SARS-COV-2 – THE LATEST GLOBAL THREAT AND THE PROSPECT OF COVID-19 THERAPY WITH THE USE OF CHITOSAN

Epidemics of infectious diseases have always been a threat to humanity and have contributed to increased mortality in the affected areas. This also applies to a new species of coronavirus identified in 2019, SARS-CoV-2, which is responsible for the COVID-19 pandemic. Despite preventive measures implemented all over the world to minimise the spread of the pathogen as well as the development of vaccines, which have been approved for emergency use, the situation is still worrying. Moreover, the problem is exacerbated by the lack of targeted treatments for COVID-19 patients. One possible solution is the using preparations based on natural raw materials, including chitosan. This biopolymer is of great interest due to a number of unique biological properties, among which its antiviral effect is a key feature. Hence, this paper presents the application possibilities of chitosan-based solutions in the prevention and treatment of viral diseases, with particular emphasis on COVID-19.

FROM CHITIN TO CHITOSAN – A POTENTIAL NATURAL ANTIMICROBIAL AGENT

Chitin is a naturally occurring polymer. Together with its derivatives such as chitosan, it has a wide spectrum of application possibilities, and many properties not yet exploited. Chitosan possesses many features desirable in an ideal antimicrobial polymer. It shows activity against multidrug-resistant bacterial and fungal strains that pose a challenge to modern medicine. Chitosan also shows activity against certain viruses, such as SARS-CoV-2. It might be used as a drug or a vaccine delivery system, is biodegradable, bioavailable and considered safe for medical use. It is important to continue exploring the potential of chitosan, as well as to investigate its sources. Indeed, many sources of this polymer are still not or have been poorly described. In this paper, we compile the current state of knowledge on the antimicrobial properties of chitosan, list alternative sources of chitin to highlight the potential of these two polymers and encourage further research.

DEVELOPMENT OF BIODEGRADABLE POLYSACCHARIDE-PROTEIN EDIBLE GEL COAT WITH ANTIMICROBIAL PROPERTIES FOR FOOD PRODUCTS

Food edible coatings are an important milestone in food production and one of the innovations in food packaging development. This article presents materials on the development of the formulation and technology for the manufacture of a novel composite coating based on sodium alginate, chitosan and protein hydrolysate obtained by the electrochemical method of double extraction from cod processing waste to obtain edible coatings for semi-finished fish products. Furthermore, the physicochemical, physical, mechanical and microbiological properties of this material are described.

NEW ASPECTS OF THE ENZYMATIC BREAKDOWN OF CHITIN: A REVIEW

This review focuses on the enzymatic breakdown of chitin, taking into account the latest scientific reports on the activity of lytic polysaccharide monooxygenase (LPMO). Chitin is a natural, abundant polysaccharide of great practical importance in the environment. However, the insolubility in water and the tightly packed crystalline structure of chitin pose a serious obstacle to enzymatic degradation. This substrate can be converted into soluble sugars by the action of glycosidic hydrolases (GH), also known as chitinases. LPMO could prove to be helpful in enzymatic processes that increase the rate of chitin depolymerisation by improving the availability of substrates for chitinases. The unique action of LPMO is based on the ability to catalyse the oxidative cleavage of glycosidic chains present in complex, resistant crystal networks of chitin, and this cleavage facilitates the subsequent action of glycolytic hydrolases.

EVALUATION OF HYDROPHILIC GLOBULES WITH SODIUM ALGINATE CONTAINING A LACTIC ACID– CHITOSAN COMPLEX

An important issue in the treatment of vaginitis is the amount of time the drug remains on the vaginal mucosa. If the contact time is too short, the drug cannot work effectively to ensure the correct pH in the vaginal environment. This study evaluated formulations of globules containing sodium alginate, lactic acid and chitosan with different pH and rheological properties. The experimental studies revealed that it is possible to produce a preparation with optimal pharmaceutical and application properties. The use of an appropriate ratio of lactic acid to chitosan in the complex and the appropriate concentration of sodium alginate produces a preparation with excellent properties to coat the surface of the vaginal mucosa.

