Degree Of Deacetylation Research Articles

PREPARATION AND ANTIFUNGAL ACTIVITIES OF CHITOSAN FROM APPLE-SNAIL (Pila ampullacea) SHELLS AS PRESERVING AGENT FOR POSTHARVEST PODANG MANGO (Mangifera indica L.) cv Podang

Podang mango, an endemic mango from Kediri, has a short post-harvest shelf life that accelerates by physiological factors and pathogenic fungal contamination. Chitosan reported as an active compound for coating. The apple-snail was reported to contain chitosan in its shell. The purposes of this study are to synthesis chitosan from Pila ampullacea, examine anti-fungal activities to Fusarium oxysporum and Aspergillus ochraceus, and verify the effect of chitosan coating on shelf life and quality of Podang mango. The effect of chitosan coating on fruit quality was analyzed using three treatments which were negative control, chitosan, and chitosan-gelatin with 3 replications. The parameters measured were color, texture, aroma, water content, vitamin C, and weight loss. Results showed that chitosan synthesized from P. ampullacea had 53.56 degrees of deacetylation. Antifungal activity test of chitosan 2% had the highest inhibitory activity against F.oxysporum and A.ochraceus growth with 14.46 mm and 10.33 mm inhibition zone. Coating with chitosan statistically affected fruit quality for 14 days of storage (sig <0.05). Chitosan-gelatin coating is the best treatment in reducing weight loss (8.97%), maintain aroma (sweet fragrance), texture (soft), water content (84%), and vitamin C (0.182%), while the color (reddish yellow) was more influenced by Chitosan coating. Chitosan coated with gelatin is recommended for application on Podang mangoes.

Characterizations and Antibacterial Efficacy of Chitosan Oligomers Synthesized by Microwave-Assisted Hydrogen Peroxide Oxidative Depolymerization Method for Infectious Wound Applications.

The use of naturally occurring materials with antibacterial properties has gained a great interest in infected wound management. Despite being an abundant resource in Vietnam, chitosan and its derivatives have not yet been intensively explored for their potential in such application. Here, we utilized a local chitosan source to synthesize chitosan oligomers (OCS) using hydrogen peroxide (H2O2) oxidation under the microwave irradiation method. The effects of H2O2 concentration on the physicochemical properties of OCS were investigated through molecular weight, degree of deacetylation, and heavy metal contamination for optimization of OCS formulation. Then, the antibacterial inhibition was examined; the minimum inhibitory concentration and minimum bactericidal concentration (MIC and MBC) of OCS-based materials were determined against common skin-inhabitant pathogens. The results show that the local Vietnamese chitosan and its derivative OCS possessed high-yield purification while the molecular weight of OCS was inversely proportional and proportional to the concentration of H2O2, respectively. Further, the MIC and MBC of OCS ranged from 3.75 to less than 15 mg/mL and 7.5–15 mg/mL, respectively. Thus, OCS-based materials induce excellent antimicrobial properties and can be attractive for wound dressings and require further investigation.

Preparation and Quality Identification of Chitosan and Chitooligosaccharide from Antarctic Krill

In this study, Antarctic krill shell was used as raw materials to prepare chitosan and chitooligosaccharide, their quality were also identified. After demineralization and deproteinization of Antarctic krill shell, deacetylation reaction conditions (alkali concentration, reaction temperature and reaction time) were explored to prepare Antarctic krill chitosan with high degree of deacetylation, and the physicochemical properties of chitosan were identified. The enzymatic hydrolysis conditions (chitosanase dosage and hydrolysis time) were explored to prepare high purity chitooligosaccharide, and the structural characteristics were identified. Results showed that Antarctic krill chitosan was finally prepared by 60% of sodium hydroxide deacetylation at 110 ℃ for 4 h, the deacetylation degree was 85.74%, the viscosity average molecular weight was 305.65 kDa, moisture content was 4.66%, ash content was 0.98% and acid insoluble content was 0.40%. The physicochemical properties of Antarctic krill chitosan met the food grade quality. Chitooligosaccharide was prepared by 0.2% (m/V) of chitosanase hydrolysis for 16 h. The yield of chitooligosaccharides from Antarctic krill chitosan was 46.0%. IR and NMR spectra showed all the characteristic signals of chitooligosaccharide. The MS results showed that chitooligosaccharide was mainly composed of disaccharide (GlcN)2, trisaccharide (GlcN)2-GlcNAc and tetrasaccharide (GlcN)3-GlcNAc. In this study, the preparation of high quality chitosan and chitooligosaccharide provided technical support for the comprehensive utilization of Antarctic krill shells and the development of Antarctic krill new products.

