High-Yield Synthesis of 20-, 24-, and 28-Membered Macropentolide, -hexolide, and -heptolide, Respectively, from (R)- or (S)-3-hydroxybutanoic acid underYamaguchi's macrolactonization conditions

The macrocyclic pentolide 1, hexolide 2, and heptolide 3 constitute ca. 80% of the oligomers formed in ca. 50% yield from enantiomerically pure 3-hydroxybutanoic acid under Yamaguchi's macrolactonization conditions. The FAB mass spectra of the MH+, M Na+, and MCs+ are reported (Figs. 2, 3, 5, and 6). No cyclic tetramer is detected. The 1H-NMR spectra of the cyclic oligomers, of the monomer, and of the polymer (PHB) are very similar (Fig. 4). Directed synthesis of the open-chain dimer and tetramer of 3-hydroxybutanoic acid and attempted cyclization do not lead to the isolation of the cyclic tetramer.

Elucidation of structure and microheterogeneity of the polypeptide antibiotics paracelsin and trichotoxin A-50 by fast atom bombardment mass spectrometry in combination with selectivein situ hydrolysis

Specific and sensitive procedures have been developed which enabled the structure elucidation of the polypeptide antibiotics (peptaibols), paracelsin isolated from Trichoderma reesei, and of trichotoxin A-50 from Trichoderma viride, by fast atom bombardment and field desorption mass spectrometry. Both peptides were found to exhibit a pronounced microheterogeneity by single and multiple exchange of amino acids. Separation by analytical and semipreparative high-performance liquid chromatography (HPLC) on octadecylsilyl-bonded, reversed-phase columns afforded a series of sequence analogues for each polypeptide. Unequivocal molecular weight and sequence identifications were obtained by positive…

Multi-step metabolic activation of benzene. Effect of superoxide dismutase on covalent binding to microsomal macromolecules, and identification of glutathione conjugates using high pressure liquid chromatography and field desorption mass spectrometry

Abstract Incubation of [ 14 C]benzene or [ 14 C]phenol with liver microsomes from untreated rats, in the presence of a NADPH-generating system, gave rise to irreversible binding of metabolites to microsomal macromolecules. For both substrates this binding was inhibited by more than 50% by addition of superoxide dismutase to the incubation mixtures. The decrease in binding was compensated for by accumulation of [ 14 C]hydroquinone, indicating superoxide-mediated oxidation of hydroquinone as one step in the activation of benzene to metabolites binding to microsomal macromolecules. Since our previous work had shown that binding occurred mainly with protein rather than ribonucleic acid and was …

Mass spectrometric investigation of polymers: Thermal degradation of truxillic and truxinic polyamides

The thermal degradation mechanism of four isomeric truxillic and truxinic polyamides were investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation reactions were followed directly by this method by detecting the thermal and electron impact-induced fragments. The results obtained have shown that the thermal degradation products are sensibly different for the head-to-head (hh) and head-to-tail (ht) polymers and that the predominant pyrolytic process is the cyclobutane ring cleavage. In the hh isomers, both symmetrical and asymmetrical cyclobutane ring cleavage was detected, while in the ht isomers only symmetrical cleavage occurs; this explains the notice…

Direct pyrolysis in the mass spectrometer of aromatic polysulfonates and polythiosulfonates

The thermal degradation mechanism of three aromatic polysulfonates and polythiosulfonates was investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation reactions were followed directly by this method by detecting the thermal and electron impact induced fragments. The results obtained have provided evidence that sulfur dioxide extrusion from the polymer backbone takes place in these polymers above 300°C. The synthesis and molecular characterization of the polymers studied are reported in the text.

