Low molecular chitosan–(poly)nitroxides: Synthesis and evaluation as antioxidants on free radical-induced erythrocyte hemolysis

Endogenous and Exogenous Antioxidants as Agents Preventing the Negative Effects of Contrast Media (Contrast-Induced Nephropathy)

The use of conventional contrast media for diagnostic purposes (in particular, Gd-containing and iodinated agents) causes a large number of complications, the most common of which is contrast-induced nephropathy. It has been shown that after exposure to contrast agents, oxidative stress often occurs in patients, especially in people suffering from various diseases. Antioxidants in the human body can diminish the pathological consequences of the use of contrast media by suppressing oxidative stress. This review considers the research studies on the role of antioxidants in preventing the negative consequences of the use of contrast agents in diagnostics (mainly contrast-induced nephropathy) and the clinical trials of different antioxidant drugs against contrast-induced nephropathy. Composite antioxidant/contrast systems as theranostic agents are also considered.

Chitosan-Based Hemostatic Hydrogels: The Concept, Mechanism, Application, and Prospects

The design of new hemostatic materials to mitigate uncontrolled bleeding in emergencies is challenging. Chitosan-based hemostatic hydrogels have frequently been used for hemostasis due to their unique biocompatibility, tunable mechanical properties, injectability, and ease of handling. Moreover, chitosan (CS) absorbs red blood cells and activates platelets to promote hemostasis. Benefiting from these desired properties, the hemostatic application of CS hydrogels is attracting ever-increasing research attention. This paper reviews the recent research progress of CS-based hemostatic hydrogels and their advantageous characteristics compared to traditional hemostatic materials. The effects of the hemostatic mechanism, effects of deacetylation degree, relative molecular mass, and chemical modification on the hemostatic performance of CS hydrogels are summarized. Meanwhile, some typical applications of CS hydrogels are introduced to provide references for the preparation of efficient hemostatic hydrogels. Finally, the future perspectives of CS-based hemostatic hydrogels are presented.

Amphiphilic chitosan-polyaminoxyls loaded with daunorubicin: Synthesis, antioxidant activity, and drug delivery capacity

The binding of aminoxyls to polymers extends their potential use as antioxidants and EPR-reporting groups and opens up new horizons for tailoring new smart materials. In this work, we synthesized and characterized non-sulfated and N-sulfated water-soluble amphiphilic chitosans with a critical micelle concentration of 0.02-0.05 mg/mL that contain 13-18% of aminoglycosides bound with various aminoxyls. Chitosan-polyaminoxyls (CPAs) formed micelles with hydrodynamic radii R_h of ca. 100 nm. The EPR spectra of CPAs were found to depend on the rigidity of the aminoxyl-polymer bond and structural changes caused by sulfation. CPAs demonstrated antioxidant capacity/activity in three tests against reactive oxygen species (ROS) of various nature. The charge of micelles and structure of aminoxyls significantly affected their antioxidant properties. CPAs were low toxic against tumor (HepG2, HeLa, A-172) and non-cancerous (Vero) cells (IC₅₀ > 0.8 mM of aminoglycosides). Sulfated CPAs showed better water solubility and the ability of binding and retaining the anti-tumor antibiotic daunorubicin (DAU). DAU-loaded micelles of CPAs (CPAs-DAU) demonstrated a 1.5-4-fold potentiation of DAU cytotoxicity against several cell lines. CPAs-DAU micelles were found to affect the cell cycle in a manner markedly different from that of free DAU. Our results demonstrated the ability of CPAs to act as bioactive drug delivery vehicles.

An Overview of Structural Aspects and Health Beneficial Effects of Antioxidant Oligosaccharides

BACKGROUND

Non-digestible oligosaccharides are versatile sources of chemical diversity, well known for their prebiotic actions, found naturally in plants or produced by chemical or enzymatic synthesis or by hydrolysis of polysaccharides. Compared to polyphenols or even polysaccharides, the antioxidant potential of oligosaccharides is still unexplored. The aim of the present work was to provide an up-to-date, broad and critical contribution on the topic of antioxidant oligosaccharides.

