Antimicrobial Chitosan and Chitosan Derivatives: A Review of the Structure-Activity Relationship.

Chitin is the most abundant aminopolysaccharide polymer occurring in nature, and is the building material that gives strength to the exoskeletons of crustaceans, insects, and the cell walls of fungi. Through enzymatic or chemical deacetylation, chitin can be converted to its most well-known derivative, chitosan. The main natural sources of chitin are shrimp and crab shells, which are an abundant byproduct of the food-processing industry, that provides large quantities of this biopolymer to be used in biomedical applications. In living chitin-synthesizing organisms, the synthesis and degradation of chitin require strict enzymatic control to maintain homeostasis. Chitin synthase, the pivotal enzyme in the chitin synthesis pathway, uses UDP-N-acetylglucosamine (UDPGlcNAc), produce the chitin polymer, whereas, chitinase enzymes degrade chitin. Bacteria are considered as the major mediators of chitin degradation in nature. Chitin and chitosan, owing to their unique biochemical properties such as biocompatibility, biodegradability, non-toxicity, ability to form films, etc, have found many promising biomedical applications. Nanotechnology has also increasingly applied chitin and chitosan-based materials in its most recent achievements. Chitin and chitosan have been widely employed to fabricate polymer scaffolds. Moreover, the use of chitosan to produce designed-nanocarriers and to enable microencapsulation techniques is under increasing investigation for the delivery of drugs, biologics and vaccines. Each application is likely to require uniquely designed chitosan-based nano/micro-particles with specific dimensions and cargo-release characteristics. The ability to reproducibly manufacture chitosan nano/microparticles that can encapsulate protein cargos with high loading efficiencies remains a challenge. Chitosan can be successfully used in solution, as hydrogels and/or nano/microparticles, and (with different degrees of deacetylation) an endless array of derivatives with customized biochemical properties can be prepared. As a result, chitosan is one of the most well-studied biomaterials. The purpose of this review is to survey the biosynthesis and isolation, and summarize nanotechnology applications of chitin and chitosan ranging from tissue engineering, wound dressings, antimicrobial agents, antiaging cosmetics, and vaccine adjuvants.

Chitin and Chitosan: Production and Application of Versatile Biomedical Nanomaterials.

A review of chitosan and its derivatives in bone tissue engineering.

Wound healing and antimicrobial effect of active secondary metabolites in chitosan-based wound dressings: A review

https://jech.bmj.com/content/jech/46/3/318.1.full.pdf

Manual of Clinical Microbiology

Chitin and chitosan were extracted from six different aquatic invertebrate species. Species dry weights varied between 5 % and 20 % chitin, and the chitosan productivity of these chitins varied between 66 % and 74 %. Chitin and chitosan structures were characterized by FTIR, TGA, XRD, and SEM. FTIR results showed that the chitins obtained from the organisms were observed in α form. Chitin thermal stabilities were in the order Ranatra linearis > Anax imperator > Hydrophilus piceus > Notonecta glauca > Agabus bipustulatus > Asellus aquaticus, and chitosan thermal stabilities in the order N. glauca > A. bipustulatus > A. imperator > R. linearis > H. piceus > A. aquaticus. The crystalline index values of chitins varied between 76.4 % and 90.6 %. Their surface morphology was examined by SEM, revealing nanofibre structures. These six aquatic invertebrate species with characterized chitin and chitosan structures may be used as alternative chitin and chitosan sources for various technological purposes.

Extraction and Characterization of α-Chitin and Chitosan from Six Different Aquatic Invertebrates

