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O carcinoma de células escamosas bucal (CCEB) representa 90% das neoplasias malignas da região intrabucal. O desenvolvimento dessa doença é multifatorial, envolvendo fatores genéticos e ambientais que podem ser, muitas vezes, desconhecidos e que podem apresentar modificação das vias metabólicas. Assim, o objetivo desta pesquisa foi identificar os metabólitos salivares de pacientes com CCEB na busca de vias metabólicas alteradas, assim como possíveis biomarcadores metabólicos. Os metabólitos salivares de 27 pacientes com CCEB foram comparados aos metabólitos de 41 pacientes controles. As amostras de metaboloma salivar foram analisadas por meio de cromatógrafo gasoso acoplado a um espectrômetro de massa (GC-MS). Os resultados indicaram 26 metabólitos específicos para o grupo CCEB e 5 específicos do grupo controle. No diagrama de Venn foram observados 77 metabólitos comuns aos dois grupos. Esta análise foi crucial para a descoberta de três vias metabólicas com diferença estatística entre os grupos: a lançadeira malato-aspartato, a via do metabolismo da beta-alanina e o efeito Warburg. Todas essas vias relacionam-se com a produção de energia celular na carcinogênese, promovendo um ambiente favorável para o alto consumo energético e sobrevivência celular. Ao comparar os metabólitos salivares de pacientes controles e com câncer bucal, 40 metabólitos foram capazes de distinguir os grupos estatisticamente, sendo 20 metabólitos aumentados nos pacientes com carcinoma e 20 aumentados nos pacientes sem a doença. Com a finalidade de identificar os metabólitos como possíveis biomarcadores salivares, a curva ROC foi traçada e um corte de 0,8 no AUC foi construído descobrindo-se 24 metabólitos. Após um novo corte nos metabólitos com AUC de 0,9, metabólitos como ureia, leucina, inosina e metionina puderam ser explorados como candidatos a biomarcadores metabolômicos salivares de pacientes com CCEB já relatados na literatura. Além destes, 6 outros metabólitos apresentaram AUC acima de 0,9 e são relatados pela primeira vez em um estudo de metaboloma salivar de pacientes sul-americanos com câncer bucal, são estes: o ácido málico, maltose, ácido protocatecuico, lactose, ácido-2-cetoadípico e catecol. Essas alterações metabólicas auxiliam na descoberta de biomarcadores salivares de pacientes com câncer bucal e despertam o interesse para que haja outros estudos com maior número de amostras no intuito de validar nossos resultados(AU)

Oral squamous cell carcinoma (CCEB) represents 90% of intraoral malignant neoplasms. The development of this disease is multifactorial, involving genetic and environmental factors that can often be unknown and can present the modification of metabolic pathways. Thus, the objective of this research was to identify the salivary metabolites of patients with CCEB in the search of altered metabolic pathways, as well as possible metabolic biomarkers. The salivary metabolites of 27 patients with CCEB were compared to the metabolites of 41 control patients. The salivary metabolome samples were analyzed using a gas chromatograph coupled to a mass spectrometer (GC-MS). The results indicated 26 specific metabolites for the CCEB group and 5 specifics for the control group. In the Venn diagram 77 other metabolites common to both groups were observed. This analysis was crucial for the discovery of three metabolic pathways with statistical difference between the groups: the malateaspartate shuttle, the beta-alanine metabolism pathway and the Warburg effect. All of these pathways are related to the production of cellular energy in carcinogenesis, promoting a favorable environment for high energy consumption and cell survival. When comparing the salivary metabolites of control patients with oral cancer, 40 metabolites were able to distinguish the groups statistically, with 20 metabolites increased in patients with carcinoma and 20 increased in patients without the disease. In order to identify the metabolites as possible salivary biomarkers, the ROC curve was drawn and a cohort of 0.8 in the AUC was performed by discovering 24 metabolites. After a new cohort of metabolites with AUC of 0.9, metabolites such as urea, leucine, inosine and methionine could be explored as possible salivary metabolomic biomarkers of patients with CCEBs already reported in the literature. In addition to these, 6 other metabolites showed AUC above 0.9 and are reported for the first time in a study of salivary metabolome in South American patients with oral cancer, these are: malic acid, maltose, protocatechuic acid, lactose, 2-ketoadipic and catechol. These metabolic changes help in the discovery of salivary biomarkers of patients with oral cancer and arouse interest for further studies with a larger number of samples in order to validate our results(AU)

