DSC studies on protein isolate of guava seeds <Emphasis Type="Italic">Psidium guajava</Emphasis>

Glutelin, the major protein fraction from guava seed, was obtained by fractioning as described by Osborne. The total proteins were extracted and the isolates obtained by isoelectric precipitation presented similar DSC curves, concordant with the results obtained by gel filtration chromatography and electrophoresis in polyacrylamide gel (PAGE-SDS). However, the DSC curves showed a higher enthalpy with regard to the denaturing protein isolate (PI) extracted at pH 10.0 when compared to a PI at pH 11.5. Such results are in accordance with those obtained for PI extracted at pH 10.0 using chromatography, this one being present in the form of molecular aggregates of greater molecular mass. The glutelin fraction, however, did not present a denaturation peak in the DSC curve, showing that the process for obtaining the same significantly altered its conformation.     

Melatonin Reverses the Warburg-Type Metabolism and Reduces Mitochondrial Membrane Potential of Ovarian Cancer Cells Independent of MT1 Receptor Activation

Ovarian cancer (OC) is the most lethal gynecologic malignancy, and melatonin has shown various antitumor properties. Herein, we investigated the influence of melatonin therapy on energy metabolism and mitochondrial integrity in SKOV-3 cells and tested whether its effects depended on MT1 receptor activation. SKOV-3 cells were exposed to different melatonin concentrations, and experimental groups were divided as to the presence of MT1 receptors (melatonin groups) or receptor absence by RNAi silencing (siRNA MT1+melatonin). Intracellular melatonin levels increased after treatment with melatonin independent of the MT1. The mitochondrial membrane potential of SKOV-3 cells decreased in the group treated with the highest melatonin concentration. Melatonin reduced cellular glucose consumption, while MT1 knockdown increased its consumption. Interconversion of lactate to pyruvate increased after treatment with melatonin and was remarkable in siRNA MT1 groups. Moreover, lactate dehydrogenase activity decreased with melatonin and increased after MT1 silencing at all concentrations. The UCSC XenaBrowser tool showed a positive correlation between the human ASMTL gene and the ATP synthase genes, succinate dehydrogenase gene (SDHD), and pyruvate dehydrogenase genes (PDHA and PDHB). We conclude that melatonin changes the glycolytic phenotype and mitochondrial integrity of SKOV-3 cells independent of the MT1 receptor, thus decreasing the survival advantage of OC cells.     

Characterization and Antineoplasic Effect of Extracts Obtained from <Emphasis Type="Italic">Pleurotus sajor</Emphasis>-<Emphasis Type="Italic">caju</Emphasis> Fruiting Bodies

Fungi of the Pleurotus genus present a great industrial interest due to their possibility of producing pharmacological compounds, pigments, aromas, organic acids, polysaccharides, enzymes, vitamins, amino acids, etc. Among the therapeutic products, we can highlight those with antineoplasic activity, attributed to the fungi cell wall components. Based on this, the objective of this work was to study the antineoplasic capacity of the polysaccharidic fractions obtained from Pleurotus sajor-caju fruiting bodies. Female Swiss mice were inoculated with the Ehrlich ascitic tumor (5 × 10⁶ cells/animal) in ascitic form. The polysaccharidic fractions were administered intraperitoneally, during a 6-day period. Fractions FI and FII presented a lower volume of ascitic liquid (3.1 and 1.8 mL, respectively) and a higher reduction in the number of neoplasic cells present in the ascitic liquid (86.2% and 85%, respectively), when compared to the positive control (group inoculated with the tumor but without treatment). These fractions were characterized in terms of monosaccharide composition. Glucose was the major component detected, followed by galactose and mannose. The anomeric carbon configuration of the β-glucan was confirmed by the ¹³C NMR (δ 103.7). Substituted and free C3 and C6 were also detected. Protein bands were confirmed through infrared analysis.     

