Negative Ion FAB-MS Research Articles

ISOLATION OF QUERCETIN GLYCOSIDES FROM LEAVES OF SEA BUCKTHORN (HIPPOPHAE RHAMNOIDES SSP. MONGOLICA)

ISHS XXVI International Horticultural Congress: Berry Crop Breeding, Production and Utilization for a New Century ISOLATION OF QUERCETIN GLYCOSIDES FROM LEAVES OF SEA BUCKTHORN (HIPPOPHAE RHAMNOIDES SSP. MONGOLICA)

Tissue distribution, excretion, and metabolism of 1,2,7,8-tetrachlorodibenzo- p-dioxin in the rat

A tissue distribution, excretion, and metabolism study was conducted using a relatively non-toxic dioxin congener, i.e., 1,2,7,8-tetrachlorodibenzo- p-dioxin (1278-TCDD), to gain a better understanding of mammalian metabolism of dioxins. Conventional, bile duct cannulated, and germ free male rats were administered mg/kg quantities as a single oral dose. Elimination of 1278-TCDD was largely complete by 72 h. Distribution of [ 14C]1278-TCDD was low in all tissues examined. Metabolites were identified in urine, bile, and feces by negative ion FAB-MS and 1H-NMR, or GC/MS. The major fecal metabolite was a NIH-shifted hydroxylated TCDD. The bile contained a glucuronide conjugate of this hydroxy TCDD, and a diglucuronide conjugate of a dihydroxy-triCDD. The major metabolites in urine were glucuronide and sulfate conjugates of 4,5-dichlorocatechol.

Mass spectrometric analysis of ceramide composition in mono-, di-, tri-, and tetraglycosylceramides from mouse kidney: an experimental model for uropathogenic Escherichia coli.

Many bacteria have been shown to bind to the carbohydrate part of glycosphingolipids, but also the lipid moieties of receptor-active glycolipids are of importance. To investigate the chemistry of the ceramides of kidney glycolipids to which the uropathogenic Escherichia coli bind, different mass spectrometric techniques were utilized. First, a mixture of glycolipids isolated from man and mice kidney was separated by thin-layer chromatography (TLC) and scanned by direct desorption from the plate by fast atom bombardment mass spectrometry (TLC/FAB-MS). Second, the glycolipids were purified by preparative TLC and analyzed by negative-ion FAB-MS. After methylation, further analyses were made with positive-ion FAB-MS, positive-ion electron ionization (EI)-MS, high-temperature capillary gas chromatography (GC/EI-MS) and positive-ion matrix-assisted laser desorption/ionization (MALDI)-MS. The ceramide compositions of the four glycolipids were determined using all these MS techniques and the reliability of the different methods for this type of analyses is discussed. Comparison of the mouse kidney glycolipids with the corresponding glycolipids from human kidney showed the same degree of hydroxylation of ceramides among mono- and disaccharide glycolipids, but a significantly higher degree of hydroxylation among mouse kidney glycolipids with three and four sugar residues. This result might be of relevance for the binding of P-fimbriated E. coli to the urinary tract tissues.

Kaempferol tetraglucosides from cabbage leaves.

Four flavonol glycosides were isolated from a leaf extract of cabbage and characterized by chemical and spectroscopic methods including 1H and 13C NMR and negative ion FAB-MS. The common structure of the four compounds was kaempferol 3-O-beta-D-[beta-D-glucopyranosyl(1-->2)glucopyranoside]-7- O-beta-D-[beta-D-glucopyranosyl(1-->4)glucopyranoside]. This compound was found unmodified or acylated at C-2"' (outer glucose in sophorosyl moiety) with either sinapic acid, ferulic acid or caffeic acid. The possible role of diversity in glycosylation and acylation patterns of flavonol glycosides for plant defences against herbivores is discussed.

Metabolism and disposition of 1,4,7,8-tetrachlorodibenzo p-dioxin in rats

Metabolism studies of 1,4,7,8-tetrachlorodibenzo p-dioxin (TCDD), a relatively nontoxic dioxin congener, were undertaken to gain a better understanding of mammalian metabolism of dioxins without the problems associated with the use of the most toxic congener, 2,3,7,8-TCDD. 14C-1,4,7,8-TCDD was dosed to conventional and bile-cannulated rats at a level of 8 mg/kg. The 14C was excreted almost entirely in 72 hours with the major routes of excretion feces and bile. Metabolites were identified from the feces, bile, and urine by GC-MS or negative ion FAB MS and 1H NMR. The two major fecal metabolites were hydroxylated tetra- and triCDDs. Glucuronide and sulfate conjugates of these hydroxyl metabolites were found in the urine and bile. Minor metabolites included dichlorocatechol, dihydroxylated tetra- and triCDDs, and conjugates of these compounds.

