High-resolution Fast-atom Bombardment Mass Spectrometry Research Articles

Stereocalpin B, a New Cyclic Depsipeptide from the Antarctic Lichen Ramalina terebrata.

Stereocalpin B, a new cyclic depsipeptide (1), and a new dibenzofuran derivative (3), were isolated from the Antarctic lichen, Ramalina terebrata (Ramalinaceae), along with a known cyclic depsipeptide (2). The structures of new compounds were characterized by comprehensive spectrometric analyses; high-resolution fast atom bombardment mass spectrometry (HR-FABMS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Stereocalpin B (1) existed in a rotameric equilibrium, which was confirmed using nuclear Overhauser effect spectroscopy (NOESY)/exchange spectroscopy (EXSY) spectrum. Absolute configurations of the amino acid units in 1 were assigned using the advanced Marfey’s method and subsequent NOESY analysis of the 5-hydroxy-2,4-dimethyl-3-oxo-decanoic acid residue confirmed the complete stereochemistry of 1. Compounds 1-3 exhibited moderate antimicrobial activities against E. coli, with the IC50 values ranging from 18–30 μg/mL. Compound 2 exhibited cell growth inhibition against HCT116 cell lines, with the IC50 value of 20 ± 1.20 μM, and compounds 1 and 2 also showed potent anti-inflammatory activities against lipopolysaccharide (LPS)-induced RAW264.7 macrophages with the IC50 values ranging from 5–7 μM.

Guaianolide Sesquiterpene Lactones from Centaurothamnus maximus.

Centaurothamnus maximus (family Asteraceae), is a leafy shrub indigenous to the southwestern Arabian Peninsula. With a paucity of phytochemical data on this species, we set out to chemically characterize the plant. From the aerial parts, two newly identified guaianolides were isolated: 3β-hydroxy-4α(acetoxy)-4β(hydroxymethyl)-8α-(4-hydroxy methacrylate)-1αH,5αH, 6αH-gual-10(14),11(13)-dien-6,12-olide (1) and 15-descarboxy picrolide A (2). Seven previously reported compounds were also isolated: 3β, 4α, 8α-trihydroxy-4-(hydroxymethyl)-lαH, 5αH, 6βH, 7αH-guai-10(14),11(13)-dien-6,12-olide (3), chlorohyssopifolin B (4), cynaropikrin (5), hydroxyjanerin (6), chlorojanerin (7), isorhamnetin (8), and quercetagetin-3,6-dimethyl ether-4’-O-β-d-pyranoglucoside (9). Chemical structures were elucidated using spectroscopic techniques, including High Resolution Fast Atom Bombardment Mass Spectrometry (HR-FAB-MS), 1D NMR; 1H, 13C NMR, Distortionless Enhancement by Polarization Transfer (DEPT), and 2D NMR (1H-1H COSY, HMQC, HMBC) analyses. In addition, a biosynthetic pathway for compounds 1–9 is proposed. The chemotaxonomic significance of the reported sesquiterpenoids and flavonoids considering reports from other Centaurea species is examined.

Lavencidin, a polyene macrolide antibiotic from Streptomyces lavendulae FRI-5.

In our screening program for new biologically active compounds, a new polyene macrolide, lavencidin (1), along with known compound RKGS-A2215A (2), was isolated from the fermentation broth of Streptomyces lavendulae FRI-5 by changing the composition of liquid medium normally used for the strain. Their structures were elucidated by spectral methods (high-resolution fast-atom bombardment mass spectrometry (HRFABMS) and nuclear magnetic resonance (NMR)). Compound 1 includes a conjugated pentaene moiety together with six hydroxy groups and a carboxylic acid as a side chain. Lavencidin (1) showed moderate growth-inhibitory activity against yeast and was cytotoxic against human cancer cell lines with low-micromolar IC50 values.

A New Chlorinated Phenolic Compound From the Antarctic Lichen, Pertusaria dactylina

A new chlorinated phenolic compound, methyl-3-chloro-2-hydroxy-4-methoxy-6-pentylbenzoate (1) and 4 known compounds (2-5) were isolated from the Antarctic lichen, Pertusaria dactylina ( Pertusariaceae). The structure of the new compound was determined by means of One-dimensional and two dimensional nuclear magnetic resonance (1D and 2D NMR) and high-resolution fast atom bombardment mass spectrometry (HRFABMS) experiments. The antimicrobial activities of compounds 1 to 5 against Staphylococcus aureus and Candida albicans were evaluated. The results showed that compound 1 exhibited a weak inhibitory effect against C. albicans with an IC50 value of 67 ± 7 μg/mL.