Optimum Preparation Conditions for Highly Individualized Chitin Nanofibers Using Ultrasonic Generator.

α-Chitin derived from crab shells was treated with 30% sodium hydroxide to prepare partially deacetylated chitin with a deacetylation degree of 36%. Partially deacetylated chitin nanofibers were prepared by applying weak ultrasonic energy generated by a domestic ultrasonic cleaner. The deacetylated chitin was easily disintegrated into nanofibers with the aid of electrostatic repulsion and osmotic pressure effect of amino cations on the chitin surfaces. The nanofibers were characterized in terms of yield, morphology, crystallinity, viscosity, and dispersibility. After a series of characterizations, ultrasonication with 45 kHz frequency and 20 min treatment was found to be the optimum conditions for obtaining fine nanofibers with a high yield.

Production of Chitosan from Crab Shells Using an Aqueous Extract of Wood Ash for the Deacetylation of Chitin: An Innovative, Eco-friendly, and Low-cost Method

The importance of chitosan has grown significantly over the last years due to its medicinal, agricultural, and industrial applications, as well as the biodegradability properties. The present study aimed to describe for the first time, the preparation of chitosan from chitin using wood ash aqueous extract as an alkaline medium. Chitin was obtained from crab shells in a microbial fermentation process using fish viscera for protease. Pilled and milled sweet potatoes and cassava water extracts were used separately in the deproteinization and demineralization steps as sources of carbon. The obtained chitin samples were then converted into the respective chitosan samples (B-C2 and M-B2) by an innovative, low-cost, and eco-friendly method using an aqueous extract (pH=12.4) prepared from wood ash, instead of the chemical process using sodium hydroxide solution in the deacetylation of chitin. The yield of the obtained chitosan was found to be 11.5% for B-C2 and 9.4% for M-C2. The presence of chitosan was determined by the analysis of the FTIR spectrum of both samples. The degree of acetylation was found to be 77.3% and 83.2% for B-C2 and M-B2, respectively, based on the IR analysis of absorption bands at 3456 and 1636 cm-1, and 75.4% and 84.1% based on the potentiometric titration. The average molecular weight (192.1 kDa for B-C2 and 194.3 kDa for M-B2) was determined using the viscometer method. The solubility of B-C2 and M-B2 in 1% acetic acid was found to be 77.8% and 63.9%, respectively. The analysis of SEM photographs of B-C2 showed an amorphous morphology while M-B2 showed a crystalline morphology. The TGA and DSC curves obtained in a dynamic air atmosphere showed three degradation stages. In the main event (the second stage), an exothermic peak was observed at 355°C for B-C2 coupled with the weigh-loss of 7%, while for M-C2 was observed at 365°C coupled with weight-loss of 10%. Due to their high degree of deacetylation, low molecular weight, and viscosity, both chitosan samples could be utilized unambiguously in the agri-food field as a biofertilizer or as a bio-adsorbent in the wastewater treatment.

KITOSAN DARI JAMUR TIRAM (Pleurotus ostreatus) DAN APLIKASINYA SEBAGAI ADSORBEN LOGAM KROM (Cr)

Oyster mushroom is one of the organisms that can be used as a chitosan source. Chitosan can be produced from chitin through deacetylation. As a chitin derivative compound, chitosan has immense application. In this study, chitin and chitosan were isolated from oyster mushrooms as much as 1.696% and 0.174% from 500 g of dried mushroom. The degree of deacetylation of chitosan is 80.70%. As a polycationic polymer, one of its applications is a metal adsorbent. Cr metal is a heavy metal that is mostly found in leather industrial waste. Chitosan is used as a Cr metal adsorbent to reduce Cr metal content in the solution. This study showed that there was a reduction of Cr metal content as much as 82.75%. Thus, chitosan isolated from oyster mushrooms in this study has the potential to be a bio-adsorbent in order to reduce Cr metal content in leather industrial waste.

