A two- step synthesis of 1,2,3-thiadiazole 28-oxo- allobetulin from 28-oxo- allobetulon was carried out for the first time. By condensation of 28-oxo- allobetulone with semicarbazide hydrochloride in an ethanol medium in the presence of potassium hydroxide, an intermediate 28-oxoallobetulin 3-semicarbazone was obtained. Its subsequent heterocyclization using the Hurd- Mori reaction in a methylene chloride medium in the presence of thionyl chloride resulted in the production of 28-oxoallobetulin 1,2,3-thiadiazole in a yield of 78.6 %. The structure of 28-oxo- allobetulin 3-semicarbazone and 28-oxo- allobetulin 1,2,3-thiadiazole was confirmed using FTIR and NMR spectroscopy, and the composition was determined by elemental analysis.

The paper describes an improved single-stage method for obtaining betulonic acid from birch bark with recrystallization from ethanol. The structure and composition of the obtained betulonic acid were confirmed by FTIR, NMR spectroscopy and elemental analysis. Thermal studies of betulonic acid were carried out using differential scanning calorimeter (DSC). The antitumor activity of betulonic acid and betulin was studied on Ehrlich ascites carcinoma culture in vivo experiments. It was found that under the influence of betulin and betulonic acid the content of dead cells of Ehrlich ascites carcinoma increased. It was shown that betulonic acid has a protective effect on the hematopoiesis system and does not have a toxic effect on the body.

Sulfation of arabinogalactan (AG) from larch wood (Larix sibirica Ledeb.) in the melt of a sulfamic acid-urea mixture has been first examined. The impact of the AG sulfation temperature on the AG sulfate yield and the sulfur content has been established. The high sulfur content (11.3-11.6%) in sulfated AG has been obtained in the temperature range of 115-120 °C for a sulfation time of 0.5 h. The process effectively prevents molecular degradation under these conditions. The incorporation of sulfate groups into the arabinogalactan structure has been confirmed by the appearance of absorption bands in the FTIR spectrum that are typical of sulfate group vibrations. The 13C NMR spectroscopy study has proven that the AG sulfation in the melt of a sulfamic acid-urea mixture leads to the substitution of some free hydroxyl groups for C6, C4, and C2 carbon atoms of the AG β-D-galactopyranose units. The advantage of the proposed AG sulfation method is that the reaction occurs without solvent, and the reaction time is only 0.5 h. The kinetics of the thermal decomposition of the initial AG and sulfated AG samples have been studied. It has been found that the sulfated AG samples have a lower thermal resistance than the initial AG. The kinetic analysis has revealed a decrease in the activation energy of the thermal degradation of the sulfated samples as compared to the initial AG.

The structure of sodium salts of arabinogalactan (AG) sulfates, obtained by sulfation of AG with sulfamic acid-urea mixture in the homogeneous medium of dimethyl sulfoxide (DMSO) was studied for the first time. According to thermal analysis (TA) data, the onset temperature of thermal decomposition of sulfated AG is 218 degrees C, and that of the initial AG is 235 degrees C. The quantitative characteristics of the kinetics of the main stage of sample pyrolysis were determined using the Coates-Redfern method. It was found that the activation energy of AG is 150 kJ/mol, whereas with the introduction of sulfate groups the activation energy decreases to 35 kJ/mol. The XRD method shows that the amorphization of arabinogalactan structure occurs during it`s sulfation. With the use of SEM method, it was found that the morphology of the obtained arabinogalactan sulfates differs from the morphology of the initial arabinogalactan. The initial AG consists mainly of globular particles with size of 10-90 mu m, while sulfated AG-of spherical particles with a diameter of 1-10 mu m. According to AFM data, the surface of film of arabinogalactan sulfates is formed by the rather homogeneous spherical particles with an average diameter of 50 nm and does not contain any impurities in its phase composition.

Sulfuric acid esters of betulin and its numerous derivatives are of interest to the chemical and pharmaceutical industry as complement inhibitors. The development of new efficient methods for the synthesis of sulfuric acid esters of betulin and its derivatives is an actual task. The sulfation of allobetulin with sulfamic acid in the presence of urea in a medium of 1,4-dioxane and N, N-dimethylformamide was studied for the first time. It was found that the reaction proceeds in a homogeneous medium at a temperature of 70-75 degrees C in 3-4 hours with the formation of allobetulin 3-sulfate. The structure of allobetulin 3-sulfate was confirmed by FTIR and NMR spectroscopy, and its composition was confirmed by elemental analysis.