New Diterpenes with a Fused 6-5-6-6 Ring System Isolated from the Marine Sponge-Derived Fungus Trichoderma harzianum.

New diterpenes, namely, trichodermanins F–H, with a fused 6-5-6-6 ring system were isolated from the fungus Trichoderma harzianum OUPS-111D-4 separated from a marine sponge Halichondria okadai. These chemical structures were elucidated by 1D and 2D NMR as well as high-resolution fast atom bombardment mass spectrometry (HRFABMS) spectral analyses. We established their absolute stereostructures by application of the modified Mosher’s method or circular dichroism (CD) spectroscopy. In addition, their cytotoxicities were assessed using several cancer cell lines, with 1 and 2 exhibiting modest activities.

Cell cycle arrest and apoptosis in human liver cancer cell line and A549 cell lines by Turbiconol– A novel sterol isolated from Turbinaria conoides

Background: Turbinaria conoides, a brown seaweed, is a rich source of oxygenated fucosterols which are capable of suppressing the proliferation of cancer cells. Their specific therapeutically significant biological activity is directly related to the unique structural features of the molecule. This study specifically focuses on extracting unconventional sterol molecules (side chain extension) from this seaweed which can be used as a lead molecule to evolve therapeutical agents. Materials and Methods: To isolate unconventional sterol molecule, for structural elucidation and bioactivity study, sufficient amount of T. conoides was collected from Mandapam, an unique biodiverse environment along the Southeast coast of India. State-of-the-art methods available for the purification and characterization of molecule (High-resolution fast-atom bombardment mass spectrometry, ultraviolet-visible spectroscopy, attenuated total reflection–fourier transform infra-red, One-dimensional nuclear magnetic resonance, and two-dimensional nuclear magnetic resonance) were put in. In vitro bioassays (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium bromide, double staining, and flowcytometry) were carried out against A549 and human liver cancer cell line (HepG2) malignant cells to assess the cytostatic potential. Data were statistically validated. Results: A unique unconventional sterol molecule (Turbiconol) with ethyl and methyl group at C-27 was isolated. This molecule induced apoptosis in A549 and HepG2. However, cell cycle assessment revealed G0/G1 cell cycle arrest in Hep G2 and G2/M checkpoint was responsible for the suppression of A549 cell line. Conclusion: A novel unconventional compound, turbiconol, is reported in this study. In vitro results highlight the potential of this molecule in developing therapeutical combination which can be used for novel treatment methods.

Carapanosins D-F from the Seeds of Andiroba (Carapa guianensis, Meliaceae) and Their Effects on LPS-Activated NO Production.

A novel nor-phragmalin-type limonoid, named carapanosin D (1), and two novel mexicanolide-type limonoids, carapanosins E (2) and F (3), were isolated from the seed oil of andiroba (Carapa guianensis Aublet), a traditional medicine in Brazil and Latin American countries. Their structures were unambiguously determined on the basis of spectroscopic analyses using one-dimensional (1D) and two-dimensional (2D) NMR techniques and High resolution Fast Atom Bombardment Mass Spectrometry (HRFABMS). Compounds 1–3 were evaluated for their effects on the production of nitric oxide (NO) in Lipopolysaccharide (LPS)-activated mouse peritoneal macrophages. The NO inhibitory assay suggested that compounds 2 and 3 have high potency as inhibitors of macrophage activation.

Cystargamide B, a cyclic lipodepsipeptide with protease inhibitory activity from Streptomyces sp.

We identified a new cyclic lipodepsipeptide, cystargamide B (1), from the mycelial extract of a Kaempferia galanga rhizome-derived actinomycete strain, Streptomyces sp. PB013. The planar structure was elucidated based on high resolution fast-atom bombardment mass spectrometry (HRFABMS) spectroscopy and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopic data. The absolute configurations of the constituent amino acids were determined using advanced Marfey's method. Cystargamide B (1) includes rare structural units: a 5-hydroxytryptophan residue and a 2,3-epoxy fatty acid side chain. Notably, cystargamide B (1) inhibited the protease activity of the NS2B/NS3 complex from dengue virus.

