Vol 44, No 7 (2018)

Strategies for the analysis of plant volatiles have changed significantly over the past 15–20 years due to the introduction of new approaches to sample preparation and analysis, including those initially developed for other areas and currently applied to the analysis of plant metabolites. Any analysis of plant substances consists of two phases. The first phase includes plant material collection, primary processing, conservation, storage, and extraction to prepare samples for research. The second phase is the analysis itself by various chromatographic, spectral, and/or hybrid (hyphenated) techniques. Most scientific publications focus their attention on the second phase, and the first remains “behind the scenes,” although it is in the first phase that the biomaterial experiences significant transformations. It is impossible to correctly and adequately evaluate the ultimate result of a study without taking these transformations into account. Specific difficulties arise in both phases, and they are reviewed in this paper. The wide distribution of modern chromatographic instruments equipped with sophisticated software allows a significant portion of an experiment to be performed automatically. However, one should realize that the improvement of experimental techniques does not change the basics of a method, and, therefore, does not eliminate its intrinsic limitations. To avoid fallacies in the publication of the results, all the experimental data obtained in the automatic mode should be subjected to an impartial revision by the experimenter with regard to all known limitations inherent in methods used for separation and detection of components. In order to correctly interpret experimental results, one should know the entire history of samples under investigation; thus, it is necessary to document carefully all manipulations with plant material from the collection of raw materials till the final sample preparation. Only with this proviso the study can be expected to provide meaningful results.

For the first time, the synthesis of water-soluble copper-containing microcrystalline cellulose sulfates (Сu-MCS) has been performed by the ion exchange method. The composition of the products has been studied by chemical methods and X-ray spectral microanalysis. The copper content in the Сu-MCS samples was 12.6–14.1%. The absence of sodium in the resulting polymer indicates the complete substitution of the sodium cations by the copper cations in the sodium salt of MCC sulfate. The structure of the copper-containing sulfates of microcrystalline cellulose has been confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and electron paramagnetic resonance (EPR). According to the XRD method, Сu-MCS and Na-MCS have an amorphous structure in contrast to the original MCC samples, which have a high degree of crystallinity. The EPR data have demonstrated the formation of a pseudocrystalline structure of the copper-containing salt system in the Сu-MCS samples. As shown by atomic-force microscopy, the surface of the Сu-MCS films consists of homogeneous crystallites, which have a spherical or slightly extended form with the size of about 70 nm. The film surface is quite homogeneous in its phase composition and contains no impurities.

A new method for preparation of organic aerogels by sol–gel polymerization of formaldehyde with polyphenols (PPs), isolated from larch bark and birch bark, was developed. The functional composition and properties of the original polyphenols were studied by thermogravimetric methods and FTIR spectroscopy. It was found that larch polyphenol material had higher thermal stability in the temperature range 25−700°C, while the process of thermal decomposition of birch bark polyphenols completes at 600°C. It has been established that polyphenol larch compounds contain more aromatic structures and hydroxyl groups. The effect of the pH of gelation solutions in the range from 4 to 12 on the porous structure of organic gels synthesized from polyphenols was studied. The porous structures and adsorption properties of polyphenol-formaldehyde organic gels were studied using the BET method, scanning electron microscopy and sorption (methylene blue and gelatin). It was shown that an increase in pH contributes to the formation of a product with a more compacted texture. The electron microscopic images of polymer gels demonstrate a uniform granular texture with visible microglobules with an average particle size of ≈50−70 nm.

In this study, lignin content data are presented for annual regenerant Iris sibirica plants, comparable to those in six-year-old intact plants. The structure of the shoots of Iris sibirica grown on artificial nutrient media was studied by the histochemical method. Features of the formation of the xylem in Iris sibirica on artificial nutrient media were revealed. Regenerants very quickly developed a complex system consisting of vascular bundles containing sieve tubes, vessels and tracheids, and hydrocyte systems. Hydrocytes of Iris sibirica were tracheids with lignified thickening, but, in contrast to tracheids and vessels of xylem (they are formed based on procambium or cambium—special lateral primary or secondary meristem), hydrocytes differentiated from the cells of permanent tissues (like phellogen), which probably possessed meristematic activity at the time of differentiation. In Iris sibirica hydrocytes covered the vascular bundle by the thick layer and strung along it up to a certain height. High lignin content in young regenerant Iris sibirica plants was due to the formation of the dense tissue from lignified tracheal elements. The study of the differentiation of xylem elements under controlled conditions can serve as a model for our understanding of wood formation processes.

Betulin diacetate (BDA) has a variety of biological activities, but poor solubility in water limits its application. The use of arabinogalactan (AG) as a complexing agent is a promising method for solving the problem of solubilization of drugs. In this study, effect of microwave (MW) irradiation on the properties of AG and BDA and their interaction in aqueous suspension with the formation of a water-soluble supramolecular complex was studied. It is shown that the microwave heating of AG under harsh conditions can lead to degradation of the biopolymer. The use of microwave heating could significantly reduce the complex preparation time compared to the conventional synthesis in a water bath. The preliminary mechanical treatment of the mixture of components, leading to the formation of mechanocomposites, inhibited the reaction between the components in the aqueous suspension under microwave irradiation. The IR spectroscopy method has shown that a supramolecular complex formed under microwave irradiation similar to that formed by conventional heating. The BDA-AG complex was isolated from a microwave heated solution as a thin film, which may be a promising material for pharmaceutical applications.

It was shown that the changes in the phenological stages of tree development, associated with the loss of frost resistance and the onset of the growing season, were accompanied by significant changes in free amino acid composition in the meristematic tissues of Picea obovata L. and Pinus sylvestris L. buds. In winter, in both species, the level of nonproteingeneous amino acids was doubled in comparison with spring. At the same time, P. obovata and P. sylvestris showed significant species-specific differences in the total content of nonproteaginous amino acids. At P. sylvestris their share in the composition of free amino acids reached 40%, which was twice as high as that of P. obovata. In the free amino acids in P. obovata and P. sylvestris, the nitrogen reserve was mainly in the form of glycine corresponding to 13 and 9%, arginine, 12 and 8%, and ornithine, 12 and 15%, respectively. In addition, in P. sylvestris an important role in the nitrogen storage was played by γ- aminobutyric acid, about 19%, and valine, about 6%; in P. obovata this role was played by lysine and glutamic acid, about 10%. At the same time, the content of proline (an amino acid, which, generally, coordinates the high−low-temperature resistance of plants) in low-resistance coniferous species was low at about 0.04–0.34%. In spring, with bud swelling in both species, the share of arginine and proline increased, and the share of ornithine and γ-aminobutyric acid sharply decreased. In addition to these amino acids, the lysine content in P. obovata was doubled. In spring, for P. sylvestris a high content of aspartic acid and asparagine of about 19% was characteristic, for P. obovata the content of amino acids with a short carbon chain (the total amount of serine + glycine) rose to 22%. As a reliable stress metabolite in both species, one may consider ornithine, whose content in bud meristems in winter was 3–5 times higher than in the meristems of swollen buds in spring.

The composition of phenolic compounds of rowanberry (Sorbus aucuparia L.) fruit extracts prepared with 40% ethanol and 95% acidified ethanol was studied. The differences in the content of flavonoids, including anthocyanins, and phenolic acids were shown. It was found that the antimetastatic activity of cyclophosphamide was most efficiently increased by the rowanberry fruit extract in 95% acidified ethanol enriched in anthocyanins. The aim of the present research was to investigate the effect of hydroalcoholic extracts of rowanberry fruit on the development of Lewis lung carcinoma and the antitumor activity of cyclophosphamide and to reveal the most effective extract containing a phenolic complex for its further study as a promising drug.

The samples of Gmelin larch (Larix gmelinii (Rupr.) Rupr.) gum, selected from a variety of trees and from different parts of the tree in vicinity of Ulan-Ude (Buryatia), were investigated with GPC, IR, quantitative NMR ¹³C spectroscopy and spectrophotometry methods. The samples were dissolved in distilled water at room temperature. The mechanical impurities were filtered, the transparent solutions were evaporated to dryness, and the dry residues were purified by reprecipitation from water to ethanol. The content of mechanical impurities was 0.1–4.8% of the mass of absolutely dry gum. Aqueous solutions of gum were weakly acidic, as well as arabinogalactan (AG) isolated from wood of Siberian and Gmelin larches. It is established that Gmelin larch gum is a high purity arabinogalactan (~99%) with minor impurities of flavonoids, tannins and mineral substances. Molecular-mass characteristics and monosaccharide composition of Gmelin larch gum arabinogalactan is similar to arabinogalactan obtained from wood of all previously studied species of larch growing in Siberia and the Far East. The data suggest recommending Gmelin larch gum for application in medicine and the veterinary, food and cosmetic industries.