Rosehip extraction: Process optimization and antioxidant capacity of extracts

This article examines the extraction of rosehip to study the recovery of a number of compounds with antioxidant properties (polyphenols, flavonoids, and β-carotene). Two varieties of rosehip, cultivated and wild are used as raw material. A detailed study of the process kinetics at different operating conditions is carried out in order to determine appropriate processing parameters, which results in extracts with higher content of target compounds and higher antioxidant capacity. Data on the concentration of active components in the different parts of the fruit (skin, seeds, and pappi) are also obtained, which gives information about their distribution within the fruit. The comparison of wild and cultivated varieties demonstrates the better quality of the cultivated one. The results are useful for production of improved and enriched rosehip extracts with higher content of antioxidant substances that have proven beneficial effects on the human health.      

Purification of Hydrogen from CO with Cu/ZSM-5 Adsorbents

The transition to a hydrogen economy requires the development of cost-effective methods for purifying hydrogen from CO. In this study, we explore the possibilities of Cu/ZSM-5 as an adsorbent for this purpose. Samples obtained by cation exchange from aqueous solution (AE) and solid-state exchange with CuCl (SE) were characterized by in situ EPR and FTIR, H₂-TPR, CO-TPD, etc. The AE samples possess mainly isolated Cu²⁺ cations not adsorbing CO. Reduction generates Cu⁺ sites demonstrating different affinity to CO, with the strongest centres desorbing CO at about 350 °C. The SE samples have about twice higher Cu/Al ratios, as one H⁺ is exchanged with one Cu⁺ cation. Although some of the introduced Cu⁺ sites are oxidized to Cu²⁺ upon contact with air, they easily recover their original oxidation state after thermal treatment in vacuum or under inert gas stream. In addition, these Cu⁺ centres regenerate at relatively low temperatures. It is important that water does not block the CO adsorption sites because of the formation of Cu⁺(CO)(H₂O)_x complexes. Dynamic adsorption studies show that Cu/ZSM-5 selectively adsorbs CO in the presence of hydrogen. The results indicate that the SE samples are very perspective materials for purification of H₂ from CO.     

Partially Hydrogenated Graphene Materials Exhibit High Electrocatalytic Activities Related to Unintentional Doping with Metallic Impurities

Partially hydrogenated graphene materials, synthesized by the chemical reduction/hydrogenation of two different graphene oxides using zinc powder in acidic environment or aluminum powder in alkaline environment, exhibit high electrocatalytic activities, as well as electrochemical sensing properties. The starting graphene oxides and the resultant hydrogenated graphenes were characterized in detail. Their electrocatalytic activity was examined in the oxygen reduction reaction, whereas sensing properties towards explosives were tested by using picric acid as a redox probe. Findings indicate that the high electrocatalytic performance originates not only from the hydrogenation of graphene, but also from unintentional contamination of graphene with manganese and other metals during synthesis. A careful evaluation of the obtained data and a detailed chemical analysis are necessary to identify the origin of this anomalous electrocatalytic activity.     

Comparison of chemical composition and free radical scavenging ability of glycosidically bound and free volatiles from Bosnian pine (Pinus heldreichii Christ. var. leucodermis)

The results obtained show that Bosnian pine is rich in glycosidically bound volatile compounds with strong free radical scavenging properties. Since volatiles can be released from nonvolatile glycoside precursors, these compounds can be considered as a hidden potential source of antioxidant substances and may contribute to the total free radical scavenging ability of Bosnian pine.     

Calcium ions effectively enhance the effect of antisense peptide nucleic acids conjugated to cationic tat and oligoarginine peptides

Cell-penetrating peptides have been widely used to improve cellular delivery of a variety of proteins and antisense agents. However, recent studies indicate that such cationic peptides are predominantly entering cells via an endosomal pathway. We now show that the nuclear antisense effect in HeLa cells of a variety of peptide nucleic acid (PNA) peptide conjugates is significantly enhanced by addition of 6 mM Ca(2+) (as well as by the lysosomotrophic agent chloroquine). In particular, the antisense activities of Tat(48-60) and heptaarginine-conjugated PNAs were increased 44-fold and 8.5-fold, respectively. Evidence is presented that the mechanism involves endosomal release. The present results show that Ca(2+) can be used as an effective enhancer for in vitro cellular delivery of cationic peptide-conjugated PNA oligomers, and also emphasize the significance of the endosomal escape route for such peptides.     

3D HCCH3-TOCSY for Resonance Assignment of Methyl-Containing Side Chains in C-Labeled Proteins

Two 3D experiments, (H)CCH₃-TOCSY and H(C)CH₃-TOCSY, are proposed for resonance assignment of methyl-containing amino acid side chains. After the initial proton–carbon INEPT step, during which either carbon or proton chemical shift labeling is achieved (t₁), the magnetization is spread along the amino acid side chains by a carbon spin lock. The chemical shifts of methyl carbons are labeled (t₂) during the following constant time interval. Finally the magnetization is transferred, in a reversed INEPT step, to methyl protons for detection (t₃). The proposed experiments are characterized by high digital resolution in the methyl carbon dimension (t_2max = 28.6 ms), optimum sensitivity due to the use of proton decoupling during the long constant time interval, and an optional removal of CH₂, or CH₂ and CH, resonances from the F₂F₃ planes. The building blocks used in these experiments can be implemented in a range of heteronuclear experiments focusing on methyl resonances in proteins. The techniques are illustrated using a ¹⁵N, ¹³C-labeled E93D mutant of Schizosacharomyces pombe phosphoglycerate mutase (23.7 kDa).     

Spectroscopic methods for determination of catecholamines: A mini-review

Catecholamines are biogenic compounds that perform a variety of vital functions, playing a key physiological role in humans and animals. They are important markers in diagnosis of diseases and dysfunctions as well as widespread components of pharmaceutical formulations. Therefore, development of highly sensitive, rapid, and economically efficient methods for the determination of catecholamines is of great interest. The spectroscopic analytical methods have a good potential in this respect. This mini-review summarizes in a concise manner some advances and trends in the determination of catecholamines by spectroscopic methods, including spectrophotometry, fluorescence spectroscopy, immunoassays with spectroscopic detection, Raman spectroscopy, and other methods. Information on mainly determined compounds and analyzed samples is given and discussed. Analytical strategies and performance for the quantitation of catecholamines in various samples are described.