Identification and quantitative determination of arbutin in the herb of Orthilia secunda

Introduction. Orthilia secunda (L.) House is a perennial herb that grows in Europe, Siberia, Asia Minor and Central Asia. The herb of Orthilia secunda is actively used in folk medicine as a diuretic, wound-healing and anti-inflammatory agent. From literary sources it is known that this medicinal plant raw material (PRM) contains flavonoids, tannins, organic acids, vitamins, as well as simple phenols and their derivatives (arbutin and hydroquinone). The presence of arbutin is responsible for the plant's high antioxidant and anti-inflammatory properties. But the use of Orthilia secunda in official medicine is limited due to the lack of complete information on the chemical composition and criteria for standardization of this type of medicinal product.Aim. Identification and quantification of arbutin by chromatographic methods in Orthilia secunda (L.) House, harvested in various phytocenotic zones.Materials and methods. The investigated medicinal plant material – the herb of Orthilia secunda – was harvested in various phytocenotic zones: in July 2018, harvesting was carried out in the northern part of Kazakhstan (Kokshetau district), in July-August 2019 in the Perm Territory and in the Tyumen Region. Preliminary identification of arbutin and related phenols – gallic acid and hydroquinone – was carried out by high performance thin layer chromatography (HPTLC) on a CAMAG instrument with a UV cabinet (Merck HPTLC silica gel 60 F154 plates, 20 × 10), semi-automatic Linomat 5 applicator (sample application). Elution of the plates was performed in a CAMAG Automatic Developing Chamber (ADC2). Image fixation was performed on a CAMAG Scanner 3 spectrodensitometer. The quantitative determination of arbutin was carried out by the method of highperformance liquid chromatography, which was carried out on a Prominence LC-20 device (Shimadzu, Japan) according to the validated method described in the European Pharmacopoeia 10.0. Diode array detector SPD-M20A, column Intersil C18 column (250–4.6 mm, 5 μm) (Phenomenex, USA). The results were processed using the LabSolution software. The identification and quantification of arbutin was carried out in comparison with a standard solution containing a reference sample (RS) of arbutin (C = 0,025 mg/ml) and RS of hydroquinone (C = 0,0125 mg/ml).Results and discussion. HPTLC analysis made it possible to detect arbutin and gallic acid – the main product of hydrolytic degradation/ precursor of the biosynthesis of tannins of the hydrolysable group – in the herb of Orthilia secunda from different places of growth. HPLC analysis demonstrates a different chromatographic profile of Orthilia herb harvested in different phytocenotic zones. However, in all studied objects, the absence of hydroquinone and the presence of substances that can presumably be attributed to its derivatives were confirmed, which is confirmed by the visual similarity of the spectra of these compounds and the proximity of the extrema. It was found that arbutin does not belong to the marker (majority) compounds of Orthilia. Its content is low and reaches a maximum (about 0,021 %) in the herb of Orthilia secunda growing on the territory of Kazakhstan, while in the herb of Orthilia harvested in the Perm Territory arbutin was not identified. From the data obtained, it follows that the greatest accumulation of arbutin occurs in areas with a warmer and drier climate (northern part of Kazakhstan).Conclusion. HPTLC analysis of the herb Orthilia secunda allowed the identification of arbutin and gallic acid (the main precursor of tannins of the hydrolysable group). The results of HPLC analysis of Orthilia herb harvested in various phytocenotic zones suggest quantitative differences in the content of arbutin depending on the region of growth. From the experimental data, it follows that Orthilia growing in the northern part of Kazakhstan accumulates the maximum (0,021%) amount of arbutin, in comparison with the samples harvested in the Tyumen region and the Perm region. At the same time, Orthilia harvested in the Perm Territory does not accumulate arbutin. The presence of hydroquinone has not been confirmed (by HPTLC and HPLC methods); therefore, it is not justified to talk about the hydrolytic cleavage of arbutin in the process of biosynthesis or drying. However, in all studied objects there are peaks of substances with spectral characteristics like hydroquinone, which makes it possible to assume the presence of its derivatives. Therefore, it is not advisable to position arbutin as a marker compound of Orthilia secunda harvested on the territory of the Russian Federation, and to standardize raw materials for this compound.

Synthesis, Spectroscopic, Antibacterial, Antioxidant, DNA Binding and Cleavage, Molecular Docking Studies of Ni(II) and Cu(II) Complexes of S and N Donor Schiff Base Ligands

Binary metal complexes of the ligands (L), H3FPT and H3FP4MT with Ni(II) and Cu(II) metal ions (M) were synthesized and characterized by different spectral and analytical techniques. Among these complexes, Ni(II)- H3FPT complex was found to be polymeric. The ligands and their complexes inhibited the growth of gram positive and gram negative bacterial strains to a moderate extent. The antioxidant nature of ligands and complexes was also established. Intercalative mode of binding of the complexes with calf thymus (CT) DNA was proposed from electronic absorption titrations, fluorescence quenching studies and viscosity measurements. The complexes showed hydrolytic cleavage of plasmid pBR322. Docking studies of metal complexes with DNA revealed that the complexes of H3FP4MT are more active than H3FPT.

