Fast Atom Bombardment Mass Spectrometry Research Articles

Mass Spectrometric Determination of Polyfunctionalized Nucleoside Phosphoramidites Using LSI/FAB

Nucleoside phosphoramidites (PAs) are the most widely used building blocks in the contemporary solid-phase synthesis of oligonucleotides. Accurate molecular weight measurements of such acid-labile compounds may be easily determined in a matrix system comprising triethanolamine (TEOA)-NaCl by liquid secondary ionization mass spectrometry (LSIMS) or fast atom bombardment mass spectrometry (FABMS), using a double-focusing mass spectrometer. The present method rapidly and easily measures the accurate MWs of various PAs as adduct ions [M+Na]⁺, affording molecular formulas in place of elemental analysis. Further, the intensities by LSIMS of [M+Na]⁺ were found to be enhanced to the highest degree by adjustment of the mole ratio of PA and NaCl, fixing the amount of TEOA. In addition, the effects of the metal ion in the matrix were investigated. The present method is a powerful tool for the mass spectral identification of polyfunctionalized nucleoside PAs.

Photoluminescent columnar zinc(II) bimetallomesogen of tridentate [ONO]-donor Schiff base ligand

A new zinc(II) bimetallomesogenic complex, [Zn2L2], of tridentate [ONO]-donor Schiff base ligand (L = N-(2-hydroxyethyl)-4-hexadecyloxysalicylaldimines) was synthesised and their mesomorphic and photoluminescence properties were investigated. The compounds were characterised by Fourier transform infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy (UV-Vis) spectroscopy, elemental analyses and fast atom bombardment (FAB) mass spectrometry. The mesomorphic behaviour of the complex was investigated by polarised optical microscopy, differential scanning calorimetry and X-ray diffraction (XRD) study. A rectangular or oblique columnar mesophase is conjectured on the basis of powder X-ray diffraction (PXRD) study. The complex is found to be blue light emitter in solution, in solid and in condensed states with broad emission maxima at ∼427–464 nm. The density functional theory (DFT) calculations revealed a distorted square planar structure around each zinc(II) centre in the dinuclear framework. Time-dependent DFT spectral correlative study was undertaken to account for the electronic transition.

Constituents of Caryopteris incana and their antibacterial activity

Two new compounds named caryocanolide (1), and caryocanoside A (2), together with nine known compounds (3-11) were isolated from the whole plant of Caryopteris incana. These structures were determined mainly on the basis of 2D nuclear magnetic resonance and high resolution fast atom bombardment mass spectroscopy data. Furthermore, the isolated compounds (1, 2, 4-11) were tested for their antibacterial activity. Compound 1 exhibited moderate antimicrobial activity against Bacillus subtilis with a minimum inhibitory concentration value of 35.7 μM.

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.

Sequences of Metanicins, 20‐Residue Peptaibols from the Ascomycetous Fungus CBS 597.80

Four linear 20-residue peptaibols, named metanicins (MTCs) A-D, were isolated from submerged cultures of the ascomycetous fungus CBS 597.80. Structure elucidation was performed by a combination of fast-atom-bombardment mass spectrometry (FAB-MS), electrospray ionization MS, Edman degradation of isolated fragments, and amino acid analysis by ion-exchange and gas chromatography, and enantioselective HPLC. The sequences of MTC A(B) are (amino acid exchange in B and C in parentheses): Ac-Aib-Ala-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib(D-Iva)-Gln-Gln-Pheol and of MTC C(D) Ac-Aib-Ala-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib(D-Iva)-Gln-Gln-Pheol (Ac, acetyl; Aib, α-aminoisobutyric acid; Iva, isovaline; Pheol, L-phenylalaninol). The peptides are related, and some of the sequences are identical, to other 20-residue peptaibols isolated from Trichoderma species. MTCs show moderate activities against Micrococcus luteus, Enterococcus faecalis, and Staphylococcus aureus, and very low activities against Bacillus subtilis. The producer has originally been identified and deposited as Metarhizium anisopliae var. anisopliae CBS 597.80. Although this identification has been withdrawn by Centralbureau voor Schimmelcultures (CBS) in the meantime, the accession number will be retained - independently from any taxonomic revisions.

