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

Dendrimers reduce toxicity of Aβ 1-28 peptide during aggregation and accelerate fibril formation

The influence of a GATG (gallic acid-triethylene glycol) dendrimer decorated with 27 terminal morpholine groups ([G3]-Mor) on the aggregation process of Alzheimer's peptide has been investigated. Amyloid fibrils were formed from the Aβ 1-28 peptide and the process was monitored by a ThT assay, changes in CD spectra, and transmission electron microscopy. In the presence of [G3]-Mor, more fibrils were built and the process significantly accelerated compared with a control. The cytotoxicity of (1) Aβ and (2) the system [G3]-Mor/Aβ was monitored at different stages of the aggregation process. Prefibrillar species were more toxic than mature fibrils. [G3]-Mor significantly reduced the toxicity of Aβ, probably because of lowering the amount of prefibrillar forms in the system by speeding up the process of fibril formationThis work was funded by the project “Biological Properties and Biomedical Applications of Dendrimers” operated within Foundation for Polish Science TEAM programme, cofinanced by the European Regional Development Fund. Financial support is also acknowledged from the Spanish MICINN (CTQ2009-10963 and CTQ2009-14146-C02-02) and the Xunta de Galicia (10CSA209021PR and CN2011/037). M.F-V. thanks the Spanish Ministry of Education for a FPU fellowship. The research was performed within the frame of the COST Action TD0802 “Dendrimers for biomedical applications.”S

Heterofunctionalized polyphenolic dendrimers decorated with caffeic acid: Synthesis, characterization and antioxidant activity

Dendrimers, branched polymer structures, have been widely studied as efficient drug carriers. Scientists are trying to find new dendrimer-based formulations with the properties needed for biomedical applications such as improved bioavailability, low toxicity and high transfection profiles. The unique drug delivery properties of carbosilane dendrimers have already been demonstrated. Their efficacy has been further improved by conju-gation with polyphenols, plant secondary metabolites with a wide range of biological activities, including antioxidant effects that are beneficial for human health. The present study focuses on synthesis and character-ization of two new types of carbosilane dendritic systems, one family presents one or two caffeic acid units and ammonium groups on the surface to make them water soluble. The other family has, in addition to the two mentioned functionalities, one or two polyethylene glycol (PEG) chains in the structure to increase the biocompatibility of the system. Carbosilane dendrimers with caffeic acid have low toxicity and protect eryth-rocytes against oxidative hemolysis. These dendrimers also decrease AAPH-induced ROS production in human fibroblasts.Various techniques demonstrating such antioxidant activities have been applied in the current research. The best antioxidant properties were shown for the dendrimer with two PEG-caffeic acid moieties. Further aspects of the biochemical characterization of the dendrimers are also considered and discussed.Ministerio de Ciencia e InnovaciónMinisterio de Economía y CompetitividadJunta de Comunidades de Castilla-La ManchaComunidad de MadridPolish National Agency for Academic Exchang

Copper (II) Metallodendrimers Combined with Pro-Apoptotic siRNAs as a Promising Strategy Against Breast Cancer Cells

Cancer treatment with small interfering RNA (siRNA) is one of the most promising new strategies; however, transfection systems that increase its bioavailability and ensure its delivery to the target cell are necessary. Transfection systems may be just vehicular or could contain fragments with anticancer activity that achieves a synergistic effect with siRNA. Cationic carbosilane dendrimers have proved to be powerful tools as non-viral vectors for siRNA in cancer treatment, and their activity might be potentiated by the inclusion of metallic complexes in its dendritic structure. We have herein explored the interaction between Schiff-base carbosilane copper (II) metallodendrimers, and pro-apoptotic siRNAs. The nanocomplexes formed by metallodendrimers and different siRNA have been examined for their zeta potential and size, and by transmission electron microscopy, fluorescence polarisation, circular dichroism, and electrophoresis. The internalisation of dendriplexes has been estimated by flow cytometry and confocal microscopy in a human breast cancer cell line (MCF-7), following the ability of these metallodendrimers to deliver the siRNA into the cell. Finally, in vitro cell viability experiments have indicated effective interactions between Cu (II) dendrimers and pro-apoptotic siRNAs: Mcl-1 and Bcl-2 in breast cancer cells. Combination of the first-generation derivatives with chloride counterions and with siRNA increases the anticancer activity of the dendriplex constructs and makes them a promising non-viral vector.Polish National Agency for Academic Exchange (NAWA)European CommissionMinisterio de Economía y CompetitividadComunidad de MadridJunta de Comunidades de Castilla-La Manch

In Vitro anticancer properties of copper metallodendrimers

Newly synthesized carbosilane copper dendrimers (CCD) with chloride and nitrate surface groups seem to be good candidates to be used as gene and drug carriers in anti-cancer therapy, due to their properties such as size and surface charge. Copper attached to the nanoparticles is an important element of many biological processes and recently their anti-cancer properties have been widely examined. Zeta size and potential, transmission electron microscopy (TEM), circular dichroism (CD), analysis of haemolytic activity, and fluorescence anisotropy techniques were used to characterize copper dendrimers. Additionally, their cytotoxic properties toward normal (PBMC) and cancer (1301; HL-60) cells were examined. All tested dendrimers were more cytotoxic against cancer cells in comparison with normal cells

Evaluation of dendronized gold nanoparticles as siRNAs carriers into cancer cells