Novel phosphorylation of aldrin-trans-diol by dieldrin-degrading fungus Mucor racemosus strain DDF

Dieldrin is one of the most persistent organic pollutants, and its oxidative degradation pathways by aerobic microorganisms to 6,7-trans-dihydroxydihydroaldrin (otherwise known as aldrin-trans-diol) and 9-hydroxydieldrin are well documented. The dieldrin-degrading fungus, Mucor racemosus strain DDF, can decrease dieldrin levels with simultaneous production of a small amount of aldrin-trans-diol. A reduction in the levels of aldrin-trans-diol by strain DDF has also been observed. Based on these results, it has been suggested that strain DDF transforms dieldrin to more polar compounds via aldrin-trans-diol. We have conducted a study to identify the metabolites arising from aldrin-trans-diol. The results showed that strain DDF gave reduced levels of aldrin-trans-diol and also produced unknown metabolites. Ultra performance liquid chromatography-electrospray ionization-mass spectroscopy (UPLC-ESI-MS) analysis indicated the metabolites to be either sulfated- or phosphorylated- derivatives of aldrin-trans-diol, but with the metabolites retaining six chlorine atoms. Therefore, the candidate derivatives were synthesized and the retention times of the natural metabolite and the synthetic phosphate were compared. As a result of a co-injection experiment, the metabolites were determined to be aldrin-trans-diol exo- and endo-phosphates. These results were also supported by high-resolution-fast atom bombardment-mass spectrometry (HR-FAB-MS) of the natural metabolite (Δ = 0.63 ppm). Phosphorylation of aldrin-trans-diol is the first reported example of phosphate conjugation in microorganisms.

Isolation and Structural Elucidation of 4-(β-D-Glucopyranosyldisulfanyl)butyl Glucosinolate from Leaves of Rocket Salad (Eruca sativaL.) and Its Antioxidative Activity

A structurally unique glucosinolate (GSL) was identified to be 4-(beta-D-glucopyranosyldisulfanyl)butyl GSL in rocket leaves. The positive-ion electrospray ionization mass spectrometry (ESI-MS) data indicated that the new GSL had a molecular weight of 521 (m/z 522, [M+H](+), as desulfo-GSL). The molecular formula of the substance was determined to be C(17)H(32)O(11)NS(3) (m/z 522.1143, [M+H](+)) based on its positive-ion high-resolution fast atom bombardment mass spectrometry (HR-FAB-MS) data. For the further confirmation, desulfated GSL of 4-(beta-D-glucopyranosyldisulfanyl)butyl GSL was prepared by commercial 1-thio-beta-D-glucose and dimeric 4-mercaptobutyl desulfo-GSL, which was also isolated from rocket leaves, and its chemical structure was then confirmed by MS data and nuclear magnetic resonance (NMR) spectroscopy. In addition, the antioxidative activity of 4-(beta-D-glucopyranosyldisulfanyl)butyl desulfo-GSL was measured by means of chemiluminescence (CL) for evaluating the functional properties. The antioxidative activity (2.089 unit/g) was relatively higher than that of dimeric 4-mercaptobutyl desulfo-GSL (1.227).

On-line identification of phenanthroindolizidine alkaloids in a crude extract from Tylophora atrofolliculata by liquid chromatography combined with tandem mass spectrometry.

Electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)) and liquid chromatography coupled with sequential mass spectrometry (LC/MS(n)) were applied to identify trace-level phenanthroindolizidine alkaloids in crude extracts from Tylophora atrofolliculata. Based on the relationship between the characteristic fragmentation reactions and the structural features of related compounds of known structure from this plant, the bioactive crude extract was analyzed in detail by positive and negative ion ESI-MS(n), LC/UV-MS and LC/MS(n) techniques. A total of nine constituents in the crude extract were identified rapidly, including several isomers; seven of these constituents are new and two are known compounds. The structures of four of these constituents were subsequently confirmed by nuclear magnetic resonance (NMR) and accurate mass measurements using high-resolution fast-atom bombardment mass spectrometry (FAB-HRMS).

Iridoid Esters from Patrinia saniculaefolia.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Iridoid esters from Patrinia saniculaefolia.

Two new iridoids, named patridoid I (1) and patridoid II (2), were isolated from the whole plant of Patrinia saniculaefolia (Valerianaceae), together with the known one, nardostachin (3). The structures of compounds 1 and 2 were established on the basis of spectroscopic methods, including two dimensional (2D NMR) and high resolution fast atom bombardment mass spectrometry (HR-FAB-MS).

ADMAdda5]-microcystins in Planktothrix agardhii strain PH-123 (cyanobacteria)--importance for monitoring of microcystins in the environment.

