Search

Further lipophilic flavonols present in Vellozia graminifolia have been determined by high temperature high resolution gas chromatography (HTHRGC) and by HTHRGC coupled to mass spectrometry (MS). These methods resulted in the detection, isolation and characterisation of a monoisoprenylated flavonol 3,5,4′-trimethoxy-3′-hydroxy-6,7-(2″-isopropenyldihydrofurano)flavone from the ethyl acetate extract of the whole plant. The structural elucidation was accomplished using spectral data, including two-dimensional NMR, and on chemical transformations. Both HTHRGC and HTHRGC-MS were shown to be alternative and extremely valuable methods for the quick screening of flavonoid aglycones and other chemical metabolites of the Velloziaceae. Copyright © 2001 John Wiley & Sons, Ltd.

The terpenes, sterols, alkaloid (glaucine) and α-tocopherol show seasonal variation for Croton hemiargyreus hemiargyreus and Croton echinocarpus. The amounts of triterpenes are higher during the tropical summer and in most samples the major sesquiterpene was characterized as caryophyllene. The seasonal variation of glaucine showed a maximum between June and October for C. hemiargyreus, and was present only in January and June in C. echinocarpus.

The developments in stationary-phase synthesis and capillary column technology have opened new perspectives in the analysis of high-molecular-weight compounds (600 daltons) and thermolabile organic compounds by high-temperature-high-resolution gas chromatography. This branch of high-resolution gas chromatography deals with analysis performed up to 390 degrees C oven temperature (with some applications going up to 420 degrees C and even a few applications to 450 degrees C maximum). The technique has been applied to many different fields of science (e.g., organic geochemistry, environmental chemistry, archeology, and natural product research). Apolar and medium-polar gum phases can now be operated at temperatures from 400 to 480 degrees C, but these higher temperatures are seldom used because of the thermostability of the material used to make the capillary tubing. This paper shows the performance of nine commercial high-temperature columns when used in routine applications.

Chiral GC separation of (+/-)-2-allyl-2-carboethoxycyclopentanone (9) and the alcohols (+/-)-3-(hydroxymethyl)-5-carboethoxy-2-oxabicyclo[3.3.0]octane (7), (+/-)-2-allyl-2-carboethoxycyclopentanol (8), and their acetylated and trifluoroacetylated derivatives were investigated on three derivatized beta-cyclodextrins (CDs) diluted in SE-54 or 1701-OH: 2,3,6-tri-O-methyl-beta-CD (PMCD); 2,3-di-O-methyl-6-O-(tert-butyldimethylsilyl)-beta-CD (DIMETBCD); 2,3-di-O-acetyl-6-O-(tert-butyldimethylsilyl)-beta-CD (DIACTBCD). The understanding of these chiral separations is extremely relevant, since cyclopentanic and bicyclic cyclopentanic rings are common structural features of many important natural products and new pharmaceutical drugs. In general DIMETBCD diluted in SE-54 showed the best chiral resolution to alcohols 7 and 8 and only DIACTBCD showed enantioselectivity to 9. Hydrogen bonds prediction and dipole moments data were obtained by molecular modeling calculations for 7ab and 8ab and Ac and TFA derivatives. Comparison of these data with the chromatographic parameters for the related compounds were used to explain the differences of their elution orders and diastereo- and enantiomeric separations on the above chiral stationary phases (CSPs). The results suggest that the CSPs enantioselectivities are not affected by the carboethoxy-functionalized cyclopentanic and bicyclic cyclopentanic rings themselves but mainly by the functional group on the other stereogenic center.

The crude ethanol extracts from the leaves of three Croton hemiargyrus hemiargyreus plants are fractionated by thin-layer chromatography, yielding five fractions. The fractions and the crude extract are analyzed by high-temperature high-resolution gas chromatography coupled with mass spectrometry (HT-HRGC-MS). Several natural products, including thermolabile components, can be characterized directly in the samples, such as alkaloids, terpenes, flavonoids, acids, alcohols, etc. The cold on-column technique proves to be appropriate for the injection of these thermolabile compounds. HT-HRGC-MS is shown to be a valuable tool and an alternative technique to classical phytochemical procedures for the simple and fast routine analysis of natural products in crude extracts.

