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In recent years, researchers have often encountered the significance of the aberrant metabolism of tumor cells in the pathogenesis of malignant neoplasms. This phenomenon, known as the Warburg effect, provides a number of advantages in the survival of neoplastic cells, and its application is considered a potential strategy in the search for antitumor agents. With the aim of developing a promising platform for designing antitumor therapeutics, we synthesized a library of conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones. To gain insight into the determinants of the biological activity of the prepared compounds, we showed that the conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones, which are cytotoxic agents, demonstrate selective activity toward a number of tumor cell lines with glycolysis-inhibiting ability. Moreover, the results of molecular and in silico screening allowed us to identify these compounds as potential inhibitors of the pyruvate kinase M2 oncoprotein, which is the rate-determining enzyme of glycolysis. Thus, the results of our work indicate that the synthesized conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones can be considered a promising platform for designing selective cytotoxic agents against the glycolysis process, which opens new possibilities for researchers involved in the search for antitumor therapeutics among compounds containing piperidone platforms.

Artemisinin is a metabolite of the plant Artemisia annua L. This sesquiterpene lactone exhibits antimalarial activity and is commercially available. Various derivatives and analogues of this compound are potent agents exhibiting a wealth of biological activities and used as efficient drugs in clinical practice. The review is devoted to the chemical reactions of artemisinin and its best known derivatives (artemisitene, dihydroartemisinin, anhydrodihydroartemisinin), whose molecular structures retain the tetracyclic skeleton with the peroxide bridge. Main methods for structure modification of their molecules under the action of various oxidizing and reducing agents, acids and bases, electrophiles and nucleophiles are described. Catalytic reactions, as well as enzymatic, and photochemical transformations of artemisinin and its analogues are considered. Reactions occurring with preservation of the tetracyclic peroxide skeleton, as well as ring rearrangement and degradation of one or more rings are analyzed. Most transformations were shown to afford biologically active products.

Abstract—Anthracyclines are a class of antibiotics of natural origin with anthraquinone chromophore and their synthetic analogs. Since their clinical introduction 50 years ago, anthracyclines have remained a cornerstone of antitumor drug therapy. Over the decades, substantial research has been conducted on the chemical modification of anthracyclines, elucidation of structure–activity relationships for each atom within the molecule, and the de novo synthesis of synthetic analogs featuring non-natural aglycones or sugars. This review highlights the chemical reactions of anthracyclines, with a particular focus on daunorubicin and doxorubicin, which have been most extensively studied as substrates. The primary pathways for chemical modification of these molecules are detailed, including reactions at the amino group (yielding acyl, alkyl, or urethane derivatives), the carbonyl group of the aglycone, and esterification at the alcohol group of the aglycone. Less commonly explored modifications at other positions in the aglycone and amino sugar are also discussed. Many of these modifications result in altered biological activity, influencing both antitumor efficacy and the cardiotoxicity commonly associated with anthracyclines.

Abstract―This review continues the discussion of known chemical transformations of anthracyclines, with a primary focus on daunorubicin and doxorubicin. In the first part, various modifications involving the amino group in the amino sugar moiety were explored. The second part shifts attention to modifications occurring at other sites within the anthracycline molecule. These include alterations at the C-13 keto group of the aglycone, such as deoxygenation and imine formation, as well as reactions involving the hydroxy groups at the C-9 and C-14 positions. Additionally, modifications to the A, B, C, and D rings of the anthraquinone nucleus are discussed in detail. Separate consideration is given to anthracyclines with non-classical structures, such as nogalomycin. For each modified anthracycline, data are provided regarding changes in biological activity, particularly with respect to antitumor efficacy and the cardiotoxicity commonly associated with anthracyclines.

Analysis of literature data and our own experimental observations have led to the conclusion that, at high deformation rates, viscoelastic liquids come to behave as rubbery materials, with strong domination by elastic deformations over flow. This can be regarded as a deformation-induced fluid-to-rubbery transition. This transition is accompanied by elastic instability, which can lead to the formation of regular structures. So, a general explanation for these effects requires the treatment of viscoelastic liquids beyond critical deformation rates as rubbery media. Behaviouristic modeling of their behaviour is based on a new concept, which considers the medium as consisting of discrete elastic elements. Such a type of modeling introduces a set of discrete rotators settled on a lattice with two modes of elastic interaction. The first of these is their transformation from spherical to ellipsoidal shapes and orientation in an external field. The second is elastic collisions between rotators. Computer calculations have demonstrated that this discrete model correctly describes the observed structural effects, eventually resulting in a “chaos-to-order” transformation. These predictions correspond to real-world experimental data obtained under different modes of deformation. We presume that the developed concept can play a central role in understanding strong nonlinear effects in the rheology of viscoelastic liquids.