Two major and two minor microcystins (MCYST) were isolated from a hepatotoxic Danish strain of Planktothrix agardhii (Gomont) Anagnostidis et Komárek by reversed-phase high-performance liquid chromatography. The microcystins were characterized by UV spectroscopy, amino acid analysis, fast atom bombardment mass spectrometry (FABMS), and high-resolution FABMS. The major microcystins were further analysed by collisionally induced tandem electrospray ionization MS. The microcystins were found to be demethylated variants of MCYST-HtyR (homotyrosine-arginine) and MCYST-LR (leucine-arginine). The two major microcystins contained an acetyl-demethyl variant (ADMAdda) of 3-amino-9-acetoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (Adda). This is the first report of [ADMAdda5]-microcystins in Planktothrix. The two [ADMAdda5]-microcystins inhibited protein phosphatase activity but showed low cross-reactivity with antibodies of an enzyme-linked immunosorbent assay (ELISA), emphasizing the potential underestimation of the toxicity of natural blooms dominated by Planktothrix when microcystin content is quantified using only an ELISA.

A Study of the Complexation of Bis(m-Phenylene) Crown Ethers and Secondary Ammonium Ions

Two macrocycles, bis(m-phenylene)-26-crown-8 (1) and bis(m-phenylene)-32-crown-10 (2), were combined with several linear components, dibenzyl- (3·PF6), di-n-butyl- (4·PF6), and diphenethyl- (5·PF6) ammonium hexafluorophosphate salts. The smaller macrocycle 1 was shown not to complex effectively with any of the ammonium salts in solution by 1H NMR, but 1:1 complexes were shown to exist in the “gas phase” as [1:3], [1:4], and [1:5] by high-resolution fast atom bombardment mass spectrometry (HRFABMS) and electrospray ionization mass spectrometry (ESIMS). The X-ray crystal structure of macrocycle 1 is reported. The larger macrocycle 2 did form 1:2 complexes with the ammonium salts in solution, which were observed as well in the solid and gas phases. X-ray crystal structures of the pseudorotaxanes [2:(3)2]·2PF6 and [2:(5)2]·2PF6 were determined and are discussed. The pseudorotaxanes are stabilized by hydrogen bonding between the ammonium hydrogens of the linear salt unit and the oxygens of the crown ether macrocycle. Secondary stabilization also occurs by edge-to-face π stacking.

Accurate Mass Measurements of Some Glucuronide Derivatives by Electrospray Low Resolution Quadrupole Mass Spectrometry

The measurement of exact masses using negative-ion quadrupole low resolution electrospray mass spectrometry (ESMS) is demonstrated with p-nitrophenol, entacapone, mitecapone and 1-hydroxypyrene glucuronides. The results are compared with those obtained by high resolution fast-atom bombardment mass spectrometry (FAB-MS). The errors with ESMS between measured and calculated values ranged from −1.7 to 3.1 ppm (−0.8 to 1.2 milli-mass units (mmu). The standard deviations of the measurements were between ±1.1 and 4.8 ppm (±0.5 and 2.3 mmu). The errors with high resolution FAB-MS were between −2.5 and 3.2 ppm (−1.1 and 1.0 mmu). These results show that accurate mass measurements using low resolution quadrupole ESMS are comparable to those achievable in practice using high resolution instruments. A precondition for a successful measurement with low resolution mass spectrometry is that the sample ion be completely separated from background ions, since even very small levels of unresolved ions can interfere with the accuracy of mass analysis. © 1997 John Wiley & Sons, Ltd.

Accurate Mass Measurements of Some Glucuronide Derivatives by Electrospray Low Resolution Quadrupole Mass Spectrometry

The measurement of exact masses using negative-ion quadrupole low resolution electrospray mass spectrometry (ESMS) is demonstrated with p-nitrophenol, entacapone, mitecapone and 1-hydroxypyrene glucuronides. The results are compared with those obtained by high resolution fast-atom bombardment mass spectrometry (FAB-MS). The errors with ESMS between measured and calculated values ranged from −1.7 to 3.1 ppm (−0.8 to 1.2 milli-mass units (mmu). The standard deviations of the measurements were between ±1.1 and 4.8 ppm (±0.5 and 2.3 mmu). The errors with high resolution FAB-MS were between −2.5 and 3.2 ppm (−1.1 and 1.0 mmu). These results show that accurate mass measurements using low resolution quadrupole ESMS are comparable to those achievable in practice using high resolution instruments. A precondition for a successful measurement with low resolution mass spectrometry is that the sample ion be completely separated from background ions, since even very small levels of unresolved ions can interfere with the accuracy of mass analysis. © 1997 John Wiley & Sons, Ltd.