Ionised silica in the estuary of a river as supply to seawater: Identification and ionization efficiency of silica species by FAB-MS

Measurement of the dissolution state of silicic acid is difficult. In river water, silica exists in particle form, but silica particles with a diameter of less than approximately 0.45 μm are considered as dissolved silica. In seawater, silica exists in two forms: ionic silica and particle silica. In this study, we focused on ionic silica. Using fast atom bombardment mass spectrometry (FAB-MS), the silica species in river water and seawater were detected as ionic forms. Ionic silica forms various chemical species in aquatic solutions, including the monomer ([Si(OH)3O−]) and dimer ([Si2(OH)5O2−]). The relative abundances of these species in aquatic solutions depend on the chemical and physical conditions. Silica species such as [Si(OH)2O2Na]− ([monomer-Na+]−), [Si2(OH)5O2]− ([dimer]−), [Si2(OH)4O3Na]−([dimer-Na+]−), [Si4(OH)7O5]− ([cyclic tetramer]−), [Si4(OH)6O6Na]− ([cyclic tetramer-Na+]−), [Si4(OH)9O4]− ([linear tetramer]−) and [Si4(OH)8O5Na]− ([linear tetramer-Na+]−) were directly observed by FAB-MS in river water and seawater. Some of these ionic silica species are expected to serve as “nutrients” for diatoms in seawater. Large silica particles are transported in river water, whereas in estuaries, a large amount of silica is precipitated and a small amount of silica is dissolved as ionic forms in sodium chloride solution. In river water, the concentration of silica was high, but the ionic silica species were hardly ionised by FAB-MS. In seawater, the concentration of silica was low, but the ionic silica species were well ionised. Thus, the ionization efficiency of silica species by FAB-MS indicates the type of silica species. The filtration process of silicic acid and the ionization of silicic acid to dissolve the silica species in seawater, which is an electrolyte (sodium chloride), occur in the estuary of a river. Thus, the estuary of a river plays an important role in the restructuring of silica from particle form to ionic form.

Determination of critical micelle concentration of dendritic surfactant synthesized via a selective ring-opening addition reaction

An azetidine-2,4-dione was applied to synthesize dendrons with four carbons in the end ([G-0.5]-C4 and [G-1]-C4) via a selective ring-opening addition reaction, which was subsequently extended to obtain a dendritic surfactant ([G-1]-C4 surfactant) by acidification. The dendrons were characterized by Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (1H NMR), elemental analyzer (EA), and fast atom bombardment mass spectrometry (FAB MS). The dendritic surfactant, with a cationic head and branched hydrophobic C4 tails, was dissolved in 2wt.% dimethyl sulfoxide (DMSO) aqueous solution for the determination of critical micelle concentration (CMC) by fluorescence and electrical conductivity measurements. The resulted CMC values were very close within measurements, ca. 0.013–0.05mM. Transmission electron microscopy (TEM) and zeta potential measurement also provided an evidence of micelle formation and shape. Moreover, anionic dyes were adsorbed onto the micelles successfully to confirm the positive charge of [G-1]-C4 surfactant.

Production and characterization of rhamnolipid biosurfactant from waste frying coconut oil using a novel Pseudomonas aeruginosa D

To improve biosurfactant production economics by the utilization of potential low-cost materials. In an attempt to utilize cost-effective carbon sources in the fermentative production of biosurfactants, various pure and waste frying oils were screened by a standard biosurfactant producing strain. Considering the regional significance, easy availability and the economical advantages, waste frying coconut oil was selected as the substrate for further studies. On isolation of more competent strains that could use waste frying coconut oil efficiently as a carbon source, six bacterial strains were isolated on cetyltrimethyl ammonium bromide-methylene blue agar plate, from a soil sample collected from the premises of a coconut oil mill. Among these, Pseudomonas aeruginosa D was selected as the potential producer of rhamnolipid. Spectrophotometric method, TLC, methylene blue active substance assay, drop collapse technique, surface tension measurement by Du Nouy ring method and emulsifying test confirmed the rhamnolipid producing ability of the selected strain and various process parameters were optimized for the production of maximum amount of biosurfactant. Rhamnolipid components purified and separated by ethyl acetate extraction, preparative silica gel column chromatography, HPLC and TLC were characterized by fast atom bombardment mass spectrometry as a mixture of dirhamnolipids and monorhamnolipids. The rhamnolipid homologues detected were Rha-Rha-C(10) -C(10) , Rha-C(12) -C(10) and Rha-C(10) -C(8) /Rha-C(8) -C(10) . These results indicated the possibility of waste frying coconut oil to be used as a very effective alternate substrate for the economic production of rhamnolipid by a newly isolated Ps.aeruginosa D. Results of this study throws light on the alternate use of already used cooking oil as high-energy source for producing a high value product like rhamnolipid. This would provide options for the food industry other than the recycling and reuse of waste frying oils in cooking and also furthering the value of oil nuts.

