Optimum conditions for the precipitation of chitosan oligomers with DP 5–7 in concentrated hydrochloric acid at low temperature

Biochemical Degradation of Chitosan over Immobilized Cellulase and Supported Fenton Catalysts

This paper describes the application of Fe-MCM-48 (Mobil Composition of Matter No.48) and cellulase-MCM-48 catalysts for the depolymerization of chitosan. The results show that H2O2 is a good oxidant for the depolymerization of chitosan in the presence of Fe-MCM-48. The average polymerization degree of the product decreased to 6.1, and decreased to 29.2 when cellulase-MCM-48 was used as a catalyst, because the effect of the enzyme was affected by the molecular structure of chitosan. When both materials were used for depolymerization, the average degree of polymerization sharply decreased to 3.8. The results show that the two degradation methods can promote each other to obtain oligosaccharides with a lower degree of polymerization. This provides a new method for the controllable degradation of chitosan and lays a good foundation for the industrial production of chitosan oligosaccharides with a low degree of polymerization.

Recent Progress in Chitosanase Production of Monomer-Free Chitooligosaccharides: Bioprocess Strategies and Future Applications

Biological activities of chitosan oligosaccharides (COS) are well documented, and numerous reports of COS production using specific and non-specific enzymes are available. However, strategies for improving the overall yield by making it monomer free need to be developed. Continuous enzymatic production from chitosan derived from marine wastes is desirable and is cost-effective. Isolation of potential microbes showing chitosanase activity from various ecological niches, gene cloning, enzyme immobilization, and fractionation/purification of COS are some areas, where lot of work is in progress. This review covers recent measures to improve monomer-free COS production using chitosanase/non-specific enzymes and purification/fractionation of these molecules using ultrafiltration and column chromatographic techniques. Various bioprocess strategies, gene cloning for enhanced chitosanase enzyme production, and other measures for COS yield improvements have also been covered in this review. COS derivative preparation as well as COS-coated nanoparticles for efficient drug delivery are being focused in recent studies.

Pengaruh Berat Molekul Kitosan terhadap Efisiensi Enkapsulasi BSA (Bovine Serum Albumin) Menggunakan Agen Crosslink Na-TPP

Telah dilakukan penelitian tentang pengaruh berat molekul kitosan terhadap efisiensi enkapsulasi BSA (bovine serum albumin) menggunakan agen crosslink Na-TPP. Penelitian ini bertujuan menentukan pengaruh berat molekul kitosan dan adanya agen crosslink Na-TPP terhadap efisiensi enkapsulasi BSA, serta memprediksi interaksi yang terjadi antara kitosan dan BSA menggunakan pemodelan molekul. Berat molekul kitosan diperkecil dengan metode hidrolisis dengan HCl 0,5N dan efisiensi enkapsulasi kitosan terhadap BSA ini ditentukan dengan pengukuran menggunakan spektrofotometer UV-Vis pada λ 278nm. Interaksi antara kitosan dan BSA dapat diketahui dengan optimasi dan penentuan energi interaksi dengan menggunakan metode ab initio dan molecular docking.. Berat molekul kitosan awal dan kitosan hasil hidrolisis HCl 0,5 N yaitu 1,666x105 Da dan 1,277x103 Da. Efisiensi enkapsulasi kitosan hasil hidrolisis lebih besar dibandingkan kitosan awal yaitu 57,111%, dengan penambahan Na-TPP menjadi 61,751%. Disimpulkan bahwa penggunaan kitosan hasil hidrolisis dengan berat molekul rendah dan adanya Na-TPP sebagai agen crosslink mampu meningkatkan kemampuan enkapsulasi kitosan. Interaksi antara kitosan dan BSA ditunjukkan dengan diperolehnya energi interaksi antara trimer kitosan dan glutamin dengan menggunakan ab initio sebesar -74,765 kJ mol-1, sedangkan dengan molecular docking adalah -13,221 kJ mol-1. Dengan molecular docking juga diperoleh energi interaksi antara trimer kitosan dengan glutamin pada rantai A dan B dari BSA sebesar -12,301 kJ mol-1 dan -9,665 kJ mol-1.

