Ion Fast Atom Bombardment Mass Research Articles

Atypical clinical presentation and successful treatment with oral cholic acid of a child with defective bile acid synthesis due to a novel mutation in the HSD3B7 gene.

We report definitive diagnosis and effective treatment with oral cholic acid in one Italian male child affected by 3β-hydroxy-Δ5-C27-steroid dehydrogenase (3β-HSD) deficiency. He presented with failure to thrive, hepatomegaly and multiple cystic images in kidneys; no biochemical evidence of cholestasis. Large amounts of bile acid metabolites was detected in urine by fast atom bombardment ionization mass spectrometry (FAB-MS). HSDH3B7 gene analysis identified one mutation in intron 4, at nucleotide 432, G>A substitution that has never been reported before.The replacement therapy with oral cholic acid started early after the diagnosis and is still ongoing. Three years later hepatomegaly is no longer evident, liver function is normal and the child is growing regularly. In our experience, clinical features of 3β-HSD deficiency can be very poor and even cholestasis can lack at diagnosis. Early replacement therapy with cholic acid is safe and leads to clinical and biochemical control of the disease.

Characterization of DHDP, a novel aldose reductase inhibitor isolated from Lysimachia christinae

The aldose reductase (AR) inhibitory effect of Lysimachia christinae was investigated as a functional food ingredient and a new AR inhibitor, DHDP, was isolated from L. christinae, guided by an affinity-based ultrafiltration-HPLC assay. The chemical structure of DHDP was determined to be 1,5-di-hydroxy-1,5-di-[(E)-3-(4-hydroxyphenyl)-2-propenoic]-3-pentanonyl ester by one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), fast atom bombardment ionization mass spectrometry (FAB-MS), and ultraviolet (UV) and (IR) infrared spectroscopy. In addition, the AR inhibitory activity and mechanism of DHDP were characterized. In vitro and in silico results demonstrated that DHDP binds to the AR active site rapidly, blocking it and competitively preventing substrate access and product formation (IC50, 194.67μM; Ki, 29.68μM). Ex vivo experiments indicated that DHDP can penetrate the eye lens and successfully inhibit AR under hyperglycemic conditions, thus preventing the accumulation of sorbitol and subsequent osmotic stress.

Abietane, Labdane, and Pimarane Diterpenoids from the Pulp of Torreya nucifera

Torreya nucifera is an evergreen coniferous tree, widely distributed in Japan, Korea, and People's Republic of China. Its seeds exhibit significant insecticidal activity. The fruits of this evergreen are widely used in folk medicine for the treatment of tapeworm infestation in Korea and to induce abortion in Japan, but most chemical studies of T. nucifera have focused on its leaves and wood. A number of sesquiterpenoids, labdane and abietane diterpenoids, ligans, and flavonoids were identified as active secondary metabolites [1–8]. T. nucifera is a Taxaceae plant endemic to Korea, Japan, and China. In order to compare its constituents with those of Taxus spp. and to understand their taxonomic relationship, we investigated the chemical composition of Torreya nucifera. Five diterpenoids were isolated for the first time from the pulp of the title plant, including one labdane diterpenoid, two abietane diterpenoids, and two pimarane-type diterpenoids. Their structures were established on the basis of 1D and 2D NMR spectrascopic analysis. We report herein the isolation and structure characterization of these diterpenoids and detailed the 1H and 13C NMR data of compounds 1–5. Melting points were measured with an MRK micro-melting point apparatus and were uncorrected. Column chromatographic separations were carried out using silica gel (300–400 mesh, Qingdao Haiyang Chemical Group Corporation, Qingdao, P. R. China). Na2SO4 was the drying agent used in all workup procedures. Solvents and reagents of analytic grade (reagent grade used without further purification) were purchased from commercial sources. TLC was performed on precoated silica gel F254 glass-backed plates without activation. Fractions were monitored by TLC with visualization under UV light (254 and 365 nm) and by dipping the plates into a solution of 10% (v/v) H2SO4 in EtOH followed by heating on a hot plate for 5 min. Analytical HPLC was performed on a Waters 2695 separation module coupled to a 2996 photodiode array detector. Preparative HPLC was carried out on a Waters Delta Prep 3000 instrument coupled to a UV 2487 dual absorbance detector. Analytical HPLC was performed using two Whatman partisil 10 ODS-2 analytical columns (4.6 250 mm) in series. Preparative HPLC was performed using a partisil 10 ODS-2 MAG-20 preparative column (9.4 250 mm). The products were eluted with a 50 min linear gradient of acetonitrile (25 to 100%) in water at a flow rate of 3 mL/min (preparative HPLC). Positive ion fast atom bombardment mass spectra (FAB-MS) was obtained with a Vacuum Generators ZAB-HS instrument. All NMR spectra were recorded on a Varian Unity INOVA 600 or 500 NMR spectrometer equipped with a 5 mm probe at ambient temperature in CDCl3 solution. The 1H and 13C chemical shifts were referenced relative to TMS residue. Typical one-dimensional (1D) 1H and 13C spectra were acquired under standard condition on a Varian Unity INOVA 500/600 spectrometer operating at 499.861/599.913 and 125.690/150.848 MHz, respectively. 1H and 13C chemical shifts are expressed in the scale as parts per million (ppm).

