Host–guest system of 4-nerolidylcatechol in 2-hydroxypropyl-β-cyclodextrin: preparation, characterization and molecular modeling

The interaction of 4-nerolidylcatechol (4-NRC), a potent antioxidant agent, and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) was investigated by the solubility method using Fourier transform infrared (FTIR) methods in addition to UV–Vis, ¹H-nuclear magnetic resonance (NMR) spectroscopy and molecular modeling. The inclusion complexes were prepared using grinding, kneading and freeze-drying methods. According to phase solubility studies in water a B_S-type diagram was found, displaying a stoichiometry complexation of 2:1 (drug:host) and stability constant of 6494 ± 837 M^?1. Stoichiometry was established by the UV spectrophotometer using Job’s plot method and, also confirmed by molecular modeling. Data from ¹H-NMR, and FTIR, experiments also provided formation evidence of an inclusion complex between 4-NRC and HP-β-CD. 4-NRC complexation indeed led to higher drug solubility and stability which could probably be useful to improve its biological properties and make it available to oral administration and topical formulations.     

First triazole-linked porphyrin-fullerene dyads

A general procedure for the synthesis of 1,2,3-triazole-linked porphyrin-fullerene dyads is described. Four of these compounds have been prepared and characterized.     

Stability of recombinant green fluorescent protein (GFPuv) in glucose solutions at different concentrations and pH values

The stability at room temperature (25°C) of recombinant green fluorescent protein (GFPuv), expressed by Escherichia coli cells and isolated by three-phase partitioning extraction with hydrophobic interaction column, was studied. The GFPuv was diluted in buffered (each 10 mM: Tris-HCl, pH 8.0; phosphate, pH 6.0 and 7.0 and acetate, pH 5.0) and in unbuffered (water for injection [WFI]; pH 6.70 ± 0.40) glucose solutions (from 1.5 to 50%). By assaying the loss of fluorescence intensity as a measure of denaturation, the stability of GFPuv in these solutions was evaluated relative to glucose concentration, pH, osmolarity, density, conductivity, and viscosity. The extent of protein denaturation (loss of fluorescence intensity) was expressed in decimal reduction time (D-value), the time required to reduce 90% of the initial fluorescence intensity of GFPuv. The D-value between 56 and 83 h of GFPuv at 1.5–15% glucose in WFI was equivalent to 20–30% glucose in a phosphate. The stability of GFPuv in 50% glucose was similar for all buffers studied and four times higher than in WFI. By the convenient measure of fluorescence intensity, GFPuv can be used as an indicator to report the extent of denaturation rates of other proteins in glucose solutions.     

Current status and future trends on automated multidimensional separation techniques employing sorbent‐based extraction columns

Determination of target analytes present in complex matrices requires a suitable sample preparation approach to efficiently remove the analytes of interest from a medium containing several interferers while at the same time preconcentrating them aiming to improve the output signal detection. Online multidimensional solid‐phase separation techniques have been widely used for the analysis of different contaminants in complex matrices such as food, environmental, and biological samples, among others. These online techniques usually consist of two steps performed in two different columns (extraction and analytical column), the first being employed to extract the analytes of interest from the original medium and the latter to separate them from the interferers. The extraction column in multidimensional techniques presents a relevant role since their variations as building material (usually a tube), sorbent material, modes of application, and so on can significantly influence the extraction success. The main features of such columns are subject of constant research aiming improvements directly related to the performance of the separation techniques that utilize multidimensional analysis. The present review highlights the main features of extraction columns online coupled to chromatographic techniques, inclusive for in‐tube solid‐phase microextraction, online solid phase and turbulent flow, aiming the determination of analytes present at very low concentrations in complex matrices. It will critically describe and discuss some of the most common instrumental set up as well as comments on recent applications of these multidimensional techniques. Besides that, the authors have described some properties and enhancements of the extraction columns that are used as first dimension on these systems, such as type of column material (poly (ether ether ketone), fused silica, stainless steel, and other materials) and the way that the extractive phase is accommodated inside the tubing (filled and open tubular). Practical applications of this approach in fields such as environment, food, and bioanalysis are also presented and discussed.     

Application of SPME to the determination of alkylphenols and bisphenol A in cyanobacteria culture media

In order to survey the influence of estrogenic compounds on cyanobacteria, solid-phase microextraction (SPME) with a carbowax-divinylbenzene fibre was used for the determination of tert-octylphenol (tert-OP), n-nonylphenol (n-NP), technical nonylphenol (tech-NP) and bisphenol A (BPA) in cyanobacteria culture media by gas chromatography with flame ionization detection. Determinations were carried out without derivatization in deionized water and filtered culture media. A comparison between f2 and Fraquil culture media was performed, which showed that only f2 allowed quantitative recoveries. Headspace SPME with salting out, requiring only 10 mL of sample, was suitable for tert-OP, n-NP, and tech-NP determination with limits of detection (LOD) of <0.05 μg L⁻¹. For BPA, direct immersion SPME could provide a LOD of 1 μg L⁻¹. Automated sampling allowed reproducible extraction. No exudate substances overlapped with the studied compounds during the chromatographic separation and no matrix effects were observed. Ecotoxicity tests can be performed by single spiking of tert-OP and tech-NP and multiple spiking of n-NP due to its lower stability.     

The equations of almost complete intersections

In this paper we inject four Hilbert functions in the determination of the defining equations of the Rees algebra of almost complete intersections of finite co-length. Because three of the corresponding modules are Artinian, some of these relationships are very effective, with the novel approach opening up tracks to the determination of the equations and also to processes of going from homologically defined sets of equations to higher degrees ones. While not specifically directed towards the extraction of elimination equations, it will show how some of these arise naturally.     

Phenolic Compounds’ Occurrence in Opuntia Species and Their Role in the Inflammatory Process: A Review

Within the Cactaceae family, Opuntia comprises the most widespread species, with a recognized importance in human life, including feeding, domestic use as home natural barriers, and as a traditional remedy for diverse diseases and conditions such asthma, edema, and burns. Indeed, scientific reports have stated that these health benefits may be due to various active compounds, particularly polyphenols, which are ubiquitously found in plants and have proven their pharmacological efficiency by displaying antimicrobial, anti-cancer, and anti-inflammatory activities, among others. Opuntia species contain different classes of phenolic compounds that are recognized for their anti-inflammatory potential. Among them, quercetin, isorhamnetin, and kaempferol derivates were reported to greatly contribute to modulate cells’ infiltration and secretion of soluble inflammatory mediators, with key implications in the inflammatory process. In this review, we make a summary of the different classes of phenolic compounds reported in Opuntia species so far and explore their implications in the inflammatory process, reported by in vitro and in vivo bioassays, supporting the use of cactus in folk medicine and valorizing them from the socio-economic point of view.     

Soft electron (low energy electron) processing of foods for microbial control

“Soft-electron” is a new term we have created referring to electrons with energies of 300 kV or lower. Homogenous irradiation of surfaces with soft electrons can decontaminate dry food ingredients such as gains, pulses, spices, dehydrated vegetables and tealeaves without detrimental effects. Treatment of soybeans with electrons of acceleration voltages at 170 kV reduced their microbial count to an undetectable level. Pre-treatment of soybeans with soft electrons enabled the extension of soymilk without sterilization process at a high temperature (120°C). The gelatinized property of soymilk from soft electron-treated beans was better than that of high-temperature sterilized soymilks. These results indicate that soft-electron sterilization improved the quality of soybeans for the processing of soymilk and Tofu(soymilk curd).