Gene therapy is one of the most promising approaches for potential application in the treatment of diseases, ranging from cancer and heritable disorders to infectious diseases. Before nucleic acid molecules can reach their site of action inside target cells, they must overcome several obstacles. Thus, to fully exploit the therapeutic potential of nucleic acids, efficient delivery systems are required. We herein evaluated gold nanoparticles (AuNPs) covered with cationic carbosilane dendrons as siRNA delivery systems. Detailed analysis of formation of AuNP:siRNA complexes using circular dichroism, zeta-potential, zeta-size, electron microscopy and gel electrophoresis was performed. The stability of complexes in presence of heparin and RNase was evaluated. Internalization of AuNPs and their complexes with siRNAs into cancer cells was estimated by ultrastructure analysis and confocal microscopy. The cytotoxicity of dendrons, AuNPs and their complexes with siRNAs on 4 cancer cell lines (Caco-2, HeLa, U937 and THP-1) was estimated. We concluded that dendronization of AuNPs is a promising way to develop siRNA carriers for anticancer gene therapyUniversidad de AlcaláMinisterio de Economía y CompetitividadComunidad de MadridJunta de Comunidades de Castilla-La ManchaEuropean Commissio

Lipid-coated ruthenium dendrimer conjugated with doxorubicin in anti-cancer drug delivery: Introducing protocols

One of the major limitations for the treatment of many diseases is an inability of drugs to cross the cell membrane barrier. Different kinds of carriers are being investigated to improve drug bioavailability. Among them, lipid or polymer-based systems are of special interest due to their biocompatibility. In our study, we combined dendritic and liposomal carriers and analysed the biochemical and biophysical properties of these formulations. Two preparation methods of Liposomal Locked-in Dendrimers (LLDs) systems have been established and compared. Carbosilane ruthenium metallodendrimer was complexed with an anti-cancer drug (doxorubicin) and locked in a liposomal structure, using both techniques. The LLDs systems formed by hydrophilic locking had more efficient transfection profiles and interacted with the erythrocyte membrane better than systems using the hydrophobic method. The results indicate these systems have improved transfection properties when compared to noncomplexed components. The coating of dendrimers with lipids significantly reduced their hemotoxicity and cytotoxicity. The nanometric size, low polydispersity index and reduced positive zeta potential of such complexes made them attractive for future application in drug delivery. The formulations prepared by the hydrophobic locking protocol were not effective and will not be considered furthermore as prospective drug delivery systems. In contrast, the formulations formed by the hydrophilic loading method have shown promising results where the cytotoxicity of LLD systems with doxorubicin was more effective against cancer than normal cells

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

Ruthenium Dendrimers against Human Lymphoblastic Leukemia 1301 Cells

Ruthenium atoms located in the surfaces of carbosilane dendrimers markedly increase their anti-tumor properties. Carbosilane dendrimers have been widely studied as carriers of drugs and genes owing to such characteristic features as monodispersity, stability, and multivalence. The presence of ruthenium in the dendrimer structure enhances their successful use in anti-cancer therapy. In this paper, the activity of dendrimers of generation 1 and 2 against 1301 cells was evaluated using Transmission Electron Microscopy, comet assay and Real Time PCR techniques. Additionally, the level of reactive oxygen species (ROS) and changes of mitochondrial potential values were assessed. The results of the present study show that ruthenium dendrimers significantly decrease the viability of leukemia cells (1301) but show low toxicity to non-cancer cells (peripheral blood mononuclear cells—PBMCs). The in vitro test results indicate that the dendrimers injure the 1301 leukemia cells via the apoptosis pathway.Funding: This work was co-financed by the Project EUROPARTNER of Polish National Agency for Academic Exchange (NAWA) and Pl-SK 2019–2020 bilateral project -PPN/BIL/2018/1/00150; supported by the project “NanoTENDO” granted by National Science Centre, Poland under the M-ERA.NET 2 of Horizon 2020 programme, project No: 685451. This research was also supported by grants from CTQ2017-86224-P (MINECO), consortiums IMMUNOTHERCAN-CM B2017/BMD-3733, NANODENDMED II-CM ref B2017/BMD-3703 and Project SBPLY/17/180501/000358 Junta de Comunidades de Castilla-La Mancha (JCCM). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008–2011, IniciativaIngenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. Acknowledgments: N.S.d.O. wishes to thank JCCM for a predoctoral fellowship. This article is based upon work from COST Action CA17140 “Cancer Nanomedicine from the Bench to the Bedside” supported by COST(European Cooperation in Science and Technology)

Chimeric Stimuli-Responsive Liposomes as Nanocarriers for the Delivery of the Anti-Glioma Agent TRAM-34

Nanocarriers are delivery platforms of drugs, peptides, nucleic acids and other therapeutic molecules that are indicated for severe human diseases. Gliomas are the most frequent type of brain tumor, with glioblastoma being the most common and malignant type. The current state of glioma treatment requires innovative approaches that will lead to efficient and safe therapies. Advanced nanosystems and stimuli-responsive materials are available and well-studied technologies that may contribute to this effort. The present study deals with the development of functional chimeric nanocarriers composed of a phospholipid and a diblock copolymer, for the incorporation, delivery and pH-responsive release of the antiglioma agent TRAM-34 inside glioblastoma cells. Nanocarrier analysis included light scattering, protein incubation and electron microscopy, and fluorescence anisotropy and thermal analysis techniques were also applied. Biological assays were carried out in order to evaluate the nanocarrier nanotoxicity in vitro and in vivo, as well as to evaluate antiglioma activity. The nanosystems were able to successfully manifest functional properties under pH conditions, and their biocompatibility and cellular internalization were also evident. The chimeric nanoplatforms presented herein have shown promise for biomedical applications so far and should be further studied in terms of their ability to deliver TRAM-34 and other therapeutic molecules to glioblastoma cells