Untersuchungen von polymeren im massenspektrometer, 4. Abbaureaktionen von polybenzylen

Die Abbaureaktionen von unsubstituierten Poly(1,4-phenylenmethylen)en (A) (Polybenzylen), Poly[(2,5-dimethyl-1,4-phenylen)methylen] [Poly(2,5-dimethylbenzyl)] (B), Poly[(2,3,5,6-tetramethyl-1,4-phenylen)methylen] [Poly(2,3,5,6-tetramethylbenzyl)] (C) und Poly(1,4-phenylenathyliden) [Poly(α-methylbenzyl)] (D) wurden durch direkte Pyrolyse im Massenspektrometer untersucht. Die Massenpyrogramme von unter verschiedenen Reaktionsbedingungen dargestellten Polybenzylen wurden verglichen, mit dem Ziel, direkt Informationen uber Strukturunterschiede wie Kettenverzweigung und unterschiedliche Verknupfung der Benzyleinheiten zu erhalten; hierbei konnten in einem Falle auf hohere Kettenverzweigung deut…

Fast atom bombardment and field desorption mass spectrometry: Comparative aspects of analytical development and bioanalytical application

Identification of conjugation and cleavage products in the thiolytic metabolism of the anticancer drug 4'-(9-acridinylamino)methanesulfon-m-anisidide.

Conjugation and cleavage products in the thiolytic metabolism of the anticancer drug 4′ -(9-acridinyl amino)methanesulfon-m-anisidide were identified primarily by high-pressure liquid chromatography in combination with field desorption mass spectrometry. The spontaneous metabolic pathway of the drug, as related to its susceptibility to nucleophilic attack by endogenous thiols at the 9-carbon atom of the acridine moiety, has been studied. Among the metabolite fraction of 4′-(9-acridinylamino)methanesulfon-m-anisidide excreted in rat bile after administration of a therapeutic dose, a conjugate was identified as the 9-acridinyl thioether of glutathione. This conjugation product and the corresp…

Photodimers of cinnamic acid and related compounds. A stereochemical study by electron-impact and field desorption mass spectrometry

The low energy (13 eV) electron-impact and field desorption mass spectra of some photodimers of cinnamic acid and related compounds containing the cyclobutane ring are reported and the fragmentation patterns analysed in order to obtain stereochemical information on the substituent position on the cyclobutane ring. Both symmetrical and asymmetrical splittings of the cyclobutane ring were detected, allowing characterisation of the head-to-head and head-to-tail structures of the title compounds. A ring opening rearrangement of the McLafferty type was also found.

Conjugation reactions of polyaromatic quinones to mono- and bisglutathionyl adducts: Direct analysis by fast atom bombardment mass spectrometry

The conjugation products of several reactive quinones with glutathione have been identified by fast atom bombardment mass spectrometry. Appropriate conditions have been developed which enabled the direct, dynamic mass spectral analysis of spontaneous, as well as glutathione transferase catalysed conjugation reactions. Applications to a series of quinones provided the direct detection and differentiation of the formation of mono- and bisglutathionyl adducts between regioisomeric quinone substrates in that only 1,4-quinones yielded bisglutathionyl adducts, which were not observed for the 1,2-isomers.

Evidence for a surface self-cleaning sputtering mechanism in fast atom bombardment mass spectrometry

Evidence for a surface self-cleaning sputtering mechanism in fast atom bombardment mass spectrometry involving significant sputtering from the bulk of the glycerol matrix has been obtained from (a) the time dependence of sample ion abundances and chemical noise for bioorganic compounds, (b) determinations of the sputtering volume in glycerol solution, and (c) studies of in situ chemical and biochemical reactions. The relevance of these results for optimal sample/matrix preparation in analytical applications is pointed out.

Field Desorption Mass Spectra of Gastrine Peptides and Glutathione Derivatives

Oligopeptides comprising the sequence of the C-terminal tetrapeptide of gastrine, Trp-Met-Asp-Phe-NH2, and several derivatives of glutathione, γ-Glu-Cys(SR)-Gly, were characterized by field desorption mass spectrometry. The field desorption mass spectra obtained at various field ion emitter temperatures reveal abundant molecular ions and fragmentation reactions that yield partial sequence information. In the series of glutathione derivatives investigated, characteristic ions formed by cleavage of the γ-Glu-Cys peptide bond determine the substituent at the Cys residue and can therefore be used to identify corresponding conjugation products of drug metabolites with glutathione.

