RESUMO
As part of the development of an analytical technique for the detection of meridianins and related compounds in biological fluids, a crude extract of the tunicate Aplidium meridianum was analysed using neutral loss tandem mass spectrometry. The 41 u neutral loss-EI(+) mass spectrum showed molecular ions corresponding to two previously undetected alkaloids. We report herein the isolation and structure elucidation of these alkaloids, meridianins F and G.
Assuntos
Alcaloides/análise , Alcaloides/química , Alcaloides Indólicos/análise , Alcaloides Indólicos/química , Urocordados/química , Animais , Estrutura Molecular , Espectrometria de Massas em TandemRESUMO
The original article to which this Erratum refers was published in Journal of Mass Spectrometry 36 (7) 2001, 699-716.
RESUMO
The 5-substituted tetrazole ring was reacted in the gas phase with an acyl ion generated as the secondary reactive chemical ionization plasma in the mass spectrometer. The product ions obtained, among others, were proposed as the rearranged 2,5-disubstituted-1,3,4-oxadiazole nucleus. Its structure was demonstrated by comparison of the product ion spectrum of the 2,5-disubstituted-1,3,4-oxadiazole derivative obtained by condensed-phase reaction and the product ion spectrum of the oxadiazole derivative generated in situ by reaction of the 5-substituted tetrazole derivative with the acyl plasma. It was proposed that the mechanism of this transformation involved the presence of an acylated tetrazole intermediary, which could not be isolated in the condensed phase, followed by the rearrangement, with nitrogen loss, to afford the oxadiazole derivative. Under our conditions we were able to isolate the intermediate ion in the first field free region and demonstrate its structure by collision induced dissociation-tandem mass spectrometry.
Assuntos
Oxidiazóis/química , Tetrazóis/química , Acilação , Butanos/química , Espectrometria de MassasRESUMO
[structure: see text] In the course of our search of new bioactive metabolites from marine invertebrates, paesslerins A and B, sesquiterpenoids with an unprecedented tricyclic skeleton, were isolated from the subAntarctic soft coral Alcyonium paessleri collected at a depth of 200 m near the South Georgia islands, and their structures were elucidated by spectroscopic techniques. These compounds show moderate cytotoxicity in preliminary assays.
Assuntos
Hidrocarbonetos Aromáticos com Pontes/química , Cnidários/química , Sesquiterpenos/química , Animais , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Fatores Biológicos/química , Fatores Biológicos/isolamento & purificação , Fatores Biológicos/farmacologia , Hidrocarbonetos Aromáticos com Pontes/isolamento & purificação , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Humanos , Biologia Marinha , Sesquiterpenos/isolamento & purificação , Sesquiterpenos/farmacologia , Células Tumorais Cultivadas/efeitos dos fármacos , Recursos HumanosRESUMO
Two new trisulfated triterpene glycosides, liouvillosides A (1) and B (2), have been isolated from the Antarctic sea cucumber Staurocucumis liouvillei. Their structures have been elucidated by spectroscopic analysis (NMR and FABMS) and chemical transformations. Liouvillosides A (1) and B (2) are two new examples of a small number of trisulfated triterpene glycosides from sea cucumbers belonging to the family Cucumariidae. Both glycosides were found to be virucidal against herpes simplex virus type 1 (HSV-1) at concentrations below 10 microg/mL.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Antivirais/química , Antivirais/farmacologia , Oligossacarídeos/isolamento & purificação , Pepinos-do-Mar/química , Triterpenos/química , Triterpenos/isolamento & purificação , Triterpenos/farmacologia , Animais , Antineoplásicos/isolamento & purificação , Antivirais/isolamento & purificação , Configuração de Carboidratos , Chlorocebus aethiops , Ensaios de Seleção de Medicamentos Antitumorais , Herpesvirus Humano 1/efeitos dos fármacos , Hidrólise , Espectroscopia de Ressonância Magnética , Metilação , Testes de Sensibilidade Microbiana , Oligossacarídeos/química , Espectrometria de Massas de Bombardeamento Rápido de Átomos , Células VeroRESUMO
In a screening for antifungal metabolites, two indole compounds of mixed biogenesis, 1H-indole-3-carboxylic acid, 1-(1,1-dimethyl-2-propenyl) methyl ester and 1H-indole-3-carboxylic acid, 1-(2,3-dihydroxy-1,1-dimethylpropyl) methyl ester were isolated from a culture of the basidiomycete Aporpiums caryae. The structural elucidation of these compounds was accomplished by spectroscopic methods.
