Publications by authors named "Paulo R Filgueiras"

Article Synopsis
  • Fabry disease (FD) is a rare genetic disorder caused by a deficiency of the enzyme alpha-galactosidase-A due to mutations in the GLA gene, leading to harmful lipid accumulation in cells and primarily affecting males.
  • The study investigates the use of attenuated total reflection Fourier-transform IR (ATR-FTIR) spectroscopy to analyze plasma samples and identify a distinct molecular profile in FD patients compared to healthy controls, achieving perfect accuracy in differentiating the two groups.
  • The findings suggest that ATR-FTIR spectroscopy, combined with advanced pattern recognition algorithms, could serve as a quick and cost-effective screening method for Fabry disease, applicable to all genders.
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Products derived from the latex of were obtained through hydrolysis and column chromatography, resulting in products rich in triterpenes, ingenol 3-esters (I3E), and other derivatives from hydrolysed latex. These products underwent evaluation for their cytotoxic activity against gastric adenocarcinoma cells (AGS). Triterpene derivatives were synthesised, and the selectivity of each product was assessed.

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leaves are a rich source of phenolic compounds with biological activities, including myricitrin. In this study, the chemical profile of nine extracts prepared with leaves collected in three regions (mountain, beach, and mangrove) and at three different times of the day (8 am, 1 pm, and 6 pm) was evaluated from spectra originating from ultra-high resolution mass spectrometry (Fourier transform ion cyclotron resonance, FT-ICR) coupled to electrospray ionisation (ESI). The best time of the day and location for collecting the leaves of used as raw materials for producing extracts and the best ethanol concentration for obtaining an extract more abundant in compounds of interest were verified.

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FTIR spectroscopy and multivariate analysis were used in the chemical study of the terroirs of Coffea canephora. Conilon coffees from Espírito Santo and Amazon robusta from Matas of Rondônia, were separated by PCA, with lipids and caffeine being the markers responsible for the separation. Coffees from Bahia, Minas Gerais, and São Paulo did not exhibit separation, indicating that the botanical variety had a greater effect on the terroir than geographic origin.

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Article Synopsis
  • ATR-FTIR spectroscopy is a new technology being researched for its potential use in medical diagnostics, specifically for classifying levels of D-dimer, a substance related to blood clotting and conditions like pulmonary embolism and COVID-19 severity.
  • The study analyzed plasma D-dimer levels from 100 patients using advanced statistical methods like PCA and machine learning algorithms (GA-LDA and PLS-DA) to accurately classify D-dimer concentrations.
  • The GA-LDA method showed impressive results with high sensitivity and specificity, suggesting that ATR-FTIR spectroscopy could improve patient diagnosis, reduce healthcare costs, and enhance overall patient care.
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Article Synopsis
  • The ASTM E1655 guidelines help determine the physical and chemical properties of materials using multivariate calibration, particularly when dealing with highly correlated data.
  • Partial least squares (PLS) is the preferred method due to its strong predictive abilities, especially in NIR and MIR spectroscopy, but may struggle with complex samples that have low correlations.
  • The study analyzed various analytical techniques and found that NIR and MIR had more correlated variables, making them suitable for PLS, while techniques like C NMR and mass spectrometry may need different approaches for more accurate results.
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Considering the great economic significance of (arabica) associated with the lower production cost of (conilon), blends of these coffees are commercially available to reduce costs and combine sensory attributes. Thus, analytical tools are required to ensure consistency between real and labeled compositions. In this sense, chromatographic methods based on volatile analysis using static headspace-gas chromatography-mass spectrometry (SHS-GC-MS) and Fourier transform infrared (FTIR) spectroscopy associated with chemometric tools were proposed for the identification and quantification of arabica and conilon blends.

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Ethanol extract from the aerial parts of L. as well as the latex of the plant suspended in water are used by the Brazilian population for the treatment of various diseases, including cancer. The purposes of this study were to determine if the ethanol extract is effective as cytotoxic agent against gastric adenocarcinoma cells (AGS) and its chemical composition by GC-MS, ESI-(-)-FT-ICR MS and (-)-ESI-LTQ-MS/MS.

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  • Rapid identification of respiratory viruses, particularly SARS-CoV-2, is critical for pandemic management, and this study focuses on improving saliva screening using a high-tech method called MALDI FT-ICR MS combined with machine learning.* -
  • The study optimized saliva sample preparation using trypsin digestion and found good results in classifying samples as positive or negative for SARS-CoV-2 with two support vector machine (SVM) models, achieving high accuracy rates.* -
  • The first SVM model (SVM1) demonstrated 100% accuracy in the calibration group and a 95.6% accuracy in the test group, indicating its potential as an effective tool for COVID-19 screening.*
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The use of drugs of abuse has grown significantly in recent decades. In forensic chemistry, methods of identifying and characterizing illicit drugs contribute to the interests of researchers, experts, and public security authorities. Among existing methods, portable Raman spectroscopy is notable for performing rapid, non-destructive, and highly selective analysis in the laboratory or on-site.

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the worst global health crisis in living memory. The reverse transcription polymerase chain reaction (RT-qPCR) is considered the gold standard diagnostic method, but it exhibits limitations in the face of enormous demands. We evaluated a mid-infrared (MIR) data set of 237 saliva samples obtained from symptomatic patients (138 COVID-19 infections diagnosed via RT-qPCR).

