavonoid conjugates constitute several classes of plant phenolic secondary metabolites including many isomeric compounds differing in the hydroxylation pattern and substitution of their rings with different groups such as alkyls, acyls or sugars. These compounds occur in plant tissues mainly as glycosides and in many cases it is necessary to have reliable and detailed information concerning the structure of these natural products. Our results were obtained using leaf extracts of Arabidopsis thaliana and Lupinus angustifolius in which different glycosides of flavones, flavonols and isoflavones are present. Analysis of collision-induced dissociation (CID)/MS/MS spectra of protonated [M + H](+), sodiated [M + Na](+) or deprotonated [M - H](-) molecules recorded during HPLC runs may bring needed information in this respect. However, registration of mass spectra of [M + Na](+) ions with a good efficiency is possible only after post-column addition of a sodium acetate solution to the LC column eluate. The retention of sodium cation on the saccharidic parts of the molecule is observed after the CID fragmentation. In many cases, the location of this cation on the glycan attached to C-3 hydroxyl group of flavonol led to assignment of its structure. Additionally, the determination of the structure of the aglycone and of the sequence of the glycan part was made possible through the CID data obtained from the [M + H](+) and [M - H](-) ions. CID spectra show a different order of sugar elimination from hydroxyl groups at C-3 and C-7 in flavonol glycosides isolated from A. thaliana leaves and give sufficient information to discriminate flavonoid O-diglycosides from flavonoid di-O-glycosides.

Citrinin, a mycotoxin from Penicillium citrinum, plays a role in inducing motility of Paenibacillus polymyxa

Paenibacillus polymyxa, a Gram-positive low-G+C spore-forming soil bacterium, belongs to the plant growth-promoting rhizobacteria. The swarming motility of P. polymyxa strain E681 was greatly induced by a secondary metabolite, citrinin, produced by Penicillium citrinum KCTC6549 in a dose-dependent manner at concentrations of 2.5-15.0 microg mL(-1) on tryptic soy agar plates containing 1.0% (w/v) agar. Flagellum staining showed that citrinin activated the production of flagella by P. polymyxa. This result was supported by reverse transcriptase-PCR analysis of gene expression, which showed increased transcriptional levels of sigD and hag homologues of P. polymyxa E681 in the presence of citrinin. The results presented here show that a mycotoxin, citrinin, has a newly identified function of inducing bacterial motility by transcriptional activation of related genes. This finding contributes to our understanding of the interactions between bacteria and fungal strains in nature.

Characterisation of historical organic dyestuffs by liquid chromatography-mass spectrometry

This review discusses the characterisation of natural organic dyestuffs of historical interest by liquid chromatography-mass spectrometry. The structures of the most important natural organic dyestuffs traditionally used are presented and discussed from the perspective of their analytical chemical determination. The practical aspects of the determination of this inhomogeneous range of compounds with different structures, such as anthraquinones, flavonoids, indigoids or tannins, are discussed with their implications for sample preparation, liquid chromatographic separation and mass spectrometric detection. The particular focus of this review is the discussion of the mass spectral fragmentation patterns of the different classes of natural organic dyestuffs, which in the ideal case allow the identification of the dyestuff actually used, and thereby provide a key to the better characterisation and understanding of historical objects dyed with natural organic dyestuffs.

Metabolism and bioavailability of flavonoids in chemoprevention: current analytical strategies and future prospectus

Flavonoids are structurally diverse and among the most ubiquitous groups of dietary polyphenols distributed in various fruits and vegetables. Many have been proposed to be bioactive compounds in the diet that are responsible for lowering the risk of cancer and have been used in chemoprevention studies using animal models of this disease. As for any xenobiotic, to evaluate the potential risks and benefits of bioflavonoids to human health, an understanding of the physiological behavior of these compounds following oral ingestion is needed as well as their absorption, distribution, metabolism, and excretion (ADME). The study on metabolism and bioavailability is very important in defining the pharmacological and toxicological profile of these compounds. Due to great structural diversity among flavonoids, these profiles differ greatly from one compound to another, so that the most abundant polyphenols in our diet are not necessarily the ones that reach target tissues. Therefore, careful analysis of flavonoids and their metabolites in biological systems is critical. Mass spectrometry in various combinations with chromatographic methods has been a mainstay in applications that involve profiling and quantification of metabolites in complex biological samples. Because of its speed, sensitivity and specificity, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become the technology of choice for sample analysis. This review describes the chemistry of polyphenols and flavonoids, their ADME, and the various mass spectrometry-based strategies used in the analysis of flavonoids, including future trends in this field.