Synthesis of New Chitosan from an Endemic Chilean Crayfish Exoskeleton (Parastacus Pugnax): Physicochemical and Biological Properties.

Chitin is one of the most abundant natural polysaccharides in the world and it is mainly used to produce chitosan by a deacetylation process. In the present study, the extraction of chitin and chitosan from the Parastacus pugnax (P. pugnax) crayfish exoskeleton was studied for the first time. Thus, the P. pugnax crayfish exoskeleton was converted to chitosan following the steps of depigmentation, deproteinization, and deacetylation. The produced chitosan (Chitosan-CGNA) was characterized in terms of the protein content, solubility, degree of deacetylation, viscosity, molecular weight, FTIR, SEM, XRD, antimicrobial, and antioxidant activity. The results showed that the obtained chitosan had a high degree of deacetylation (91.55%) and a medium molecular weight (589.43 kDa). The antibacterial activity of the chitosan was tested against bacterial strains relevant for the food industry and the lowest minimum inhibitory concentration (MIC) values were evidenced with Salmonella tiphymurium (S. typhimurium), Staphylococcus aureus (S. aureus), Enterococcus faecalis (E. faecalis) and Listeria. Monocytogenes (L. monocytogenes). Moreover, the Chitosan-CGNA showed an effect on DPPH radical scavenging activity, and its antioxidant activity was dependent on concentration and deacetylation degree. These results suggest that P. pugnax exoskeleton could be an excellent natural source for the production of chitosan with potential applications in the health system, and to prevent infections associated with pathogens strains.

EXTRACTION, CHARACTERIZATION AND APPLICATION OF CHITOSAN DERIVED FROM MAGGOT (BLACK SOLDIER FLY) WASTE AS EDIBLE COATING FOR RED GRAPES (Vitis vinifera)

<p class="Abstrak"><span class="tlid-translation"><span lang="EN-GB">Black Soldier Fly (BSF) farming showed an increasing trend in the past 5 years. The production process generates a leftover, that is the exuviae which are still untapped. BSF exuviae contain chitin and chitosan which can be utilized in various fields, one of which is fruit preservatives. Grapes (<em>Vitis vinifera</em>) is known to have many benefits and has a content of vitamins A, B, C, and E but it has a short shelf life. The purpose of this study was to characterize chitosan from BSF exuviae and choose the best edible coating method to be applied to grapes to prolong the grape’s storage time. Characterization includes physical condition, percent solubility, degree of deacetylation, and yield of the chitosan. Then, edible coating tests were carried out with 2% acetic acid solvent followed by two different methods, namely dyeing method with 5, 10 and, 15 minutes immersion time and spray method with a chitosan solution concentration of 0,5%, 1%, 1,5%, 2 %, and 2,5%. The results showed that chitosan extracted from BSF exuviae produced a physical appearance in the form of white brown powder with 55% solubility and a degree of deacetylation of 91,88%. The chitin yield is 16,2%, followed by the chitosan yield of 4,8%. The best edible coating method which can maintain the physical appearance of grapes and inhibiting fruit decayed was obtained by dipping method at a concentration of 2,5% for 10 minutes. Based on the overall observations, however, the results obtained from the dip and spray method were not significantly different.</span></span></p>

Preparation and characteristics analysis of an ecoenvironmental protection cyclic solidification dust-fixing agent extracted from waste shrimp shells to suppress dust in coal resource-based cities

