Chitinase has a wide industrial application prospect. For example, it can degrade shrimp shells, crab shells and other crustacean waste into high value-added chitooligosaccharides. However, the low catalytic efficiency of chitinase greatly limits the production of chitooligosaccharides. In previous study, the we expressed a chitinase Chisb with high catalytic efficiency and studied its enzymatic properties. In order to further improve the catalytic efficiency of Chisb, with R13NprB-C-SP-H as the parent, here error-prone PCR was used to construct random mutant library to conduct directed evolution of chitinase Chisb. Two mutants C43D and E336R were obtained with 96-well plate primary screening and shaker-screening, and their enzymatic properties were also studied. The optimum temperature of C43D and E336R was 55 °C, and the optimum pH of C43D was 5.0, while that of E336R was 9.0. The catalytic efficiency of C43D and E336R was 1.35 times and 1.57 times higher than that of control. The chitooligosaccharide concentration of E336R and C43D was 2.53 g/L and 2.06 g/L, improved by 2.84 times and 2.31 times compared with the control (0.89 g/L), respectively. In addition, the substrate conversion rate of mutants E336R and C43D was 84.3% and 68.7%, improved by 54.6% and 39% compared with the control (29.7%), respectively. In summary, the study indicates that random mutation introduced by error-prone PCR can effectively improve the catalytic efficiency of chitinase Chisb. The positive mutants with higher catalytic efficiency obtained in the above study and their enzymatic property analysis have important research significance and application value for the biosynthesis of chitooligosaccharides.
Biocatalysis ; Chitin ; analogs & derivatives ; Chitinases ; Hydrogen-Ion Concentration ; Polymerase Chain Reaction

OBJECTIVETo investigate the effect of oligochitosan in promoting intestinal absorption of protoberberine alkaloids in extracts from Corydalis saxicola total alkaloids.

METHODThe in vitro single-pass intestinal perfusion model in rats was established to study the changes in absorption kinetic parameters of dehydrocavidine, berberine hydrochloride and palmatine chloride in C. saxicola total alkaloids after the addition of different concentrations oligochitosan and evaluate the effect of oligochitosan in promoting intestinal absorption of the drugs.

RESULTThe concentration of oligochitosan had different effects on the absorption rate constant (Ka) and apparent permeability coefficient (Peff) of the three active component in rat intestines. Ka and Peff in 0.5% oligochitosan group significantly increased, indicating a stronger effect in promoting the absorption.

CONCLUSIONOligochitosan has a certain effect in promoting the intestinal absorptions of protoberberine alkaloids in C. saxicola total alkaloids.

Animals ; Berberine Alkaloids ; administration & dosage ; pharmacokinetics ; Chitin ; administration & dosage ; analogs & derivatives ; Corydalis ; chemistry ; Drugs, Chinese Herbal ; administration & dosage ; pharmacokinetics ; Intestinal Absorption ; drug effects ; Intestines ; drug effects ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley

P-glycoprotein (P-gp) located in the apicalmembranes of intestinal absorptive cells is an energy-dependent efflux pump which can reduce the bioavailability of a wide range of substrate drugs. There is increasingly interest in enhancing the bioavailability of these molecules by inhibiting intestinal P-gp. A classification of excipient inhibitors of intestinal P-gp nonionic surfactants, poly (ethylene glycol), derivates of beta-cyclodextrin and thiolated chitosan will be presented and then the inhibition mechanism will be discussed. Compared with traditional P-gp inhibitor, excipient inhibitors appear to have minimal nonspecific pharmacological activity, thus potential side effects can be mostly avoided. These excipient inhibitors, which hold the promise of replacing the traditional ones, will be extensively employed to significantly improve the intestinal absorption of poorly soluble and absorbed drugs as a result of P-gp inhibition, and thus to enhance the bioavailability of these drugs. However, the further studies of both the mechanism and clinical application are urgently needed.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; pharmacokinetics ; Animals ; Biological Availability ; Chitin ; analogs & derivatives ; pharmacology ; Excipients ; pharmacology ; Glycerol ; analogs & derivatives ; pharmacology ; Humans ; Intestinal Absorption ; drug effects ; Polyethylene Glycols ; pharmacology ; Surface-Active Agents ; pharmacology ; beta-Cyclodextrins ; pharmacology

OBJECTIVETo study the mechanism of oligochitosan-induced macrophage activation.

METHODSOligochitosan was chemically modified with fluorophore 2-aminoacridone (2-AMAC). The cellular events of 2-AMAC-oligochitosan-macrophage interaction were analyzed with confocal laser microscopy and the fluorescence intensity of cells was analyzed by BD LSR flow cytometer. The mechanism of oligochitosan uptake by macrophages was studied by competitive inhibition test and the effect of calcium, trypsin and colchicine on oligochitosan recognition and internalization were also determined. RT-PCR was performed to investigate the level of TNF-alpha secretion.

RESULTMacrophage could bind and uptake oligochitosan, which was dependent on the temperature: the uptake proceeded rapidly at 37 degrees C and at 4 degrees C macrophage could only bind oligochitosan. EDTA decreased oligochitosan uptake. Trypsin treatment significantly reduced the internalization, and uptake was recovered by trypsin termination. Colchicine significantly inhibited the internalization process and was dose dependent. 0.1 mol/L mannose inhibited TNF-alpha expression induced by oligochitosan.