Микробиологический синтез [2H]инозина высокого уровня дейтерированности грамположительной хемогетеротрофной бактериейBacillus subtilis

A 2H-labeled purine ribonucleoside inosine was microbiologically synthesized (yield, 3.9 g/L of culture liquid) using a deuterium-adapted strain ofthe gram-positive chemoheterotrophic bacterium Bacillus subtilis, cultivated in a heavy water medium with a high degree of deuteration (99.8 at % 2H) containing 2% hydrolysate of deuterated biomass of the methylotrophic bacterium Brevibacterium methylicum as a source of 2H-labeled growth substrate produced in an M9 minimal medium with 98% 2H20 and 2% [2H]-methanol. The inosine extracted from the culture liquid of the producer strain was fractionated by adsorption (desorption) on an activated carbon surface, extraction with 0.3 M ammonium-formate buffer (pH 8.9), subsequent crystallization in 80% ethanol, and ion exchange chromatography on a column with AG50WX 4 cation exchange resin equilibrated with 0.3 M ammonium-formate buffer containing 0.045 M NH4Cl. Fast atom bombardment (FAB) mass spectrometry demonstrated incorporation of five deuterium atoms in the inosine molecule (62.5% 2H), three of which were contained in the ribose moiety and two in the hypoxanthine moiety.

Oxidative damage to DNA constituents by iron-mediated Fenton reactions – the thymidine family

The degradative products formed from the exposure of derivatives of thymidine to iron-mediated Fenton reactions were identified by chromatographic resolution and analysis by UV absorption spectroscopy, radio-labeling, and positive and negative mode fast atom bombardment mass spectrometry. Fe2+/H2O2 and Fe3+/H2O2 were utilized to generate oxy-radicals and the effects of ethanol and N2-flushing were studied. Substrates included thymidine, 3′- and 5′-dTMP, TpT, oligo(dT), and oligo(dT)·poly(dA) and the results are compared to those reported for ionizing radiation. It is evident from the comparisons of the products that the damaging radical species and the product distribution are perturbed by interaction of the iron atom with the various phosphomono- and diester species that are present.

Deodorizing Effects of Phlorotannins from Edible Brown Alga Eisenia bicyclis on Methyl Mercaptan

In search for new deodorizing compounds, we were identified three phlorotannins; eckol (1), dioxinodehydroeckol (2) and dieckol (3) from edible brown seaweed Eisenia bicyclis and characterized by Fast-atom bombardment mass spectrometry (FAB-MS) and nuclear magnetic resonance (NMR). The deodorizing activity of those compounds was evaluated against methyl mercaptan, which is well known as a major causative material of halitosis and off-flavor. Among them, compound 3 exhibited the highest deodorizing activity against methyl mercaptan at the IC50 values of 26.71 ± 4.16 µg mL-1, followed by compound 2 (40.57 ± 0.63 µg mL-1) and compound 1 (43.62 ± 1.52 µg mL-1). Thus, these results suggest that the phlorotannins derived from E. bicyclis can be an effective deodorizing constituent in the food industry and pharmaceutical industries.

Selectivity of silica species in ocean observed from seasonal and local changes

Silicic acids, derived from SiO2 (silica), have several chemical forms in solution. Silica is a nutrient for diatoms, which are phytoplankton in oceans. Silica species can be used as a tracer to examine the behavior of silica in nature. The speciation for silica by FAB-MS (fast atom bombardment mass spectrometry) has been carried out for seawater samples from Tokyo Bay and Sagami Bay to investigate the seasonal and locational changes of the depth profiles of silica species. The species, [Si(OH)2O2Na+]−, [Si2(OH)5O2]− ([dimer]−), [Si2(OH)4O3Na+]−, [Si4(OH)7O5-] ([cyclic tetramer]−), [Si4(OH)6O6Na+]−, [Si4(OH)9O4]− ([linear tetramer]−) and [Si4(OH)8O5Na+]− were mainly identified by FAB-MS. The seasonal and locational changes and the reproducibility of depth profiles of silica species were determined from October 2001 to July 2002. The depth profile of the ratio of linear tetramer to cyclic tetramer reflects the activity of diatoms, implying that the linear tetramer is the preferred “food” for diatoms. In particular, the depth profile for the ratio of linear tetramer to cyclic tetramer exhibits a critical changes that depend on the season. Furthermore, the depth profiles for the samples from Sagami Bay (open ocean) indicate that seawater is easily exchanged by ocean currents (the Japan Current). Thus, silica speciation by FAB-MS can give us a new tracer indicating the characteristics of the seawater budget, which change with depth, season and ocean locality.

