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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 A(1) 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 A(1) adenosine receptor antagonist, but not A(2A) receptor inhibitor, mimicked the effect of caffeine, suggesting that the effect of caffeine occurs through A(1) 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.

Diosgenina e uma sapogenina importante usada na industria farmaceutica como materia-prima para sintese de hormonios esteroidais. Alem disto, a bioatividade deste metabolito secundario tem sido avaliada em diversos alvos moleculares, tornando a diosgenina promissora como novo farmaco. Um metodo de CLAE-UV-DAD para determinacao de diosgenina foi desenvolvido neste trabalho. O metodo foi validado e considerado adequado, demonstrando boa sensibilidade e linearidade no intervalo de concentracao de 0,25 a 10,0 µg mL-1. Alem disso, o metodo apresentou boa repetibilidade (CV% 1,0-3,3), boa precisao intermediaria (CV% 0,9-3,7) e elevados valores de recuperacao (93,1-97,7%). Os limites de deteccao e de quantificacao foram respectivamente 2,0 e 8,0 mg de diosgenina por kg de farinha seca de amostra, melhores do que outros reportados anteriormente na literatura que usaram a mesma tecnica analitica. Amostras de Dioscorea bulbifera e Dioscorea trifida foram avaliadas pelo metodo proposto, entretanto, diosgenina nao foi encontrada nas condicoes de analise.

A method of high performance liquid chromatography with UV detection (HPLC-UV) was implemented and validated for formaldehyde determination in bovine milk. A formaldehyde derivatization reaction with 2,4-dinitrophenylhydrazine, at pH 4.0, enabled its detection in milk at 360 nm. The clean up treatment of milk samples by liquid-liquid extraction with low temperature partitioning (LLE-LTP) was thoroughly optimized. The linearity of the method was shown by analytical curves ranging from 10.0 to 400.0 μg L − 1 in aqueous solutions and milk samples that were characterized by R 2 > 0.99. The limit of quantification of 20.0 μg L − 1 demonstrated the high sensitivity of the method to determinate formaldehyde residues in milk. Extracts of milk samples fortified with formaldehyde at three concentration levels, led to a mean overall recovery of 102.2 ± 1.3% (n = 9), which satisfies the performance criteria established by the Codex Alimentarius for analytical methods suitable for determination of food residues. The accuracy was evaluated by comparison with a well-established procedure using the Student t -test. Comparable results were obtained at a 95% confidence level, demonstrating the usefulness and effectiveness of the proposed method.

A simple and low-cost multipurpose analytical method using HPLC-UV-DAD was developed and validated, following international guidelines, for the determination of six synthetic food dyes: Tartrazine, Sunset Yellow, Amaranth, Allura Red, Indigotine, and Brilliant Blue. The method required a simple sample preparation step that consisted of dissolution or dilution of the samples in water, followed by pH adjustment and filtering through PVDF filters. No significant matrix effect was verified. Linear working ranges varied from 0.25 to 6.0 mg L−1. Appropriate limits of quantification (0.10 to 0.15 mg L−1), mean recoveries (90.2 to 106.6%), and repeatability and intermediate precision (

A highly sensitive analytical method was developed and validated, following international guidelines, for the determination of the residues of five macrocyclic lactones (MLs) (abamectin, doramectin, eprinomectin, ivermectin and moxidectin) in cheese. The extracts were concentrated by rotary-evaporation and derivatized; no clean-up was necessary. Despite matrix complexity, no significant matrix-effect was verified, and standards were prepared in solvents. Linear working ranges varied from 0.25 to 5.0 μg L−1. Excellent limits of quantification (0.58–0.87 μg kg−1), mean recoveries (91–103%), and repeatability and intermediate precision (