A glass capillary column coated with PS-086 (15% phenyl-80% methylpolysiloxane, 15 m x 0.30-mm i.d., 0.1-microm film thickness) is used to analyze extracts from Lonchocarpus urucu (Derris urucu). Several secondary metabolites (8 flavonoids, 10 rotenoids) are characterized without derivatization, and the rotenoids are quantitated by high-temperature high-resolution gas chromatography (HTHRGC) and HTHRGC coupled with mass spectrometry (HTHRGC-MS). The limit of detection in flame ionization detection of rotenone is approximately 0.5 microg/mL, and the limit of quantitation was 2 microg/mL. Derris urucu bark is an excellent source of rotenone isomers (80 mg/g), deguelin (30 mg/g), and rotenolone (26 mg/g). Single solvent extractions (hexane, methylene dichloride, acetone, or methanol) are not able to fully extract the flavonoids and rotenoids. Complete extraction is achieved using a mixture of methanol-methylene dichloride (1:1), indicating a complex association of these compounds with the plant tissue. HTHRGC and HTHRGC-MS are shown to be quick and informative tools for the rapid analysis of crude extracts without the need for prior derivatization and fractionation.

Two extraction/clean-up analytical procedures were investigated and compared regarding their recovery and matrix-purification efficiency for screening beta2-agonist residues in fortified bovine urine by high-resolution gas chromatography-mass spectrometry (GC-MS). The first procedure, based on an analytical method originally developed for detecting anabolic steroids, consists of the employment of the nonionic resin, Amberlite XAD-2, a styrene-divinylbenzene copolymer for solid-phase extraction (SPE), followed by liquid-liquid extraction with diethyl ether. The second focuses on the use of a mixed SPE cartridge (reversed-phase and ion-exchange sorbent, Bond Elut Certify). In both cases, the trimethylsilylated derivatives were analyzed by GC-MS with an ion-trap detector. Clenbuterol, salbutamol, and terbutaline were used to spike urine samples during the comparison experimental phase. Afterwards, tulobuterol, mabuterol, mapenterol, cimbuterol, and brombuterol were included in the evaluation of the second procedure (the Bond Elut Certify procedure). At this stage, the detection was accomplished by GC-MS (quadrupole mass analyzer) with selective ion monitoring acquisition. The isotopic dilution method with the hexadeuterated analogues of clenbuterol and salbutamol was applied to prepare calibration curves and calculate recovery percentages. With XAD-2 resin, terbutaline and salbutamol (resorcinol and phenol-type beta2-agonists, respectively) could not be detected at 20 ng/mL or at 40 ng/mL. In spite of clenbuterol having been detected at 20 ng/mL, the results obtained were not reproducible. The use of the reversed-phase and ion-exchange sorbent Bond Elut Certify allowed multiresidue detection and showed several advantages for the screening of clenbuterol such as higher recoveries, cleaner final extracts, reduced sample preparation time, less labor intensive, and easier solvent consumption and disposal. Recoveries over 88% (concentrations ranging from 0.5 to 10 ppb) and limits of detection equal to 0.5 ppb were met for all the beta2-agonists studied with the last method.

Utilization of whole oil biomarker analysis in oil prospecting through routine work with HRGC. Several measures, to prevent deposition of involatile material in the column inlet and to guarantee good resolution and sensitivity are proposed

[Abstract [ A method and evaluated for screening and confirmation of diethylstilbestrol (DES), cr and [~-zearalanol in bovine urine was developed. The residues were extracted from urine by Cls cartridges and purified on alumina columns. For screening and confirmation purposes, the anabolic derivatives were analyzed by gas chromatography-mass spectrometry after derivatization with BSTFA + 1% TMCS or a solution of PFPMacetone (1:2, v/v), respectively. The recovery of most analytes for the whole procedure was higher than 96%, with a detection limit of 0.5 ppb. This procedure is being routinely applied to the Brazilian National Program for the Control of Residues in Meat (PNCRBC).