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A method to simultaneously extract polar (PC) and non-polar compounds (NPC) from microalgae was developed for further determination of intracellular metabolites by gas chromatography. The proposed method was validated and used to characterize two Chlorophyceae, Chlorella vulgaris and Scenedesmus obliquus, and two Cyanobacteria, Aphanothece microscopica Nagëli and Phormidium autumnale. The compounds were extracted with a reduced amount of organic solvent mixture (methanol-chloroform), compared to the reference method, under different conditions of homogenization and/or cell disruption. The NPC were derivatized by acid catalysis, whereas the PC fraction was derivatized using N-methyl,N-tert-Butyldimethylsilyltrifluoroacetamide (MTBSTFA) in alkaline medium. The following parameters for method validation were considered: selectivity, linearity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. All methods of homogenization and cell disruption extracted both PC and NPC from Chlorophyceae and Cyanobacteria. Derivatization of PC presented satisfactory validation parameters. Eleven fatty acids, six free amino acids, and three organic acids were found within the evaluated microalgae species, succinic, malic, and citric acids, important intermediates of the tricarboxylic acid cycle. Glutamic acid was the amino acid found in greatest quantities in all species. Chlorophyceae presented a higher concentration of unsaturated fatty acids, while Cyanobacteria had more saturated fatty acids. Thus, the proposed method was suitable to metabolically characterize both PC and NPC from microalgae.

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2,5-Hexanedione (2,5-HD) is the most important metabolite of n-hexane and methyl ethyl ketone in human urine. Urinary 2,5-HD is used as a biomarker for biological monitoring of workers exposed to n-hexane. A simple method using headspace solid-phase microextraction (HS-SPME) and gas chromatography (GC) equipped with a flame-ionization detector (FID) was developed. The parameters that affect the HS-SPME-GC-FID process were optimized (i.e., fiber coating, sample volume, adsorption and heating time, salt addition, and extraction temperature). The assay presented linearity in the range of 0.075 to 20.0 mg/L, precision (coefficient of variation < 7.0%), and detection limit of 0.025 mg/L for 2,5-HD in urine. The method was successfully applied to the analysis of 2,5-HD in urine samples from eight workers occupationally exposed to n-hexane in shoemaker's glue.

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D003 is a new product composed of a mixture of aliphatic fatty acids (C(24:0) to C(36:0)), which shows antiplatelet, antithrombotic, antioxidant, and cholesterol-lowering effects in experimental models and human beings. A gas chromatographic method using a DB-5 wide-bore column and 1-nonadecanoic acid as internal standard was developed and validated in order to determine D003 in 10 mg film-coated tablets. The acids were analysed as methyl esters derivatives, prepared using 5% aqueous HCl-methanol. Developed method was specific for the active principle, even when samples were subjected to stress conditions. Good linearity (correlation coefficient > 0.99) and accuracy (total average recovery = 100.29%) were proven over a range 50-150% of the nominal concentration. Within-day and intermediate precisions at the nominal dose (100%) were < 1.5%. Robustness was examined through an intralaboratory study, quantification and resolution were only affected by the injection volume increase and no other of the 7 operational changes evaluated affected the results. The method was suitable for quality control and stability studies of these tablets.

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This review covers theoretical principles and experimental procedures for the determination of gas-liquid partition coefficients, KL, by gas chromatography. In order to precisely define the relationship between KL, retention time and experimental parameters, the retention theory, both for ideal and for imperfect gas phase, is expounded. The most important sources of systematic error, as peak asymmetry, mixed retention mechanisms, column hold-up time and stationary phase mass determination, are discussed. Although the review is focussed on packed columns, comparison to capillary columns is discussed in those aspects in which these last show advantages.

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The method's accuracy of a compound quantitation by chromatography depends on the calibration procedure with a pure standard of the target analyte, if the latter is unavailable uncertainty is unavoidable. The group method is a different approach in GC quantitative analysis that shows a practicable way for avoiding this uncertainty and accurately quantify a mixture containing one or more unavailable components. This paper is concerned with the definition of the group method quantitative parameters, the application procedures for their calculation, the determination of the quantitative proportion of a group of unavailable components of a mixture and the partial or total quantitation of the latter. The paper also describes the steps for carrying out the so-called group-correlation method in the determination of the response factors of unavailable compounds, which belong to a homologous series. The GC experimental corroboration of the group method approach employing model mixtures of compounds is also presented.

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Se evaluaron dos técnicas cromotográficas: cromotografía líquida de alta resolución en los análisis de cuatro productos comerciales de cipermetrina (concentrados emulsificables). Determinó que la cromotografía de gases fue la metodología más sencilla, presentando ventajas y confiabilidad en los análisis realizados

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