RESUMEN
Comprehensive two-dimensional gas chromatography (GC×GC) has been an important technique used to acquire as much information as possible from a wide variety of samples. Qualitative contour plots analysis provides useful information and in daily use it ends up being handled as images of the volatile organic compounds by analysts. Cachaça samples are used in this paper to showcase the use of two-dimensional chromatographic images as the main source for authentication purposes through one-class classifiers, such as data-driven soft independent modeling of class analogy (DD-SIMCA). The proposed workflow summarizes this fast and easy process, which can be used to certify a specific brand in comparison to other brands, as well as to authenticate if samples have been adulterated. Lower quality cachaças, non-aged cachaças and cachaças aged in different wooden barrels were tested as adulterants. Chromatographic images allowed for the distinction of all brands and nearly every adulteration tested. Sensitivity was estimated at 100% for all models and specificity ranged from 96% to 100%. Different approaches were used, alternating from working with whole-sized images to working with smaller resized versions of those images. Resized chromatographic images could be potentially useful to easily compensate for slight chromatographic misalignments, allowing for faster calculations and the use of simpler software. Reductions to 50% and 25% of the original size were tested and the results did not greatly differ from whole images model. As such, 2D chromatographic images have been found to be an interesting form of evaluating a product's authenticity.
Asunto(s)
Compuestos Orgánicos Volátiles , Cromatografía de Gases , Cromatografía de Gases y Espectrometría de Masas , Compuestos Orgánicos Volátiles/análisisRESUMEN
In this study, a series of polymeric ionic liquid (PIL) sorbent coatings is evaluated for the extraction of polar volatile organic compounds (VOCs) from Brazilian wines using headspace solid-phase microextraction (HS-SPME), including samples from 'Isabella' and 'BRS Magna' cultivars-the latter was recently introduced by the Brazilian Agricultural Research Corporation - National Grape & Wine Research Center. The structurally tuned SPME coatings were compared to the commercial SPME phases, namely poly(acrylate) (PA) and divinylbenzene/carboxen/poly(dimethylsiloxane) (DVB/CAR/PDMS). The separation, detection and identification of the aroma profiles were obtained using comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS). The best performing PIL-based SPME fiber, namely 1-hexadecyl-3-vinylimidazolium bis[(trifluoromethyl)sulfonyl]imide with 1,12-di(3-vinylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide incorporated cross-linker supported on an elastic nitinol wire, exhibited superior performance to DVB/CAR/PDMS regarding the average number of extracted peaks and extracted more polar analytes providing additional insight into the aroma profile of 'BRS Magna' wines. Four batches of wine were evaluated, namely 'Isabella' and 'BRS Magna' vintages 2015 and 2016, using highly selective PIL-based SPME coatings and enabled the detection of 350+ peaks. Furthermore, this is the first report evaluating the aroma of 'BRS Magna' wines. A hybrid approach that combined pixel-based Fisher ratio and peak table-based data comparison was used for data handling. This proof-of-concept experiment provided reliable and statistically valid distinction of wines that may guide regulation agencies to create high sample throughput protocols to screen wines exported by Brazilian vintners. Graphical abstract Highly selective extraction of wine aroma using polymeric ionic liquid.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Líquidos Iónicos/química , Odorantes/análisis , Microextracción en Fase Sólida/métodos , Vino/análisis , Brasil , Análisis Discriminante , Polímeros/químicaRESUMEN
In recent years, the antitumoral activity of antimicrobial peptides (AMPs) has been the goal of many research studies. Among AMPs, gomesin (Gm) displays antitumor activity by unknown mechanisms. Herein, we studied the cytotoxicity of Gm in the Chinese hamster ovary (CHO) cell line. Furthermore, we investigated the temporal ordering of organelle changes and the dynamics of Ca(2+) signaling during Gm-induced cell death. The results indicated that Gm binds to the plasma membrane and rapidly translocates into the cytoplasm. Moreover, 20 µM Gm increases the cytosolic Ca(2+) and induces membrane permeabilization after 30 min of treatment. Direct Ca(2+) measurements in CHO cells transfected with the genetically encoded D1-cameleon to the endoplasmic reticulum (ER) revealed that Gm induces ER Ca(2+) depletion, which in turn resulted in oscillatory mitochondrial Ca(2+) signal, as measured in cells expressing the genetically encoded probe to the mitochondrial matrix (mit)Pericam. This leads to mitochondria disruption, loss of mitochondrial membrane potential and increased reactive oxygen species prior to membrane permeabilization. Gm-induced membrane permeabilization by a Ca(2+)-dependent pathway involving Gm translocation into the cell, ER Ca(2+) depletion and disruption, mitochondrial Ca(2+) overload and oxidative stress.