Efficient Synthesis of Some Unsaturated [1,2,3]‐Triazole‐Linked Glycoconjugates

Thermal 1,3‐dipolar cycloaddition of ethyl 4‐azido‐2,3,4‐trideoxy‐α‐D‐erythro‐hex‐2‐enopyranosides with diethyl acetylenedicarboxylate or copper‐catalyzed reaction with various functionalized alkynes gave the corresponding 1‐(ethyl 2,3,4‐trideoxy‐α‐D‐erythro‐hex‐2‐enopyranosid‐4‐yl)‐1H‐1,2,3‐triazole derivatives in quite good yields. These unsaturated compounds could be transformed into 1‐(ethyl 2,3‐di‐O‐acetyl‐4‐deoxy‐α‐D‐mannopyranosid‐4‐yl)‐1H‐1,2,3‐triazoles by a simple dihydroxylation reaction. Copper‐catalyzed condensation of ethyl 6‐O‐acetyl‐4‐azido‐2,3,4‐trideoxy‐α‐D‐erythro‐hex‐2‐enopyranoside with 1,3,5‐triethynylbenzene or 1,3,5‐tris(prop‐2‐ynyloxy)benzene afforded the corresponding trivalent glycoconjugate clusters.     

The Biginelli Reaction with an Imidazolium–Tagged Recyclable Iron Catalyst: Kinetics,Mechanism, and Antitumoral Activity

The present work describes the synthesis, characterization, and application of a new ion‐tagged iron catalyst. The catalyst was employed in the Biginelli reaction with impressive performance. High yields have been achieved when the reaction was carried out in imidazolium‐based ionic liquids (BMI ? PF₆, BMI ? NTf₂, and BMI ? BF₄), thus showing that the ionic‐liquid effects play a role in the reaction. Moreover, the ion‐tagged catalyst could be recovered and reused up to eight times without any noticeable loss in activity. Mechanistic studies performed by using high‐resolution electrospray‐ionization quadrupole‐time‐of‐flight mass (HR‐EI‐QTOF) spectrometry and kinetic experiments indicate only one reaction pathway and rule out the other two possibilities under the development conditions. The theoretical calculations are in accordance with the proposed mechanism of action of the iron catalyst. Finally, the 37 dihydropyrimidinone derivatives, products of the Biginelli reaction, had their cytotoxicity evaluated in assays against MCF‐7 cancer cell linages with encouraging results of some derivatives, which were virtually non‐toxic against healthy cell linages (fibroblasts).     

Effect of the composition on the thermal behaviour of the SrSn1−xTixO3 precursor prepared by the polymeric precursor method

Strontium stannate titanate Sr(Sn, Ti)O₃ is a solid solution between strontium stannate (SrSnO₃) and strontium titanate (SrTiO₃). In the present study, it was synthesized at low temperature by the polymeric precursor method, derived from the Pechini process. The powders were calcined in oxygen atmosphere in order to eliminate organic matter and to decrease the amount of SrCO₃ formed during the synthesis. The powders were annealed at different temperatures to crystallize the samples into perovskites-type structures. All the compositions were studied by thermogravimetry (TG) and differential thermal analysis (DTA), infrared spectroscopy (IR) and X-ray diffraction (XRD). The lattice former, Ti⁴⁺ and Sn⁴⁺, had a meaningful influence in the mass loss, without changing the profile of the TG curves. On the other hand, DTA curves were strongly modified with the Ti⁴⁺:Sn⁴⁺ proportion in the system indicating that intermediate compounds may be formed during the synthesis being eliminated at different temperature ranges, while SrCO₃ elimination occurs at higher temperature as shown by XRD and IR spectra.     

Genipin‐Cross‐Linked Chitosan as a Support for Laccase Biosensor

In this study a biosensor with laccase immobilized in a chitosan matrix was developed. Prior to the laccase immobilization the chitosan was cross‐linked with genipin, a naturally‐occurring cross‐linking agent, and incorporated into a carbon‐paste electrode. Analytical parameters for caffeic acid, such as repeatability (2.7 %), reproducibility (3.0 %), linearity (0.27 and 33 µM; r²≥0.9983), limit of detection (LOD=0.18 µM) and recovery (96–103 %), were determined. The method was applied in the determination of the total phenolic content of mate herb samples. The good performance of the method can be attributed to the effective immobilization of laccase in the cross‐linked support.     

Highly Ordered TiO2 Nanotubes for Electrochemical Sensing of Hair Dye Basic Brown 17

Self‐organized Ti/TiO₂ nanotubular array electrodes were prepared by electrochemical anodization and used to monitor the reduction of the hair dye basic brown 17 (BB17) at a potential of ?0.60 V vs. Ag/AgCl. Analytical curves were obtained from 1.0×10^?6 to 8.0×10^?5 mol L^?1 with a detection limit of 1.3×10^?7 mol L^?1 by using the best experimental conditions, linear scan voltammetry at pH 6, scan rate=60 mV s^?1, and accumulation time=5 min. The detection system performance was not interfered by other hair dyes and successfully used to determine the dye in tap water samples.     

