Use of spinning band distillation equipment for fractionation of volatile compounds of Copaifera oleoresins for developing a validated gas chromatographic method and evaluating antimicrobial activity

Copaifera is a tree that produces an oleoresin that has great historical and economic importance. These oleoresins display several pharmacological properties, such as anti‐inflammatory and antimicrobial, among others. The commercialization of Copaifera oleoresin occurs, in many cases, without any quality control, which facilitates its adulteration. Validated analytical methods can provide a safe quality control. In this work, the 800 Automatic Spinning Band Distillation equipment was used to perform the fractionation of the volatile oils obtained by hydrodistillation of Copaifera multijuga, C. paupera, C. Publifora and C. langsdorffii, aiming to isolate and purify the major compounds present in these oils. For purification, classical column chromatography was used, furnishing six isolated sesquiterpenes. The sesquiterpenes were used as standards in the development and validation of the method by GC–FID. The evaluated parameters were selectivity, linearity, precision, accuracy and robustness and they are all in accordance with ANVISA and International Conference on Harmonization guidelines. The developed method is reliable for the quantification of sesquiterpenes in Copaifera oleoresins. Both volatile oils and isolated sesquiterpenes had their minimum inhibitory concentration determined against strains of Gram‐negative and Gram‐positive bacteria and yeasts. Copaifera langsdorffi oleoresin was the only one active against all of the evaluated microorganisms, displaying good antimicrobial potential.     

Search for stratospheric bromine reservoir species: theoretical study of the photostability of mono-, tri-, and pentacoordinated bromine compounds

Previous work has shown that pentacoordinated bromine compounds have their lowest excited electronic states shifted to the blue relative to monocoordinated bromine molecules, and that this shift may be large enough to render them photostable in the lower stratosphere. Our earlier work has also shown that certain pentacoordinated bromine compounds are thermodynamically stable relative to their mono- or tricoordinated isomers, suggesting that if a bromine stratospheric reservoir species exists, it may be a pentacoordinated compound. In this study we have examined the singlet and triplet excited electronic states of several bromine compounds, using time dependent density functional theory, to assess their photostability under stratospheric conditions and in order to elucidate the nature of lowest excited states in mono-, tri-, and pentacoordinated bromine molecules. The triplet states have been included due to the strong spin-orbit mixing in bromine. We have found several pentacoordinated bromine/oxygen compounds that could be photostable in the lower stratosphere, but we have also found that monovalent bromine compounds where the bromine atom is bonded to an atom with no lone-pair p-electrons is far and away the most photostable. Attachment/detachment electron density plots have been useful in ascertaining the nature of the excited electronic states and their likely path to photodissociation.     

Block ionomer complexes containing cationic antibiotics to kill intracellular Brucella melitensis in vitro

Brucellosis, caused by Brucella spp., is the most common zoonotic disease worldwide. It is difficult to eradicate because the pathogen resides partially within phagocytic host cells and the polar antibiotics that are recommended for treatment do not enter cells efficiently. Core‐shell block ionomer complexes (BICs) carrying antibiotics in their cores were designed to transport these drugs into cells. Polyether–polyacrylate copolymers were condensed with cationic aminoglycoside antibiotics to form BICs with diameters of 170–340 nm in water. An anionic poly(acrylate‐b‐ethylene oxide‐b‐propylene oxide‐b‐ethylene oxide‐b‐acrylate) copolymer blended with a poly(ethylene oxide‐b‐acrylate) diblock was condensed with gentamicin to afford complexes containing up to 42 wt% of the antibiotic. The poly(propylene oxide) contributed hydrophobic interactions that enhanced stability of the complexes in aqueous media, whereas the hydrophilic blocks provided a steric brush to keep the structures dispersed. In vitro efficacy of the BICs to reduce intracellular Brucella was studied in murine macrophage‐like cells. Significant bacterial reductions of 2.78 and 2.85 logs were obtained relative to only 0.75 logs for the free drug. This suggests that the BICs are efficient transporters of polar antibiotics into phagocytic cells. Copyright © 2011 John Wiley & Sons, Ltd.     

Removal of sample background buffering ions and myoglobin enrichment via a pH junction created by discontinuous buffers in capillary electrophoresis

Traditional CE sample stacking is ineffective for samples containing a high concentration of salt and/or buffer. We recently reported the use of a discontinuous buffer system for protein enrichment that was applicable to samples containing millimolar concentrations of salt. In this paper, the technique was investigated for samples containing unwanted buffering ions, including TRIS, MES, and phosphate, which are commonly used in biological sample preparation. Using myoglobin as a model protein, the results demonstrated that background buffering ions can be effectively removed or separated from the enriched protein. The key is to use either the acid or the base of the discontinuous buffers to adjust the pH of the sample, such that the net charge of the unwanted buffering ions is near-zero. The successful isolation and enrichment of myoglobin from up to 100 mM TRIS and 50 mM MES was demonstrated. The enrichment factors remained at approximately 200. Removal of phosphate was more challenging because its net charge was anionic in both the acid and the base of the discontinuous buffers. The enrichment was only achievable up to 30 mM of sodium phosphate, the enrichment factors observed were significantly lower, below 50, and the process was delayed due to the higher ionic strength resulted from phosphate. The migration of phosphate during enrichment was studied using a UV-absorbing analogue, phenyl phosphate. In addition, Simul 5.0 was used to simulate the discontinuous buffers in the absence and presence of TRIS and phosphate. The stimulated TRIS and phosphate concentration profiles were generally in agreement with the experimental results. The simulation also provided a better understanding on the effect of phosphate on the formation of the pH junction.     

Effects of notches on the surface pressure field downstream of a wall-mounted spoiler

Notched spoilers have been observed to be more effective than uniform spoilers to suppress the flow-induced cavity resonance of vehicles with open sunroofs. In this study, a few mechanisms possibly involved in buffeting suppression from notched spoilers were investigated experimentally and numerically. One objective was to investigate the spatial coherence and phase of the wall pressure fluctuations downstream of notched spoilers in comparison with the same quantities for uniform spoilers. Another objective was to gather detailed measured data to allow the verification of computer simulations of the flow over the notched spoiler. Experiments were performed to measure the velocity and wall pressure fields downstream of spoilers mounted on the rigid floor of a closed test section wind tunnel. Efforts were made to reproduce the spoiler and wind tunnel geometry and boundary conditions of the experimental setup in the numerical simulations. The numerical investigation used the Lattice Boltzmann Method (LBM), with the so-called Very Large Eddy Simulation (VLES) viscosity turbulence model. The results of the numerical investigation were in satisfactory agreement with measured data at low frequencies, where buffeting is expected to occur. The results suggested that the notches break down the homogeneity of the leading edge cross-stream vortices predominantly responsible for the cavity excitation. This decreased the cross-stream coherence of the surface pressure field, thereby reducing the magnitude of the net equivalent excitation force acting over the surface downstream.