Vanicosides C-F, new phenylpropanoid glycosides from Polygonum pensylvanicum.

The isolation of the protein kinase C inhibitors, vanicoside A (1) and vanicoside B (2), from Polygonum pensylvanicum prompted continued interest in the active principles of this plant. A new, more efficient isolation procedure has been developed to facilitate separation of homologues of vanicosides A and B from the complex extract. Several new phenylpropanoid glycosides have since been isolated. The structures of these principles were determined to be 2'-O-acetylhydropiperoside (4), 6'-O-p-coumarylhydropiperoside (5), 4'-O-acetylvanicoside A (6), and 3'-O-acetylvanicoside B (7) using negative ion FABMS, 1H NMR, and 2D NMR techniques.

High Performance Liquid Chromatographic Isolation and Spectroscopic Characterization of Metabolites from the Bile of Rats Receiving Rapamycin (Sirolimus) Intravenously

Ten major metabolites of rapamycin (M2, M3, M8, M9, M10, M11, M13, M14, M15, and M16) were isolated from pooled bile of intravenously dosed rats. Metabolites were extracted from the bile with ethyl acetate prior to isolation by HPLC using a Supelcosil SPLC-18, μm, 10 × 250 mm column. The mobile phase was a methanol/ammonium acetate linear gradient system. The isolated metabolites were characterized by negative ion FAB MS, ion-spray MS and ion-spray MS/MS analyses. Metabolite M2 is oxygenated in the southern portion of rapamycin and the macrolide ring is opened. M3 is a structural isomer of rapamycin where the lactone ring is opened. M10 is oxygenated in the southern portion of rapamycin and the macrolide ring is intact. M13 is a monohydroxylation and demethylation metabolite and both biotransformations occurred at the southern portion. M8, M9, and M11 are monohydroxylation and demethylation metabolites. M14 and M15 are di-hydroxylation metabolites. M16 is mainly a dihydroxylation metabolite. † This work was presented at the Fourth International ISSX Meeting, Seattle, WA, August 1995.

Fast Atom Bombardment Tandem Mass Spectrometry of Benzyloxycarbonyl-Protected Tetrapeptide Derivatives Containing Proline.

Fragmentations of N-benzyloxycarbonyl-protected tetrapeptide ethyl esters containing L-proline and L-alanine in the gas phase were examined by the collisional-activated decomposition of the deprotonated molecule and the fragment ions produced by the cleavage of the tetrapeptide derivatives, in which changes in both the number and positions of the prolyl residues were observed, in negative-ion FAB-MS. The cleavage patterns of these ions in the collisional-activated decomposition mass spectra were observed to depend on the number and positions of prolyl residues in the peptide derivatives. These results indicate that the conformational difference in the tetrapeptide derivatives due to the existence of L-proline may be an important factor responsible for the fragmentations of peptide molecules in the gas phase.

A study of the negative ion FABMS of tris(perfluorophenyl)phosphine and related compounds: matrix effects

The mass spectra of tris(perfluorophenyl)phosphine obtained under negative ion Fast Atom Bombardment conditions showed formation of an unusual ion at m/z 397 attributed to ((C6F5)2PO2)−. The matrix effects involved in this reaction are discussed. Negative ion FAB spectra of tris(perfluorophenyl)arsine and tris(perfluorophenyl)stibine are also reported. Keywords: pentafluorophenylphosphine, -arsine, -stibine; negative ion FABMS; matrix effects.

High Performance Liquid Chromatographic Isolation and Spectroscopic Characterization of Three Major Metabolites from the Plasma of Rats Receiving Rapamycin (Sirolimus) Orally

Abstract Three major metabolites of rapamycin (M2, M3, and M5) were isolated from pooled plasma of orally dosed rats. Metabolites were extracted from the plasma with ethyl acetate/methanol prior to isolation by HPLC using a Supelcosil SPLC-18, 5μm, 10 × 250 mm column. The mobile phase was a methanol/ammonium acetate linear gradient system. The isolated metabolites were characterized by negative ion FAB MS, ion-spray MS and ion-spray MS/MS. Metabolite M2 is oxygenated in the southern portion of rapamycin and the macrolide ring is opened. M3 is a structural isomer of rapamycin where the lactone ring is opened. M5 is O-demethylated on the C41 methoxy moiety and the macrolide ring is intact.