Assuntos
Alcaloides/isolamento & purificação , Fungos/química , Alcaloides/química , Indóis/química , Estrutura Molecular , Análise EspectralRESUMO
Fifteen illudalane sesquiterpenoids, alcyopterosins A-O (1-15) have been isolated from the subAntarctic soft coral Alcyonium paessleri which was collected at a depth of 200 m near the South Georgia Islands, and their structures were elucidated by spectroscopic techniques. Eight of these compounds (2, 3, 5-8, 10, and 13) are the first natural nitrate esters, while the other four (1, 4, 11, and 12) are chlorinated. These compounds are as well the first illudalane sesquiterpenoids to be isolated from the marine environment. Compounds 1, 3, 5, and 8 showed mild cytotoxicity toward human tumor cell lines.
Assuntos
Cnidários/química , Ésteres/química , Nitratos/química , Nitratos/isolamento & purificação , Sesquiterpenos/química , Sesquiterpenos/isolamento & purificação , Animais , Regiões Antárticas , Linhagem Celular , Ésteres/isolamento & purificação , Ésteres/toxicidade , Humanos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Nitratos/toxicidade , Sesquiterpenos/toxicidade , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
In order to correlate the lipid composition of the membrane of Lactobacillus acidophilus CRL 640 with the freeze-thaw behaviour of the cultures grown at different temperatures, fatty acid methyl esters (FAMEs) from extracts grown at 25, 30, 37 and 40 degrees C were obtained and compared. Cultures grown at 25 degrees C (M25) exhibited more resistance to the freeze-thaw process probably because of an increase in C18:2 and C16:0 fatty acids. This culture also exhibited a lesser amount of phospholipids as shown by the sugar: phosphorus ratio. In all cases, the presence of the uncommon 10-hydroxyoctadecanoic acid was determined. From the extracts of the M25 and M37 cultures, diacylphosphatidylglycerol, cardiolipin, diglycosyldiglycerides, triglycosyldiglycerides and neutral lipids were isolated and identified. The structural elucidation was carried out by FAMEs and sugar analysis and by mass spectrometry using fast atom bombardment ionization. The changes in lipid composition due to different growth temperatures could be indicative of the resistance of the bacteria to freeze-thaw processes.
Assuntos
Criopreservação , Ácidos Graxos/análise , Lactobacillus acidophilus/química , Lactobacillus acidophilus/crescimento & desenvolvimento , Temperatura Baixa , Ésteres , Espectrometria de Massas de Bombardeamento Rápido de Átomos , TemperaturaRESUMO
Electrospray ionization followed by collision-induced dissociation in a quadrupole ion trap mass spectrometer of mixtures of deprotonated phosphatidyldiacylglycerols afforded a group of three diagnostic ions of convenient abundance for each phosphatidyldiacylglycerol (PG) present in the mixture. Thus, it was possible to determine unmistakably the identity and substitution positions (sn-1 or sn-2) for both acyl groups of each PG present in the mixture. The method also allows the study of isomeric mixtures of PG and mixtures containing minor amounts of some PG from crude extracts of Lactobacillus acidophillus. The present results improve those of previous studies using fast atom bombardment and electrospray ionization tanden mass spectrometry, in which it was reported that it was possible to differentiate the identity and position of the sn-2 acyl substituent only by the presence of one ion, with variable abundance.
Assuntos
Lactobacillus acidophilus/química , Fosfatidilgliceróis/análise , Espectrometria de Massas por Ionização por Electrospray , Fosfatidilgliceróis/químicaRESUMO
From the water-insoluble lipid fraction of the methylene chloride/methanol extract of the starfish Cosmasterias lurida, two new glucosylceramides together with a known glucosylceramide, ophidiacerebroside E, were isolated by chromatographic procedures and characterized by spectroscopic (1H and 13C nuclear magnetic resonance, mass spectrometry) methods. The new compounds were identified as (2S,3R,4E,8E,10E)-1-(beta-D-glucopyranosyloxy)-3 -hydroxy-2-[(R)-2-hydroxyheptadecanoyl)amino]-9-methyl-4,8,10-o ctadecatriene (3) and (2S,3R,4E,8E,10E)-1-(beta-D-glucopyranosyloxy)-3 -hydroxy-2-[(R)-2-hydroxyoctadecanoyl)amino]-9-methyl-4,8,10-oc tadecatriene (4).