There are a lot of coal cinder and dust in the development of coal resource-based cities. Improper handling will cause dust flying, which has a great impact on urban residents and the environment. The purpose of this research is to follow the principle of waste recycling, to use waste shrimp shells to extract chitosan as a raw material, to carry out graft polymerization with acrylic acid and polyvinyl alcohol-1788, and to carry out amidation crosslinking reactions with ethylenediamine tetraacetic acid to produce products. The results showed that the degree of deacetylation of chitosan reached 85% with the optimized extraction method, which greatly shortened the process cycle. Through orthogonal experiments and osmotic wetting experiments, the best preparation process was determined. The reaction process, structure of the product and adhesive structure of the solidified layer were analyzed by FTIR, XPS and SEM. The thermal stability of the product was analyzed by thermogravimetry. Relevant performance tests showed that the product had good adhesion with dust, the hardness of the solidified layer could reach 98 HA, and the dust fixation rate was 92.67% when the wind speed was 15–18 m/s. It has the advantage of circulating dust fixation, which improves the utilization rate of resources.

Factors Influencing the Antibacterial Activity of Chitosan and Chitosan Modified by Functionalization

The biomedical and therapeutic importance of chitosan and chitosan derivatives is the subject of interdisciplinary research. In this analysis, we intended to consolidate some of the recent discoveries regarding the potential of chitosan and its derivatives to be used for biomedical and other purposes. Why chitosan? Because chitosan is a natural biopolymer that can be obtained from one of the most abundant polysaccharides in nature, which is chitin. Compared to other biopolymers, chitosan presents some advantages, such as accessibility, biocompatibility, biodegradability, and no toxicity, expressing significant antibacterial potential. In addition, through chemical processes, a high number of chitosan derivatives can be obtained with many possibilities for use. The presence of several types of functional groups in the structure of the polymer and the fact that it has cationic properties are determinant for the increased reactive properties of chitosan. We analyzed the intrinsic properties of chitosan in relation to its source: the molecular mass, the degree of deacetylation, and polymerization. We also studied the most important extrinsic factors responsible for different properties of chitosan, such as the type of bacteria on which chitosan is active. In addition, some chitosan derivatives obtained by functionalization and some complexes formed by chitosan with various metallic ions were studied. The present research can be extended in order to analyze many other factors than those mentioned. Further in this paper were discussed the most important factors that influence the antibacterial effect of chitosan and its derivatives. The aim was to demonstrate that the bactericidal effect of chitosan depends on a number of very complex factors, their knowledge being essential to explain the role of each of them for the bactericidal activity of this biopolymer.

Determination of indicators allowing to evaluating the hemostatic activity of chitosan without a biological experiment

The biopolymer chitosan is widely used for the development of local hemostatic agents. However, the physicochemical parameters of chitosan that determine its hemostatic properties have not yet been determined. Standard quality control of chitosan-containing raw materials and medical products on its basis do not allow us to make a conclusion about the effectiveness of their use for stopping bleeding. The most reliable method for assessing hemostatic activity remains in vivo experiment on large animals. The aim of this study was to determine additional physicochemical parameters of chitosan, which would make it possible to predict its hemostatic activity without conducting a biological experiment. In this work, using the methods of nuclear magnetic resonance spectroscopy, spectrophotometry and viscometry, it has been shown that the ability to initiate hemostasis is depending of the molecular weight and degree of deacetylation of chitosan, but not enough linearly. The hemostatic properties in vitro increases in a series of samples with a relatively constant molecular weight with an increase in the degree of deacetylation. As well as in a series with the same degree of deacetylation with an increase in molecular weight. However, at molecular weight values more than 300 kDa, the viscosity of the polymer causes the opposite effect: with an increase in the degree of deacetylation, the hemostatic activity decreases. The best ability to initiate hemostasis have chitosan samples with a degree of deacetylation of 90.0%–97.4% and molecular weight 145.7–284.7 kDa, in which at pH of solution close to physiological, a significant part of the molecules transitioned from conformation state rigid rod to state globule. It was accompanied by an abrupt change in light transmission of the solution. It was concluded, that it is possible to study conformational states by spectrophotometry to assess the hemostatic activity of chitosan samples without performing biological experiment.

