Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 50
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Astrobiology ; 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32167834

RESUMO

The detection of biosignatures on Mars is of outstanding interest in the current field of Astrobiology and drives various fields of research, ranging from new sample collection strategies to the development of more sensitive detection techniques. Detailed analysis of the organic content in Mars analog materials collected from extreme environments on Earth improves the current understanding of biosignature preservation and detection under conditions similar to those of Mars. In this article, we examined the biological fingerprint of several locations in the Atacama Desert (Chile), which include different wet and dry, and intermediate to high elevation salt flats (also named salars). Liquid Chromatography and Multidimensional Gas Chromatography Mass Spectrometry measurement techniques were used for the detection and analysis of amino acids extracted from the salt crusts and sediments by using sophisticated extraction procedures. Illumina 16S amplicon sequencing was used for the identification of microbial communities associated with the different sample locations. Although amino acid load and organic carbon and nitrogen quantities were generally low, it was found that most of the samples harbored complex and versatile microbial communities, which were dominated by (extremely) halophilic microorganisms (most notably by species of the Archaeal family Halobacteriaceae). The dominance of salts (i.e., halites and sulfates) in the investigated samples leaves its mark on the composition of the microbial communities but does not appear to hinder the potential of life to flourish since it can clearly adapt to the higher concentrations. Although the Atacama Desert is one of the driest and harshest environments on Earth, it is shown that there are still sub-locations where life is able to maintain a foothold, and, as such, salt flats could be considered as interesting targets for future life exploration missions on Mars.

2.
Life (Basel) ; 9(1)2019 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-30884807

RESUMO

The biomolecular homochirality in living organisms has been investigated for decades, but its origin remains poorly understood. It has been shown that circular polarized light (CPL) and other energy sources are capable of inducing small enantiomeric excesses (ees) in some primary biomolecules, such as amino acids or sugars. Since the first findings of amino acids in carbonaceous meteorites, a scenario in which essential chiral biomolecules originate in space and are delivered by celestial bodies has arisen. Numerous studies have thus focused on their detection, identification, and enantiomeric excess calculations in extraterrestrial matrices. In this review we summarize the discoveries in amino acids, sugars, and organophosphorus compounds in meteorites, comets, and laboratory-simulated interstellar ices. Based on available analytical data, we also discuss their interactions with CPL in the ultraviolet (UV) and vacuum ultraviolet (VUV) regions, their abiotic chiral or achiral synthesis, and their enantiomeric distribution. Without doubt, further laboratory investigations and upcoming space missions are required to shed more light on our potential extraterrestrial molecular origins.

3.
Phytochemistry ; 149: 64-81, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29477626

RESUMO

Guaiacwood oil is a common perfume ingredient used in modern compositions for its suave woody-rosy scent. This essential oil is a byproduct of the timber industry obtained by hydrodistillation of the heartwood of Bulnesia sarmientoi, a tree native from Latin America. Despite being widely used in perfumery, guaiacwood oil has been poorly described in the past. This study aims at giving an in-depth characterisation of its chemical composition as well as disclosing the odorant compounds responsible for its characteristic fragrance. Our methodology was based on a combination of fractionation and analytical techniques, including comprehensive two-dimensional gas chromatography coupled to mass spectrometry and preparative capillary-gas chromatography. The entire analytical work led to the isolation of 20 constituents among which 14 have never been reported so far in natural extracts. Each isolated compound was fully characterised by spectroscopic methods. Finally, the accurate knowledge of the chemical composition permitted the identification of the odour-active constituents by gas chromatography-olfactometry.


Assuntos
Odorantes/análise , Óleos Voláteis/química , Sesquiterpenos/química , Zygophyllaceae/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Monoterpenos/análise , Olfatometria , Perfumes/análise
4.
Biochim Biophys Acta Proteins Proteom ; 1866(7): 743-758, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29357311

RESUMO

Living organisms on the Earth almost exclusively use l-amino acids for the molecular architecture of proteins. The biological occurrence of d-amino acids is rare, although their functions in various organisms are being gradually understood. A possible explanation for the origin of biomolecular homochirality is the delivery of enantioenriched molecules via extraterrestrial bodies, such as asteroids and comets on early Earth. For the asymmetric formation of amino acids and their precursor molecules in interstellar environments, the interaction with circularly polarized photons is considered to have played a potential role in causing chiral asymmetry. In this review, we summarize recent progress in the investigation of chirality transfer from chiral photons to amino acids involving the two major processes of asymmetric photolysis and asymmetric synthesis. We will discuss analytical data on cometary and meteoritic amino acids and their potential impact delivery to the early Earth. The ongoing and future ambitious space missions, Hayabusa2, OSIRIS-REx, ExoMars 2020, and MMX, are scheduled to provide new insights into the chirality of extraterrestrial organic molecules and their potential relation to the terrestrial homochirality. This article is part of a Special Issue entitled: d-Amino acids: biology in the mirror, edited by Dr. Loredano Pollegioni, Dr. Jean-Pierre Mothet and Dr. Molla Gianluca.