Differential pulse adsorptive stripping voltammetric determination of methotrexate using a functionalized carbon nanotubes-modified glassy carbon electrode

A glassy carbon electrode (GC) containing multiwalled functionalized carbon nanotubes (MWCNTs) immobilized within a dihexadecylhydrogenphosphate film (DHP) is proposed as a nanostructured platform for determination of methotrexate (MTX) concentration (a drug used in cancer treatment) using differential pulse adsorptive stripping voltammetry (DPAdSV). The voltammograms for a MTX solution using MWCNTs-DHP/GC electrode presented an oxidation peak potential at 0.98 V vs. Ag/AgCl (3.0 mol L^?1 KCl) in a 0.1 mol L^?1 sulphuric acid. The apparent heterogeneous electron transfer rate constant of 0.46 s^?1 was calculated. The recovery area of 2.62×10^?9 mol cm² was also obtained. Under the optimal experimental conditions, the analytical curve was linear in the MTX concentration range from 5.0×10^?8 to 5.0×10^?6 mol L^?1, with a detection limit of 3.3×10^?8 mol L^?1. The MWCNTs-DHP/GC electrode can be easily prepared and was applied for the determination of MTX in pharmaceutical formulations, with results similar to those obtained using a high-performance liquid chromatography comparative method.      

Raman spectroscopy as a tool to the in situ study of three lichens species from Antarctica and Brazil

In this investigation the chemistry of the lichens Gondwania regalis, Teloschistes exilis and Xanthoria candelaria (Teloschistaceae) have been recorded by means of Raman spectroscopy. The non‐destructive analysis provided the recognition of parietin and conjugated polyenes, probably belonging to the carotenoid family for all the investigated specimens. Bands at ca. 1370 and 1600 cm⁻¹, respectively, assigned to the ν(C―O) and ν(CO) modes of the phenyl group of the anthraquinone compound, as well the bands at ca. 1005, 1158 and 1527 cm⁻¹, possibly assigned to the β‐carotene in the FT‐Raman spectra, have provided valuable spectroscopy data for the identification of the biomarkers for these lichen pigments. Thus, this is the first report of parietin and carotenoid in T. exilis and X. candelaria tissues even as the parietin anthraquinone for G. regalis tissues, which are effective pigments against free radicals from UV radiation. Copyright © 2014 John Wiley & Sons, Ltd.     

Optimization of Xylanase Production by Filamentous Fungi in Solid-State Fermentation and Scale-up to Horizontal Tube Bioreactor

Five microorganisms, namely Aspergillus niger CECT 2700, A. niger CECT 2915, A. niger CECT 2088, Aspergillus terreus CECT 2808, and Rhizopus stolonifer CECT 2344, were grown on corncob to produce cell wall polysaccharide-degrading enzymes, mainly xylanases, by solid-state fermentation (SSF). A. niger CECT 2700 produced the highest amount of xylanases of 504?±?7 U/g dry corncob (dcc) after 3 days of fermentation. The optimization of the culture broth (5.0 g/L NaNO₃, 1.3 g/L (NH₄)₂SO₄, 4.5 g/L KH₂PO₄, and 3 g/L yeast extract) and operational conditions (5 g of bed loading, using an initial substrate to moistening medium of 1:3.6 (w/v)) allowed increasing the predicted maximal xylanase activity up to 2,452.7 U/g dcc. However, different pretreatments of materials, including destarching, autoclaving, microwave, and alkaline treatments, were detrimental. Finally, the process was successfully established in a laboratory-scale horizontal tube bioreactor, achieving the highest xylanase activity (2,926 U/g dcc) at a flow rate of 0.2 L/min. The result showed an overall 5.8-fold increase in xylanase activity after optimization of culture media, operational conditions, and scale-up.     

Development,Characterization, and Immunomodulatory Evaluation of Carvacrol-loaded Nanoemulsion

Carvacrol (CV) is an essential oil with numerous therapeutic properties, including immunomodulatory activity. However, this effect has not been studied in nanoemulsion systems. The objective of this study was to develop an innovative carvacrol-loaded nanoemulsion (CVNE) for immunomodulatory action. The developed CVNE comprised of 5% w/w oily phase (medium chain triglycerides + CV), 2% w/w surfactants (Tween 80^®/Span 80^®), and 93% w/w water, and was produced by ultrasonication. Dynamic light scattering over 90 days was used to characterize CVNE. Cytotoxic activity and quantification of cytokines were evaluated in peripheral blood mononuclear cell (PBMC) culture supernatants. CVNE achieved a drug loading of 4.29 mg/mL, droplet size of 165.70 ± 0.46 nm, polydispersity index of 0.14 ± 0.03, zeta potential of −10.25 ± 0.52 mV, and good stability for 90 days. CVNE showed no cytotoxicity at concentrations up to 200 µM in PBMCs. CV diminished the production of IL-2 in the PBMC supernatant. However, CVNE reduced the levels of the pro-inflammatory cytokines IL-2, IL-17, and IFN-γ at 50 µM. In conclusion, a stable CVNE was produced, which improved the CV immunomodulatory activity in PBMCs.     

Bioaerogels: Promising Nanostructured Materials in Fluid Management,Healing and Regeneration of Wounds

Wounds affect one’s quality of life and should be managed on a patient-specific approach, based on the particular healing phase and wound condition. During wound healing, exudate is produced as a natural response towards healing. However, excessive production can be detrimental, representing a challenge for wound management. The design and development of new healing devices and therapeutics with improved performance is a constant demand from the healthcare services. Aerogels can combine high porosity and low density with the adequate fluid interaction and drug loading capacity, to establish hemostasis and promote the healing and regeneration of exudative and chronic wounds. Bio-based aerogels, i.e., those produced from natural polymers, are particularly attractive since they encompass their intrinsic chemical properties and the physical features of their nanostructure. In this work, the emerging research on aerogels for wound treatment is reviewed for the first time. The current scenario and the opportunities provided by aerogels in the form of films, membranes and particles are identified to face current unmet demands in fluid managing and wound healing and regeneration.