Chitosan and Hydroxy Propyl Methyl Cellulose as a Carrier for Aceclofenac for Prolonged Release

Numerous natural polymers either alone or in combination with other polymers were found effective in controlling the drug release. In this study the attempts were made to combine chitosan (degree of deacetylation 84.14 %) and as hydroxylpropyl methylcellulose (HPMC K 15M) to retard the release of aceclofenac in tablet formulation. The tablets were prepared by wet granulation and evaluated for pre and post- compression parameters. All the pre-compression parameters were found within the limit. Hardness and friability values were found in the range of 4.30-4.89 kg/cm2 and 0.1-0.6% respectively. These results proved the good mechanical strength of the formulations. The drug content was found in the range of 97.56 – 99.10 %. Weight variation was found within the official limit. The percent drug release and swelling index was found to be dependent on the concentration of polymer. With increasing the concentration of both the polymers the swelling index was increased and drug release decrease. Highest concentration of both the polymers was found to retard the drug release up to 8 h. The effect of Chitosan and HPMC on drug release was evaluated by design expert software to achieve the optimized formulation. The response of the drug release after 4h was considered to check the drug release. It was found that the enhanced concentration of both the polymers had negative effective on the drug release. The formulation containing highest concentration of the chitosan and HPMC was found be fit in the limits of optimized formulations. The optimized formulation was found to be stable at accelerated stability storage conditions.

Chitin-derived polymer deacetylation regulates mitochondrial reactive oxygen species dependent cGAS-STING and NLRP3 inflammasome activation

Chitosan is a cationic polysaccharide that has been evaluated as an adjuvant due to its biocompatible and biodegradable nature. The polysaccharide can enhance antibody responses and cell-mediated immunity following vaccination by injection or mucosal routes. However, the optimal polymer characteristics for activation of dendritic cells (DCs) and induction of antigen-specific cellular immune responses have not been resolved. Here, we demonstrate that only chitin-derived polymers with a high degree of deacetylation (DDA) enhance generation of mitochondrial reactive oxygen species (mtROS), leading to cGAS-STING mediated induction of type I IFN. Additionally, the capacity of the polymers to activate the NLRP3 inflammasome was strictly dependent on the degree and pattern of deacetylation and mtROS generation. Polymers with a DDA below 80% are poor adjuvants while a fully deacetylated polyglucosamine polymer is most effective as a vaccine adjuvant. Furthermore, this polyglucosamine polymer enhanced antigen-specific Th1 responses in a NLRP3 and STING-type I IFN-dependent manner. Overall these results indicate that the degree of chitin deacetylation, the acetylation pattern and its regulation of mitochondrial ROS are the key determinants of its immune enhancing effects.

Formulation of Insect Chitosan Stabilized Silver Nanoparticles with Propolis Extract as Potent Antimicrobial and Wound Healing Composites

Skin wounds are frequently influenced with microbial infections and inflammation, which need innovative agents for disputing them. Chitosan (Csn) was extracted from larvae of BSF “black soldier fly, Hermetia illucens” and ethanolic propolis extract (Pro) was employed for synthesizing silver nanoparticles (Ag-NPs), using facile biogenic protocol. The BSF-Csn was acquired with a yield of 1.56%, 91.3% deacetylation degree, and 88.600 Dalton molecular weight. The Ag-NPs were effectually biosynthesized using Pro, with a mean diameter of 8.73 nm and zeta potential of -21.34 mV. The antimicrobial activities assessment of insect Csn, Pro, synthesized Ag-NPs with Pro, and their composite against skin pathogens (Staphylococcus aureus and Candida albicans) revealed the elevated efficiency of the individual agents and the superior action of their composite (Csn/Pro/Ag-NPs), with 26.3 and 23.4 mm inhibition zones and inhibitory concentrations of 35.0 and 45.0 μg/mL from the composite toward S. aureus and C. albicans, respectively, which exceeded the actions of commercial antibiotics. The treatment of rat’s wounds with this composite promisingly led to faster healing of wounds and absence of inflammation and infection signs. The powerful actions of Csn/Pro/Ag-NPs as antimicrobial and wound healing composite strongly advocate their applications for skin protection, disinfection, and regeneration.

