Analysis of toxicity and biocompatibility of chitosan derivatives with different physico-chemical properties

A comparative study of the toxicity and hemocompatibility of chitosan and its derivatives with different acetylation degrees, molecular masses, charges, and hydrophobicity has been performed. It has been shown that only positively charged chitosan derivatives activate platelets and suppress cell proliferation, regardless of the acetylation degree, molecular mass, and hydrophobicity. Chitosan quaternization decreases toxicity at a low degree of substitution and abruptly increases it at a high one. Negatively charged chitosan derivatives were nontoxic and compatible with blood components. It was concluded that the toxicity of chitosan and its derivatives is defined by their charge and solubility at a neutral pH.     

Prospects for the Use of Metal Nanoparticles and Chitosan Nanomaterials with Metals to Combat Phytopathogens

Applied Biochemistry and Microbiology - The review considers the prospects for the use of chitosan nanoforms with metals to combat phytopathogens. Nanoparticles of metals and metal oxides exhibit...     

Study of the Protective Activity of Chitosan Hydrolyzate Against Septoria Leaf Blotch of Wheat and Brown Spot of Tobacco

Chitosan hydrolyzate containing low-molecular-weight chitosan (≤24 kDa) and its oligomers (≤1.2 kDa) has been obtained via chemical depolimerization of high-molecular-weight chitosan by nitric acid. The fractions of the obtained chitosan hydrolyzate have been characterized by high performance gel permeation chromatography and proton magnetic resonance. The test performed on detached leaves of wheat has shown that the hydrolyzate completely inhibits the development of Stagonospora nodorum, a casual agent of the septoria leaf blotch, at a concentration of 200 μg/mL. A similar test with detached tobacco leaves has shown that the hydrolyzate at a concentration of 100 μg/mL also inhibits the development of Alternaria longipes, which causes brown spot of tobacco, by 75%.     

Thromboresistance of Polyurethane Plates Modified with Quaternized Chitosan and Heparin

Applied Biochemistry and Microbiology - To obtain modified polyurethane (PU) plates, quaternized chitosan (QuatCh; degree of substitution 50%, degree of deacetylation 87%) and unfractionated...     

Antifungal action of chitosan in combination with fungicides in vitro and chitosan conjugate with gallic acid on tomatoes against Botrytis cinerea

In the present work, a positive effect was obtained by using low molecular weight chitosan compounds in combination with synthetic fungicides. Antifungal activity against Botrytis cinerea, determined by the radial growth method, was more than 75%, with a 25?×?10^??10 g/L concentration of fludioxonil or difenoconazole in compounds. Metabolic activity of B. cinerea fungus was about 15% when using a chitosan compound containing fludioxonil at a concentration of 25?×?10^??7 g/L. The combined action of chitosan with difenoconazole at a fungicide concentration of 25?×?10^??4 g/L is 2–3 times more effective than the action of each component separately. Results of studies for artificially inoculated B. cinerea tomato fruit when treated with low molecular chitosan and chitosan conjugate with gallic acid reduced the frequency of rotting fruit by 50 and 83%, respectively. Chitosan-gallic acid conjugate were obtained from chitosans with Mw of 28 kDa (Ch28GA) was proved to be effective as a preventive treatment for 3 days and can potentially be used as a biofungicide against B. cinerea on tomatoes in the post-harvest period.

     

Antibacterial effect of peptide conjugates with a quaternized chitosan derivative and its estimation by the method of atomic force microscopy

We obtained a number of conjugates based on a quaternized chitosan derivative and antimicrobial peptides (melittin and warnerin) crosslinked by microbial transglutaminase. We determined the optimal conditions for the synthesis (30 minutes, with a mole ratio of peptides and chitosan derivative of 1.4: 100) and studied the antibacterial properties of obtained conjugates. The antibacterial effect of the conjugates was found to be greater than that of their components. The antibacterial activity of the conjugates was determined by the double-dilution method and by atomic force microscopy.     

Search for Efficient Chitosan-Based Fungicides to Protect the 15th‒16th Centuries Tempera Painting in Exhibits from the State Tretyakov Gallery

Microbiology - Growth inhibition by chitosans (with molecular weight 6, 12, 18, 25 and 45 kDa) was demonstrated for 10 filamentous fungi belonging to the families Aspergillaceae, Cladosporiacea,...     

Properties of Functional Films Based on Chitosan Derivative with Gallic Acid

Conjugates of chitosan (molecular weight 28 and 830 kDa) with gallic acid were synthesized by a reaction initiated by a free radical. The conjugates contained 106 and 119 mg of polyphenol per g of polymer. Thin films were obtained from solutions of synthesized chitosan derivatives, and their physico-chemical characteristics (thickness of 0.058–0.076 mm and moisture content of 7.92–9.44%), as well as the antioxidant (inhibiting activity with respect to 2,2-diphenyl-1-picrylhydrazyl) and antimicrobial properties, were studied in relation to Staphylococcus epidermidis and Escherichia coli.     

Antibacterial Activity of Alkylated and Acylated Derivatives of Low–Molecular Weight Chitosan

A number of alkylated (quaternized) and acylated derivatives of low–molecular weight chitosan were obtained. The structure and composition of the compounds were confirmed by the results of IR and PMR spectroscopy, as well as conductometric titration. The effect of the acyl substituent and the degree of substitution of N-(2-hydroxy-3-trimethylammonium) propyl fragment appended to amino groups of the C₂ atom of polymer chains on antibacterial activity against typical representatives of gram-positive and gramnegative microorganisms (Staphylococcus epidermidis and Escherichia coli) was studied. The highest activity was in the case of N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan chloride (HTCC) with the maximal substitution (98%). The minimal inhibitory concentration of the derivative was 0.48 μg/mL and 3.90 μg/mL for S. epidermis and E. coli, respectively.     

Neutralization of anticoagulant activity of heparin by N-[(2-hydroxy-3-trimethylammonium) propyl] chloride derivatives of chitosan

Alkylated derivatives of low molecular weight chitosan with different substitution degrees of 98, 40, and 9% (I, II, and III respectively) have been synthesized. The structure of the obtained derivatives was defined by spectral assays (IR-spectroscopy and proton magnetic resonance). Chitosan derivatives were characterized with positive zeta-potential (33–51 mV) and solubility from 2 to 100 mg/mL in pH 7.4 and 25°C. It was shown that, at a concentration of 0.0014–0.0029 mg/mL, derivative I, as well as protamine sulfate, could be used to neutralize the anticoagulant activity of unfractionated or low molecular weight heparin. At a concentration of 0.0029–0.58 mg/mL, derivative I enhanced platelet aggregation, which would be necessary when hemostatic compounds or materials were used. Derivatives II and III enhanced platelet aggregation to a lesser extent.