Simultaneous determination of zinc,copper, lead,and cadmium in fuel ethanol by anodic stripping voltammetry using a glassy carbon–mercury-film electrode

A new, versatile, and simple method for quantitative analysis of zinc, copper, lead, and cadmium in fuel ethanol by anodic stripping voltammetry is described. These metals can be quantified by direct dissolution of fuel ethanol in water and subsequent voltammetric measurement after the accumulation step. A maximum limit of 20% (v/v) ethanol in water solution was obtained for voltammetric measurements without loss of sensitivity for metal species. Chemical and operational optimum conditions were analyzed in this study; the values obtained were pH 2.9, a 4.7-m thickness mercury film, a 1,000-rpm rotation frequency of the working electrode, and a 600-s pre-concentration time. Voltammetric measurements were obtained using linear scan (LSV), differential pulse (DPV), and square wave (SWV) modes and detection limits were in the range 10^–9–10^–8 mol L^–1 for these metal species. The proposed method was compared with a traditional analytical technique, flame atomic absorption spectrometry (FAAS), for quantification of these metal species in commercial fuel ethanol samples.     

Mixture Design PARAFAC HPLC-DAD Metabolomic Fingerprints of Fractionated Organic and Basic Extracts from <Emphasis Type="Italic">Erythrina speciosa</Emphasis> Andrews Leaves

HPLC-DAD analysis of statistical mixture design extracts of Erythrina speciosa Andrews leaves provided chromatographic and UV–visible profiles of their basic and organic fractions that were treated with the PARAFAC multivariate method. The design extracts provided greater varieties and amounts of metabolites than could be obtained by classical extraction methods. Fractionation provided more diverse fingerprint information than obtained previously from only the crude extract. The two largest chromatographic peaks, one with a 4.8 min elution time having an intense spectral band at 235 nm and the other a 5.8 min peak with an intense 238 nm band for the basic fraction were obtained with the ternary 1:1:1 ethanol–dichloromethane–hexane mixture. These can be assigned to diene-type and lactonic alkaloids. Peaks with the same retention times are also found in the organic fraction but are extracted with different mixtures and have distinct spectral behavior in the 235 nm region, probably being aromatic alkaloids. The above strategy permits a more unambiguous assignment of metabolic groups to specific chromatographic peaks. This can be expected to provide higher quality chromatographic fingerprints for natural products’ chemistry.     

Voltammetric determination of chlorothalonil and its respective reduction mechanism studied by density functional theory

Journal of Solid State Electrochemistry - A simple, fast, and direct electroanalytical method has been developed for the pesticide chlorothalonil determination using a boron-doped diamond electrode...     

When a Red–NIR-Emissive Cs2[Mo6Br14] Interacts with an Active Diureasil–PEO Matrix: Design of Tunable and White-Light-Emitting Hybrid Material

Hybrid materials that combine diureasil matrices and octahedral molybdenum clusters have been synthesized to design lead-, cadmium- and rare-earth-free emitters for lighting or optoelectronic applications. This association leads to homogeneous and stable hybrids, for which the emission color can be tailored in the entire visible range, including white light; this is thanks to effective energy transfers from the host to the nanocluster.     

Chemical mechanism of controlled nitric oxide release from trans-[RuCl([15]aneN4)NO](PF6)2 as a vasorelaxant agent

The nitrosyl ruthenium complex, trans-[RuCl([15]aneN₄)NO](PF₆)₂, ([15]aneN₄?=?1,4,8,12-tetraazacyclopentadecane), exhibits vasorelaxation characteristics attributed to its nitric oxide release properties. The observed in vitro and in vivo vasodilation is dependent on noradrenaline concentration. We report here the chemical mechanism of the reaction between noradrenaline and trans-[RuCl([15]aneN₄)NO](PF₆)₂ in aqueous phosphate buffer solution at pH 7.40. NO measurement by NO-sensor electrode, cyclic voltammetry, ³¹PNMR and HPLC analysis were used to investigate the reduction process as the fundamental step for NO release characteristic of trans-[RuCl([15]aneN₄)NO](PF₆)₂. A supramolecular species containing HPO₄ ^2? as a bridging group between noradrenaline and trans-[RuCl([15]aneN₄)NO](PF₆)₂ is suggested as an intermediate prior to the reduction of the nitrosyl ruthenium complex.