THE EFFECT OF CHITOSAN HYDROLYSATE ON THE FUNGI ALTERNARIA SOLANI, FUSARIUM SOLANI AND RHIZOCTONIA SOLANI IN VITRO

Chitosan hydrolysate was obtained using nitric acid; the prevailing fraction had a molecular weight of 30 kDa and a deacetylation degree of 95%. The effect of chitosan hydrolysate when added to potato dextrose agar (PDA) in different concentrations (0.5, 1, 1.5, 2, 4, 6 and 8 mg/mL) was studied on the growth of the fungi Alternaria solani Sorauer, Fusarium solani (Mart.) Sacc. and Rhizoctonia solani J.G. Kühn. A. solani was the most sensitive to the addition of chitosan hydrolysate to PDA in radial growth experiments. On days 3 and 7 of incubation, the antifungal activity of the phytopathogen growth was 69%-92% and 69%-88%, respectively, in the concentration range of 0.5-2 mg/ml.

INFLUENCE OF PECTIN AND CHITOSAN ON THE PROPERTIES OF GELS PROTECTING THE OESOPHAGEAL MUCOSA

Among the diseases of the digestive tract, gastro-oesophageal reflux is one of the most troublesome ailments. It is estimated that in highly developed countries, reflux symptoms occur in about 5%-10% of people every day. It has also been found that about 20% of people experience such symptoms once a week. The incidence of this disease increases with age, regardless of gender. The aim of the study was to investigate the physicochemical properties of gels intended for the protection of the oesophageal mucosa. Preparations containing 3.0% pectin showed the lowest pH. These gels can be used in the treatment of advanced alkaline reflux. The addition of chitosan to all tested gels increased their pH and dynamic viscosity. The texture tests showed the effect of pectin concentration on the adhesion work of the tested gels.

EFFECT OF CHITOSAN AND LIPID LAYERS DEPOSITED ONTO POLYETHYLENE TEREPHTHALATE (PET) ON ITS WETTING PROPERTIES

The wetting properties of chitosan (Ch) and single 1,2-dipalmitoylsn-glycero-3-phosphocholine (DPPC), cholesterol (Chol) and binary DPPC-Chol layers deposited onto polyethylene terephthalate activated by low-temperature air plasma (PETair) were examined. PET is widely used in tissue engineering, but its low hydrophilicity limits its integration with the surrounding tissues. Ch is a biocompatible polysaccharide, distinguished by its antimicrobial properties, widely distributed in medicine. DPPC and Chol are the major building components of cell membrane, so they can perfectly mimic membrane behaviour during contact with the Ch layer. Monolayers of lipids were deposited onto PETair with or without the Ch layer using the Langmuir-Blodgett technique. The total surface free energy (SFE)and its components changes were calculated from theoretical approaches. Wettability strongly depended on the monolayer composition as well as the Ch layer. The Ch film decreased the contact angle and increased SFE of the PET surface with the lipid monolayers due to specific organisation of molecules within the chitosan scaffold. The most promising combination of surface modification for tissue engineering applications seems to be the PETair/Ch/DPPC-Chol system.

BIOMATERIALS BASED ON CHITOSAN AND ITS DERIVATIVES TO PREVENT ADHESION FORMATION

An increase in the number and volume of surgical interventions leads to an increase in the frequency of postoperative adhesions. The development of the adhesion process in the abdominal cavity causes pain, a decrease in the quality of life of patients, a violation of the reproductive function of women as well as acute adhesion intestinal obstruction. Recently, polymer biomaterials, including those based on chitosan, have been widely used for the prevention of adhesions. Due to their biocompatibility and biodegradation ability, they do not require repeated operations to extract the material. It is believed that these materials act as barriers, physically separating the damaged surfaces. The molecular mechanism of their action is still poorly understood. In this review, the main mechanisms of adhesion formation, as well as ways to prevent them with the help of materials based on chitosan and its derivatives, are discussed.

HYDROGEL ANTIBACTERIAL COATING FOR SILICONE MEDICAL DEVICES

Effective antibacterial coatings are in demand in medicine, especially for urological medical devices such as catheters and stents. We propose the production method of an antibacterial hydrogel coating on polydimethylsiloxane (PDMS, silicone), a popular surface for medical materials. The coating process consists of the following steps: PDMS surface activation (introduction of hydroxyl groups), silanisation (introduction of amine groups) and application of chitosan/alginate hydrogel with the addition of lysozyme as an antibacterial agent using the layer-by-layer method. We investigated the effect of polyion concentration on the coating mass, swelling ratio and stability. We analysed the adsorption of Micrococcus luteus, Escherichia coli and Proteus rettgeri on a PDMS surface using confocal laser scanning microscopy. The chitosan/alginate hydrogel coating with immobilised lysozyme protected the PDMS surface against adhesion for all three tested bacterial strains.