Bioconversion of Sodium Dodecyl Sulphate to Rhamnolipid by Pseudomonas aeruginosa: A Novel and Cost-Effective Production Strategy

The utility of rhamnolipids in industry is currently limited due to the high constraints in its economic production. In this scenario, the novel utility of sodium dodecyl sulphate (SDS) as carbon source could serve as promising cost-effective strategy. Screening of effective SDS biodegraders led to the isolation of Pseudomonas aeruginosa S15 capable of concomitant SDS degradation and biosurfactant synthesis. SDS-based rhamnolipid production was proved on SDS minimal agar plates using cetyl trimethylammonium bromide-methylene blue method and optimised in SDS-based minimal salt (SBS) medium. SDS proved to be an ideal carbon source for rhamnolipid synthesis with a high substrate to product conversion rate yielding 6.9 g/l of rhamnolipids from 1 g/l SDS in 5 days. Fast atom bombardment mass spectroscopy analysis of the purified biosurfactant proved the presence of mono- and di-rhamnolipids, viz., Rha-C(10)-C(10), Rha-C(10)-C(12) and Rha-Rha-C(10)-C(10) with surface active properties. The secreted rhamnolipids were not utilised by S15 as a carbon source, but it caused a dispersion of bacterial biofilms in SBS medium. To the best of our knowledge, this is the first report on bioconversion of synthetic detergent to biodetergent. This SDS-based novel methodology presents a more economised mode of rhamnolipid synthesis utilising SDS as sole carbon source.

Mass-spectrometric study of the formation of silver nanoclusters in polyether media: 2. Fast atom bombardment and modeling

Within the problem of the synthesis of silver nanoclusters and nanoparticles in polyether media, systems containing silver nitrate AgNO3 and low-molecular-weight polyethers, poly(ethylene glycol) PEG-400 or oxyethylated glycerol OEG-5, were studied by fast atom bombardment (FAB) mass spectrometry. The formation of stable clusters of polyether oligomers (M m ) with silver cations M m · Ag+ was shown, in agreement with the previous data of laser desorption/ionization. Quantum-chemical DFT calculations have shown that the M m · Ag+ clusters are stabilized by wrapping of the polyether chain around the silver cation with the cation coordinating ether oxygen atoms. Silver nanoclusters were not found in the FAB mass spectra of liquid systems, but Ag n + clusters were detected for silver nanoparticles separated from the reaction medium. No products of chemical transformations of PEG-400 or OEG-5 were observed by FAB. A plausible mechanism of the reduction of silver cations involving nitrate anions is discussed.

Synthesis and properties of new fluorenonocrownophanes having a stilbene fragment and their reaction with paraquat

New crownophanes containing 2,7-dioxyfluorenone and 4,4′-dioxystilbene fragments linked through di-, three, tetra-, and pentaethylene glycol linkers were synthesized. The formation of pseudorotaxanetype host-guest complexes in reactions of these crownophanes with 1,1′-dimethyl-4,4′-bipyridinium dication was detected by fast atom bombardment mass spectrometry, 1H NMR, and electron spectroscopy.

Flavonoid glycosides from the fruit of Rhus parviflora and inhibition of cyclin dependent kinases by hyperin

Chrysoeriol-7-O-β-d-glucopyranoside (1), luteolin-7-O-β-d-glucopyranoside (2), quercetin-3-O-β-d-glucopyranoside (3), quercetin-3-O-β-d-galactopyranoside (4), and quercetin-3-O-α-l-rhamnopyranoside (5) were isolated for the first time from the fruits of Rhus parviflora. The chemical structures of the compounds were determined using nuclear magnetic resonance, fast atom bombardment mass spectrometry, and infrared spectroscopy. Compound 4 (hyperin) inhibited cyclin dependent kinases (CDK2 and CDK5) in vitro with IC50 values of 21.02 and 10.28 μM, respectively.

Cytotoxic and neuroprotective biflavonoids from the fruit of Rhus parviflora

Six biflavonoids, succedaneaflavanone (1), mesuaferrone B (2), rhusflavanone (3), rhusflavone (4), agathisflavone (5), and cupressuflavone (6), were isolated from the fruits of Rhus parviflora. The chemical structures of the compounds were determined based on NMR, fast atom bombardment mass spectrometry, and IR. Biflavonoid compounds were evaluated for cytotoxicity against human cancer cell lines, including human colon carcinoma (HCT-116), human breast carcinoma (MCF-7), and human cervical carcinoma (HeLa). Biflavonoids 2, 3, and 5 showed significant cytotoxicity with IC50 values of 17.25 μM (mesuaferrone B against HCT-116), 17.50 μM (rhusflavone against MCF-7), and 15.20 μM (agathisflavone against HeLa). Compound 5 showed inhibition of β-secretase activity at a 10 μM concentration. Compound 6 showed inhibition of cyclin-dependent kinases (CDK2 and CDK5) with IC50 values of 18.58 and 9.29 μM, respectively.