Different Distributions of Glycosphingolipids in Mouse and Rabbit Skeletal Muscle Demonstrated by Biochemical and Immunohistological Analyses1

The expression of neutral glycosphingolipids and gangliosides was investigated in mouse and rabbit skeletal muscle by means of biochemical and immunochemical techniques. Neutral glycosphingolipids from muscle of the inbred rabbit strain used in this study showed a simple TLC pattern, comprising mainly monohexosylceramide. In addition to this compound, lactosylceramide, lacto-N-neotetraosylceramide, globoside and Forssman GSL were detected in mouse muscle. The major ganglioside in both species was GM3; GM3 (Neu5Ac) and GM3(Neu5Gc) were found in a 3:1 ratio in mouse muscle, whereas the absence of GM3(Neu5Gc) is characteristic of rabbit muscle. As a general structural feature of all muscle GM3 gangliosides investigated, a C18 fatty acid and C18 sphingosine were the major components besides minor C22 and C24:1 fatty acids of the respective ceramide portions, as revealed by positive and negative ion FAB-MS. alpha 2-3 sialylated lacto-N-neotetraosyl-ceramide (sialylparagloboside) was expressed in both species, whereas the alpha 2-6 sialylated isomeric compound was found only in mouse muscle. Minute quantities of ganglio-series GM1, GD1a, GD1b, and GT1b were detected in muscles from both species. Glycosphingolipid expression could be confirmed immunohistochemically by examining transverse and longitudinal cryosections of skeletal muscle samples. The results provide the basis for the investigation of muscle specific glycosphingolipids that might modulate membrane protein functions in muscle.

Preparation and characterization of four new variously deacetylated lysogangliosides, breakdown products of GM 1

Four new deaceylated lysogangliosides were obtained through alkaline hydrolysis of either C 18 or C 20 sphingosine homologues of GM 1. By this procedure, both the fatty acids residue and they N-acetyl group of sialic acid were removed to give mono- N-acetyl-lysoGM 1 (C 18 and C 20); the additional loss of the N-acetyl group of the acetylgalactosamine moiety gave de- N-acetyl-lysoGM 1 (C 18 and C 20) with thee free amino groups. The structures of four deacetylated lysogangliosides were unambiguously characterized by chemical analysis and 1H and 13C NMR spectroscopy as well as by negative ion FABMS. The aim of this study was to isolate pure breakdown products of gangliosides, enabling the evaluation of the mechanism of action of glycosphingolipids through their cleavage and identification of structures of potential pharmacological activity. These new substances were prepared as candidates to influence eicosanoid production and the mechanism dependent on protein kinase C and phospholipase A 2.

Acylated flavonol glycosides from cabbage leaves

Seven flavonol glycosides were isolated from a leaf extract of cabbage and characterized by chemical and spectroscopic methods including 1H and 13C NMR and negative ion FAB-MS. Five compounds were new natural products or were fully characterized for the first time. They are derivatives of kaempferol-3- O-β- d-sophoroside-7- O-β- d-glucoside acylated at C-2‴ with either caffeic acid, p-coumaric acid or ferulic acid, and of quercetin-3- O-β- d-sophoroside-7- O-β- d-glucoside acylated with either caffeic acid or ferulic acid. Kaempferol-3- O-β- d-sophoroside-7- O-β- d-glucoside and kaempferol-3- O-β- d-(2-sinapoylsophoroside)-7- O-β- d-glucoside were found for the first time in cabbage, but they have previously been found in other Brassica species.

Human cervical epidermal carcinoma-associated intracellular localization of glycosphingolipid with blood group A type 3 chain.