Chitosan Application as Edible Packaging Raw Material

Chitosan extracted from shrimp or crab can be made as raw material for biodegradable packaging. The purpose of this article is to review the advantages of chitosan as a raw material for packaging, the extraction method of chitosan, the properties and quality of chitosan, biodegradable packaging, manufacturing methods, and properties of packaging made from chitosan and the development of chitosan products for packaging materials. Chitosan is a raw material for packaging that can be parsed, commonly called biodegradable packaging, non-toxic and anti-bacterial. The method of making chitosan is removing minerals and removing protein from shrimp, crab, or ranjungan shells to obtain chitin, followed by the chitin acetylation process to obtain chitosan. The quality of chitosan is listed in SNI No.7949 (2013), where this standardization includes color, moisture content, ash content, nitrogen content, and degree of deacetylation. Chitosan has been used for edible coating material and edible film material, both of which have different manufacturing methods and characteristics. The development of chitosan as raw material for degradable packaging is that chitosan is made in nanoparticle size.

Evaluation of the Physicochemical Properties of Chitosans in Inducing the Defense Response of Coffea arabica against the Fungus Hemileia vastatrix.

Chitosan is a natural polymer, and its biological properties depend on factors such as the degree of deacetylation and polymerization, viscosity, molecular mass, and dissociation constant. Chitosan has multiple advantages: it is biodegradable, biocompatible, safe, inexpensive, and non-toxic. Due to these characteristics, it has a wide range of applications. In agriculture, one of the most promising properties of chitosan is as an elicitor in plant defense against pathogenic microorganisms. In this work, four kinds of chitosan (practical grade, low molecular weight, medium molecular weight, and high-density commercial food grade) were used in concentrations of 0.01 and 0.05% to evaluate its protective effect against coffee rust. The best treatment was chosen to evaluate the defense response in coffee plants. The results showed a protective effect using practical-grade and commercial food-grade chitosan. In addition, the activity of enzymes with β-1,3 glucanase and peroxidase was induced, and an increase in the amount of phenolic compounds was observed in plants treated with high-molecular-weight chitosan at 0.05%; therefore, chitosan can be considered an effective molecule for controlling coffee rust.

Study of the formation of structures in solutions of chitosan – polyvinyl alcohol polymer blends

The aim of this work was the investigation of the formation of structures in solutions of individual polymers, as well as their blends with each other in buffer solvents with different values of pH. In this study we used a sample of chitosan (degree of deacetylation ~ 84 %, M = 130,000), which is a polycation when dissolved, and polyvinyl alcohol (r = 1.25 g/cm3, M = 5000). Buffer systems based on acetic acid and sodium acetate with pH = 3.8, 4.25, and 4.75 were used as solvents. Viscosimetry was used to determine the intrinsic viscosity, the degree of structuring, and the Huggins constant. The Kriegbaum method was used to determine the nature of the aggregates formed by the blend of the studied polymers. In the course of the research, it was shown that an increase in the pH of the acetate buffer used as a solvent was accompanied by a compression of the macromolecular coil (a decrease in intrinsic viscosity values), a deterioration in the quality of thesolvent (an increase in Huggins constant values), and an increase in the degree of polymer aggregation in a solution for chitosan polyelectrolyte. At the same time for a solution of polyvinyl alcohol the pH of the buffer practically did not affect the nature of the polymer-solvent interaction. It has been proved that polymer blends are characterized by an increase in aggregation processes and a decrease in the thermodynamic quality of the solvent in comparison with solutions of individual polymers. The size of the “combined” macromolecular coil, characterized by the intrinsic viscosity value for the polymer blend, which can be both above (buffer solvent with pH = 3.80) and below (buffer solvent with pH = 4.25 and 4.75) additivevalues, changed depending on the type of formed polymer-polymer aggregates (homo- or hetero-). It was established that the type of aggregates (homo- or hetero-) formed in solutions of polymer blends was determined not only by the thermodynamic quality of the used solvents, but also by the concentration of the polymers in the initial solutions

Waste-Derived NPK Nanofertilizer Enhances Growth and Productivity of Capsicum annuum L.