Assuntos
Aminoácidos/química , Evolução Molecular , Meio Ambiente Extraterreno , Fotólise , Aminoácidos/síntese química , Luz , Estereoisomerismo
5.
J Nat Prod ; 80(2): 526-537, 2017 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-28195478

RESUMO

Guaiacwood oil from Bulnesia sarmientoi Lorentz ex. Griseb is a common natural ingredient of the perfume industry used in both domestic and luxury fragrances for its highly appreciated woody-rosy odor, as well as its excellent fixative properties. Despite its long and traditional use as a perfume ingredient, guaiacwood oil has not been extensively studied. Thus, the chemical characterization of its constituents by using a full array of GC-hyphenated techniques (GC-MS, GC × GC-MS, and pc-GC) combined with conventional chemical fractionation was undertaken. In the course of this work, 15 new sesquiterpenoids mostly belonging to the 5,11- and 10,11-epoxyguaiane families were identified. Each isolated compound was fully characterized by NMR and MS. Collectively, the specific chemical relationships observed between sesquiterpene oxides and alcohols permitted the formulation of probable formation pathways regarding their presence as natural constituents of guaiacwood extracts.


Assuntos
Óleos Voláteis/química , Óleos Vegetais/química , Sesquiterpenos de Guaiano/química , Vias Biossintéticas , Cromatografia Gasosa-Espectrometria de Massas , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular
6.
J Chromatogr A ; 1487: 248-253, 2017 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-28139224

RESUMO

This work presents the development of a simple and efficient analytical protocol for the direct enantioselective resolution of sugars. A racemic mixture of the C3 sugar d,l-glyceraldehyde and the C5 monosaccharides d,l-arabinose, d,l-ribose, d,l-xylose, and d,l-lyxose was subjected to derivatization with trifluoroacetic anhydride, and corresponding derivatives were separated on a ß-cyclodextrin column with excellent resolution factors. Even though each aldopentose shows beside the linear form four predominant cyclic hemiacetals being the α- and ß-furanose along with the α- and ß-pyranose, we show that the overall enantiomeric excess of each compound can be precisely determined. Moreover, the measured detection limit for derivatized aldopentoses ranges from 0.015 to 0.019pmol on the column, while the quantification limit varies from 0.5 to 0.64pmol on the column.


Assuntos
Cromatografia Gasosa/métodos , Monossacarídeos/análise , Arabinose/análise , Arabinose/isolamento & purificação , Monossacarídeos/química , Monossacarídeos/isolamento & purificação , Pentoses/análise , Pentoses/isolamento & purificação , Ribose/análise , Ribose/isolamento & purificação , Estereoisomerismo , Xilose/análise , Xilose/isolamento & purificação
7.
Science ; 355(6321): 141, 2017 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-28082555

RESUMO

We detected ribose and related sugars in the organic residues of simulated interstellar ices using multidimensional gas chromatography. Kawai questions the formation of sugar compounds in the ices and suggests that they arise from a classical formose reaction during sample workup for analysis. We disagree with this hypothesis and present additional data to argue that Kawai's criticism does not apply.


Assuntos
Gelo/análise , Ribose , Meio Ambiente Extraterreno , Compostos Orgânicos , Raios Ultravioleta
8.
Astrobiology ; 17(6-7): 655-685, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31067288

RESUMO

The Mars Organic Molecule Analyzer (MOMA) instrument onboard the ESA/Roscosmos ExoMars rover (to launch in July, 2020) will analyze volatile and refractory organic compounds in martian surface and subsurface sediments. In this study, we describe the design, current status of development, and analytical capabilities of the instrument. Data acquired on preliminary MOMA flight-like hardware and experimental setups are also presented, illustrating their contribution to the overall science return of the mission. Key Words: Mars-Mass spectrometry-Life detection-Planetary instrumentation. Astrobiology 17, 655-685.