Thioglycerol matrix interactions in the positive ion fast atom bombardment mass spectrometry of several Hantzsch and Biginelli ester derivatives of boronic acids

Fast atom bombardment (FAB) ionization is a valuable tool for analyzing non-volatile or thermally labile compounds when harder ionization methods (EI or CI) have been unsuccessful. Unexpected interactions between matrix and analyte may, however, occur in FAB ionization leading to the formation of artifacts whose structures have to be determined. We used esters synthesized by our research group following green chemistry protocols. Artifacts relating to the target molecules were produced in the solvent cage using positive ion FAB using thioglycerol as the matrix and analyzed by accurate mass measurement. Through interactions between thioglycerol and the boron atom, various adducts associated with boron-containing Hantzsch and Biginelli ester derivatives appeared in the FAB mass spectra. These interactions must arise in a solvent cage involving a Lewis acid-base bond. Accurate mass determinations of these adducts confirmed the presence of the target molecules. Interactions between the thioglycerol matrix and the eleven boron-containing Hantzsch and Biginelli ester derivatives in addition to the three reagents were seen in their FAB(+) spectra. These interactions, together with their accurate mass determinations, allowed us to determine the structures of the new molecules.

ChemInform Abstract: Mass Spectrometry of Prenylated Flavonoids

The fragmentation patterns originating from the degradation of prenyl group(s) in positive ion electron ionization (EI), fast-atom bombardment (FAB) and chemical ionization (CI) mass spectrometry (MS) of prenylated flavonoids were reviewed. The EI spectra showed the characteristic fragmentation patterns reflecting the location of prenyl group in the flavonoid compounds, whereas the FAB and CI spectra showed relatively monotonous patterns. It was described how the EI and FAB fragmentation patterns are useful for the identification of prenylated flavonoids

ChemInform Abstract: Molecule Liftoff from Surfaces

Molecular dynamics simulations have been used to model the kiloelectronvolt particle bombardment of organic layers on metal substrates such as occurs in the analytical techniques of secondary ion mass spectrometry and fast atom bombardment mass spectrometry. Vignettes of insights gained from the simulations along with comparisons to experimental data are presented in this Account. Topics include intact molecular ejection vs fragmentation, prediction of reaction pathways, influence of the substrate, and quantitative predictions of energy and angular distributions.

Hydrolyzed reactive dyes. Part 1: Analyses via fast atom bombardment and electrospray mass spectrometry

This paper provides a summary of results from the use of negative ion fast atom bombardment (FAB) and negative ion electrospray (ES) mass spectrometry to characterize dye structures remaining following the dyeing of cotton with reactive dyes. It was found that the ES method gave peaks of higher relative abundance in the molecular weight region and better signal to noise ratios than the FAB ionization process.