Induced columnar mesomorphism in non-discoid VO2+ salphen complexes: Transition between two rectangular columnar phases

A new series of oxovanadium(IV) complexes of the type [VOL], L = N, N′-di-(4-n-alkoxysalicylidene)-4-Me-l,2-diamino-benzene (n = 14,16, 18) have been synthesised and their mesomorphic properties investigated. The compounds were characterised by Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, ultraviolet–visible spectroscopy, elemental analyses, solution electrical conductivity measurements and fast atom bombardment mass spectrometry. The phase behaviour of the compounds was examined by differential scanning calorimetry and polarised optical microscopy. The ligands are non-mesogenic, but upon coordination with vanadium(IV), exhibited enantiotropic rectangular columnar mesomorphism. The mesophase symmetry and the molecular organisation in the mesophases were confirmed by variable temperature powder X-ray diffraction study. An interesting phase behaviour exhibiting two types of rectangular columnar phases (Colr1 to Colr2) was observed for the vanadyl complexes, the former (Colr1) being stable down to room temperature. Solution electrical conductivity measurements showed non-electrolytic nature of the complexes. Cyclic voltammetry revealed a single electron quasi-reversible response (VO2+/VO3+) for the complexes. Density functional theory study carried out using the DMol3 program indicated a distorted square pyramidal geometry for the complexes.

Identification of Novel Fluorochemicals in Aqueous Film-Forming Foams Used by the US Military

Aqueous film-forming foams (AFFFs) are a vital tool to fight large hydrocarbon fires and can be used by public, commercial, and military firefighting organizations. In order to possess these superior firefighting capabilities, AFFFs contain fluorochemical surfactants, of which many of the chemical identities are listed as proprietary. Large-scale controlled (e.g., training activities) and uncontrolled releases of AFFF have resulted in contamination of groundwater. Information on the composition of AFFF formulations is needed to fully define the extent of groundwater contamination, and the first step is to fully define the fluorochemical composition of AFFFs used by the US military. Fast atom bombardment mass spectrometry (FAB-MS) and high resolution quadrupole-time-of-flight mass spectrometry (QTOF-MS) were combined to elucidate chemical formulas for the fluorochemicals in AFFF mixtures, and, along with patent-based information, structures were assigned. Sample collection and analysis was focused on AFFFs that have been designated as certified for US military use. Ten different fluorochemical classes were identified in the seven military-certified AFFF formulations and include anionic, cationic, and zwitterionic surfactants with perfluoroalkyl chain lengths ranging from 4 to 12. The environmental implications are discussed, and research needs are identified.

Oxidative damage to DNA constituents by iron-mediated Fenton reactions: the deoxyadenosine family

The effect of exposing 2′-deoxyadenosine (dA), 5′-dAMP, 3′-dAMP, dApA, dA(pdA)19, and poly(dA): oligo(dT) to iron/H2O2 in the presence and absence of ethanol or NADH has been studied. HPLC retention times, enzyme treatments, radio-labeled substrates, UV absorption spectra, and fast atom bombardment mass spectrometry (FABMS) have been used to distinguish 20 products arising from the reaction, of which 16 have been identified and four anomers proposed by comparison with earlier gamma radiation studies. The radical responsible for the reactions seems to be analogous to radiation-derived , has many products in common, but has some novel ones probably specific for Fenton-induced damage. Two new dimeric adducts arising from the generation of hydroxylamine at N7 and its subsequent condensation with two known sugar damage products, dR-adenine-N1-oxide, and two isomers of dR-FAPy arising from radical attacks at C4 and C5, may be considered novel in the present study. Unlike radiation-derived , the radical under study is difficult to eliminate due to its generation in the proximity of the substrate molecules. It is proposed that the iron binds to the phosphate group and generates the radical in its vicinity. Strand breaks in dA(pdA)11 resulting from the Fenton reaction are of two types, spontaneous and alkali-labile. Duplex DNA is less sensitive to attack by this radical, as its various degradation products are a subset of those obtained with monomer substrates and only dR-FAPy production is relatively enhanced for poly (dA): oligo (dT) as compared to those from other substrates.