9.
Angew Chem Int Ed Engl ; 55(44): 13719-13723, 2016 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-27699963

RESUMO

Frankincense (olibanum) is one of the oldest aromatic materials used by humans, but the key molecular constituents contributing to its characteristic odor remained unknown. Reported herein is the discovery that (1S,2S)-(+)-trans- and (1S,2R)-(+)-cis-2-octylcyclopropyl-1-carboxylic acids are highly potent and substantive odorants occurring in ppm amounts in all of the frankincense samples analyzed, even those showing radically different volatile compositions. These cyclopropyl-derived acids provide the very characteristic old churchlike endnote of the frankincense odor.

10.
Science ; 352(6282): 208-12, 2016 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-27124456

RESUMO

Ribose is the central molecular subunit in RNA, but the prebiotic origin of ribose remains unknown. We observed the formation of substantial quantities of ribose and a diversity of structurally related sugar molecules such as arabinose, xylose, and lyxose in the room-temperature organic residues of photo-processed interstellar ice analogs initially composed of H2O, CH3OH, and NH3 Our results suggest that the generation of numerous sugar molecules, including the aldopentose ribose, may be possible from photochemical and thermal treatment of cosmic ices in the late stages of the solar nebula. Our detection of ribose provides plausible insights into the chemical processes that could lead to formation of biologically relevant molecules in suitable planetary environments.


Assuntos
Radiação Cósmica , Gelo , Origem da Vida , RNA/química , Ribose/síntese química , Ácido Acético/química , Amônia/química , Arabinose/síntese química , Meio Ambiente Extraterreno , Meteoroides , Pentoses/síntese química , Processos Fotoquímicos , Raios Ultravioleta , Xilose/síntese química
11.
J Chromatogr A ; 1433: 131-6, 2016 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-26803906

RESUMO

This work presents an improved analytical procedure for the resolution and quantification of amino acid enantiomers by multidimensional gas chromatography. The procedure contains a derivatization step, by which amino acids were transformed into N(O,S)-ethoxycarbonylheptafluorobutyl esters. It was optimized for the resolution of non-proteinogenic amino acids in the matrix of complex non-terrestrial samples. The procedure has proven to be highly sensitive and shows a wide linearity range with 0.005-3 pmol detection limits for quantitative determinations. The developed procedure was tested on a sample of the Murchison meteorite, for which obtained chromatograms show excellent peak resolution, minimal co-elution and peak overlap. We conclude that comprehensive two dimensional chromatography, in combination with the optimized derivatization method is a highly suitable technique for the analysis of samples with very limited quantities and containing potentially prebiotic molecules, such as interstellar ice analogs and meteorites.


Assuntos
Aminoácidos/isolamento & purificação , Meteoroides , Cromatografia Gasosa/métodos , Estereoisomerismo
12.
Science ; 349(6247): aab0689, 2015 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-26228156

RESUMO

Comets harbor the most pristine material in our solar system in the form of ice, dust, silicates, and refractory organic material with some interstellar heritage. The evolved gas analyzer Cometary Sampling and Composition (COSAC) experiment aboard Rosetta's Philae lander was designed for in situ analysis of organic molecules on comet 67P/Churyumov-Gerasimenko. Twenty-five minutes after Philae's initial comet touchdown, the COSAC mass spectrometer took a spectrum in sniffing mode, which displayed a suite of 16 organic compounds, including many nitrogen-bearing species but no sulfur-bearing species, and four compounds­methyl isocyanate, acetone, propionaldehyde, and acetamide­that had not previously been reported in comets.

13.
J Agric Food Chem ; 63(20): 4922-32, 2015 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-25942486

RESUMO

This study investigates the concentrations of 54 multiclass pesticides during the transformation processes from rose petal to concrete and absolute using roses spiked with pesticides as a model. The concentrations of the pesticides were followed during the process of transforming the spiked rose flowers from an organic field into concrete and then into absolute. The rose flowers, the concrete, and the absolute, as well as their transformation intermediates, were analyzed for pesticide content using gas chromatography/tandem mass spectrometry. We observed that all the pesticides were extracted and concentrated in the absolute, with the exception of three molecules: fenthion, fenamiphos, and phorate. Typical pesticides were found to be concentrated by a factor of 100-300 from the rose flowers to the rose absolute. The observed effect of pesticide enrichment was also studied in roses and their extracts from four classically phytosanitary treated fields. Seventeen pesticides were detected in at least one of the extracts. Like the case for the spiked samples in our model, the pesticides present in the rose flowers from Turkey were concentrated in the absolute. Two pesticides, methidathion and chlorpyrifos, were quantified in the rose flowers at approximately 0.01 and 0.01-0.05 mg kg(-1), respectively, depending on the treated field. The concentrations determined for the corresponding rose absolutes were 4.7 mg kg(-1) for methidathion and 0.65-27.25 mg kg(-1) for chlorpyrifos.