Waste generation is a global issue that necessitates effective management for both human and animal health as well as environment. There are several ways to reduce waste, but recycling appears to be the best choice. By recycling, not only will the problem of pollution be resolved, but valuable compounds could be generated to be used as nutrients for plants. In this study, eco-friendly methods were established to produce α- and β-chitosan (CS) (as a source of nitrogen) with different degrees of deacetylation from shrimp shells and squid pin waste, phosphorous through degreasing and calcination of bovine bone and potassium from evaporation of banana peels Kolakhar. The waste bulk products were physically characterized and dry-milled into nano-powders. Different concentrations of the produced nano-NPK fertilizer (10%, 25%, 50% and 100%) were foliar-applied to Capsicum annum L. cv. Cordoba plants and compared to commercial chemical fertilizer and untreated control plants. The obtained results revealed that the nano-composite NPK with 25% concentration significantly promoted growth, yield and harvest of C. annuum as compared with the control and chemical fertilizer-treated plants. This study demonstrated that the use of an eco-friendly preparation of waste NPK composites, with a low concentration, could be applied as foliar fertilizer over chemical fertilizer to enhance the growth and productivity of Capsicum.

Toxicity of chitosan derivatives to Varroa destructor (Anderson and Trueman) and their effects on immune gene expression in honey bees

Varroasisis caused by Varroa destrucor (Anderson and Trueman) is considered the most dangerous honey bee disease. V. destructor mites parasitize both brood and adults, causing considerable losses to the colony population. The control of Varroa mites is highly dependent on the application of synthetic acaricides, however, acaricide resistance can develop. To eliminate the risk of Varroa mite resistance and to reduce residues in hive products, organic-based substances for Varroa mite control are being applied. In the present study, the acaricidal activity of N-alkyl and O-acyl chitosan derivatives against Varroa mites and their side effects on honey bees have been evaluated. Chitosan has been extracted from the corpses of honey bees. The yield, degree of deacetylation, and molecular weight of chitosan from the chitin of honey bee corpses were determined as 89%, 90%, and 20 kDa, respectively. Varroa mite mortalities were observed between 6.28-84.38% and 0.00-90.47% by N-alkyl and O-acyl chitosan derivatives, respectively. The best derivatives against Varroa mite were N-(3-phenylbutyl)chitosan (NAC-5) and O-(heptanoyl)chitosan (OAC-4). The results showed that different lethal concentrations of NAC-5 and OAC-4 had side effects against honey bees less than 26%. No significant difference was found between honey bee mortalities at 24, 48, and 72 hours post-treatment, while mortalities significantly differed between 4, and 24 h post-treatment. Immune gene expression in honey bees exposed to a lethal concentration of NAC-5and OAC-4 showed that the expressions of AmHym, AmBask, and AmSpz were significantly lower compared with those of control honey bees.

Preparation and Characterization of Chitosan from Perna viridis (Linnaeus, 1758) shell waste as raw material

Chitosan is extracted from Perna viridis as the staring source via the cycle of chitin deacetylation, which is conducted at 90°C for 6 hours using 40% NaOH. Physiochemical properties such as yield (18%), ash content (0.626%), moisture content (2.9%), and solubility, degree of deacetylation (55), fat binding capability (209%) and water binding ability (254 %) revealed that P.viridis is an important alternative source of chitosan. Fourier transforms infrared spectroscopy (FTIR) analysis showed the characteristic peaks of OH at 3400cm-1 and amine at 1660cm-1, the X-ray diffraction (XRD) analysis suggested two critical characteristic peaks at 18° and 34° at (2θ). Scanning electron microscope (SEM) was used to evaluate the surface morphology of isolated chitosan. Thermogravimetric analysis (TG/DTA) was also used to describe the thermal stability of P.viridis chitosan. The procoagulant capacity, plasma recalcification time assays and minimal bactericidal activity verified the hemocompatibility and antibacterial activity of the preparation of chitosan.