An empirical equation relating electrophoretic mobility and ionic strength was proposed. The equation includes a number of parameters that are found using the mobilities of reference ions: two coefficients in the numerator describing the linear relationship of the multiplier in front of the square root of the ionic strength with the product of the ion mobility in the background electrolyte (BGE) without additives by the modulus of the charge number, raised to a certain power, and also the multiplier in the denominator before the square root of the ionic strength. The proposed equation was tested using the mobilities measured in BGEs with the addition of sodium chloride to adjust ionic strength and sulfated β-cyclodextrin (S-β-CD) for 11 anions with charge numbers from -1 to -4. Measuring anion electrophoretic mobility over a wide range of values, from -17 to -76 × 10-9 m2 V-1 s-1, was achieved through a combination of conventional separation and separation in a thermostatically controlled part of a capillary. The equation describes experimental data much more accurately (the discrepancy is no more than 1.1%) compared to the previously used simple empirical equation. For the S-β-CD complexes of betulin derivatives, the apparent binding constants determined are equal to 40-60 M-1.

Host–guest complexation of betulin 3,28-diphthalate (DPhB), that is poorly soluble in water and is an amphiphilic compound, with β-cyclodextrin (β-CD) was studied by spectrophotometry in 10 mM sodium tetraborate solution at pH 9.18 (ionic strength of 20 mM). This interaction was found to lead to a bathochromic shift of the DPhB absorption bands and an increase in absorption. Using the first derivative spectra of solutions with a fixed concentration of DPhB (0.01 mM) and a variable concentration of β-CD (0–10 mM), the logarithms of binding constants for 1:1 and 1:2 complexes of DPhB with β-CD were determined with 95

The paper describes a one -step method for obtaining betulonic acid directly from birch bark, based on the use of the Jones reagent. The influence of the duration and liquid solid ratio (LSR) of the process on the yield of betulonic acid has been studied. By the method of mathematical optimization using full factorial experiment type 3(2) and the Statgraphics Centurion XVI software package, the optimal conditions were established to ensure the yield of betulonic acid of 15.9 wt.%: duration - 3.5 h, LSR - 15. The structure of betulonic acid obtained under optimal conditions was established by methods FTIR and NMR spectroscopy, composition - by elemental analysis.

The influence of conditions on the separation of betulin (BT), betulinic (BIA), and betulonic (BOA) acids by reversed-phase high-performance liquid chromatography (RP-HPLC) with isocratic elution was studied. It was shown that the order of peaks in chromatograms changed with varying the acetonitrile (ACN) content in the mobile phase, and a poor separation under certain conditions was observed. The highest peak resolution with minimal retention times was at a column temperature of 20 C-circle, flow rate of 0.25 ml/min, and 92.5% ACN in the mobile phase. The extracts from jujube (Ziziphus jujuba) dried fruit, chaga mushroom (Inonotus obliquus), and white birch bark (Betula pendula) were studied using the obtained conditions. For extracts from the first two sources, it was found that peaks of the compound studied interfered with unknown peaks. By varying the ACN content in the mobile phase with a small step from run to run and tracking the peaks, a baseline separation was achieved. The optimal % ACN in the mobile phase was 87 and 89 for the extracts from jujube and chaga mushroom, respectively. Jujube dried fruit was found to contain, in terms of dry weight of the jujube, 0.223 +/- 0.008mg/g of BIA and 0.044 +/- 0.006 mg/g of BOA. Chaga mushroom studied contains 0.022 +/- 0.004 mg/g of BT and 0.062 +/- 0.009 mg/g of BIA. White birch bark contains 50.9 +/- 0.7mg/g of BT, 11.2 +/- 0.3 mg/g of BIA, and 2.5 +/- 0.3mg/g of BOA.

The synthesis of polysaccharide sulfates without harmful solvents used is a serious environmental problem. A method for the synthesis of xylan sulfate using the sulfamic acid-urea melt as a sulfating agent without solvents is proposed. The melt is prepared by heating the sulfamic acid-urea mixture with a molar ratio of 1 : 1 at a temperature of 110 & DEG;C. This ratio allows significant reduction of side reactions, in particular, carbamation of xylan. Sulfation is carried out at temperatures of 110,115, 120, 125, and 130 & DEG;C. The maximum yield and degree of substitution (DSsulfate 1.40) are attained at atemperature of 115 & DEG;C. The proposed method makes it possible to synthesize xylan sulfate rapidly (for 0.5 h) and without contamination of the obtained product with toxic solvents, e. g., dimethyl sulfoxide, pyridine, etc. The composition and structure of initial and sulfated xylan are confirmed by FTIR, NMR, GC, and elemental analysis. A green method for the synthesis of xylan sulfates in the sulfamic acid-urea melt has been proposed for the first time. This method excludes the use of harmful and dangerous solvents (pyridine and DMSO) and aggressive reagents (chlorosulfonic acid and SO3-pyridine complexes) in the reaction process. The synthesis time is reduced to 30 min.image