Structural determination of monoacylglycerols extracted from marine sponge by fast atom bombardment tandem mass spectrometry

Five new monoacylglycerols (MAGs) were isolated from the marine sponge Stelletta sp. by reversed-phase high-performance liquid chromatography and analyzed by positive ion fast atom bombardment mass spectrometry (FAB-MS). FAB mass spectra of these compounds produced abundant sodium-adducted molecules [M+Na]+ from a mixture of 3-nitrobenzyl alcohol and sodium iodide. The structural elucidation of these sponge MAGs was carried out by FAB tandem mass spectrometry (MS/MS). To find diagnostic ions for the characterization of the MAGs, authentic MAGs were initially analyzed by collision-induced dissociation (CID) MS/MS. The CID MS/MS of [M+Na]+ precursor ions resulted in the formation of numerous characteristic product ions via a series of dissociative processes. The product ions formed by charge-remote fragmentation (CRF) provided important information for the characterization of acyl chains substituted at the glycerol backbone, and product ions at m/z 84, 97, 113 and 139 were diagnostic for the sodiated glycerol backbone. On the basis of these fragmentation patterns, the structures of five MAGs extracted from marine sponge were elucidated. In addition, high-resolution mass measurement was performed to obtain the elemental compositions of the MAGs.

Immunoregulation of Cellular Life Span

Our current studies focus on the molecular changes induced by aging. During aging, changes in proteins occur that alter their function and render them immunogenic. These "neoantigens" are recognized by physiologic autoantibodies. Physiologic autoantibodies and their corresponding antigens offer therapeutic strategies for disease intervention through the innate immune response. Early studies done in the 1970s showed humans and animals to have physiologic antibodies that bind to a neoantigen called senescent cell antigen (SCA), which appears on senescent and damaged cells and initiates their removal by macrophages. These studies led to the discovery that oxidation can generate a new antigen in situ. Oxidation accelerated aging of red cells, generated SCA and IgG binding, and triggered removal of red cells by macrophages. Since then, a number of laboratories have found that oxidation can generate other neoantigens. For example, oxidized LDL (OxLDL) induces antibodies that can modify the natural progression of atherosclerosis. Apoptotic cells express oxidatively modified moieties on their surfaces that are involved in macrophage recognition and phagocytosis. Physiologic autoantibodies were used to isolate SCA from brain tissue. HPLC and fast atom bombardment ionization mass spectrometry (FAB-MS) of the isolated antigen suggested that the aging antigen is a subset of band 3, a family of proteins also called anion exchange proteins (AE1-3). FAB-MS results indicate that residues matching all three band 3 isoforms (AE1, AE2, and AE3) are detected in aging antigen fractions. Among the fragments identified with FAB-MS was a sequence corresponding to an aging epitope, human band 3 sequence LFKPPKYHPDVPYVKR, residue 812-830 in AE1; HHPDVTYVK, residue 1144-1152 in AE2; or HHPEQPYVTK, residue 1135-1144 in AE3. A residue that is close to that region was identified in mouse AE1 ASGPGAAAQIQEVK, residue 762-775. The potential for altering the natural progression of diseases using select peptide-defined epitopes within or overlapping the aging antigenic site (547-553 and 824-829) is discussed using the innate immune response to band 3 in malaria as an example.

Mapping of senescent cell antigen on brain anion exchanger protein (AE) isoforms using HPLC and fast atom bombardment ionization mass spectrometry (FAB-MS).

Molecular recognition of senescent cells involves oxidation of a crucial membrane protein leading to generation of a neoantigen, called 'senescent cell antigen' (SCA), and binding of physiologic autoantibodies. These IgG autoantibodies trigger macrophage removal of the cell prior to its lysis at a time when anion transport has decreased but the membrane is still grossly intact. The neoantigen SCA is generated by oxidation of a major anion transport protein called band 3 or anion exchange protein. In this study, we use IgG physiologic autoantibodies from senescent red cells to isolate SCA from brain, and HPLC and fast atom bombardment ionization mass spectrometry (FAB-MS) to compare brain SCA to band 3. HPLC peptide maps of band 3 and SCA showed substantial homology, suggesting that SCA is a subset of band 3, and includes an estimated >/=45% of the band 3 molecule. FAB-MS results indicate that residues matching all three band 3 isoforms (AE1, AE2 and AE3) are detected in SCA fractions. These findings suggest that other isoforms of band 3 may undergo the same aging changes that AE1 on red blood cells undergoes to generate SCA. This provides confirmation that SCA is on non-erythroid cell types. Implications of these studies to the generation of neoantigens by oxidation and their recognition by autoantibodies to them are discussed.