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The chemical complexity of coffee influences the sensory evaluation of the beverage, the main method used to define the quality of the coffee. In view of the subjectivity that method offers, we propose the association of an instrumental method with multivariate calibration (PLS and GA-SVR) to predict the quality of arabica coffee as support for sensory analysis. Arabica coffee samples were submitted to sensory evaluation using the Specialty Coffee Association (SCA) protocol and HS-SPME-GC/MS analysis.

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Milk is a homogeneous mixture of substances such as lactose, proteins, and glycerides. Among carbohydrates, lactose is a disaccharide composed of glucose and galactose, and it is present in bovine milk at a level of 4.6%.

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The consumption of design drugs, frequently known as new psychoactive substances (NPS), has increased considerably worldwide, becoming a severe issue for the responsible governmental agencies. These illicit substances can be defined as synthetic compounds produced in clandestine laboratories in order to act as analogs of schedule drugs mimetizing its chemical structure and improving its pharmacological effects while hampering the control and making regulation more complicated. In this way, the development of new methodologies for chemical analysis of NPS drugs is indispensable to determine a novel class of drugs arising from the underground market.

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Rationale: Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) is an important analytical technique used for the elucidation of crude oil polar compounds at the molecular level, providing thousands of heteroatom compounds in a single analysis. Due to the high resolution, the complexity of data produced, and steps involved in spectra acquisition and processing, it is necessary to estimate its intermediate precision.

Methods: Intermediate precision was estimated for positive- and negative-ion ionization modes (ESI(±)) using Composer® software for two Brazilian crude oil samples.

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We have built an online tool with a user-friendly and browser-based interface to facilitate the processing of high resolution and precision oil mass spectrometry data. DropMS does not require software installations. Mass spectra are sent and processed by the server using various algorithms reported in the literature, such as S/N ratio filters, recalibrations, chemical formula assimilations, and data visualization using graphs and diagrams popularly known in mass spectrometry as Van Krevelen and Kendrick diagrams and DBE vs C#.

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The study of Brazilian Conilon coffee genotypes with unknown chemical composition and sensory quality is extremely important since these data may contribute to the launching of new coffee cultivars in the international market with high cup quality. The present study aimed to investigate the metabolic profile of 3 genotypes of Conilon and compared them to Robusta Tropical and Arabica coffees, all collected at 3 different levels of ripeness. The extracts were analysed by ESI-LTQ-ORBITRAP, and 11 attributes were evaluated by sensory analysis.

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Ethnopharmacological Relevance: Euphorbia tirucalli L. is widely used by Brazilian folk medicine, mainly for its anticancer activity. However, its commercialization was banned by The Brazilian National Sanitary Surveillance Agency (ANVISA) due to the presence of some compounds considered toxic, such as the diterpene esters.

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Article Synopsis
  • The study investigates the effects of turbulent flow on a 400 ppm solution of guar gum, focusing on how molecular degradation impacts drag reduction.
  • Analysis techniques like spectroscopy and viscosimetry reveal that the drag reduction benefits diminish as the guar gum breaks down, mainly due to hydrolysis of its glycosidic bonds.
  • Results also indicate that this degradation reduces the thermal stability of the polysaccharide, providing insights necessary for developing more efficient biopolymers to enhance drag reduction.
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Guar gum is used in low concentrations as a drag reducing agent in turbulent flows to significantly accelerate flow in oil pipelines, oil well operations and aqueous systems. Drag reduction also promotes a decrease in energy demand in pumping systems. However, the polymers undergo mechanical degradation and lose the ability to promote drag reduction over time.

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Marijuana, a drug derived from the Cannabis sativa L. plant, is the world's most consumed illicit drug. In this paper, a total of 156 marijuana samples seized in the state of Espírito Santo (ES), Brazil were studied and analysed by proton nuclear magnetic resonance (H NMR) spectroscopy to identify the major cannabinoids present.

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The use of portable micro-spectrometers such as a micro near infrared region (microNIR) spectrometer is a promising technique for solving analytical problems in several areas of science. This work evaluated the potential of microNIR in quality control of Arabica coffee. Arabica coffee has a high commercial value product, motivating the development of analytical methods with high sensitivity and accuracy for detection of its adulteration.

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Fuel quality control has gained interest in many countries owing to the potential damage of low-quality fuel to engines, the environment, and economy. Thus, the application of analytical techniques to verify quality control of fuels has become crucial. The portable micro-spectrometer in the near infrared region (microNIR) has gained credibility as a successful analytical technique in several quality control sectors.

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Cocaine is a stimulant drug of the central nervous system (CNS) extracted from the leaves of Erytroxylum coca. It is defined as a tropane alkaloid containing 1R-(exo,exo)-3-(benzoyloxy)-8-methyl-8-azabicyclo[3.2.

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Thin layer chromatography (TLC) is a simple and inexpensive type of chromatography that is extensively used in forensic laboratories for drugs of abuse analysis. In this work, TLC is optimized to analyze cocaine and its adulterants (caffeine, benzocaine, lidocaine and phenacetin) in which the sensitivity (visual determination of LOD from 0.5 to 14mgmL(-1)) and the selectivity (from the study of three different eluents: CHCl3:CH3OH:HCOOHglacial (75:20:5v%), (C2H5)2O:CHCl3 (50:50v%) and CH3OH:NH4OH (100:1.

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