Primary structure of cyanelle peptidoglycan of Cyanophora paradoxa: a prokaryotic cell wall as part of an organelle envelope

The peptidoglycan layer surrounding the photosynthetic organelles (cyanelles) of the protist Cyanophora paradoxa is thought to be a relic of their cyanobacterial ancestors. The separation of muropeptides by gel filtration and reverse-phase high-performance liquid chromatography revealed four different muropeptide monomers. A number of muropeptides were identical in retention behavior to muropeptides of Escherichia coli, while others had remarkably long retention times with respect to their sizes, as indicated by gel filtration. Molecular mass determination by plasma desorption and matrix-assisted laser desorption ionization mass spectrometry showed that these unusual muropeptides had molecular masses greater by 112 Da or a multiple thereof than those of ones common to both species. Fast atom bombardment-tandem mass spectrometry of these reduced muropeptide monomers allowed the localization of the modification to D-glutamic acid. High-resolution fast atom bombardment-mass spectrometry and amino acid analysis revealed N-acetylputrescine to be the substituent (E. Pittenauer, E. R. Schmid, G. Allmaier, B. Pfanzagl, W. Löffelhardt, C. Quintela, M. A. de Pedro, and W. Stanek, Biol. Mass Spectrom. 22:524-536, 1993). In addition to the 4 monomers already known, 8 dimers, 11 trimers, and 6 tetramers were characterized. An average glycan chain length of 51 disaccharide units was determined by the transfer of [U-14C]galactose to the terminal N-acetylglucosamine residues of cyanelle peptidoglycan. The muropeptide pattern is discussed with respect to peptidoglycan biosynthesis and processing.

Isolation and structures of microcystins from a cyanobacterial water bloom (Finland)

A hepatotoxic cyanobacterial (blue-green algal) water bloom was collected from a constructed water reservoir in Finland. The water bloom contained two cyanobacterial species, Microcystis aeruginosa and Aphanizomenon flos-aquae. Two hepatotoxins, 1 and 2, were isolated from extracts of lyophilized cells. The structures of 1 and 2 were assigned based upon their amino acid analyses on a Waters Pico Tag HPLC system and a chiral GC capillary column (Chirasil Val III), fast atom bombardment mass spectrometry (FABMS), high resolution FABMS, and tandem FABMS data. Toxin 1 was identical to a previously reported compound, [d-Asp3]microcystin-RR. Toxin 2 was new and was assigned the structure [d-Asp3]microcystin-YR.

Isolation and characterization of hepatotoxic microcystin homologs from the filamentous freshwater cyanobacterium Nostoc sp. strain 152

A strain of the filamentous cyanobacterium Nostoc sp. isolated from a lake in Finland was found to produce at least nine hepatotoxic peptides with chemical and toxicological properties similar to those of the hepatotoxic hepta- and pentapeptides produced by other cyanobacteria. Toxins were isolated and purified by high-performance liquid chromatography. Amounts available for five of the purified toxins (P6, P14, P15, P16, and P18) were adequate for high-performance liquid chromatography amino acid analysis and determination of molecular weight by fast-atom bombardment-mass spectrometry (FAB-MS). Quantities of three toxins (P14, P15, and P16) were adequate for further analysis by high-resolution FAB-MS, FAB-MS/MS, and 1H-nuclear magnetic resonance. Analysis showed that the toxins are new types of microcystin-LR homologs. Microcystin-LR contains equimolar amounts of D-alanine, L-leucine, D-erythro-beta-methylaspartic acid, L-arginine, ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid), D-glutamic acid, and N-methyldehydroalanine (molecular weight [MW], 994). Nostoc sp. strain 152 was found to produce the following microcystin-LR homologs: (i) P6 contains an extra methylene group most probably due to the presence of N-methyldehydrobutyrine instead of N-methyldehydroalanine (MW, 1,008); (ii) P14 is O-acetyl-O-demethyl ADDA-microcystin-LR (MW, 1,022); (iii) P15 is 3-demethyl-O-acetylADDA-homoarginine-microcystin-LR (MW, 1,036); (iv) P16 is 3-demethyl-O-acetyl-O-demethylADDA-microcystin-LR (MW, 1,008); (v) P18 is 3-demethyl-O-acetyl-O-demethylADDA-homoarginine-microcystin- LR (MW, 1,022). The toxicities of the new microcystin homologs were not significantly different from those of microcystin-LR or demethylmicrocystin-LR.