The thermal degradation mechanism of three aromatic polymers containing double bridged phenylether units was investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation reactions were followed directly by this method detecting the thermal and electron impact induced fragments. The results obtained have provided evidence that the double bridge between the aromatic rings is the preferred fragmentation site in these polymers. Furthermore in the double sulfur bridged polymer III, extrusion of S2 from the polymer backbone takes place above 400°C. The synthesis of polymers studied is reported in the text. Der Mechanismus des thermischen Abbaus von drei aromatisc…

Differentiation of isomeric cyclic diamides by electron impact mass spectra

The behaviour under electron impact of two series of isomeric cyclopentane- and cyclohexane-1, 2- and -1, 3-dicarboxylic acid dipiperidides was studied. Diagnostic fragmentation pathways were found to differentiate the isomeric diamides. Additional evidence was obtained from the metastable transitions.

Untersuchungen von polymeren im massenspektrometer, 6. Poly(oxy-1,4-phenylen), poly(thio-1,4-phenylen) und poly(dithio-1,4-phenylen)

Der thermische Abbau von Poly(oxy-1,4-phenylen), Poly(thio-1,4-phenylen) und Poly(dithio-1,4-phenylen) wurde durch direkte Pyrolyse in der Ionenquelle des Massenspektrometers untersucht. Bei verringerter Elektronenenergie (15 eV) konnten die elektronenstosinduzierten Fragmentierungen der Pyrolysebruchstucke weitgehend zuruckgedrangt und die thermischen Abbaumechanismen ermittelt werden. In Abhangigkeit von den Bruckenatomen werden charakteristische Unterschiede im Abbauverhalten und in der Art der gebildeten Bruchstucke gefunden. Am Beispiel des Poly(dithio-1,4-phenylen)s kann gezeigt werden, das temperaturprogrammierte Pyrolyse und Verwendung eines Datensystems zur Ermittlung von thermisch…

Characterisation of disaccharide fragments from the enzymatic digestion of heparin by liquid secondary ion mass spectrometry

Disaccharide fragments resulting from the enzymatic digestion of heparins with heparinase have been purified by gel filtration chromatography and directly analyzed by positive and negative ion liquid secondary ion mass spectrometry (LSIMS). Following the chromatographic purification from excess sodium salt, the mass spectra of di- and tetrasaccharide fragment mixtures enabled the identification of up to three covalently bound sulfate moieties per glycosaminoglycan-disaccharide unit, by means of their molecular ions, containing the corresponding alkali-counterions.

Strukturuntersuchungen von polyamiden aus cyclischen dicarbonsäuren und piperazin durch direkten abbau im massenspektrometer

Polyamide aus 1,2-Cyclobutan-, 1,2-Cyclopentan- und 1,2-Cyclohexandicarbonsaure und Piperazin wurden direkt in der Ionenquelle eines Massenspektrometers pyrolysiert. Die hohe Empfindlichkeit der massenspektrometrischen Methode erlaubt, bei Abbauraten von ca. 1%/min zu pyrolysieren und dadurch selektive thermische Abbaumechanismen neben den Fragmentierungsreaktionen nachzuweisen. Durch thermischen Abbau werden dabei Oligomere mit Piperazinendgruppen sowie gesattigte und ungesattigte Cyclobutan-, -pentan- und -hexanendgruppen gebildet. Polyamides of 1,2-cyclobutane-, 1,2-cyclopentane- and 1,2-cyclohexane-dicarboxylic acid and piperazine were pyrolyzed directly in the ion source of a mass spec…

Copolyamides from adipic and truxillic acids: Synthesis and characterization by direct pyrolysis in the mass spectrometer

The synthesis of a series of polyamides and copolyamides containing α-truxillic and adipic units in the chain is reported. The thermal degradation of these polymers was investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation reactions were followed directly by this method by detecting the thermal- and electron-impact-induced fragments. The results obtained show a good correlation between the intensity of mass peaks characteristic of truxillic and adipic moieties and the composition of the copolyamides, as ascertained by elemental analysis. This is an important result since it shows the potential of the direct pyrolysis method in the analysis of copolym…