Clostebol is a synthetic androgenic steroid with anabolic effects that is frequently used in sports to increase physical performance. Because of medical and ethical reasons, the use of clostebol is prohibited by the International Olympic Committee (IOC) (1), and its misuse would fall under the strict liability rule of the IOC and the World Antidoping Agency. It is therefore the responsibility of athletes to submit evidence contrary to any ruling issued against them by the appropriate sports body. Despite the prohibition against the use of clostebol, abuse of this steroid is increasing, mainly in Brazilian athletes. In Brazil, clostebol acetate is present in medicines for dermatologic and gynecologic treatments, whereas in the US, the Food and Drug Administration does not approve of the use of medicines that contain anabolic agents. Our laboratory, LABDOP, is accredited by the IOC …

The distributions of biomarkers (triterpanes, steranes) in the hydrocarbon fractions of the Tremembe (Sao Paulo), Marau (Bahia), and Irati (Parana) oil-shales were examined by gas chromatography-mass spectrometry. The stereochemistry of these biomarkers allowed inferences about the relative levels of maturity of the shales, with the carbon number distributions of the steranes yielding information as to lhe principal types of organic input to the sediments. The distributions of biomarkers in extracts were confirmed by examination of pyrolyzates, an approach which proved effective in ruling out the possibility of low level impregnation of one of the shales (Marau) by petroleum from the sub-surface.

This study involves the use of molecular parameters (steranes and terpanes) and carbon isotopes as stratigraphic correlation markers in a Lower Cretaceous lacustrine sequence from the Espirito Santo Basin, southeast Brazil. The biomarker variations revealed changes in sedimentary environment that had not been detected by sedimentological, paleontological and seismistratigraphic methods. Additionally, the observed variations, assumed to have been contemporary for the whole Basin, could also be used as chronostratigraphic markers. The carbon isotope data led to the recognition of two sedimentary sequences. The upper sequence ( δ 13 C around − 26‰ ) begins with very low amounts of gammacerane and of a novel C24 tetracyclic alkane, apparently with a des-A-hopane structure. A sharp increase in concentration of the C24 compound divided the upper sequence into two stratigraphic subunits, the second of which shows an increasing gammacerane concentration with depth. The lower sequence ( δ 13 C around − 28‰ ) starts with a distinct drop in abundance levels of the C24 tetracyclic alkane and of methyl-steranes. Gammacerane concentrations attain a maximum at the top of this sequence, showing subsequently a decreasing trend with depth, but remaining reasonably high throughout the sequence. However, a second sharp decrease of the C24 tetracyclic alkane shows a modification in sedimentary environment downwards. Combined, all these stratigraphic changes delimitate four depositional cycles which could be easily recognized in wells from the eastern part of the basin showing gradual erosion updip to the west. Such sedimentary changes could be correlated with independent geochemical information on neighbouring lacustrine sequences, of the same age, suggesting a dominant freshwater influence in the basal part of the sequence, contrasted with a more saline environment in the upper levels. The use of these markers has been of great value in redefining stratigraphic correlations in the Espirito Santo Basin and may prove useful to resolve similar difficulties in vicinal areas.

The distributions of polycyclic alkanes were monitored in a Neocomian sequence (well 1-ESS-34) from the Espirito Santo Basin, southeast Brazil. The profiles included, apart from regular hopanes, significant concentrations of 18α(H), 28,30-bisnorhopane and subordinate amounts of gammacerane. Sterane concentrations, normally with hopane/sterane

Resting cells of Kluyveromyces marxianus were used in the bioreduction of ethyl 4,4,4-trifluoro-3-oxobutanoate and ethyl 4,4,4-trichloro-3-oxobutanoate with 81% and 4% yields and 29% and 73% enantiomeric excess, respectively. The differences observed were attributed to the tri-halide structures.

A new cassane diterpene was isolated from the bark of seeds of Dipterix odorata together with four known diterpenoids with the same skeleton.

The quinic acid derivatives (including 4-feruoyl quinic and 5-ferruoyl quinic acids characterized for first time in propolis samples) and other phenolic compounds were quantified in thirteen Brazilian propolis samples by HPLC analysis. For chemometrical analysis, the distribution of quinic acid derivatives and other phenolic compounds were considered. The results suggest that the Brazilian propolis with floral origin from Citrus sp. have the highest concentration of the quinic acid derivatives (between 11.0 to 58.4 mg/mg of the dried crude hydroalcoholic extract) and therefore would probably show a more effective hepatoprotective activity.

