Extraction of cellulose fibers from flax and hemp: a review

Cellulose - The paper is a review on the extraction processes of cellulosic fibers from flax and hemp. The two lignocellulosic crops have a long history of use by humans for extraction of the bast...     

Aromatic Homologation by Non‐Chelate‐Assisted RhIII‐Catalyzed CH Functionalization of Arenes with Alkynes

Larger condensed arenes are of interest owing to their electro‐ and photochemical properties. An efficient synthesis is the catalyzed aromatic annulation of a smaller arene with two alkyne molecules. Besides difunctionalized starting materials, directed C? H functionalization can be used for such aromatic homologation. However, thus far the requirement of either pre‐functionalized substrates or suitable directing groups were limiting this approach. Herein, we describe a rhodium(III)‐catalyzed method allowing the use of completely unbiased arenes and internal alkynes. The reaction works best with copper(II) 2‐ethylhexanoate and decabromodiphenyl ether as the oxidant combination. This aromatic annulation tolerates a variety of functional groups and delivers homologated condensed arenes. Aside from simple benzenes, naphthalenes and higher condensed arenes provide access to highly substituted and highly soluble acenes structures having important electronic and photophysical properties.     

Carbaborane‐Substituted 1,2,3‐Triphospholanes and 1‐Aza‐2,5‐diphospholane: New Synthetic Approaches

New phosphorus‐containing, five‐membered P,P,P and P,N,P heterocycles were synthesized and fully characterized. The P,P,P heterocycles, 1,2,3‐triphospholanes, can be synthesized by two different facile pathways, whereas the P,N,P compound, a 1‐aza‐2,5‐diphospholane, can only be obtained with silylamine.     

From Enantiopure Hydroxyaldehydes to Complex Heterocyclic Scaffolds: Development of Domino Petasis/Diels–Alder and Cross‐Metathesis/Michael Addition Reactions

One‐step assembly of hexahydroisoindole scaffolds by a sequence that combines the Petasis (borono‐Mannich) and Diels–Alder reactions is described. The unique selectivity observed experimentally was confirmed by quantum calculations. The current method is applicable to a broad range of substrates, including free sugars, and holds significant potential to efficiently and stereoselectively build new heterocyclic structures. This easy and fast entry to functionalized polycyclic compounds can be pursued by further transformations, for example, additional ring closure by a cross‐metathesis/Michael addition domino sequence.     

Analysis of trace elements in the fingernails of breast cancer patients using instrumental neutron activation analysis

Journal of Radioanalytical and Nuclear Chemistry - The aim of this study was to find trace elements that increase risk of breast cancer based on the deviation of the concentration of trace elements...     

Oversampling Free Energy Perturbation Simulation in Determination of the Ligand-Binding Free Energy

Determination of the ligand-binding affinity is an extremely interesting problem. Normally, the free energy perturbation (FEP) method provides an appropriate result. However, it is of great interest to improve the accuracy and precision of this method. In this context, temperature replica exchange molecular dynamics implementation of the FEP computational approach, which we call replica exchange free energy perturbation (REP) was proposed. In particular, during REP simulations, the system can easily escape from being trapped in local minima by exchanging configurations with high temperatures, resulting in significant improvement in the accuracy and precision of protein–ligand binding affinity calculations. The distribution of the decoupling free energy was enlarged, and its mean values were decreased. This results in changes in the magnitude of the calculated binding free energies as well as in alteration in the binding mechanism. Moreover, the REP correlation coefficient with respect to experiment ( R^REP = 0.85 ± 0.15 ) is significantly boosted in comparison with the FEP one ( R^FEP = 0.64 ± 0.30 ). Furthermore, the root-mean-square error (RMSE) of REP is also smaller than FEP, RMSE^REP = 4.28 ± 0.69 versus RMSE^FEP = 5.80 ± 1.11 kcal/mol, respectively. © 2019 Wiley Periodicals, Inc.     