For the first time, the process of birch ethanol lignin sulfation with a sulfamic acid-urea mixture in a 1,4-dioxane medium was optimized experimentally and numerically. The high yield of the sulfated ethanol lignin (more than 96%) and containing 7.1 and 7.9 wt % of sulfur was produced at process temperatures of 80 and 90 °C for 3 h. The sample with the highest sulfur content (8.1 wt %) was obtained at a temperature of 100 °C for 2 h. The structure and molecular weight distribution of the sulfated birch ethanol lignin was established by FTIR, 2D 1H and 13C NMR spectroscopy, and gel permeation chromatography. The introduction of sulfate groups into the lignin structure was confirmed by FTIR by the appearance of absorption bands characteristic of the vibrations of sulfate group bonds. According to 2D NMR spectroscopy data, both the alcohol and phenolic hydroxyl groups of the ethanol lignin were subjected to sulfation. The sulfated birch ethanol lignin with a weight average molecular weight of 7.6 kDa and a polydispersity index of 1.81 was obtained under the optimum process conditions. Differences in the structure of the phenylpropane units of birch ethanol lignin (syringyl-type predominates) and abies ethanol lignin (guaiacyl-type predominates) was manifested in the fact that the sulfation of the former proceeds more completely at moderate temperatures than the latter. In contrast to sulfated abies ethanol lignin, the sulfated birch ethanol lignin had a bimodal and wider molecular weight distribution, as well as less thermal stability. The introduction of sulfate groups into ethanol lignin reduced its thermal stability.

The values of the apparent binding constants for β‐cyclodextrin complexes of betulin derivatives determined by mobility shift affinity capillary electrophoresis were found to be independent of the composition of the two background electrolytes used (tetraborate buffer, pH 9.18, and phosphate buffer, pH 8.00, both of them with 20 mM ionic strength). It has been found that if there is not a constant plateau on the binding curve then four independent parameters can be determined: binding constants (also referred to as stability, association, or formation constants) and ionic mobilities of 1:1 and 1:2 complexes. However, at least 10–12 data points in the binding curve should be used to reliably estimate the parameters. For the first time, the apparent binding constants for complexes of ester betulin derivatives with dimethyl‐β‐cyclodextrin have been determined by mobility shift affinity capillary electrophoresis. The logarithms of the constants for 1:1 and 1:2 complexes at 25°C for betulin 3,28‐diphthalate with a 95% confidence interval are 4.98 (4.95–5.01) and 7.52 (7.26–7.68); for betulin 3,28‐disulfate, the values are 4.97 (4.89–5.03) and 8.24 (6.82–8.52). It has been found that betulin 3,28‐disuccinate forms only a 1:1 complex and the binding constant logarithm is 5.25 ± 0.02.

Sulfation of birch wood xylan in 1,4-dioxane by sulfamic acid in the presence of urea at 90 and 100 °C was studied for the first time. The effect of the duration of xylan sulfation on the yield of xylan sulfates and the sulfur content in them was studied. It was found that the sulfur content in the obtained xylan sulfates increases from 12.5 to 17.5 wt% with an increase in the duration of sulfation from 2 to 4 hours. The structure of initial and sulfated xylan was studied by FTIR and NMR spectroscopy. The ease of purification of the obtained xylan sulfates from 1,4-dioxane in comparison with the purification of xylan sulfates obtained by sulfation in pyridine and N, N‑dimethylformamide is an advantage of the proposed method of xylan sulfation

In this article, capillary electrophoresis was used to measure the effective electrophoretic mobility of ester betulin derivatives as a pH function and to study their complexation with γ‐cyclodextrin (γ‐CD). The electrophoretic mobility of betulin 3,28‐diphthalate (DPhB) and 3,28‐disuccinate (DScB) changed unusually with decreasing pH: instead of decreasing, it first increased and then decreased. This fact as well as the turbidity of sample solutions at pH from 2.5 to 6, broadening of electrophoretic peaks and a decrease in the surface tension of the solutions indicates that these betulin derivatives, being amphiphilic compounds and weak acids, exist as micelles in aqueous solutions at pH 6 and below. The inclusion complexation of betulin derivatives with γ‐CD at pH 9.18 and 4.5 was studied by mobility shift affinity capillary electrophoresis. At pH 9.18, the apparent binding (stability) constant logarithms for 1:1 γ‐CD complexes of DPhB, betulin 3,28‐disulfate (DSB) and DScB with 95% confidence interval limits were equal to 7.44 ± 0.02, 7.09 (7.01–7.19), and 6.97 (6.87–7.08) at 25°C, respectively. At pH 4.5, the binding constant for the DSB complex was slightly lower, while the micelle formation did not allow determining the exact values of the constants for the DPhB and DScB complexes.