Assuntos
Perfumes/análise , Resíduos de Praguicidas/química , Rosa/química , Flores/química , Cromatografia Gasosa-Espectrometria de Massas
14.
Orig Life Evol Biosph ; 45(1-2): 149-61, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25773582

RESUMO

All life on Earth is characterized by its asymmetry - both the genetic material and proteins are composed of homochiral monomers. Understanding how this molecular asymmetry initially arose is a key question related to the origins of life. Cometary ice simulations, L-enantiomeric enriched amino acids in meteorites and the detection of circularly polarized electromagnetic radiation in star-forming regions point to a possible interstellar/protostellar generation of stereochemical asymmetry. Based upon our recently recorded anisotropy spectra g(λ) of amino acids in the vacuum-UV range, we subjected amorphous films of racemic (13)C-alanine to far-UV circularly polarized synchrotron radiation to probe the asymmetric photon-molecule interaction under interstellar conditions. Optical purities of up to 4% were reached, which correlate with our theoretical predictions. Importantly, we show that chiral symmetry breaking using circularly polarized light is dependent on both the helicity and the wavelength of incident light. In order to predict such stereocontrol, time-dependent density functional theory was used to calculate anisotropy spectra. The calculated anisotropy spectra show good agreement with the experimental ones. The European Space Agency's Rosetta mission, which successfully landed Philae on comet 67P/Churyumov-Gerasimenko on 12 November 2014, will investigate the configuration of chiral compounds and thereby obtain data that are to be interpreted in the context of the results presented here.


Assuntos
Alanina/química , Evolução Química , Raios Ultravioleta , Anisotropia , Meio Ambiente Extraterreno , Estereoisomerismo , Síncrotrons
15.
J Chromatogr A ; 1383: 134-43, 2015 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-25622519

RESUMO

Comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) has been shown to permit for the unprecedented chromatographic resolution of volatile analytes encompassing various families of organic compounds. However, peak identification based on retention time, two-dimensional mapping, and mass spectrometric fragmentation only, is not a straightforward task yet. The possibility to establish molecular links between constituents is of crucial importance to understand the overall chemistry of any sample, especially in natural extracts where biogenetically related isomeric structures are often abundant. We here present a new way of using GC×GC that allows searching for those molecular connectivities. Analytical investigations of essential oil constituents by means of GC×GC-MS permitted to observe in real time the thermally-induced transformations of various sesquiterpenic derivatives. These transformations generated a series of well-defined two-dimensional peak bridges within the 2D-chromatograms connecting parent and daughter molecules, thus permitting to build a clear scheme of structural relationship between the different constituents. GC×GC-MS appears here as a tool for investigating chromatographic phenomena and analyte transformations that could not be understood with conventional GC-MS only.


Assuntos
Técnicas de Química Analítica/instrumentação , Cromatografia Gasosa-Espectrometria de Massas , Óleos Voláteis/análise , Espectroscopia de Ressonância Magnética , Óleos Voláteis/química , Sesquiterpenos/análise , Sesquiterpenos/isolamento & purificação , Terpenos/análise , Terpenos/química
16.
Proc Natl Acad Sci U S A ; 112(4): 965-70, 2015 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-25583475

RESUMO

Evolved interstellar ices observed in dense protostellar molecular clouds may arguably be considered as part of precometary materials that will later fall on primitive telluric planets, bringing a wealth of complex organic compounds. In our laboratory, experiments reproducing the photo/thermochemical evolution of these ices are routinely performed. Following previous amino acid identifications in the resulting room temperature organic residues, we have searched for a different family of molecules of potential prebiotic interest. Using multidimensional gas chromatography coupled to time-of-flight mass spectrometry, we have detected 10 aldehydes, including the sugar-related glycolaldehyde and glyceraldehyde--two species considered as key prebiotic intermediates in the first steps toward the synthesis of ribonucleotides in a planetary environment. The presence of ammonia in water and methanol ice mixtures appears essential for the recovery of these aldehydes in the refractory organic residue at room temperature, although these products are free of nitrogen. We finally point out the importance of detecting aldehydes and sugars in extraterrestrial environments, in the gas phase of hot molecular clouds, and, more importantly, in comets and in primitive meteorites that have most probably seeded the Earth with organic material as early as 4.2 billion years ago.

