Annibal Duarte Pereira Netto

O objetivo da pesquisa foi avaliar n-alcanos (C15 a C40) e esteróis, como indicadores da origem da matéria orgânica em sedimentos superficiais das lagoas costeiras do sistema lagunar de Jacarepaguá na cidade do Rio de Janeiro. As amostras de sedimentos foram coletas em 4 pontos de amostragem, extraídas em banho ultrassom para retirada da fase orgânica. O extrato foi fracionado de acordo com a polaridades dos grupos de compostos de interesse em cromatografia de coluna de sílica gel, adaptado em uma pipeta pasteur. Os alcanos e esteróis foram separados e quantificados por cromatografia a gás com detector de ionização de chama (CG-DIC) e suas identificações foram realizadas por comparação com tempo de retenção do padrão analítico. Os resultados mostraram que as concentrações individuais dos n-alcanos detectados variaram entre 0,65 a 71 µg g-1, e as concentrações totais de esteróis foram 0,55 a 13,42 µg g-1. O perfil de distribuição de alcanos teve destaque para Cmax de C28, C29, e C32 e outros indicadores avaliados como a predominância de compostos com número de carbonos pares e ímpares, UCM, ACL indicaram possíveis contribuições de misturas de fontes petrogênicas e biogênicas. Elevados valores de esteróis, como coprostanol (0,71 a 2,92 µg g-1) e colestanol oriundo da possível degradação microbiana a partir do colesterol mostrando a presença evidente da influência antropogênica na região das lagoas. Observou-se nessa região impacto pela degradação do ambiente aquático principalmente por tráfego de embarcações, ocupação do solo pelo crescimento populacional desordenado e exploração turística, com baixa contribuição de origem autóctones da matéria orgânica, assim como da presença marcante de esgoto doméstico.

Although postharvest coffee fruit fermentation can improve coffee flavour and quality, the mycotoxin ochratoxin A (OTA) can also be a result of microbiological activity, albeit in the later drying step of coffee processing. To evaluate the possible occurrence of OTA contamination in postharvest fruit fermentation, fourteen coffees that entailed two different postharvest fruit fermentation times were evaluated. These coffees originated in the surroundings of the village of Pedra Menina in the qualified Denomination of Origin and coffee producer region of Caparaó on the border between Minas Gerais and Espírito Santo states in Brazil. All coffees were classified according to the Specialty Coffee Association (SCA) protocol and 12 achieved specialty level. OTA was determined in all 14 coffees using immunoaffinity for sample clean-up and high-performance liquid chromatography with fluorescence detection for quantification. One sample presented an OTA concentration of 0.75 µg kg⁻¹ and two samples showed OTA concentrations of 0.87 µg kg⁻¹. The other samples had concentrations of OTA below the limit of quantification obtained in this work (0.64 µg kg⁻¹). Thus, all samples showed OTA concentrations far below the most stringent maximum residue limit (MRL) of 5 µg kg⁻¹ established for roasted coffees by European legislation. These low levels were similar to most of the previous results for Brazilian coffees listed and tabled in this work. This comparison showed that OTA contamination due to this kind of postharvest process – fruit fermentation – should not be a concern for producers and consumers of these fermented coffees. GRAPHICAL ABSTRACT

In infants, the main cause of blindness is retinopathy of prematurity that stems in a hypoxic-ischemic condition. Caffeine is a psychoactive compound that at low to moderate concentrations, selectively inhibits adenosine A₁ and A_2A receptors. Caffeine exerts beneficial effects in central nervous system of adult animal models and humans, whereas it seems to have malefic effect on the developing tissue. We observed that 48-h exposure (during synaptogenesis) to a moderate dose of caffeine (30 mg/kg of egg) activated pro-survival signaling pathways, including ERK, CREB, and Akt phosphorylation, alongside BDNF production, and reduced retinal cell death promoted by oxygen glucose deprivation in the chick retina. Blockade of TrkB receptors and inhibition of CREB prevented caffeine protection effect. Similar signaling pathways were described in previously reported data concerning chemical preconditioning mechanism triggered by NMDA receptors activation, with low concentrations of agonist. In agreement to these data, caffeine increased NMDA receptor activity. Caffeine decreased the levels of the chloride co-transporter KCC2 and delayed the developmental shift on GABA_A receptor response from depolarizing to hyperpolarizing. These results suggest that the caffeine-induced delaying in depolarizing effect of GABA could be facilitating NMDA receptor activity. DPCPX, an A₁ adenosine receptor antagonist, but not A_2A receptor inhibitor, mimicked the effect of caffeine, suggesting that the effect of caffeine occurs through A₁ receptor blockade. In summary, an in vivo caffeine exposure could increase the resistance of the retina to ischemia-induced cell death, by triggering survival pathways involving CREB phosphorylation and BDNF production/TrkB activation.

Introduction: The usual quality control for Uncaria tomentosa (Willd. ex Schult.) DC. barks requires highly specific analytical standards and methods based on high‐performance liquid chromatography (HPLC), which impacts the costs of the analytical process and the final products. Objective: To obtain an analytical reference standard of mitraphylline by isolation from U. tomentosa barks and develop a spectrophotometric method for determination of total alkaloids in samples of U. tomentosa . Methodology: An alkaloid‐enriched extract was obtained by acid–base partition and mitraphylline was selectively precipitated using an 80:20 v/v toluene/hexane solution. The compound was characterised by HPLC‐UV/DAD (diode‐array detector), mass spectrometry, UV‐visible, infrared (IR) and ¹ H‐ and ¹³ C‐nuclear magnetic resonance (NMR) spectroscopy. Sample preparation for the spectrophotometric method consisted of an extraction with boiling methanol (3 × 10 mL, 15 min), followed by a strong cation exchange solid phase extraction (SCX‐SPE) clean‐up. Results: Mitraphylline with a purity of 98% was isolated in 0.05% m/m yield. All characterisation results were in agreement with previous published data. The spectrophotometric method showed linear range between 0.40 and 20 μg/mL; limits of detection and quantification of 0.15 and 0.49 μg/mg, respectively; dispersion of results lower than 5% for repeatability and intermediate precision; statistically proven accuracy by comparison with reference values obtained by Soxhlet and an HPLC‐UV/DAD method; and robustness in relation to sample mass extracted and extraction time. Conclusion: The methods developed to obtain mitraphylline analytical standard from U. tomentosa barks and to determine total alkaloids by spectrophotometry provided a cheaper and faster quality control alternative for U. tomentosa samples.