Isolation and identification of indigestible pyroglutamyl peptides in an enzymatic hydrolysate of wheat gluten prepared on an industrial scale.

An enzymatic hydrolysate of wheat gluten was further digested in vitro with porcine pepsin and pancreatin to obtain an indigestible peptide. Indigestible pyroglutamyl peptide was isolated from the digest by strong cation-exchange, size-exclusion, and reversed-phase chromatographies. The pyroglutamyl peptide was digested with pyroglutamate aminopeptidase, and the digest was reacted with phenyl isothiocyanate. The resultant phenylthiocarbamyl (PTC) peptides were purified by reversed-phase HPLC by using binary gradient elution with ammonium acetate buffer, pH 6.0, and acetonitrile. The PTC peptides were analyzed with an automatic peptide sequencer on the basis of the Edman degradation method with a modified program. Some pyroglutamyl peptides were also analyzed by fast-atom bombardment ionization mass spectrometry without the pyroglutamate amino peptidase digestion. Consequently, pyroGlu-Asn-Pro-Gln, pyroGlu-Gln-Gln-Pro-Gln, pyroGlu-Gln-Pro-Gln, pyroGlu-Gln-Pro-Gly-Gln-Gly-Gln, pyroGlu-Gln, pyroGlu-Gln-Pro, pyroGlu-Ile-Pro-Gln, pyroGlu-Ile-Pro, pyroGlu-Gln-Pro-Leu, pyroGlu-Gln-Phe-Pro-Gln, pyroGlu-Ser-Phe-Pro-Gln, pyroGlu-Phe-Pro-Gln, and pyroGlu-Gln-Pro-Pro-Phe-Ser were identified.

Lewis acidity dependency of the electrochemical window of zinc chloride–1-ethyl-3-methylimidazolium chloride ionic liquids

Negative ion fast atom bombardment mass spectra (FAB-MS) recorded for ZnCl 2–1-ethyl-3-methylimidazolium chloride (ZnCl 2–EMIC) ionic liquids with various compositions indicate that various Lewis acidic chlorozincate clusters (ZnCl 3 −, Zn 2Cl 5 − and Zn 3Cl 7 −) are present in ZnCl 2–EMIC ionic liquids depending on the percentage of ZnCl 2 used in preparing the ionic liquids; higher ZnCl 2 percentage favors the larger clusters. Cyclic voltammetry reveals that the potential limits for a basic 1:3 ZnCl 2–EMIC melt correspond to the cathodic reduction of EMI + and anodic oxidation of Cl −, giving an electrochemical window of approximately 3.0 V which is the same as that observed for basic AlCl 3–EMIC ionic liquids. For acidic ionic liquids that have a ZnCl 2/EMIC molar ratio higher than 0.5:1, the negative potential limit is due to the deposition of metallic zinc, and the positive potential limit is due to the oxidation of the chlorozincate complexes. All the acidic ionic liquids exhibit an electrochemical window of approximately 2 V, although the potential limits shifted in the positive direction with increasing ZnCl 2 mole ratio. Underpotential deposition of zinc was observed on Pt and Ni electrodes in the acidic ionic liquids. At proper temperatures and potentials, crystalline zinc electrodeposits were obtained from the acidic ionic liquids.

Quantification of galactosylsphingosine in the twitcher mouse using electrospray ionization-tandem mass spectrometry

Globoid cell leukodystrophy (Krabbe disease) is an autosomal recessive inherited neurodegenerative disorder caused by the deficiency of the lysosomal enzyme beta-galactosylceramidase. The pathogenesis of the disorder has been proposed to arise from the accumulation of the cytotoxic metabolite galactosylsphingosine (psychosine). The twitcher mouse is a naturally occurring murine model of globoid cell leukodystrophy. We have developed a rapid, sensitive, and specific mass spectrometric method for determining the galactosylsphingosine concentration in the tissues of twitcher mice. Galactosylsphingosine is extracted from the tissues in methanol, isolated using strong cation-exchange and C18 solid-phase extraction chromatography, and then directly analyzed using electrospray ionization-tandem mass spectrometry. A lactosylsphingosine internal standard has been employed for quantification. The assay demonstrated significant accumulation of galactosylsphingosine in the brain, spinal cord, and kidney of twitcher mice. It is anticipated that this method may be of use in the monitoring of experimental therapies for globoid cell leukodystrophy.

