Side Radical Research Articles

THE EFFECT OF IONIC STRENGTH ON THE ACID – BASE PROPERTIES OF GLYCINE IN AN AQUEOUS SOLUTION

The processes of glycine ionization (Gly) have been studied by potentiometry and the values of pKa1 and pKa2 at 288.15 K, the ionic strength of the solution (Na(H)CIO4) have been calculated) 0.1, 0.25, 0.5, 0.75, 1.0 mol/l and concentrations 1.0÷3.0 · 10-3 mol/l with a confidence probability of P = 0.95. With an increase in ionic strength and temperature, the pK of both amino and carboxyl groups and functional groups of the side radical decreases, which indicates an increase in the degree of their ionization and is consistent with the theory of weak electrolytes.

Synergistically boosting performances of organic solar cells from dithieno[3,2-b]benzo[1,2-b;4,5-b′]dithiophene-based copolymers via side chain engineering and radical polymer additives

A wise strategy to improve the performance of NFA-OSCs from DTBDT-based polymer donors via synergistic employment of side-chain engineering and radical conjugated polymer additives is presented.

Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating.

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

Synthesis and In Vitro Neuroprotective Activity of Glycine Analogs of Gk-2 Dimeric Dipeptide Mimetic of Nerve Growth Factor 4th Loop

A dimeric dipeptide mimetic of nerve growth factor (NGF), bis-(N-monosuccinyl-L-glutamyl-L-lysine) hexamethylenediamide (GK-2), was previously developed at V. V. Zakusov State Institute of Pharmacology, activated specific TrkA receptors, and exhibited neuroprotective activity in vitro (10–5 – 10–9 M) and in vivo (0.1 – 10 mg/kg i.p. and p.o.). GK-2 was designed based on the beta-turn (-Asp94-Glu95-Lys96-Gln97-) of the NGF 4th loop and preserved the central dipeptide fragment (-Glu95-Lys96-). The Asp94 residue was replaced by its monosuccinyl bioisostere. The dimeric structure of NGF was reproduced using a bivalent hexamethylenediamine spacer. The structure—activity (neuroprotective) relationship for GK-2 was studied in the present work using a glycine scan, i.e., successive replacement of the peptide side groups by H. The bis-(N-acetyl-L-glutamyl-L-lysine) (GK-2Ac), bis-(N-monosuccinylglycyl-L-lysine) (GK-2-Gly1), and bis-(N-monosuccinyl-L-glutamylglycine) hexamethylenediamides (GK-2-Gly2) were less active with neuroprotective activity in vitro under oxidative stress for HT22 cells at concentrations 10 – 100 times greater than GK-2. The conclusion was drawn that each side radical of GK-2 was important for manifestation of the full neuroprotective activity of dimeric dipeptide GK-2, a mimetic of the NGF 4th loop. However, removal of any of the side radicals would probably not change the active structure of the beta-turn so that the two remaining side radicals should retain the ability to bind to their TrkA subsites. This could explain the retention of neuroprotective activity in the GK-2 glycine analogs.

SELECTION OF PROTECTIVE GROUPS UPON OPTIMIZING THE SYNTHESIS OF γ-PNA BASED ON L-GLU

This work is devoted to optimization of the synthesis of γ-S-carboxyethyl monomers of PNA based on L-Glu. PNA are promising compounds that hybridize with DNA or RNA, and due to their properties they are used in molecular biology, personalized medicine, and can also be used to create nanomaterials. To increase the yield of the desired monomers, it has been proposed to replace the benzyl protecting group with the carboxy function of the side radical by cyclohexyl one. Two synthetic schemes were proposed. In the first of them, γ-benzyl-N-Boc-glutamic acid, which was reduced to β-amino alcohol, was the starting compound. The hydroxyl group was protected by a dimethyl-tert-butylsilyl group. The benzyl ester in the side radical was cleaved by reduction on a palladium catalyst using ammonium formate. However, the subsequent acylation of cyclohexyl alcohol failed. In the second of the proposed schemes, a known sequence of reactions was used, which led to the formation of a cyclic derivative of Cbz-protected glutamic acid. Then, the resulting compound was acylated with cyclohexyl alcohol to give the desired ester. The subsequent transformation of the protective groups of the ester resulted in the diprotected L-glutamic acid in three stages. Subsequent reduction gave the desired protected β-amino alcohol containing a cyclohexyl protecting group in the side radical. This compound was further used in the Mitsunobu reaction to obtain a completely protected core of the PNA monomer. Subsequent thiolysis reaction resulted in the formation of the target secondary amine, the stability of which substantially exceeded the stability of its analog with benzyl protection, obtained and investigated before. The structure of the new compounds obtained is confirmed by 1H-NMR spectroscopy.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ СОСТАВА НИЗКОМОЛЕКУЛЯРНЫХ ПРОДУКТОВ СВЕРХКРИТИЧЕСКОЙ ЭКСТРАКЦИИ СОЛОМЫ ПШЕНИЦЫ ЭТАНОЛОМ И ДИМЕТИЛКАРБОНАТОМ