METHODS

The search was performed by crossing the words oligosaccharides and antioxidant. Whenever possible, attempts at establishing correlations between chemical structure and antioxidant activity were undertaken.

RESULTS

The most representative in vitro and in vivo studies were compiled in two tables. Chitooligosaccharides and xylooligosaccharides and their derivatives were the most studied up to now. The antioxidant activities of oligosaccharides depend on the degree of polymerization and the method used for depolymerization. Other factors influencing the antioxidant strength are solubility, monosaccharide composition, the type of glycosidic linkages of the side chains, molecular weight, reducing sugar content, the presence of phenolic groups such as ferulic acid, and the presence of uronic acid, among others. Modification of the antioxidant capacity of oligosaccharides has been achieved by adding diverse organic groups to their structures, thus increasing also the spectrum of potentially useful molecules.

CONCLUSION

A great amount of high-quality evidence has been accumulating during the last decade in support of a meaningful antioxidant activity of oligosaccharides and derivatives. Ingestion of antioxidant oligosaccharides can be visualized as beneficial to human and animal health.

Effect of Chitosan-(Poly)Nitroxides on Normal and Tumor Cells under Conditions of Induced Oxidative Stress

The cytotoxicity and antioxidant effects of chitosan-(poly)nitoxides of different molecular weights containing a nitroxide radical of the piperidine structure were studied on tumor (HeLa, A172, and HepG2) and normal (Vero) cell lines. The chitosan-(poly)nitroxides exhibited low cytotoxicity. Under conditions of oxidative stress induced with tert-butyl hydroperoxide, the most pronounced decrease in ROS levels in the presence of chitosan-(poly)nitroxides was observed in normal cells. In cell homogenates, the decrease in malondialdehyde levels was observed only in the presence of low-molecular-weight chitosan-(poly)nitroxide irrespective of the cell line. Our data demonstrate that the cell-specific antioxidant properties of chitosan-(poly)nitroxides are related to their penetration into cells and interaction with intracellular membranes.

Zinc-Modified Nanotransporter of Doxorubicin for Targeted Prostate Cancer Delivery

This work investigated the preparation of chitosan nanoparticles used as carriers for doxorubicin for targeted cancer delivery. Prepared nanocarriers were stabilized and functionalized via zinc ions incorporated into the chitosan nanoparticle backbone. We took the advantage of high expression of sarcosine in the prostate cancer cells. The prostate cancer targeting was mediated by the AntiSar antibodies decorated surface of the nanocage. Formation of the chitosan nanoparticles was determined using a ninhydrin assay and differential pulse voltammetry. Obtained results showed the strong effect of tripolyphosphine on the nanoparticle formation. The zinc ions affected strong chitosan backbone coiling both in inner and outer chitosan nanoparticle structure. Zinc electrochemical signal depended on the level of the complex formation and the potential shift from -960 to -950 mV. Formed complex is suitable for doxorubicin delivery. It was observed the 20% entrapment efficiency of doxorubicin and strong dependence of drug release after 120 min in the blood environment. The functionality of the designed nanotransporter was proven. The purposed determination showed linear dependence in the concentration range of Anti-sarcosine IgG labeled gold nanoparticles from 0 to 1000 µg/mL and the regression equation was found to be y = 3.8x - 66.7 and R² = 0.99. Performed ELISA confirmed the ability of Anti-sarcosine IgG labeled chitosan nanoparticles with loaded doxorubicin to bind to the sarcosine molecule. Observed hemolytic activity of the nanotransporter was 40%. Inhibition activity of our proposed nanotransporter was evaluated to be 0% on the experimental model of S. cerevisiae. Anti-sarcosine IgG labeled chitosan nanoparticles, with loaded doxorubicin stabilized by Zn ions, are a perspective type of nanocarrier for targeted drug therapy managed by specific interaction with sarcosine and metallothionein for prostate cancer.