The catalytic oxidation of natural and pre-extracted cedar bark (Pinus Sibirica) by molecular oxygen is studied. Tannins were shown to inhibit the formation of vanillin while oxidizing the bark. The yields of vanillin are 5–7 wt.% based on bark lignin, which is of 3–4 times lower compared to the results of wood oxidation. The presence of tannins in the raw material complicates the lignin analysis and can overestimate the results twice

The complexation of ester betulin derivatives with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) was studied by mobility shift affinity CE. Electrophoretic mobility for triangular peaks was calculated using the parameter a1 of the Haarhoff-Van der Linde function instead of the peak top time. Dependences of the viscosity corrected electrophoretic mobility on HP-β-CD concentration were not described on the basis of only complexes with 1:1 stoichiometry due to the fact that these binding curves did not reach a plateau. However, the dependences were well described taking into account both 1:1 and 1:2 complexes. The presence of higher order equilibria was also revealed by x-reciprocal plots. The values of apparent binding constant logarithm, obtained for the first time, for 1:1 and 1:2 HP-β-CD complexes of betulin 3,28-diphthalate and betulin 3,28-disuccinate with 95% confidence interval limits in brackets are the same within error and are equal to 4.85 (4.73-4.95), 8.56 (7.75-8.82), 4.92 (4.86-4.97), and 8.54 (8.23-8.72) at 25°C, respectively. These values for 1:1 and 1:2 HP-β-CD complexes of betulin 3,28-disulfate at 25°C are 4.61 (4.57-4.64) and 7.11 (6.57-7.34), respectively. The binding constants for betulin 3,28-disulfate agree with the previously obtained results from the separation in the thermostatted capillary segment.

Inclusion complexes of ester betulin derivatives (pentacyclic lupane triterpenoids) with β-cyclodextrin (β-CD) were studied by affinity capillary electrophoresis. Stability constants were calculated from dependencies of viscosity-corrected effective electrophoretic mobilities on β-CD concentration (0-10 mM) in background electrolytes using nonlinear regression fitting. Logarithms of stability constants at 25 °C for 1:1 and 1:2 β-CD complexes of betulin 3,28-diphthalate, betulin 3,28-disuccinate and betulin 3,28-disulfate (95 % confidence interval) are 4.25 (4.16-4.32) and 7.27 (6.73-7.50), 4.38 (4.26-4.48) and 7.58 (6.90-7.84), 4.04 (4.00-4.08) and 5.91 (4.60-6.20), respectively.

Complexation plays an important role in many biological phenomena, the analysis of different samples, optimization of separation processes, and increasing the pharmacological activity of drugs. This paper discusses the features of using mobility shift affinity capillary electrophoresis for studying strong complexation. Electrophoretic peaks for this case are often triangular. It was shown that the use of electrophoretic mobility obtained from the peak apex time to calculate binding constants leads to significant systematic and random errors, and the parameter a1 of the Haarhoff-Van der Linde function should be used instead of the apex time. Distorted triangular peaks with dips were shown to be observed at too high a ratio of analyte concentration in the sample to ligand concentration in the background electrolyte, and the peaks and parameter a1 significantly shifted. It was found that the permissible excess of analyte concentration over ligand concentration was approximately 10–35, provided that the parameter a1 was used, but the peak shape should be used as a landmark, and only triangular peaks without dips should be fitted with the function. The lowest possible analyte concentration should be utilized, which allows the use of a wider range of ligand concentration leading to higher precision of determining the binding constants values. Kinetically labile 1:1 complexes between (2-hydroxypropyl)-γ-cyclodextrin (HP-γ-CD) and betulin 3,28-diphthalate (DPhB) and betulin 3,28-disuccinate (DScB) were studied as an example. The binding constant logarithms at 25 °C are 7.23 ± 0.03 and 7.13 ± 0.10 for the HP-γ-CD complexes of DPhB and DScB, respectively.

The process of abies ethanol lignin sulfation with sulfamic acid in 1,4-dioxane medium in the presence of urea was optimized by calculation methods. The influence of such factors, as the ratio of lignin/sulfating complex (L/SC), temperature and time of the sulfation process on the sulfur content in the resulting sulfated ethanol lignin and its yield, has been established. The variance analysis of the obtained mathematical models testifies their good predictive properties. The optimal conditions of abies ethanol lignin sulfation process, which provide the formation of water-soluble sulfated lignin with a high yield (to 100 % wt.) and sulfur content (up to 7.9 % wt.), have been established. They are: temperature of 95-100 °C, the ratio L/SC 1:2,3-1:2:9 and the time of the process 119-137 minutes