Comparison of negative ion electrospray mass spectra measured by seven tandem mass analyzers towards library formation

A library of negative ion electrospray ionization mass spectra and tandem mass spectra (MS/MS) of sulfonated dyes has been developed for fast identification purposes. The uniform protocol has been elaborated and applied to the measurements of more than 50 anionic dyes. Three collision energies are selected in our protocol which ensures that at least one of them provides a suitable ratio of product ions to the precursor ion. The robustness is investigated with altered values of tuning parameters (e.g. the pressure of the nebulizing gas, the temperature and the flow rate of drying gas, and the mobile phase composition). The results of the inter-laboratory comparison of product ion mass spectra recorded on seven different tandem mass spectrometers (three ion traps, two triple quadrupoles and two hybrid quadrupole time of flight instruments) are presented for four representative anionic dyes--azo dye Acid Red 118, anthraquinone dye Acid Violet 43, triphenylmethane dye Acid Blue 1 and Al(III) metal-complex azo dye. The fragmentation patterns are almost identical for all tandem mass analyzers, only the ratios of product ions differ somewhat which confirms the possibility of spectra transfer among different mass analyzers with the goal of library formation.

Fragmentation study of a 8-C-glycosyl isoflavone, puerarin, using electrospray ion trap time-of-flight mass spectrometry at high resolution

A mass spectrometry method that combines electrospray with an ion trap time-of-flight mass analyzer has been used to characterize puerarin (7,4'-dihydroxyisoflavone-8-C-beta-D-glucoside). MS(n) spectra (n <or= 6) were obtained in positive and negative ion mode. The combination of accurate mass measurement in MS(2) spectra and sequential MS(n) experiments enabled fragmentation pathways to be elucidated in detail. A novel structure for [M+H-150]+ has been found.

Profiling the metabolic difference of seven tanshinones using high-performance liquid chromatography/multi-stage mass spectrometry with data-dependent acquisition

Tanshinones are a class of bioactive constituents in the roots of Salvia miltiorrhiza named Dan-Shen in Chinese, which possess diverse pharmacological activities. In this study, we employed a sensitive high-performance liquid chromatography/multi-stage mass spectrometry (HPLC/MS(n)) method with data-dependent acquisition and a dynamic exclusion program for the identification of phase I metabolites of seven tanshinones in rat bile after intravenous administration. These seven tanshinones are tanshinone IIA, sodium tanshinone IIA sulfonate (abbreviated as STS, a water-soluble derivate of tanshinone IIA), cryptotanshinone, 15,16-dihydrotanshinone I, tanshinone IIB, przewaquinone A and tanshinone I. Altogether 33 metabolites underwent monohydroxylation, dihydroxylation, dehydrogenation, D-ring hydrolysis or oxidation reactions in the C-4 or C-15 side chain which were characterized by analyzing the LC/MS(n) data. Different metabolic reactions for tanshinones were dependent on the degree of saturation and the substituent group in the skeleton. Dehydrogenation was the major metabolic modification for cryptotanshinone with saturated A and D rings. 15,16-Dihydrotanshinone I containing a saturated D ring was mainly metabolized through D-ring hydrolysis. For tanshinone IIA, possessing a saturated A ring, hydroxylation was the major metabolic pathway. When there was hydroxyl group substitution in the C-17 or C-18 position, such as przewaquinone A and tanshinone IIB, or sulfonic group substitution in the C-16 position, such as STS, higher metabolic stability than that of tanshinone IIA was shown and only trace metabolites were generated. Oxidation in the C-4 or C-15 side chain was a characteristic reaction for tanshinone IIA and hydroxylated tanshinone IIA. For tanshinone I, bearing unsaturated A and D rings simultaneously, no metabolites were detected.