Publications by authors named "Cesar Raposo"

Water mint () is used in many formulations worldwide as a functional food and natural remedy to treat gastrointestinal disorders, lung diseases, and certain mental disorders such as epilepsy and depression. This study assessed the bioactivity of its infusion extract (INF) and hydroethanolic extract (HE) to highlight its health benefits. These extracts were analyzed for their chemical composition by HPLC-DAD-ESI-MSn, their antioxidant and antidiabetic properties, and their capacities to protect human erythrocytes against induced hemoglobin oxidation and lipid peroxidation.

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  • Seven species of lichens were collected from Arequipa, Peru, and analyzed for their usnic acid (UA) and fatty acid (FA) content using advanced chromatography techniques.
  • The study evaluated the antimicrobial properties of these lichen extracts against various bacterial strains, along with their antioxidant capacities through multiple assays.
  • Results indicated that one lichen species showed potential as a source of antimicrobial metabolites, while another exhibited significant antioxidant activity due to its high polyphenol content.
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  • This study investigates the chemical composition of extracts from two lichen samples collected in Algeria, using hexane, chloroform, and ethanol as solvents for extraction.
  • Hexane extracts were fractionated based on solubility in methanol, leading to the identification of various fatty acids and orsellinic acid derivatives via GC-MS analysis.
  • The chloroform and ethanol extracts also underwent analysis using HPLC-MS/MS, revealing characteristic substances, including chloroatranorin and stictic acid, with some variations in their chemical profiles.
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The present study provides new data concerning the chemical characterisation of Nimis, a rare Mediterranean species belonging to the family Physciaceae. The phytochemical screening was carried out using GC-MS, HPLC-ESI-MS-MS, and NMR techniques. Hot extraction of n-hexane was carried out, followed by separation of the part insoluble in methanol: wax (WA-hex), from the part soluble in methanol (ME-hex).

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Administration of enantiomerically pure β-adrenergic agonists and antagonists increases their activity and reduces side effects. We report here a small-molecule artificial receptor (SMAR) that, by mimicking the β-adrenergic receptor, is able to enantioselectively extract commercial β-adrenergic interacting drugs. The selectivity is justified according to DFT calculations and X-ray diffraction experiments.

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Urine is a suitable biological fluid to look for markers of physiological and pathological processes, including renal and nonrenal diseases. In addition, it is an optimal body sample for diagnosis, because it is easily obtained without invasive procedures and can be sampled in large quantities at almost any time. Rats are frequently used as a model to study human diseases, and rat urine has been analyzed to search for disease biomarkers.

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Ras small GTPases function as transducers of extracellular signals regulating cell survival, growth and differentiation. There are three major ras isoforms: H-, N- and K-Ras. To improve the understanding of H- and N-Ras protein signalling networks, we compared total proteome changes in mouse embryonic fibroblasts knock out for H-ras and/or N-ras, using proteomics tools combining 2DE, semi-quantitative image analysis, in-gel trypsin digestion and mass spectrometry.

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Ureas, carbamoyl derivatives, amides, and sulfonamides can be easily prepared from the strained (R,R)-cylohexanediamine urea (1) in high yield, leaving a free amino group that shows good catalytic activity in intramolecular aldol condensations. The preparation of Wieland-Miescher ketone has been studied with these catalysts.

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A key aspect for the clinical handling of acute kidney injury is an early diagnosis, for which a new generation of urine biomarkers is currently under development including kidney injury molecule 1 and neutrophil gelatinase-associated lipocalin. A further diagnostic refinement is needed where one specific cause among several potentially nephrotoxic insults can be identified during the administration of multidrug therapies. In this study we identified increases in regenerating islet-derived protein III beta (reg IIIb) and gelsolin as potential differential urinary markers of gentamicin's nephrotoxicity.

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The reaction between acetone and 4-nitrobenzaldehyde catalyzed by aniline prolinamide 1 was studied in depth. Working in different solvents with equimolar amounts of reagents and monitoring the reaction by 1H NMR, we detected and identified several imidazolidinones, such as those of the acetone 4, the aldol products 5a and 5b, and aldehydes 10a and 10b. According to our results, these compounds could influence the reaction rate and diminish product enantioselectivity.

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Xanthone derivatives were tested as organocatalysts for the Michael addition of pyrrolidine to an alpha,beta-unsaturated lactam. The receptors combine a double H-bond donor pattern that resembles the oxyanion hole in natural enzymes, with a sulfone or sulfoxide that acts as a proton-transfer group. Since these compounds cannot be obtained enantiomerically pure from natural sources, chiral resolution was necessary to study their enantioselectivity.

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A new fluorescent sensor based on a dimethylxanthene skeleton has beensynthesized. Because of its oxyanion hole structure, this receptor includes a suitablecavity for the association of carboxylic acids. The receptor's fluorescence is quenchedupon addition of dinitrobenzoic acid.

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We have used a newly developed qualitative computational approach, PROFEC (Pictorial Representation of Free Energy Changes), to visualize the areas of the ligand biotin where modifications of its structure might lead to tighter binding to the protein streptavidin. The PROFEC analysis, which includes protein flexibility and ligand solvation/desolvation, led to the suggestion that the pro-9R hydrogen atom of biotin, which is in alpha-position to the CO(2)(-) group, might be changed to a larger group and lead to better binding with streptavidin and avidin. Free energy calculations supported this suggestion and predicted that the methyl analogue should bind approximately 3 kcal/mol more tightly to streptavidin, with this difference coming exclusively from the relative desolvation free energy of the ligand.

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