Supercritical extraction is a promising method for the preparation of lignocellulosic raw material for subse-quent biochemical processing. This paper presents a comparative analysis of low-molecular-weight prod-ucts extracted from wheat straw in a batch-type autoclave at a temperature of 285С for 10 min. Ethanol and dimethyl carbonate were used as solvents, since these compounds are known to be similar in terms of their dissolution ability but different in terms of their alkylating properties. It is found that wheat straw ex-traction using dimethyl carbonate demonstrates a high level of efficiency. Compared to ethanolysis, a greater extract yield characterized by a high content of hexanol-soluble compounds was obtained. These compounds predominantly included methyl esters of carboxylic acids. On the other hand, lignin fragmentation products were dominated by veratrous-type compounds. A mechanism is proposed for obtaining low-molecular lignin fragmentation products under the conditions of supercritical extraction, which is based on the processes of a radical cleavage of alkyl aryl ester bonds and C-C bonds in the side radical, as well as on the reactions of dehydration, esterification and re-esterification. When this mechanism is applied under the conditions of supercritical ethanolysis, it additionally involves the reactions of hydrogenation and keto-enol rearrangement with the formation of ketones.

STANDARD FORMATION ENTHALPIES OF L-ARGININE AND PRODUCTS OF ITS DISSOCIATION IN AQUEOUS SOLUTION

Depending on the chemical nature of side radicals, amino acids can be divided into aromatic and aliphatic ones, as well as amino acids that have non-polar or polar functional groups in their side radical. Since specific features of individual amino acids in the protein are determined by the nature (physicochemical properties) of their side radicals that exist in the hydrated state, it also seems extremely important to study the thermodynamic characteristics of hydration of side radicals of amino acids of different chemical nature. In order to obtain empirical correlations that would establish a relationship between the thermodynamic parameters of interaction of a dissolved compound with the solvent and the size of molecules being dissolved (that have different physicochemical nature), one needs to accumulate a sufficient amount of experimental data on heats of dissolution of amino acids and peptides. This would allow one to verify the addictively of contributions of intermolecular interactions for different groups of molecules. Reagent L-arginine was used without additional purification. Prior to weighing, the substance was dried at 110 °C. The heats of dissolution of crystalline L-arginine were measured using an isothermal-jacket calorimeter with automatic recording of the temperature-time curve. The performance of the calorimetric setup was verified in accordance with the conventional calorimetric standards: the heat of dissolution of crystalline potassium chloride in water and the heat of neutralization of a strong acid with a strong base. The agreement between the experimental enthalpies of dissolution of KCl (cr.) in water and the heats of neutralization of nitric acid with a KOH solution with the most reliable published data indicates that there are no evident systematic errors in the performance of the calorimetric setup. The equilibrium compositions of solutions were calculated using RRSU software. The heats of dissolution of crystalline amino acid in water and potassium hydroxide solutions at 298.15 K were measured by direct calorimetry. The standard enthalpies of formation of L-arginine and the products of its dissociation in aqueous solutions were calculated.Forcitation:Lytkin A.I., Chernikov V.V., Krutova O.N., Krutov P.D. Standard formation enthalpies of L-arginine and products of its dissociation in aqueous solution. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 40-45

A decrease of cyclophosphane toxic effect by the combined action with amino acids in the tissue culture of liver

