Photoinitiated Rearrangement of Aromatic Azides to 2-Aminonicotinates.

This study describes a one-pot photoinduced method for azepine synthesis and their subsequent rearrangement into pyridines. The rearrangement of the azepine, formed during photolysis, occurs due to both thermal and photochemical activation of the reaction. This requires an electron-donating substituent at the second position of the azepine and an electron-withdrawing substituent at the third position of the azepine. A reaction mechanism has been proposed to explain the role of water and the nature of the azepine substituents.

The Influence of Polycation and Counter-Anion Nature on the Properties of Poly(ionic liquid)-Based Membranes for CO2 Separation.

The current investigation is focused on the development of composite membranes based on polymeric ionic liquids (PILs) containing imidazolium and pyridinium polycations with various counterions, including hexafluorophosphate, tetrafluoroborate, and bis(trifluoromethylsulfonyl)imide. A combination of spectroscopic methods was used to identify the synthesized PILs and characterize their interaction with carbon dioxide. The density and surface free energy of polymers were performed by wettability measurements, and the results are in good agreement with the permeability and selectivity obtained within the gas transport tests. It was shown that the membranes with a selective layer based on PILs exhibit relatively high permeability with CO2 and high ideal selectivity CO2/CH4 and CO2/N2. Additionally, it was found that the type of an anion significantly affects the performance of the obtained membranes, with the most pronounced effect from bis-triflimide-based polymers, showing the highest permeability coefficient. These results provide valuable insights into the design and optimization of PIL-based membranes for natural and flue gas treatment.

Scaffold Chemical Model Based on Collagen-Methyl Methacrylate Graft Copolymers.

Polymerization of methyl methacrylate (MMA) in aqueous collagen (Col) dispersion was studied in the presence of tributylborane (TBB) and p-quinone: 2,5-di-tert-butyl-p-benzoquinone (2,5-DTBQ), p-benzoquinone (BQ), duroquinone (DQ), and p-naphthoquinone (NQ). It was found that this system leads to the formation of a grafted cross-linked copolymer. The inhibitory effect of p-quinone determines the amount of unreacted monomer, homopolymer, and percentage of grafted poly(methyl methacrylate) (PMMA). The synthesis combines two approaches to form a grafted copolymer with a cross-linked structure-"grafting to" and "grafting from". The resulting products exhibit biodegradation under the action of enzymes, do not have toxicity, and demonstrate a stimulating effect on cell growth. At the same time, the denaturation of collagen occurring at elevated temperatures does not impair the characteristics of copolymers. These results allow us to present the research as a scaffold chemical model. Comparison of the properties of the obtained copolymers helps to determine the optimal method for the synthesis of scaffold precursors-synthesis of a collagen and poly(methyl methacrylate) copolymer at 60 °C in a 1% acetic acid dispersion of fish collagen with a mass ratio of the components collagen:MMA:TBB:2,5-DTBQ equal to 1:1:0.015:0.25.

One-Pot Lewis Acid Mediated Water-Promoted Transformation of Styrenes to α-Substituted Conjugated Enals.

We report herein an unusual one-pot preparation of α-benzyl-substituted conjugated enals via ZnCl2/LiCl/H2O-mediated transformation of styrenes. On the basis of experimental and computational studies, an underlying mechanism including electrophilic addition and hydride transfer with iminium cations has been proposed. The effect of the LiCl/ZnCl2/H2O combination on the reaction yield has been studied, demonstrating their participation in the activation and the key isomerization of an iminium electrophile.

Design, Synthesis and In Vitro Biological Activity of Novel C-7 Methylene Congeners of Furanoallocolchicinoids.

A series of novel heterocyclic colchicine derivatives bearing a C-7 methylene fragment were synthesized via Wittig, Horner-Wadsworth-Emmons and Nenajdenko-Shastin olefination approaches. The in vitro biological activities of the most promising compounds were investigated using MTT assays and cell cycle analyses. Compounds with an electron withdrawing group on the methylene fragment exhibited substantial antiproliferative activity towards COLO-357, BxPC-3, HaCaT, PANC-1 and A549 cell lines. The spatial orientation of the substituent at the double bond significantly influenced its biological activity.

Microcirculation and blood rheology abnormalities in chronic heart failure.

BACKGROUND: Generalized restricted blood flow is hallmark of CHF of any etiology, but the extent of microcirculation restriction and the role of intrinsic blood properties in heart failure remains unknown. OBJECTIVE: The aim of this study was to estimate the microvascular blood flow and hemorheological properties in chronic heart failure to test the hypothesis that CHF patients have altered peripheral blood flow which contributes to the tissue perfusion disturbances. METHODS: Cutaneous microvascular blood flow was estimated by Laser Doppler and Optical Tissue Oximetry techniques. Whole blood and plasma viscosity were measured by capillary viscometer, red blood cell aggregation was evaluated by direct microscopic method, erythrocyte deformability was assessed as elongation index in flow microchamber. Hematocrit-to-viscosity ratio was used as index of oxygen transport efficacy. RESULTS: Depression of the regulatory mechanisms of microvascular blood flow as well as decreased tissue perfusion indicated the restricted blood flow in microcirculatory network in CHF. Increased blood and plasma viscosity, enhanced red blood cell aggregation and decreased erythrocyte deformability were registered in CHF. CONCLUSIONS: Complex impairment of peripheral blood flow in CHF including restricted microcirculation, attenuated regulatory mechanisms and impaired hemorheological properties caused the reduced oxygen utilization contributing to symptoms and advance of heart failure.

Interrelation of blood coagulation and hemorheology in cancer.

Cancer progression is associated with activation of blood coagulation. Blood coagulation process, platelet hemostasis and hemorheological properties were evaluated in patients with solid tumors (n = 27) before and after surgery and in healthy control (n = 20). The main features of blood coagulation process in cancer patients were elevated intensity and shortened period of contact phase of coagulation and inhibited fibrinolysis stage. Such prothrombotic state was fixed before surgery as well as in early postoperative period in spite of preventing thromboprophylactic treatment. Platelets depletion within the high level of spontaneous and ADP-induced platelet aggregation was fixed in cancer. The main cause of blood viscosity decrease in cancer patients was dramatic fall of Hct, because blood viscosity adjusted by Hct 40% was increased owing to the rise of plasma viscosity and substantially worsened RBC microrheological properties. The results of our study indicated close correlation between hemorheological and hemostasis parameters; these interrelations were more numerous and strong in cancer. In cancer patients the combination of a high aggregation activity of platelets, reduced number of erythrocytes (Hct), an increase of RBC aggregation and plasma viscosity caused impairment of blood oxygen transportation efficacy that provoke hypoxia in the microcirculation favoring thrombosis, settlement of tumor and metastasis.

Synthesis and biological evaluation of novel anticancer bivalent colchicine-tubulizine hybrids.

A series of novel antimitotic hybrids were synthesized in good yields by linking of azide-containing colchicine congeners with acetylene-substituted tubulizine-type derivatives using copper-mediated 1,3-dipolar cycloaddition. Obtained compounds exhibit good cytotoxicity against HBL100 epithelial cell lines (IC(50)=0.599-2.93 µÐœ). Several newly synthesized compounds are the substoichiometric inhibitors of microtubule assembly (R=0.41-0.78). The results highlight the importance of the length of spacer linking the tubulin binding ligands in heterodimeric molecules.