Untersuchungen von polymeren im massenspektrometer, 5. Fragmentierungsreaktionen oligomerer oxy- und thio-1,4-phenylene

Als Modellverbindungen zur Differenzierung von thermischen und elektronenstosinduzierten Abbaureaktionen von entsprechenden Polymeren im Massenspektrometer wurden die Fragmentierungsreaktionen oligomerer 1,4-Phenylene mit Sauerstoff-, Schwefel- und Disulfidbrucken sowie eine Reihe alternierender Co-oligomersysteme untersucht. Bei verringerter Ionisationsenergie (15 eV) treten in den Massenspektren aller unzersetzt fluchtigen Oligomeren die Molekulionen als intensivste Peaks auf, so das–bei strukturell gleichen Polymeren–eine eindeutige Identifizierung von thermischen Abbauprodukten erwartet werden kann. In Abhangigkeit von den Bruckenatomen werden charakteristische Unterschiede in den Inten…

A number of acryl and methacryl derivatives of different sulfanilamides (1a—I) were prepared and polymerized. The fixation of the sulfonamide to the polymerizable group was carried out directly, using the acryl- and methacrylamides, and by means of spacer groups, to favour the enzymatic or hydrolytic release of the drug moiety. Selected sulfonamide types of different pKA values were used, and the pH-dependant solubility of the corresponding polymers was studied. The monomeric acryloyl and methacryloyl sulfonamides were homopolymerized radically by AIBN. For distribution studies polysulfadiazineacrylamide, 14C-labelled in the main chain (2e'), was synthesized. Copolymerization with 2-methyls…

Investigation of polymers in the mass spectrometer, 7. Pyrolysis-gas chromatography-mass spectrometry of low molecular and high polymeric sulfanilamides

A number of low molecular, monomeric and polymeric sulfanilamide derivatives, which have found interest as possibly selective antitumour agents, were investigated by pyrolysis-gas chromatography (GC)-mass spectrometry (MS). Thermal degradation mechanisms were studied using also direct polymer pyrolysis in the ion source of the mass spectrometer. Thermal degradation products as well as low molecular weight sulfanilamides and related model compounds were characterized in their fragmentation behaviour by low and high resolution electron impact and field desorption mass spectrometry. Thermal fragments of structural significance were found, and a differentiation of the low and high molecular sul…

PYROLYSIS-MASS SPECTROMETRY OF TRUXILLIC AND TRUXINIC POLYAMIDES AND RELATED COPOLYAMIDES

Identification and quantitation of methotrexate and methotrexate metabolites in clinical high-dose therapy by high pressure liquid chromatography and field desorption mass spectrometry.

High-pressure liquid chromatography in combination with field desorption mass spectrometry as techniques of high specificity and sensitivity have been applied to the identification and quantitation of the anticancer drug methotrexate and its metabolites which occur in clinical high-dose therapy. Field desorption mass spectra of methotrexate and several methotrexate and folic acid derivatives, when investigated as free acids or ammonium salts, yield abundant protonated molecular ions and a consistent pattern of structurally significant fragments. High-pressure liquid chromatographic separation of methotrexate metabolites was performed on reverse-phase, C-18 columns using a volatile, ammonium…

Isolation and structural characterization of polypeptide antibiotics of the peptaibol class by high-performance liquid chromatography with field desorption and fast atom bombardment mass spectrometry

Abstract A number of polypeptide antibiotics of the peptaibol class, i.e., trichotoxin, alamethicin, suzukacillin, hypelcin and paracelsin, have been separated into components and isolated by high-performance liquid chromatography on spherical, porous octadecylsilyl bonded phases. All peptaibols were found to reveal a strong microheterogeneity due to single or multiple amino acid exchange. Most of the closely related and partially isobaric sequence analogue could be resolved using mixed alcohol—water eluents. As demonstrated by the structure analysis of the paracelsins and the main component of trichotoxin A-50, high-performance liquid chromatography with field desorption and fast atom bomb…

Poly(9,10-dihydroanthrylenetrimethylene) (2) comprises a novel chain-type structure in which 9,10-dihydroanthracene units are linked by flexible spacer groups. Upon dehydrogenation with sulfur at elevated temperature, polymer 2 is converted into the corresponding polyanthrylene system 3. NMR- and UV-spectroscopic data provide firm evidence for the dehydrogenation process. The polymer 3 was subjected to reduction with active lithium, and the resulting polyanions were characterized by NMR spectroscopy and by quenching experiments. It appears that each anthracene unit of the chain can be charged with two electrons.