A monoclonal antibody, MRG‐1, was produced by immunizing a mouse with a human ovarian mucinous cyst adenocarcinoma‐derived cell line, RMUG‐L. By immunohistochemical staining, the antigen was found to be exclusively localized in the intracellular structures of the cells used as the antigen and of the epithelial cells in normal human cervical glands. However, although the antigen was predominantly detected in the plasma membrane and the intercellular structure of the middle layer of normal human cervical squamous epithelium (92%), it was also contained in the intracellular structure of cervical epidermal carcinoma at a high frequency (80%). The striking difference in the distribution of the MRG‐1 antigen between normal and cancerous tissues was found to be a cervical carcinoma‐associated phenomenon and a useful tumor marker for immunohistochemical examination. Since the antigen was found to be of a blood group A‐related nature by immunohistochemical staining of the tissues and to be a glycosphingolipid, it was purified from human erythrocytes of blood group A, and the structure was concluded to be GalNAcα1–3Gal(2–1αFuc)jβ1–3GalNAcα1–3Gal(2–1αFuc)‐ β1–4GlcNAcβ1–3Galβl‐4Glcβ1–1′Cer, blood group A type 3 chain‐containing glycosphingolipid, by NMR, negative ion FABMS and permethylation analysis. In the subcellular localization analysis of the antigen, type 3‐A glycosphingolipid antigen was detected in the Golgi body and the microsomes of RMUG‐L cells, and the distribution coincided with the finding by immunohistochemical staining. In addition, in cervical epidermal carcinoma, although the blood group A, mainly type 2‐A chain, was localized in the plasma membrane and the intercellular structure, the blood group A type 3 chain was selectively found in the perinuclear structure. Also, the blood group A type 3 chain in cervical dysplasia as well as that in normal cervix was predominant in the plasma membrane. Thus, the selective intracellular localization of blood group A type 3 chain was a phenomenon characteristic of cervical epidermal carcinoma and the carcinoma in situ.

Characterization of lipid A from Pseudomonas aeruginosa O-antigenic B band lipopolysaccharide by 1D and 2D NMR and mass spectral analysis

The Lipid A from the lipopolysaccharide of Pseudomonas aeruginosa was examined by high-field nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). The backbone structure and the position of phosphate substituents were unambiguously established by one- and two-dimensional 1H, 13C, and 31P NMR techniques on a de- O-acylated Lipid A sample. The Lipid A has a β-(1,6)-glucosamine disaccharide structure which is substituted by phosphomonoesters through glycosidic bonds at C-1 and at C-4′. The configuration of the glycosidically linked phosphate at position C-1 was identified as α which is the same as that of Enterobacterial Lipid A. Chemical analysis revealed that the Lipid A contained 2-hydroxydodecanoic, 3-hydroxydodecanoic, dodecanoic, 3-hydroxydecanoic, and hexadecanoic acids in the approximate molar ratios 2.2:2.0:0.2:0.8:0.4. From 1H NMR and fast atom bombardment (FAB) mass spectrometry on the de- O-acylated Lipid A, it was established that both glucosamine residues were N-acylated by 3-hydroxydodecanoic acid. The identity and positions of the ester bound fatty acids in the intact Lipid A were investigated by negative ion FAB-MS. In addition to the hexaacyl and pentaacyl Lipid A species, a tetraacyl species was identified. Heterogeneity due to hydroxylated and nonhydroxylated dodecanoic acid esters could be uniquely localized to the nonreducing β-glucosamine residue from the fragmentation pattern observed in the negative ion FAB-MS. The complete structure of the Lipid A from P. aeruginosa will be useful in understanding the determinants responsible for the endotoxin activity of this molecule.

Phytosphingosine-containing neutral glycosphingolipids and sulfatides in the human female genital tract: their association in the cervical epithelium and the uterine endometrium and their dissociation in the mucosa of fallopian tube with the menstrual cycle.

In human cervical epithelium and uterine endometrium, globo-series neutral glycosphingolipids with N-alpha-hydroxy fatty acyl phytosphingosine (4-D-hydroxysphinganine) as the ceramide and sulfatide (I3SO3-GalCer), which were contained in trace amount at the follicular phase, significantly increased in concentration at the luteal phase, comprising about 20% of the individual neutral glycosphingolipids and about 15% of the total acidic glycosphingolipids, respectively. However, in the mucosa of fallopian tube, neutral glycosphingolipids with the same polarity as those in the cervical epithelium and uterine endometrium at the luteal phase and sulfatide remained at a constant and higher level independently of the menstrual cycle. The structures of neutral glycosphingolipids in the fallopian tube, having the same polarity as that of N-alpha-hydroxy fatty acyl phytosphingosine-containing molecules appeared in the cervical epithelium and uterine endometrium at the luteal phase, were determined to be N-alpha-hydroxy palmitoyl 4-sphingenine-containing ones by negative-ion FABMS. Also, laminin, but not collagen type IV, was found to be contained in the concentration correlated well with that of sulfatide in the genital tract, when determined by western blotting with monoclonal anti-laminin and anti-collagen type IV antibodies, indicating a possible function of sulfatide as a receptor for laminin in the human female genital tract.