Characterization of the Radical Product Formed from the Reaction of Nitric Oxide with the Spin Trap 3,5-Dibromo-4-Nitrosobenzene Sulfonate

Previously, 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) has been used in combination with electron paramagnetic resonance (EPR) spectrometry to trap nitric oxide (NO•). The reaction between DBNBS and NO• yields a radical product which gives rise to an EPR signal consisting of three lines with an AN = 0.96 mT, but the structure of this product is unknown. A two-stage high-performance liquid chromatography fractionation was performed to isolate the radical product from the other components in the DBNBS/NO• reaction mixture. The fractions containing the radical product were identified by the presence of the three-line EPR signal, and then these fractions were analyzed by negative ion fast atom bombardment–mass spectrometry (FAB–MS). Collectively, the FAB–MS data suggested that the radical product is the monosodium electrostatic complex with the dianion, bis(2,6-dibromo-4-sulfophenyl) nitroxyl. Analysis of the Gaussian and Lorentzian linewidths of the EPR signal suggested that bis(2,6-dibromo-4-sulfophenyl) nitroxyl molecules may group together to form micelles. Further studies also indicated that significant amounts of nitrogen and nitrate were produced during the reaction between DBNBS and NO•. A reaction scheme consistent with these results is presented.

Inactivation of the Peroxisomal Multifunctional Protein-2 in Mice Impedes the Degradation of Not Only 2-Methyl-branched Fatty Acids and Bile Acid Intermediates but Also of Very Long Chain Fatty Acids

According to current views, peroxisomal beta-oxidation is organized as two parallel pathways: the classical pathway that is responsible for the degradation of straight chain fatty acids and a more recently identified pathway that degrades branched chain fatty acids and bile acid intermediates. Multifunctional protein-2 (MFP-2), also called d-bifunctional protein, catalyzes the second (hydration) and third (dehydrogenation) reactions of the latter pathway. In order to further clarify the physiological role of this enzyme in the degradation of fatty carboxylates, MFP-2 knockout mice were generated. MFP-2 deficiency caused a severe growth retardation during the first weeks of life, resulting in the premature death of one-third of the MFP-2(-/-) mice. Furthermore, MFP-2-deficient mice accumulated VLCFA in brain and liver phospholipids, immature C(27) bile acids in bile, and, after supplementation with phytol, pristanic and phytanic acid in liver triacylglycerols. These changes correlated with a severe impairment of peroxisomal beta-oxidation of very long straight chain fatty acids (C(24)), 2-methyl-branched chain fatty acids, and the bile acid intermediate trihydroxycoprostanic acid in fibroblast cultures or liver homogenates derived from the MFP-2 knockout mice. In contrast, peroxisomal beta-oxidation of long straight chain fatty acids (C(16)) was enhanced in liver tissue from MFP-2(-/-) mice, due to the up-regulation of the enzymes of the classical peroxisomal beta-oxidation pathway. The present data indicate that MFP-2 is not only essential for the degradation of 2-methyl-branched fatty acids and the bile acid intermediates di- and trihydroxycoprostanic acid but also for the breakdown of very long chain fatty acids.

Negative fast atom bombardment ionization of aromatic sulfonic acids: unusual sample-matrix interaction.