In organotypic culture investigated the combined effect iproto-like agent cyclophosphamide and the encoded L-amino acids on the development of the processes of proliferation and apoptosis in explants of the liver tissue of Mature rats. Various amino acids, in a concentration of 0.05 ng/ml had either a stimulating or a depressing effect on the cellular proliferation in the growth zone of explants. When introduced into the culture medium of cyclophosphamide at a concentration of 1 mg/ ml was inhibition of cell proliferation due to the development of apoptosis, verified with immunocytochemical detection of enhanced expression of protein p53. Coadministration of cyclophosphamide in conjunction with each of the amino acids led to a significant decrease in the inhibitory effect of cyclophosphamide. Amino acids with charged side radical, acid from glutamic acid and arginine at a major – was able to completely eliminate the inhibitory effect of cyclophosphamide in organotypic tissue culture of rat liver. Amino acids with charged side chains can be considered as the simplest of the regulators and stimulants of physiological functions. We know that of all the physico-chemical properties of amino acids is the hydrophobicity of the side groups are important for their intermolecular interactions. Mechanisms of action of these amino acids, the cells can have universal features, which is consistent with the assumption about the participation of electrostatic and hydrophobic interactions in these processes. Thus, L amino acids can have a protective effect on the cell proliferation of the liver tissue from the toxic action iproto-like agents.

Development of viscometric methods for studying the interaction of various porphyrins with DNA. Part III: Meso-tetra-(3N-alylpyridyl)porphyrin and its Cu-, Co- and Zn-containing derivatives

Present research continues the development of viscometry method for studying porphyrin–DNA interactions.Water soluble cationic meso-tetra-(3[Formula: see text]-alylpyridyl) porphyrin (H2TAlPyP3) and its Cu-, Co- and Zn-containing derivatives were studied using UV-vis absorption spectroscopy and viscometry in order to clarify the effect of chemical structure (presence of double bond in structure of a side radical) of porphyrins and ability to affect the DNA structure. Their binding constant ([Formula: see text] and stoichiometry ([Formula: see text] were determined based on the absorbance spectra for each DNA–porphyrin complex. The results were compared with results of previously conducted similar studies with meso-tetra-(3[Formula: see text]-hydroxyethylpyridyl) porphyrins. It was shown, that the planar porphyrins H2TAlPyP3 and CuTAlPyP3 interact with DNA predominantly by intercalation at low relative concentrations of [Formula: see text](([Formula: see text] [Formula: see text] [Porphyrin]/[DNA])) and by external binding mode at high values of [Formula: see text], whereas the change of chemical structure of peripheral radicals of porphyrins does not absolutely affect on the mechanism of interaction of outside binders CoTAlPyP3 and ZnTAlPyP3 with DNA.

Spin Excitation Under Electron Delocalization of Side Radicals in Quasi-One-Dimensional Organic Ferromagnet

Spin excitation in poly(1,4-bis(2,2,6,6-tetramethyl-4-oxy-piperidyl-1-oxyl)-butadiin) (poly-BIPO), a quasi-one-dimensional organic ferromagnet, was investigated based on the extended Su–Schriffer–Heeger model by considering electron hopping and the spin correlation between the main chain and side radicals. The lattice, charge density, and spin density configurations of the single spin as well as spin domain excited states of the organic ferromagnet poly-BIPO were systematically studied. The side radical spin excitation gives rise to lattice distortion, charge density localization, and a spin density defect on the main chain. A peak induced by spin excitation is predicted to appear in the density of states of the organic ferromagnet poly-BIPO based on calculations for different spin electron states. These results expand knowledge on elementary excitation in organic materials and have significant implications for the design of spintronic devices.

Laparoscopic radical nephroureterectomy for urothelial carcinoma in a horseshoe kidney: A case report and literature review