Structures of asparagine-linked oligosaccharides from hen egg-yolk antibody (IgY). Occurrence of unusual glucosylated oligo-mannose type oligosaccharides in a mature glycoprotein

Asparagine-linked oligosaccharides present on hen egg-yolk immunoglobulin, termed IgY, were liberated from the protein by hydrazinolysis. After N-acetylation, the oligosaccharides were labelled with a UV-absorbing compound, p-aminobenzoic acid ethyl ester (ABEE). The ABEE-derivatized oligosaccharides were fractionated by anion exchange, normal phase and reversed phase HPLC, and their structures were determined by a combination of sugar composition analysis, methylation analysis, negative ion FAB-MS, 500 MHz 1H-NMR and sequential exoglycosidase digestions. IgY contained monoglucosylated oligomannose type oligosaccharides with structures of Glc alpha 1-3Man7-9-GlcNAc-GlcNAc, oligomannose type oligosaccharides with the size range of Man5-9GlcNAc-GlcNAc, and biantennary complex type oligosaccharides with core region structure of Man alpha 1-6(+/- GlcNAc beta 1-4)(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4(+/- Fuc alpha 1-6)GlcNAc. The glucosylated oligosaccharides, Glc1Man8GlcNAc2 and Glc1Man7GlcNAc2, have not previously been reported in mature glycoproteins from any source.

Acidic Glycosphingolipids of Human Amnion1

Six major acidic glycosphingolipids were isolated from human amnion using DEAE Sephadex A-25 and silica beads column chromatography. The structures of these glycosphingolipids were determined by methylation analysis, TLC immunostaining and/or negative ion FAB-MS, and were concluded to be II3 alpha NeuAcLacCer(GM3), IV3 alpha NeuAcnLc4-Cer (sialyl[alpha 2-3]paragloboside), IV6 alpha NeuAcnLc4Cer (sialyl[alpha 2-6]paragloboside), IV3 alpha NeuAcIII4 alpha FucLc4Cer (sialyl Lea), VI3 alpha NeuAcnLc6Cer (i-ganglioside) and II3 alpha (NeuAc alpha 2----8NeuAc)LacCer (GD3). In addition, several minor glycosphingolipids were detected with specific monoclonal antibodies, including glycolipids with NeuAc alpha 2-3Gal beta 1-4GlcNAc-beta 1- or NeuAc alpha 2-6Gal beta 1-4GlcNAc beta 1- determinant. Our results show that the glycosphingolipids of human amnion are characterized by having mainly type II chain analogues and onco-fetal antigens.

Monoclonal antibody-defined antigen of human uterine endometrial carcinomas is Leb.

A monoclonal antibody, MSN-1, generated by immunizing a mouse with a human uterine endometrial adenocarcinoma cell line, SNG-II, was strongly and specifically reactive with neutral glycosphingolipids from cancer tissues of patients with uterine endometrial adenocarcinomas. The glycosphingolipid antigen was purified from pooled human meconia, which contained the antigen at the concentration of 1.95 mumol/g dry weight. Its structure was determined by NMR, negative ion FABMS, permethylation analysis, and TLC-immunostaining with monoclonal anti-Lc4Cer antibody, and was concluded to be the III4IV2Fuc2Lc4Cer,Leb antigen of the human Lewis blood system. On ELISA, the monoclonal antibody was found to be strongly reactive with Leb, slightly with Lea and not at all with A, B, H, or IV2FucGg4Cer. The amount of Leb in cancerous regions in the patients with the Lea-b+ blood group was significantly increased compared to that in normal regions in the same patients, and it was a newly appearing antigen in the cancerous tissue of a patient with the Lea+b- blood group.

A flavonol glycoside from Epimedium diphyllum

A novel flavonol glycoside named diphylloside C was isolated from the underground parts of Epimedium diphyllum and its structure was determined on the basis of spectral analyses (negative ion FAB-MS, 1H- 1H COSY, NOESY, INEPT and 1H- 13C COSY, etc) as des- O-methylanhydroicaritin 3- O-β- d-glucosyl-(1 → )2-α- l-rhamnoside 7- O-β- d-glucosyl-(1 → 2)-β- d-glucoside.