The most intense ion(s) in negative ion fast atom bombardment (FAB) mass spectra of 2- and 4-benzaldehyde sulfonic acid (BSA) in glycerol or 3-nitrobenzyl alcohol matrix corresponds to a covalent association of the analyte with one or two matrix molecules accompanied by the elimination of a molecule of water. The molecular ion [M - H](-), however, is of low abundance. The identity of the resulting ions [M + nA - H(2)O - H](-) (where M is the analyte and A is the matrix) was confirmed by exact mass measurement using the peak matching technique. These covalent matrix-analyte complexes were not observed when the sulfonic acid functionality in BSA was substituted with COOH, NO(2), and OH or when the sulfonic acid was in salt form. These observations indicate that the free sulfonic acid group in BSA is responsible for the covalent adduct formation. To our knowledge, analyte-matrix covalent association in negative ion FAB spectra of BSA has not been reported previously.

Molecule liftoff from surfaces.

Molecular dynamics simulations have been used to model the kiloelectronvolt particle bombardment of organic layers on metal substrates such as occurs in the analytical techniques of secondary ion mass spectrometry and fast atom bombardment mass spectrometry. Vignettes of insights gained from the simulations along with comparisons to experimental data are presented in this Account. Topics include intact molecular ejection vs fragmentation, prediction of reaction pathways, influence of the substrate, and quantitative predictions of energy and angular distributions.

Chiral recognition of cellulose tris(5-fluoro-2-methylpheylcarbamate) toward (R)- and (S)-1,1′-bi-2-naphthol detected by negative ion fast-atom bombardment mass spectrometry

Chiral recognition between cellulose tris(5-fluoro-2-methylphenylcarbamate) (MW > 120,000) as a host compound and (R,S)-1,1'-binaphthol (MW 286) as a guest compound was investigated by fast-atom bombardment mass spectrometry (FAB-MS). The use of negative ion FAB-MS made it possible to obtain a very simple mass spectrum of the guest compound with a high signal-to-noise ratio. Additionally, when nitrophenyl octyl ether, which has no OH group, was utilized as matrix, chiral recognition between the host and the guest compounds was unequivocally detected. Copyright 1999 John Wiley & Sons, Ltd.

Analysis of saponins from black bean by electrospray ionization and fast atom bombardment tandem mass spectrometry.

Saponins from black bean (Vigna mungo L. Hepper) were analyzed using positive and negative ion fast atom bombardment mass spectrometry (FAB-MS) and liquid chromatography/mass spectrometry. Methanol was used to extract the saponins from defatted black bean, which was partially purified by extraction with n-butanol, and the extract was dialyzed with 3000 M(r) cut-off tubing. The dialyzate was analyzed using mass spectrometry. According to FAB-MS/MS, mixtures from black bean contain soyasaponin I as the predominant saponin. In addition, MS/MS analysis was performed in which the structures of saponins of black bean cotyledon were determined to be soyasaponin I, soyasaponin II, soyasaponin V, 3-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-galactopyranosyl-(1 --> 2)-beta-D-glucuronopyranosyl]complogenin (saponin A) and 3-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl-(1 --> 2)-beta-D-glucopyranosyl]oleanolic acid (saponin B). For the black bean shell and the root of black bean sprout, analysis confirmed the saponins of soyasaponin I, soyasaponin II, soyasaponin V, saponin A, saponin B, acetylsoyasaponin A(4) and soyasaponin beta(g). Moreover, all the studied saponins were found in the stem and leaves of the black bean sprouts, except soyasaponin beta(g) and acetylsoyasaponin A(4), respectively.

Formation of pyrochlorophylls and their derivatives in spinach leaves during heating

The changes of chlorophylls and their derivatives during heating of spinach leaves were studied. Chlorophylls and their derivatives were analyzed by high performance liquid chromatography (HPLC) with photodiode-array detection or positive ion fast atom bombardment mass spectrometry (FAB–MS). No chlorophyll derivatives were detected in fresh spinach leaves. The degradations of both chlorophylls, a and b, fit the first-order model, and the rate constant (min −1) by microwave cooking or blanching was greater than that by steaming or baking. The major chlorophyll derivatives formed during baking and blanching included chlorophyll epimers and pheophytins. Pyrochlorophylls a and b were detected in spinach leaves after steaming for 30 min or microwave cooking for 1 min. Pyropheophytins a and b were not formed until steaming or microwave cooking time reached 30 or 5 min, respectively. Steaming favored the formation of pheophytins a and b while microwave cooking favored that of pyrochlorophylls a and b.