17.
Angew Chem Int Ed Engl ; 54(5): 1402-12, 2015 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-25431250

RESUMO

Life, as it is known to us, uses exclusively L-amino acid and D-sugar enantiomers for the molecular architecture of proteins and nucleic acids. This Minireview explores current models of the original symmetry-breaking influence that led to the exogenic delivery to Earth of prebiotic molecules with a slight enantiomeric excess. We provide a short overview of enantiomeric enhancements detected in bodies of extraterrestrial origin, such as meteorites, and interstellar ices simulated in the laboratory. Data are interpreted from different points of view, namely, photochirogenesis, parity violation in the weak nuclear interaction, and enantioenrichment through phase transitions. Photochemically induced enantiomeric imbalances are discussed more specifically in the topical context of the "chirality module" on board the cometary Rosetta spacecraft of the ESA. This device will perform the first enantioselective in situ analyses of samples taken from a cometary nucleus.

18.
Chem Biodivers ; 11(11): 1821-42, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25408325

RESUMO

Vetiver oil is a highly esteemed basic ingredient of modern perfumery, but the nature of the constituents that really impart its typical and most sought woody-earthy scent has remained controversial. Indeed, vetiver oil is considered as one of the most complex essential oils, being mostly composed of several hundreds of sesquiterpene derivatives with a large structural diversity. Its complexity has hindered the direct identification of its odoriferous components. We thus aimed at using a combination of GC×GC/MS and GC-Olfactometry in order to identify most of its odor-impact constituents. The olfactory analysis of vetiver oil and vetiveryl acetate revealed a huge variety of odors in both products. While khusimone has almost unanimously been recognized as the most characteristic vetiver odorant, we have identified several even more important contributors to the typical vetiver character.


Assuntos
Vetiveria/química , Odorantes/análise , Óleos Vegetais/química , Cromatografia Gasosa , Espectrometria de Massas , Conformação Molecular , Olfatometria
19.
Chem Biodivers ; 11(11): 1843-60, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25408326

RESUMO

A series of eleven ß-santalol analogs, including nine new derivatives, was prepared by semisynthesis from natural (-)-(Z)-ß-santalol and studied by gas chromatography-olfactometry (GC-O) to characterize their olfactory properties and potencies. These compounds and 45 others selected in the literature were used to build three olfactophores by molecular modelling. Three models were obtained that gather structural and physicochemical constraints that will be useful for further design of new sandalwood odorants.


Assuntos
Odorantes , Santalum/química , Sesquiterpenos/química , Sesquiterpenos/síntese química , Cromatografia Gasosa , Estrutura Molecular , Olfatometria
20.
Anal Bioanal Chem ; 406(30): 8041-8, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25344932

RESUMO

Damascena and centifolia roses are cultivated worldwide for their petal extracts that contain key odorant ingredients of perfumes. The analytical identification and quantification of pesticides in rose petals have never been described in the literature. Here, we report on a newly developed method using dispersive solid-phase extraction (d-SPE) cleanup followed by gas chromatography-tandem mass spectrometry for the quantitative determination of multi-residue pesticides in rose petals. Analytes were extracted from the matrix using acetonitrile and a mixture of salts containing magnesium sulfate, sodium citrate, sodium chloride, and sodium sesquihydrate. Samples were cleaned up twice by d-SPE applying primary and secondary amines (PSAs), magnesium sulfate, C18, and graphitized carbon black (GCB). Two fortification levels of 0.05 and 0.5 mg kg(-1) were assessed for method validation purposes. The obtained pesticide recoveries were in the range of 70-120 % with a relative standard deviation (RSD) of less than 20 %. The newly developed method was allowed for the quantification of 57 pesticides residues. It was applied to pesticide residue detection in rose petals from an organic field, without treatment, compared to those from a field with classic phytosanitary treatment using fungicide and/or insecticide. We did not detect pesticide residues in rose petals from the organic field. The classically treated samples of roses contained pesticides such as chlorpyriphos and methidathion which are in accordance with the previous application of these pesticides on the roses. Insecticides were quantified at 0.05 mg kg(-1) rose petal maximum.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Rosa/química , Extração em Fase Sólida/métodos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA