Influence of valoneoyl groups on the interactions between Euphorbia tannins and human serum albumin

Abstract Tannins belonging to plant polyphenols, are large group of compounds with diverse biological activity. Many of them are being studied as potential natural medicine due to their antioxidant, antiviral, antibacterial or anticancer properties. However, so far little is known about the structural and functional relations in protein-tannin interactions, in particularly the role of valoneoyl groups in tannin structure. In this study we first investigated the mechanisms of interaction 1,2-di-O-galloyl-4,6-valoneoyl-β-D-glucose (Tannin 1), 2-O-galloyl-4,6-valoneoyl-β-D-glucose (Tannin 2), 3-O-galloyl-1,2-valoneoyl-β-D-glucose (Tannin 3) isolated from Euphorbia plants with human serum albumin (HSA). To get more detailed information about nature of albumin-tannin interactions besides standard Trp fluorescence quenching analysis we used also transmission electron microscopy (TEM), circular dichroism (CD) and fluorescence labelling (ANS dye) techniques. It was shown that all the tannins strongly interacted with HSA and quenched the tryptophan amino acid (Trp) fluorescence but slightly changed protein secondary structure (circular dichroism CD analysis). TEM demonstrated that all used compounds formed complexes with HSA. Tannin 3 most strongly quenched HSA fluorescence and changed protein dynamic as well as had the highest binding constant (12.4 ± 1.1 × 1013 M−1 s−1 in comparison with 7.0 ± 0.38 × 1013 M−1 s−1 for tannin 1 and 8.6 ± 1.1 × 1013 M−1 s−1 for tannin 2). For tannin 1 that was the largest of the studied compounds was observed the weakest influence on the fluorescence parameters, probably due to the effect of steric hindrancelimiting interaction with albumin Trp pocket. On the other hand T1 induced the strongest changed secondary structure of HSA in comparison to another studied tannins. Our results demonstrated that all used tannins interact with albumin by complex formation but in the manner depends on chemical structure and flexibility of studied compounds

Hippophae rhamnoides L. leaf and twig extracts as rich sources of nutrients and bioactive compounds with antioxidant activity

Plants have served for centuries as sources of compounds useful for human health such as antioxidant, anti-diabetic and antitumor agents. They are also rich in nutrients that improve the human diet. Growing demands for these compounds make it important to seek new sources for them. Hippophae rhamnoides L. is known as a plant with health-promoting properties. In this study we investigated the chemical composition and biological properties of bioactive components of ethanol extracts from leaves and twigs of H. rhamnoides L. Chemical components such as the total content of phenolic compounds, vitamins and amino acids and the antioxidant activities of these compounds in cellular and cell-free systems were assessed. The results suggest that the studied extracts are rich in bioactive compounds with potent antioxidant properties. Cytotoxicity and hemotoxicity assays showed that the extracts had low toxicity on human cells over the range of concentrations tested. Interaction with human serum albumin was investigated and conformational changes were observed. Our results indicate that leaf and twig extracts of H. rhamnoides L. should be considered as a non-toxic source of bioactive compounds which may be of interest to the food, pharmaceutical and cosmetic industries

Cultural Practices in the Socio-Cultural Space of the Krasnoyarsk Territory: An Exhibition Dedicated to the 175th Anniversary of Surikov in Krasnoyarsk

Исследование посвящено анализу культурных практик в области искусства в социально-культурном пространстве Красноярского края на основании представления о культурных практиках как активно формирующих идентичность разного уровня (социальную, локально-региональную, глобально-региональную, национальную и т.д.). Основной метод исследования – культурологический анализ культурных практик Красноярского края в их историческом контексте. Принимая во внимание, что теория культурных практик формируется в настоящее время, понятие «культурные практики» рассмотрено авторами как функциональный механизм культуры, благодаря которому реализуются конструктивные процессы трансляции и изменения социоцентрической и культуросозидающей деятельности в конкретном социокультурном пространстве. При этом поликультурное и исторически сформированное под влиянием большого количества факторов социально-культурное пространство Красноярского края представляет особый интерес с позиции анализа культурных практик в области искусства. В статье представлен анализ масштабного выставочного проекта – выставки, посвященной 175-летию В. И. Сурикова, созданной при активном сотрудничестве двух сильных акторов культурной жизни Красноярска и края, Красноярского художественного музея им. В. И. Сурикова и Музейного центра «Площадь Мира». Интересен этот проект и тем, что обращается к предельно значимой для региональной идентичности фигуре художника со всероссийской славой – Василия Ивановича Сурикова, прославившего Красноярск, ставшего классиком русской живописи и не утратившего своей связи с Сибирью – ни в жизни, ни в творчествеThe study is devoted to the analysis of cultural practices in the field of art in the socio-cultural space of the Krasnoyarsk Territory based on the idea of cultural practices as actively shaping the identity of different levels (social, local-regional, global-regional, national, etc.). Taking into account that the theory of cultural practices is being formed at the present time, the concept of “cultural practices” is considered by the authors as a functional mechanism of culture, thanks to which the constructive processes of translation and change of sociocentric and culture-creating activities in a particular sociocultural space are realized. At the same time, the socio-cultural space of the Krasnoyarsk Territory, which is multicultural and historically formed under the influence of a large number of factors, is of particular interest from the standpoint of analyzing cultural practices in the field of art. The article presents an analysis of a large-scale exhibition project – an exhibition dedicated to the 175th anniversary of V. I. Surikov, created with the active cooperation of two strong actors in the cultural life of Krasnoyarsk and the region, the Krasnoyarsk Art Museum. IN AND. Surikov and the Peace Square Museum Center. This project is also interesting in that it refers to the figure of the artist with all-Russian fame, extremely significant for regional identity – Vasily Ivanovich Surikov, who glorified Krasnoyarsk, became a classic of Russian painting and did not lose his connection with Siberia – both in life and in creativit

Regional Originality of the Grand Style: Siberian Modern

В статье рассматривается проблема определения сибирского модерна в качестве самостоятельного явления в архитектуре Сибири начала XX столетия. Выявляются черты модерна в архитектуре Красноярска, созданной выдающимися сибирскими архитекторами рубежа XIX–$ 5X веков В. А. Соколовским и Л. А. Чернышёвым. В качестве репрезентантов рассматриваются особняк В. Н. Гадаловой В. А. Соколовского – образец городского особняка с усадебной территорией и особняк архитектора Л. А. Чернышева, являющегося также автором проекта знаменитого на всю Россию Красноярского краевого краеведческого музея, построенного им как стилизация под древнеегипетский храм. Сибирский модерн в архитектуре Красноярска начала XX века носит эклектичный, но целостный характер, демонстрируя высокий уровень эстетического мышления и инженерных решений. Также рассматриваются три примера обращения современного художественного сообщества к культурному наследию архитектуры модерна – на примере города Томска: архитектура служит источником вдохновения и рефлексии. Обнаруживается способность архитектуры модерна стать в одном случае «холстом» для работ художников, в другом – объектом исследования, поднимать проблемные для города и для художника вопросыThe article examines the problem of defining Siberian Art Nouveau as an independent phenomenon in the architecture of Siberia at the beginning of the 20th century. The features of modernism are revealed in the architecture of Krasnoyarsk, created by the outstanding Siberian architects of the turn of the 19th – 20th centuries V. A. Sokolovsky and L. A. Chernyshev. As a representatives are being studied the mansion of V. N. Gadalova V. A. Sokolovsky – an example of a city mansion with a manor area and a mansion of the architect L. A. Chernyshev, who is also the author of the project of the Krasnoyarsk Regional Museum of Local Lore, famous throughout Russia, which he built as a stylization of an ancient Egyptian temple. Siberian Art Nouveau in the architecture of Krasnoyarsk at the beginning of the 20th century is eclectic but holistic in nature, demonstrating a high level of aesthetic thinking and engineering solutions. Three examples of the modern artistic community’s appeal to the cultural heritage of modern architecture are also considered – using the example of the city of Tomsk: architecture serves as a source of inspiration and reflection. The ability of modern architecture to become, in one case, a “canvas” for artists’ works, and in another, an object of research, is revealed, to raise problematic issues for the city and for the artis

Ferutinin as a Ca²⁺ complexone: Lipid bilayers, conductometry, FT-IR, NMR studies and DFT-B3LYP calculations

Calcium ionophoretic properties of ferutinin were re-evaluated in solvent-containing bilayer lipid membranes. The slopes of conductance-concentration curves suggest that in the presence of a solvent in the membrane the majority of complexes appear to consist of a single terpenoid molecule bound to one Ca ion. By contrast, the stoichiometry of ferutinin-Ca2+ complexes in acetone determined using the conductometric method was 2 :1. While the cation-cation selectivity of ferutinin did not change, the cation-anion selectivity slightly decreased in solvent containing membranes. FT-IR and NMR data together with DFT calculations at the B3LYP/6-31G(d) level of theory indicate that in the absence of Ca ions ferutinin molecules are hydrogen-bonded at the phenol hydroxyl groups. The variations of absorption assigned to -OH and -C-O stretching mode suggest that ferutinin interacts strongly with Ca ions via the hydroxyl group of ferutinol and carboxyl oxygen of the complex ether bond. The coordination through the carbonyl group of ferutinin was demonstrated by theoretical calculations. Taken together, ferutinin molecules form H-bonded dimers, while complexation of Ca2+ by ferutinin ruptures this hydrogen bond due to spatial re-orientation of the ferutinin molecules from parallel to antiparallel alignment.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Interaction of <i>Rhus typhina</i> Tannin with Lipid Nanoparticles: Implication for the Formulation of a Tannin–Liposome Hybrid Biomaterial with Antibacterial Activity

Tannins are natural plant origin polyphenols that are promising compounds for pharmacological applications due to their strong and different biological activities, including antibacterial activity. Our previous studies demonstrated that sumac tannin, i.e., 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-D-glucose (isolated from Rhus typhina L.), possesses strong antibacterial activity against different bacterial strains. One of the crucial factors of the pharmacological activity of tannins is their ability to interact with biomembranes, which may result in the penetration of these compounds into cells or the realization of their activity on the surface. The aim of the current work was to study the interactions of sumac tannin with liposomes as a simple model of the cellular membrane, which is widely used in studies focused on the explanation of the physicochemical nature of molecule–membrane interactions. Additionally, these lipid nanovesicles are very often investigated as nanocarriers for different types of biologically active molecules, such as antibiotics. In the frame of our study, using differential scanning calorimetry, zeta-potential, and fluorescence analysis, we have shown that 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-D-glucose interacts strongly with liposomes and can be encapsulated inside them. A formulated sumac–liposome hybrid nanocomplex demonstrated much stronger antibacterial activity in comparison with pure tannin. Overall, by using the high affinity of sumac tannin to liposomes, new, functional nanobiomaterials with strong antibacterial activity against Gram-positive strains, such as S. aureus, S. epidermitis, and B. cereus, can be formulated

The Structural Changes in the Membranes of Staphylococcus aureus Caused by Hydrolysable Tannins Witness Their Antibacterial Activity

Polyphenols, including tannins, are phytochemicals with pronounced antimicrobial properties. We studied the activity of two hydrolysable tannins, (i) gallotannin&mdash;1,2,3,4,5-penta-O-galloyl-&beta;-D-glucose (PGG) and (ii) ellagitannin&mdash;1,2-di-O-galloyl-4,6-valoneoyl-&beta;-D-glucose (dGVG), applied alone and in combination with antibiotics against Staphylococcus aureus strain 8324-4. We also evaluated the effect of these tannins on bacterial membrane integrity and fluidity and studied their interaction with membrane proteins and lipids. A correlation between the antimicrobial activity of the tannins and their membranotropic action depending on the tannin molecular structure has been demonstrated. We found that the antibacterial activity of PGG was stronger than dGVG, which can be associated with its larger flexibility, dipole moment, and hydrophobicity. In addition, we also noted the membrane effects of the tannins observed as an increase in the size of released bacterial membrane vesicles