This study examined two gregarious Orthoptera species (Calliptamus barbarus and Oedaleus decorus) as potential sources of chitin. The chitin content of the dry weight of C. barbarus was 20.5 ± 0.7%, and it was 16.5 ± 0.7% for O. decorus. Furthermore, the yield of chitosan (70 ~ 75% deacetylation degree) from the grasshopper species was found to be 74 ~ 76%, which is close to the yield of commercial preparations obtained from the unused parts of crabs and shrimp. The chitin and chitosan obtained in this way were analyzed using FTIR, TGA, XRD and SEM techniques, and the antimicrobial properties of chitosans obtained from C. barbarus and O. decorus against pathogenic microorganisms of humans and fish were investigated using the disc diffusion and microdilution broth methods. The antimicrobial screening procedures indicated that the chitosan showed significant antimicrobial activity against all of the tested pathogenic microorganisms. The MBC or MFC values were determined to be 0.16 ~ 2.50 mg/mL. The IC50 values for the chitins obtained from C. barbarus and O. decorus were 10.68 ± 0.27 and 10.91 ± 0.96 mg/mL, respectively, which were greater than the value for butylated hydroxytoluene (BHT): 0.04 ± 0.01 mg/mL. These results suggest that these two species, which are currently considered to be pests because of over-breeding, are potentially alternative sources of chitin and chitosan, which are used in the food/feed industry for their antimicrobial and antioxidant properties.

Extraction and Characterization of Chitin and Chitosan with Antimicrobial and Antioxidant Activities from Cosmopolitan Orthoptera Species (Insecta)

The paper describes the isolation and characterization of chitin and chitosan from Daphnia longispina resting eggs harvested from a reservoir. Resting eggs are fertilized eggs that are encased in chitinous shells called ‘ephippia’ and which ensure the survival of the Daphnia population in adverse conditions. The chitin-content of D. longispina resting eggs was found to be 23 ∼ 25% and the chitosan (having a 70 ∼ 75% deacetylation degree) yield of the chitin was 76 ∼ 77%. This high chitin-content indicates that D. longispina resting eggs can be exploited as a chitin source. The structure and thermal properties of chitin, extracted from D. longispina resting eggs, were characterized by employing Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. The crystallinity of the chitin was found to be very low (48%). Physicochemicallycharacterized chitosan and the produced O-carboxymethyl chitosan were tested for their antimicrobial and antioxidant activity. It has been observed that chitosan displays antimicrobial activity against all pathogenic bacteria, whereas O-carboxymethyl chitosan only exhibits inhibition activity against L. garvieae, L. Monocytogenes ATCC 7644, Y. enterocolitica NCTC 11175 and S. aureus ATCC 25923. In a free radical scavenging activity assay, the IC50 values of chitosan, O-carboxymethyl chitosan and butylated hydroxytoluene were found to be 23.01, 56.43 and 0.05, respectively. The ferric-reducing power of O-carboxymethyl chitosan (EC50 = 8.30) indicated higher activity than chitosan (EC50 = 10.12).

New Chitin, Chitosan, and O-Carboxymethyl Chitosan Sources from Resting Eggs of Daphnia longispina (Crustacea); with Physicochemical Characterization, and Antimicrobial and Antioxidant Activities

Chitin extraction and characterization from Daphnia magna resting eggs.

Chitin and its derivatives are commercially important biopolymers due to their applications in medicine, agriculture, water treatment, cosmetics and various biotechnological areas. Since chitin and its derivatives exhibit different chemical and physical properties depending on the source and isolation method, there is a growing demand for new chitin sources other than crab and shrimp worldwide. In this study Gammarus, a Crustacea, was investigated as a novel chitin source. Gammarus, which belongs to the family Gammaridae Crustacea, lives in the bottom of aquatic ecosystems. More than 200 species are known worldwide. One of these species, G. argaeus was investigated for chitin isolation. The alpha chitin isolated from G. argaeus was characterized by using analysis techniques such as infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). All these analyses confirmed that the isolated chitin from G. argaeus was in the alpha form. Furthermore, we described that dry weight of this species contained 11-12 % chitin. SEM examination of the isolated α-chitin revealed that it was composed of nanofibrils (15-55 nm) and pores (about 150 nm).

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Kabil Özcan Tozak

Papers

Extraction and Characterization of α-Chitin and Chitosan from Six Different Aquatic Invertebrates

Extraction and Characterization of Chitin and Chitosan with Antimicrobial and Antioxidant Activities from Cosmopolitan Orthoptera Species (Insecta)

New Chitin, Chitosan, and O-Carboxymethyl Chitosan Sources from Resting Eggs of Daphnia longispina (Crustacea); with Physicochemical Characterization, and Antimicrobial and Antioxidant Activities

Chitin extraction and characterization from Daphnia magna resting eggs.

Natural porous and nano fiber chitin structure from Gammarus argaeus (Gammaridae crustacea)