The features of precipitation and its spatial distribution over the territory of the Primorsky krai during the passage of Typhoon Hinnamnor (September 4–7, 2022), as well as the characteristics of the flood caused by the typhoon, are studied based on ground observational data and the ERA5-Land reanalysis. A list of the settlements affected by the flood and an assessment of the impact of the disaster on transport infrastructure are given. The relationship between the precipitation maxima and the movement of storm cells is shown. Deformations were recorded for 30% of the length of the Primorsky krai river channels as a result of the typhoon passage. The relationship among the changes in the channels, spatial characteristics of precipitation (including their intensity) and the slope of the catchment were determined. Areas of extreme channel deformations (including mudflows) and their magnitudes on rivers of different scales are described.

We present direct evidence of the macromolecular network behavior at high deformation rates based on macroscopic simulation of these systems by a group of elastics as a model of flexible-chain polymer concentrated solutions or melts. It was shown that at low deformation rates, the disentanglement process really takes place providing a possibility to irreversible deformations (flow), while at high deformation rates, the dominating effect is the formation of large inhomogeneous structures (“grains” or “bundles”) consisting of flocks of entangled chains. This is a model of the deformation induced flow-to-rubbery transition, which makes the irreversible flow impossible. The attempt to increase the deformation rate leads to the rupture of elastics. So, we constructed a model for the deformation-induced fluid-to-rubber transition at high rates and confirmed it by direct measurements of elastic-to-plastic strain ratio as a function of deformation rate.

Comb-like polymethylsiloxanes consisting of a silsesquioxane backbone and dimethylsiloxane side chains were synthesized by means of the “grafting to” method using a linear polyfunctional matrix [SiMe(ONa)O] n and monofunctional oligomers (CH 3 ) 3 Si[OSi(CH 3 ) 2 ] n OCOCH 3 . The effects of architecture of the synthesized methylsiloxane polymers on their physicochemical properties, rheology, and behavior at the air–water interface were studied and compared with those for the linear analogue – polydimethylsiloxane.

The effect of deformation on the behavior of intermolecular entanglements in melts and in concentrated solutions of polymers is simulated with the use of knots formed by long flexible threads. Two cases are discussed: the behavior of individual junctions and the pattern of change in the entanglements in a network of statistically entangled threads. It is shown that, at low strain rates, the junctions disentangle and threads slip out of the entanglements. This situation simulates an irreversible flow of macromolecules in the classical tube model. At high rates, the junctions tighten, a phenomenon that simulates the impossibility of irreversible motion of macromolecules. The transition from slipping to tightening of entanglements simulates the change in the pattern of behavior of the melt, i.e., from flow to rubberlike deformations. A generalized dependence of elastic deformations on the Weissenberg number is constructed; it shows that the transition occurs at Weissenberg numbers on the order of 3–5, which correspond to the characteristic lifetimes of an entanglement junction. At high strain rates, redistribution and local accumulation of entanglements are observed.

Two unusual experimental phenomena that were found for polymer melts or solutions containing the dispersed phases of Na-montmorillonite or detonation synthesis nanodiamond have been studied. These phenomena consist in the reduction of viscosity upon addition of specified amount of particles and in the formation of regular morphology by these particles in strong flows looking as a system of concentric rings. In other words, under certain conditions, there is transition to stratified shear stream and the viscosity of such a regular heterogeneous system canbe lower than that for the polymer matrix itself. Hence, both phenomena are mutually related; and the main problem here is the analysis of driving forces leading to the regular texture formation taking place in intense flows for unfilled viscoelastic polymers as well. As a preliminary explanation, the conception of the special kind of the elastic instability is discussed. This instability appears either in the regular helix-like structure formation or in the irregular elastic turbulence. The particles of the filler play a role of tracers that revealed the relief of texture.