All the methyl-proton resonances of friedelin (1) have been assigned by n.O.e.-difference spectroscopy. The observation of substantial enhancements between Me-26 and Me-28, and between Me-28 and Me-30 can be explained by invoking boat conformations for rings D and E, in agreement with the crystal structure of a related compound. Methyl assignments were independently confirmed by lanthanide-shift experiments. Methyl spin–lattice relaxation times reflect steric crowding by other methyl groups and may provide a useful assignment tool.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTITUIÇÕES COMUNITÁRIAS DE ENSINO PARTICULARES Este trabalho teve como objetivo caracterizar química e morfologicamente material particulado (PM2.5 e PM10) coletado na zona sul e oeste da cidade de Rio de Janeiro e na região metropolitana, utilizando técnicas como a Cromatografia de íons (CI), Espectrometria de Massas com Plasma Indutivamente Acoplado (ICPMS) e a Microscopia Eletrônica de Varredura acoplada ao Espectrômetro de RaiosX por Dispersão de Energia (MEV-EDX). Além disso, foram realizados ensaios toxicológicos com C. elegans para avaliar os efeitos da exposição ao material particulado (MP), nas diferentes frações de tamanho. Concentrações médias anuais de PM2.5 entre 7,40 +/- 3,96 (micrograma)m-3 e 17,4 +/- 7,38 (micrograma) m-3 foram medidas durante os anos 2015 e 2018, as quais foram inferiores ao padrão intermediário da qualidade do ar, estabelecido pelo CONAMA, registando-se as maiores médias anuais durante o 2016, ano em que foram realizados os Jogos Olímpicos. Resultados das análises químicas mostraram que o MP em todos os pontos de coleta estava constituído principalmente por espécies iônicas como Cl- , NO3 - , Na+ e SO4 2- e elementos como V, Ni, Cu, Cd, Sn e Pb, sendo determinadas apenas variações significativa (p menor que 0,05) nas concentrações de SO4 2- , NO3 - , Na+ , Cu e Sn, entre os períodos estudados. Através dos resultados das análises de MEV-EDX as partículas atmosféricas se classificaram segundo sua morfologia – Fuligem, esféricas, biológica e minerais- e segundo sua composição elementar – partículas com teor de enxofre, de cloro e de ferro -. Finalmente, efeitos tóxicos foram observados pela exposição ao PM10 e PM2.5 em organismos C. elegans, alterando parâmetros fisiológicos (e.g. crescimento e reprodução) e promovendo respostas dos mecanismos antioxidantes, como resultado do estresse oxidativo gerado por espécies presentes no MP. This work aimed to characterize chemically and morphologically particulate matter (PM2.5 and PM10) collected in the south and west zones of the city of Rio de Janeiro and in the metropolitan region, using techniques such as ion chromatography (IC), inductively coupled plasma mass spectrometry (ICP-MS) and Scanning electron microscopy- energy dispersive spectrometry (SEM-EDX). Annual mean concentrations of PM2.5 between 7,40 +/- 3,96 microgram m-3 e 17,4 +/- 7,38 microgram m-3 were measured during the years 2015 and 2018, which were lower than the intermediateair quality standard established by CONAMA, with the highest annual averages recorded during 2016, the year in which the Olympic Games were held. In addition, toxicological tests were performed with C. elegans to evaluate the effects of exposure to particulate matter (PM) in the different size fractions. Results of the chemical analysis showed that PM at all collection sites consists mainly of ionic species such Cl- , NO3 - , Na+ and SO4 2- and elements such as V, Ni, Cu, Cd, Sn and Pb, being determined only significant variations (p less than 0,05) in the concentrations of SO4 2- , NO3 - , Na+ , Cu, and Sn, between the studied periods. Based on the results of the SEM-EDX analysis, atmospheric particles were classified according to their morphology – Soot, spherical, biological and minerals- and according to their elemental composition – particles with sulfur, chlorine and iron content. Finally, toxic effects were observed by exposure C. elegans organisms to PM10 and PM2.5, altering physiological parameters (e.g growth and reproduction) and promoting antioxidant mechanisms responses, as a result of oxidative stress generated by compounds present in the PM.