Instantaneous Degelling Thermoresponsive Hydrogel

Responsive polymeric hydrogels have found wide application in the clinic as injectable, biocompatible, and biodegradable materials capable of controlled release of therapeutics. In this article, we introduce a thermoresponsive polymer hydrogel bearing covalent disulfide bonds. The cold aqueous polymer solution forms a hydrogel upon heating to physiological temperatures and undergoes slow degradation by hydrolytic cleavage of ester bonds. The disulfide functionality allows for immediate reductive cleavage of the redox-sensitive bond embedded within the polymer structure, affording the option of instantaneous hydrogel collapse. Poly (ethylene glycol)-b-poly (lactic acid)-S-S-poly (lactic acid)-b-poly (ethylene glycol) (PEG-PLA-SS-PLA-PEG) copolymer was synthesized by grafting PEG to PLA-SS-PLA via urethane linkages. The aqueous solution of the resultant copolymer was a free-flowing solution at ambient temperatures and formed a hydrogel above 32 °C. The immediate collapsibility of the hydrogel was displayed via reaction with NaBH4 as a relatively strong reducing agent, yet stability was displayed even in glutathione solution, in which the polymer degraded slowly by hydrolytic degradation. The polymeric hydrogel is capable of either long-term or immediate degradation and thus represents an attractive candidate as a biocompatible material for the controlled release of drugs.

Abstract MP213: Activation Of Biosynthetic Pathways Regulates Cardiomyocyte Cell Cycle Induction In Human Cardiomyocyte

Induction of cardiomyocyte proliferation is a promising therapeutic approach to treat heart failure. Several studies have identified metabolism as an important regulator of myocyte proliferation; however, the changes in metabolism during cardiomyocyte division remain unclear. Here, we use ectopic expression of cyclin B1, Cyclin D1, CDK1, and CDK4 (termed 4F) as a tool for understanding how metabolism influences cardiomyocyte proliferation. Mature hiPS-CMs stimulated to proliferate by 4F expression showed significant downregulation of oxidative phosphorylation genes, decreased glucose oxidation, and upregulation of genes that regulate biosynthetic pathways of glucose metabolism such as those involved in NAD(P) + synthesis ( NAMPT, NADK1, NNT ), the hexosamine biosynthetic pathway (HBP) and protein O-GlcNAcylation ( GFPT1 , OGT, OGA ), and the serine biosynthesis pathway (SBP; PHGDH , PSAT1 , SHMT2 ). In 4F-expressing hiPSC-CMs, stable isotope tracing indicated higher enrichment of glucose-derived 13 C in pentose phosphate intermediates, UDP-hexose, phospholipid precursors, NAD + , pyrimidines, UDP-HexNAc, and products of the serine biosynthesis pathway and one-carbon metabolism, suggesting that cell cycle induction activates biosynthetic pathways in cardiomyocytes. Knocking down nicotinamide phosphoribosyltransferase (NAMPT), a critical enzyme in the NAD + salvage pathway, 2 days before 4F overexpression significantly inhibited cell cycle progression in 4F-transduced hiPS-CMs. OGA overexpression, which catalyzes the hydrolytic cleavage of O-GlcNAc from post-transitionally modified proteins, completely abolished 4F-mediated cell cycle induction. Furthermore, NCT503, an inhibitor of the rate-limiting step in the serine biosynthesis pathway, abolished 4F-mediated increases in cell cycle markers. In a gain-of-function approach, we overexpressed phosphoenolpyruvate carboxykinase 2 (PCK2), which can drive carbon from the Krebs cycle to the glycolytic intermediate pool. PCK2 overexpression significantly augmented 4F-mediated cell cycle entry. These findings suggest that a metabolic shift from catabolic to anabolic activity is a critical step for cardiomyocyte cell cycle entry and is required to facilitate proliferation.