Field desorption mass spectrometric characterization of thiol conjugates related to the oxidative metabolism of the anticancer drug 4′-(9-acridinylamino)-methanesulfon-m-anisidide

Conjugation products with glutathione (GSH) and other endogenous thiol derivatives related to the oxidative metabolism of the anticancer drug, 4′-(9-acridinlyamino) methanesulfon-m-anisidide (m-AMSA) were synthesized and characterized by field desorption mass spectrometry. The primary microsomal oxidation product of m-AMSA, m-AQDI, was prepared by MnO2 oxidation of the parent drug and reacted with equimolar GSH, cysteine, N-acetylcysteine and N-acetylcysteine methyl ester to form m-AMSA-(5′)-thiol conjugates linkedat the aniline ring, as major products. Field desorption mass spectra of the conjugates provided abundant [MH]plus; ions, and characteristic fragment ions by cleavage at the thioe…

Untersuchungen von polymeren im massenspektrometer, 3. Fragmentierungsreaktionen oligomerer benzyle

Beim thermischen Abbau von Polybenzylen im Massenspektrometer werden oligomere Benzylbruchstucke mit gesattigten (Phenyl-, Alkyl-) und ungesattigten (Chinonmethid)-Endgruppen gebildet. Zur Differenzierung der thermischen und elektronenstosinduzierten Abbaureaktionen wurden die Fragmentierungsreaktionen oligomere Benzyle vom Typ 1a, b im Massenspektrometer untersucht. Bei Anwendung niedriger Elektronenstosenergien wurden als Hauptfragmentierungsreaktionen Alkyl-, α-Benzyl- und β-Benzylspaltung sowie die fur 1,2-disubstituierte Benzyle strukturspezifische ortho-Umalgerung gefunden, die eine Differenzierung stellungsisomerer Oligobenzyle ermoglicht. Die genannten Reaktionen wurden durch Hochau…

Identification of acetyl-T-2 toxin, a trichothecene, in moldy rice by HPLC and FDMS

Identification and quantification of metabolite conjugates of activated cyclophosphamide and ifosfamide with mesna in urine by ion-pair extraction and fast atom bombardment mass spectrometry.

The high bladder toxicity of the alkylating oxazaphosphorine anticancer drugs, cyclophosphamide and ifosfamide is effectively reduced by the concomitant administration of mesna (sodium 2-mercaptoethane sulphonate). The formation and rapid urinary excretion of conjugates of the activated (4-hydroxylated) oxazaphosphorine metabolites with mesna has been suggested as the pharmacological basis for the selective detoxification, but separation and identification of such metabolites in vivo have been extremely difficult due to their high polarity and chemical lability. In this study an ion-pair extraction procedure in combination with positive and negative ion fast atom bombardment mass spectromet…

Synthesis and characterization of polymeric derivatives of the folic acid antagonist, Methotrexate, N-[4-(N-methyl-2,4-diamino-6-pteridinylmethylamino)benzoyl] glutamic acid (1a), a widely used antitumor agent, are described. Derivatives of poly(L-lysine), poly(iminoethylene), poly(vinyl alcohol), and carboxymethylcellulose with various contents (3–15 mole-%) of substituted repeating units were prepared by polymer-analogous amidation and transesterification of the dimethyl ester of 1a and with N-[2-(N-methylmorpholinio)ethyl]carbodiimide p-toluenesulfonate as coupling reagent. By nucleophilic addition reactions of the pteridinyl amino groups under mild conditions, 1a was bound without cross…