Synthesis and Transformation of 4-(1-Chloro-1-nitroethyl)-6,7-dimethoxy-2-methylquinazoline: Spectral Characterization and Anti-cancer Properties of some Novel Quinazoline Derivatives

An efficient and simple method has been reported for the synthesis of 4-(1-Chloro-1-nitroethyl)-6,7-dimethoxy-2-methylquinazoline ( 2 ) as a key compound for further transformation to other novel 6,7-dimethoxy-2-methyl-4-substituted quinazolines. The structure of the synthesized compounds was characterized by spectroscopic methods. The pathway of some unprecedented reactions was proposed. (E)-1-(6,7-dimethoxy-2-methylquinazolin-4-yl)-3-(4-nitrophenyl)prop-2-en-1-one (11) exhibits high in vitro cytotoxicity on three cell lines, Hepatocellular carcinoma (Hep-G2), Human lung carcinoma (LU-1), and Human breast carcinoma (MCF-7) with IC₅₀ of 2.1, 11.6 and 2.2 μM, respectively.     

The Optimization of a Novel Hydrogel—Egg White-Alginate for 2.5D Tissue Engineering of Salivary Spheroid-Like Structure

Hydrogels have been used for a variety of biomedical applications; in tissue engineering, they are commonly used as scaffolds to cultivate cells in a three-dimensional (3D) environment allowing the formation of organoids or cellular spheroids. Egg white-alginate (EWA) is a novel hydrogel which combines the advantages of both egg white and alginate; the egg white material provides extracellular matrix (ECM)-like proteins that can mimic the ECM microenvironment, while alginate can be tuned mechanically through its ionic crosslinking property to modify the scaffold’s porosity, strength, and stiffness. In this study, a frozen calcium chloride (CaCl₂) disk technique to homogenously crosslink alginate and egg white hydrogel is presented for 2.5D culture of human salivary cells. Different EWA formulations were prepared and biologically evaluated as a spheroid-like structure platform. Although all five EWA hydrogels showed biocompatibility, the EWA with 1.5% alginate presented the highest cell viability, while EWA with 3% alginate promoted the formation of larger size salivary spheroid-like structures. Our EWA hydrogel has the potential to be an alternative 3D culture scaffold that can be used for studies on drug-screening, cell migration, or as an in vitro disease model. In addition, EWA can be used as a potential source for cell transplantation (i.e., using this platform as an ex vivo environment for cell expansion). The low cost of producing EWA is an added advantage.     

Portable capillary liquid chromatography for pharmaceutical and illicit drug analysis

A newly developed portable capillary liquid chromatograph was investigated for the separation of various pharmaceutical and illicit drug compounds. The system consists of two high‐pressure syringe pumps capable of delivering capillary‐scale flow rates at pressures up to 10 000 psi. Capillary liquid chromatography columns packed with sub‐2 μm particles are housed in cartridges that can be inserted into the system and easily connected through high‐pressure fluidic contact points by simply applying a specific, predetermined torque rather than using standard fittings and less precise sealing protocols. Several over‐the‐counter analgesic drug separations are demonstrated, along with a simple online measurement of tablet dissolution. Twenty illicit drug compounds were also separated across six targeted drug panels. The results described in this study demonstrate the capability of this compact liquid chromatography instrument to address several important drug‐related applications while simplifying system operation, and greatly reducing solvent usage and waste generation essential for onsite analysis.     

Peptide Stapling with Anion‐π Catalysts

We report design, synthesis and evaluation of a series of naphthalenediimides (NDIs) that are bridged with short peptides. Reminiscent of peptide stapling technologies, the macrocycles are conveniently accessible by a chromogenic nucleophilic aromatic substitution of two bromides in the NDI core with two thiols from cysteine sidechains. The dimension of core‐bridged NDIs matches that of one turn of an α helix. NDI‐stapled peptides exist as two, often separable atropisomers. Introduction of tertiary amine bases in amino‐acid sidechains above the π‐acidic NDI surface affords operational anion‐π catalysts. According to an enolate chemistry benchmark reaction, anion‐π catalysis next to peptides occurs with record chemoselectivity but weak enantioselectivity. Catalytic activity drops with increasing distance of the amine base to the NDI surface, looser homocysteine bridges, mismatched, shortened and elongated α‐helix turns, and acyclic peptide controls. Elongation of isolated turns into short α helices significantly increases activity. This increase is consistent with remote control of anion‐π catalysis from the α‐helix macrodipole.