Indicators of acidity and methods of its neutralization during preventive conservation and restoration of architectural graphics

The purpose of the article is to analyze the impact of pH of the paper on the state of preservation, to describe the main methods of neutralization of acidity in the implementation of restoration and conservation measures for the preservation of architectural graphics. To indicate the need to monitor the pH state when preserving paper-based collections. Methodology. To analyze the art, methods of systematization, comparison, and generalization to determine and describe the optimal techniques and experience for the preservation of collections of architectural graphics on a paper basis. The scientific novelty consists in a comprehensive study of the relationship between pH and the state of preservation of architectural graphics and methods of neutralization of the acidity in the process of conservation and restoration. Conclusions. It is established that the acidity is due to the parameters of paper production, due to natural aging processes, air pollution, adsorption of acid impurities in the paper, storage conditions, a technique using certain pigments, and so on. It is necessary to monitor the acidity when implementing preventive conservation measures as it is an important indicator of physico-chemical changes in the paper. Acidity accelerates the process of hydrolytic cleavage of cellulose molecules and is one of the reasons for the loss of paper-based collections. A large number of monuments requires conservation and restoration measures to neutralize the pH. Existing methods of stabilization and buffering of acidity are effective, but the search for new, easier to implement, cheaper solutions is ongoing. The new methods can have a longer effect and can be widely used in collections.

Synthesis and biological activity of N6-mannopyranosyladenines

In this work, potentially bioactive condensation products of adenine with D-mannose and 6-deoxy-L-mannose (L-rhamnose) were synthesized in water and ethanol solutions. According to FTIR spectroscopy and elemental analysis, mono-N6-glycosylated adenines were isolated from water systems in satisfactory yields, while ethanol solutions contained mixtures of N6 and N9-products, as well as complexes of the latter with copper ions. A detailed analysis of the vibrational spectra of N6-glycosyladenines confirmed the structure of carbohydrate fragments in the form of pyranose rings, while some part of the product was obtained in the form of deoxyaminoketosis. N-rhamnosyladenine was formed with a more than double yield because of a higher stability of rhamnose with regard to side reactions. The reflection spectra of model solutions of glycosyladenines, recorded 4 days after preparation, showed no bands characteristic of free adenine in the range of 1250-1110 cm-1, which indicates a sufficient resistance of the synthesized products towards hydrolytic cleavage under experimental conditions. The conducted biotesting of the isolated products on wheat seeds (Triticum aestivum L.) showed an increase in the content of chlorophylls in seedlings for both mannosilade-nines compared to the control. A decrease in the concentration of synthesized products in germination solutions from 0.1 to 0.001% led to an increase in the accumulation of photosynthetic pigments, while this effect was more pronounced for rhamnosyladenine. The latter can be connected with the structural features of car-bohydrate fragments, in particular, the differences in the hydroxylation degree of glucoside fragments. Future research will investigate the mechanisms of transformation and action of N6-substituted adenines.

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

Imines are fundamental organic compounds used as synthetic intermediates and as ligands in coordination chemistry. They are also found to be important pharmacophores in various bioactive compounds. In this report, two Schiff bases were prepared using the traditional condensation of 4-pyridinecarboxaldehyde with 2-thiophenemethylamine and 2-quinolinecarboxaldehyde with furfurylamine to form (E)-1-(pyridin-4-yl)-N-(thiophen-2-ylmethyl)methanimine (L1) and (E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine (L2) respectively. L1 and L2 were complexed with silver perchlorate in 2:1 [M:L] stoichiometry to obtain complexes 1 and 2, respectively. The crystal structures of 1 and 2 were unequivocally determined by single-crystal X-ray diffraction analysis. The resulting structures revealed 2 to be a four-coordinate as expected. In contrast, an unexpected chemoselective hydrolytic cleavage of one mole of the (CH=N) imine ligands occurred in complex 2 and, further, the amines (thiophenemethylamine) homo-coupled to form a new imine ligand derivative in situ (L1a) before coordinating to the Ag(I) center along with L1. This observation described an alternative synthetic route to be explored to synthesize a diverse range of imine derivatives, which involves the Ag(I)-promoted homo-coupling of amines. Herein, the crystal structures of Ag(I) complexes of pyridinyl [Ag(L1)(L1a)]ClO4 (1) and quinolinyl [Ag(L2)2]ClO4 (2) Schiff bases are presented.

Chemical and physical interactions of regenerated cellulose yarns and isocyanate-based matrix systems

In the development of structural composites based on regenerated cellulose filaments, the physical and chemical interactions at the fibre-matrix interphase need to be fully understood. In the present study, continuous yarns and filaments of viscose (rayon) were treated with either polymeric diphenylmethane diisocyanate (pMDI) or a pMDI-based hardener for polyurethane resins. The effect of isocyanate treatment on mechanical yarn properties was evaluated in tensile tests. A significant decrease in tensile modulus, tensile force and elongation at break was found for treated samples. As revealed by size exclusion chromatography, isocyanate treatment resulted in a significantly reduced molecular weight of cellulose, presumably owing to hydrolytic cleavage caused by hydrochloric acid occurring as an impurity in pMDI. Yarn twist, fibre moisture content and, most significantly, the chemical composition of the isocyanate matrix were identified as critical process parameters strongly affecting the extent of reduction in mechanical performance. To cope with the problem of degradative reactions an additional step using calcium carbonate to trap hydrogen ions is proposed.