Physicochemical Characterization of Thermally Treated Chitosans and Chitosans Obtained by Alkaline Deacetylation

The thermal depolymerization of chitosan and alkaline deacetylation of chitin were characterized by measurement of viscosity, gel permeation chromatography (GPC), potentiometric titration (PT), and proton nuclear magnetic resonance spectroscopy (H1NMR). The depolymerization rates (DR) measured by kinematic viscosity (KV), apparent viscosity (AV), and GPC (Mw) until 4 h of treatment wereDRKV=21.9,DRAV=25.5, andDRMw=23.3% h-1and for 5 to 10 h of treatment they decreased slowly to produce ofDRKV=0.545,DRAV=0.248, andDRMw=1.11% h-1. The mole fraction of N-acetylglucosamine residuesFAof chitosans was not modified after 10 h of thermal treatment at 100°C. The initialFAvalues of chitosan without any treatment wereFAPT=0.21andFAHNMR1=0.22and of chitosan treated for 10 h wereFAPT=0.27andFAHNMR1=0.22. The variables used to characterize the depolymerization process showed a good correlation. Six hours of thermal treatment as sufficient to obtain chitosans with a molar mass 90% smaller than that of the control chitosan without treatment.

Access to tetra-N-acetyl-chitopentaose by chemical N-acetylation of glucosamine pentamer

Nowadays, the easy access of tetra-N-acetyl-chitopentaose and its counterparts is highly interesting since such chemical compounds are precursors of biological signal molecules with a strong agro-economic impact. The chemical synthesis of tetra-N-acetyl-chitopentaose by controlled N-acetylation of the glucosamine pentamer hydrochloride under mild conditions is described herein. A systematic study on the influence of the different parameters involved in this reaction, such as the solvent, the acetylating agent, and the base used for the deprotonation of ammonium groups of the starting material was carried out. The characterization of final reaction products by HPLC and MALDI-TOF mass spectrometry showed that each of these parameters affects differently the acetylation reaction. Whereas the solvent plays an important role in the N- or O-acetylation selectivity, the acetylating agent and the base were found to influence both the degree of N-acetylation and the distribution of the partially N-acetylated derivatives in the product mixtures. Based on these results, optimized reaction conditions have been established allowing tetra-N-acetyl-chitopentaose to be synthesized in a one-pot deprotonation/N-acetylation of the glucosamine pentamer hydrochloride in a moderate yield (ca 30%).

A new controlled-release liquid delivery system based on diclofenac potassium and low molecular weight chitosan complex solubilized in polysorbates

A complex of low molecular weight chitosan (LMWC) with oleic acid and diclofenac potassium (DP) was prepared and dispersed in high concentrations of polysorbate 20, 60 and 80 in water to form a solution which releases its components slowly. The formed complex was characterized using different analytical methods. The size of the resulted nanoparticles and the effect of tweens on size were followed using dynamic light scattering (DLS). The release of DP from this delivery system was monitored by altering the molecular weight of chitosan and the type and concentration of the polysorbates used. The most suitable preparation consisted of DP, LMWC 13 kDa, and oleic acid. This was dispersed in 5% Tween 80 and the release was followed by the adaptation of USP II apparatus using a cellophane bag. This preparation offers a release of up to 24 h.

One-pot synthesis in aqueous system for water-soluble chitosan-graft-poly(ethylene glycol) methyl ether

Chitosan is functionalized with poly(ethylene glycol) methyl ether (mPEG) at the amino and hydroxyl groups via a single step reaction in a homogeneous aqueous system. A chitosan aqueous solution obtained from the mixture of chitosan and hydroxybenzotriazole (HOBt) in water is a key factor in providing mild conditions to conjugate mPEG by using a carbodiimide conjugating agent. The reaction at ambient temperature for 24 h gives chitosan-g-mPEG with water solubility with mPEG content as high as 42%. This work demonstrates that a water-soluble chitosan-HOBt complex is an effective system for the preparation of chitosan derivatives via the aqueous system without the use of acids or organic solvents.