s / Urological Science 26 (2015) 301e310 309 NDP26: LAPAROSCOPIC RADICAL NEPHROURETERECTOMY FOR UROTHELIAL CARCINOMA IN A HORSESHOE KIDNEY: A CASE REPORT AND LITERATURE REVIEW Shu-Chi Wang , Siu-Wan Hung , Kun-Yuan Chiu . Division of Urology, Department of Surgery, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Radiology, Taichung Veterans General Hospital, Taichung, Taiwan A 75-year-old male suffered from gross hematuria for months and was diagnosed with urothelial carcinoma in the left moiety of a horseshoe kidney. Laparoscopic left side radical nephroureterectomy with open bladder cuff excision through a Gibson incision. The patient was discharged on post-operative day five uneventfully. Preoperative computed tomography is quite valuable for the evaluation of the anatomical variations in horseshoe kidneys. In conclusion, laparoscopic approach is effective for managing malignancy in horseshoe kidneys. NDP27: SINGLE MASSIVE URETER POLYP CAUSING URETER INTUSSUSCEPTION: A CASE REPORT AND LITERATURE REVIEW Pao-Hwa Chen, Chun-Chi Chen, Bai-Fu Wang, Jesen Lin, Heng-Chieh Chiang, Meng-Yi Yan, Chang-Pao Chang, Sheng-Hsien Huang, Kuo-Hsuan Huang, Hung-Jen Shih, Jian-Xiang Zhang, Jian-ting Chen. Divisions of Urology, Department of Surgery, Changhua Christian Hospital, Changhua,

Radical Compatibility with Nonaqueous Electrolytes and Its Impact on an All‐Organic Redox Flow Battery

AbstractNonaqueous redox flow batteries hold the promise of achieving higher energy density because of the broader voltage window than aqueous systems, but their current performance is limited by low redox material concentration, cell efficiency, cycling stability, and current density. We report a new nonaqueous all‐organic flow battery based on high concentrations of redox materials, which shows significant, comprehensive improvement in flow battery performance. A mechanistic electron spin resonance study reveals that the choice of supporting electrolytes greatly affects the chemical stability of the charged radical species especially the negative side radical anion, which dominates the cycling stability of these flow cells. This finding not only increases our fundamental understanding of performance degradation in flow batteries using radical‐based redox species, but also offers insights toward rational electrolyte optimization for improving the cycling stability of these flow batteries.

Radical Compatibility with Nonaqueous Electrolytes and Its Impact on an All-Organic Redox Flow Battery.

Nonaqueous redox flow batteries hold the promise of achieving higher energy density because of the broader voltage window than aqueous systems, but their current performance is limited by low redox material concentration, cell efficiency, cycling stability, and current density. We report a new nonaqueous all-organic flow battery based on high concentrations of redox materials, which shows significant, comprehensive improvement in flow battery performance. A mechanistic electron spin resonance study reveals that the choice of supporting electrolytes greatly affects the chemical stability of the charged radical species especially the negative side radical anion, which dominates the cycling stability of these flow cells. This finding not only increases our fundamental understanding of performance degradation in flow batteries using radical-based redox species, but also offers insights toward rational electrolyte optimization for improving the cycling stability of these flow batteries.

In Defence of War

Just war theory has always been a matter of controversy in the Christian tradition. How could war possibly be just according to a belief based on the teaching of ‘the Prince of Peace’? In the history of Christianity, one finds on the one side radical Christians arguing for pacifism, and on the other Church Fathers, bishops and theologians who elaborate a doctrine of just war. Oxford theologian Nigel Biggar's book In Defence of War is as the title indicates a vigorous argumentation in support of the doctrine of just war. A main target is ‘wishful thinking’. Biggar is very critical of idealists who believe that tyranny could be reasoned away. Integrated in the Christian version of the doctrine is the idea that human beings are sinful creatures and as a consequence force and war are sometimes necessary means to combat evil: war in the service of love. Biggar refers to the ideas of Augustine, Aquinas, Grotius and Vitoria, and he applies their doctrines to some recent and controversial wars; the NATO attack on Serbia in 1999 to protect Kosovo, and the United States’ and Britain's invasion of Iraq in 2003. Chapters are also devoted to critique of Christian pacifism and critique of liberal individualism.

Synthesis of networked polymers by crosslinking reactions of polybenzoxazine bearing allyl group in the side chain

AbstractA polybenzoxazine bearing allyl group in the side chain was synthesized by the ring‐opening polymerization of N‐allyl‐benzoxazine and was crosslinked by the two different processes, (1) thermally induced oligomerization of the allyl side chains and (2) radical addition of dithiol (thiol‐ene reaction) to the allyl side chains. The former process was promoted by adding 2,5‐dimethyl‐2,5‐di(tert‐butylperoxy)hexane as a radical source, leading to the improved yield of the networked polymer isolated as acetone‐insoluble fraction. The thiol‐ene reaction with using 1,6‐hexanedithiol was also an efficient method for crosslinking the polybenzoxazine. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

ChemInform Abstract: Native Chemical Ligation Combined with Desulfurization and Deselenization: A General Strategy for Chemical Protein Synthesis

AbstractReview: 49 refs.

Native Chemical Ligation Combined with Desulfurization and Deselenization: A General Strategy for Chemical Protein Synthesis

AbstractOf the many approaches proposed to generalize the native chemical ligation approach for protein synthesis, the simple procedure of global desulfurization of peptide thiols has become the most widely adopted. In this review, the development of the native ligation–desulfurization strategy is described, focusing on the conversion of Cys to Ala following ligation at N‐terminal Cys residues. Subsequent variations on this theme have broadened the scope to other natural amino acids including Phe, Leu, Val, and Lys, and even non‐native peptide linkages such as isopeptide bonds on lysine side chains. Using insights from both selenocysteine–peptide side reactions and radical initiated desulfurization procedures, a new method for the selective deselenization of peptides containing both selenocysteine and cysteine residues has been developed. Together, these approaches represent a robust and flexible methodology for the synthesis of complex polypeptides without the use of protecting groups.

Effect of organic co-solvents on the solvation enthalpies of amino acids and dipeptides in mixed aqueous solutions

Transition enthalpies (ΔtrHo) of substances from water to binary solutions were calculated at 298.15 K on the basis of standard dissolution enthalpies (ΔsolHo) for six amino acids and five dipeptides in the mixtures of water with organic solvents of various chemical natures. The enthalpy pair coefficients of interaction hxy for biomolecules with organic component of mixture were estimated within the formalism of the McMillan-Mayer theory. The change in the character of the interaction of the components of solution was demonstrated in dependence on the physicochemical properties of the solvent and nature of the side radical of the dissolved bioorganic substance. Quantitative estimation of the type of interaction of the substance with the solvent was performed on the basis of correlation ratios relating the enthalpy characteristics of bioorganic substances to properties of organic cosolvents. It was shown that in the solutions under study, the effects of both the specific (mainly electron donor) and non-specific solvation of amino acids and peptides are observed.

Effect of disturbance on spin polarized transport through an organic ferromagnetic device

Based on the tight-binding model and the Greens function method, the effects of atomic disorder of lattice configuration and the orientation disorder of side radical spins on the spin polarized transport through a metal/organic-ferromagnet/metal structure are investigated. The results show that the atomic disorder reduces the threshold voltage of the device and suppresses the conducting current. The staircase structure of the current-voltage curve for a molecular device is eliminated when the disorder is enhanced. The current keeps a high spin polarization if the atomic disorder is not strong. The orientation disorder of side radical spins reduces the spin splitting of molecular energy levels, which increases the threshold voltage of the device. The current and its spin polarization are reduced apparently at a low bias when the strength of disorder is enhanced. We further simulate the effect of temperature on the spin polarized transport through the device by taking into account two kinds of disorders.

Late pulmonary metastases of renal cell carcinoma immediately after post-transplantation immunosuppressive treatment: a case report

IntroductionWe report a case of pulmonary metastatic recurrence of renal adenocarcinoma soon after radical nephrectomy that was followed by renal transplant and immunosuppressive medication. Increased risk of metastatic recurrence of renal cell carcinoma should be considered in the immediate post-transplant period when immunosuppressive medication is administered, even if nephrectomy had been performed many years earlier.Case presentationIn 1986 the patient demonstrated renal insufficiency secondary to mesangial glomerulonephritis. In 1992 he underwent left side radical nephrectomy with histopathological diagnosis of clear cell adenocarcinoma. Mesangial glomerulonephritis in the remaining right kidney progressed to end-stage renal failure. In October 2000 he received a kidney transplant from a cadaver and commenced immunosuppressive medication. Two months later, several nodules were found in his lungs, which were identified as metastases from the primary renal tumor that had been removed with the diseased kidney 8 years earlier.ConclusionRecurrence of renal cell carcinoma metastases points to tumor dormancy and reflects a misbalance between effective tumor immune surveillance and immune escape. This case demonstrates that a state of tumor dormancy can be interrupted soon after administration of immunosuppressant medication.