CONCLUSIONMacrophage could uptake oligochitosan via mannose receptor mediated pinocytosis. Mannose receptor is crucial for the oligochitosan-induced macrophages activation.

Cells, Cultured ; Chitin ; analogs & derivatives ; pharmacology ; Humans ; Lectins, C-Type ; metabolism ; Macrophage Activation ; drug effects ; Macrophages ; cytology ; Mannose-Binding Lectins ; metabolism ; Pinocytosis ; drug effects ; Receptors, Cell Surface ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

Hydroxyethyl chitin (HECH) is a water soluble chitin derivative made by etherification of chitin, ethylene chlorohydrin was used as etherification reagent in this reaction. A novel interpenetrating polymer network (IPN) composed of HECH/PAA was prepared. The IR spectra confirmed that HECH/PAA was formed through chemical bond interaction. The sensitivity of this hydrogel to temperature and pH was studied. The swelling ratio of this hydrogel in artificial intestinal juice is much greater than that in artificial gastric juice. The IPN hydrogel exhibited a typical pH-sensitivity, and its degree of swelling ratio increased with the increase of temperature. The sustained-release drug system of Dichlofenac potassium was prepared by using HECH/PAA as the drug carrier. The release experiment showed a perfect release behavior in artificial intestinal juice. This IPN is expected to be used as a good drug delivery system of enteric medicine.
Acrylates ; administration & dosage ; chemistry ; Anti-Inflammatory Agents, Non-Steroidal ; administration & dosage ; Chitin ; administration & dosage ; analogs & derivatives ; chemistry ; Delayed-Action Preparations ; Diclofenac ; administration & dosage ; Drug Carriers ; chemical synthesis ; Drug Delivery Systems ; Hydrogel, Polyethylene Glycol Dimethacrylate ; administration & dosage ; chemistry ; Hydrogen-Ion Concentration

OBJECTIVETo prepare microbubble, made of N-carboxymethyl chitosan, as ultrasound contrast agent and evaluate its characteristics and acoustic effects in vivo.

METHODSOil-Water-Oil multiple emulsion/solvent evaporation method was used to prepare the microbubble contrast agent. Both optical micrography and scanning electron micrography were performed to determine the bubble size and morphology. The acoustic effect of the N-carboxymethyl chitosan echo contrast agent was evaluated in vivo in rabbit. Liver echo images were recorded with ultrasound machine before and after intravenous bolus injecting 0.5 ml of the agent.

RESULTSThe novel N-carboxymethyl chitosan echo contrast agent was formulated as lyophilized product, with a mean diameter of 2-3 microm and a shell thickness of 250-300 nm. Its size is relatively uniform. The imaging effect was remarkably enhanced with the ultrasonic contrast agent when applied in rabbit livers.

CONCLUSIONIt is feasible to prepare excellent microbubble ultrasound contrast agent with N-carboxymethyl chitosan as membrane components.

Animals ; Chitin ; analogs & derivatives ; chemical synthesis ; chemistry ; Contrast Media ; Liver ; diagnostic imaging ; Microbubbles ; Rabbits ; Ultrasonics ; Ultrasonography

This study examined the effectiveness of Holmium-166 (Ho-166) chitosan complex therapy for a malignant glioma. Cultured C6 glioma cells (100, 000 in 5microliter) were injected into the caudate/putamen of 200 - 250 gram Wistar rats. Five days later, a Ho-166 chitosan complex was injected into the same site of the glioma injection. Four injection doses were administered: the control group received PBS 10microliter, group 1 received an injection of 100micro Ci (10microliter), group 2 received an injection of 50microCi (5microliter), and group 3 received an injection of 10micro Ci (1microliter). The average tumor volume for each group was 1.385 mm3 for the control group, 0.036 mm3 for group 1, 0.104 mm3 for group 2, and 0.111 mm3 for group 3. Compared with the control group, the size of the tumors in groups 1, 2 and 3 was reduced by an average of 97.4%, 92.5% and 91.9%, respectively. The Kaplan-Meier survival curve of group 2 was the longest, followed by groups 3, group 1 and the control. The mean survival was 22.8, 59, 60, and 44.6 days for the control group and groups 3, 2 and 1, respectively. H-E staining revealed that group 2 yielded the best results in the destruction of the malignant glioma. TUNEL staining and immunohistochemical studies indicated apoptotic features. The Ho-166 chitosan complex proved to be effective in destroying the malignant glioma.
Animals ; Brachytherapy ; Brain Neoplasms/mortality/pathology/*radionuclide imaging ; Cell Line, Tumor ; Chitin/analogs & derivatives/*pharmacology ; Disease Models, Animal ; Glioma/mortality/pathology/*radionuclide imaging ; Holmium/*pharmacology ; Radioisotopes/*pharmacology ; Rats ; Rats, Wistar ; Research Support, Non-U.S. Gov't

AIMTo study the cellular uptake of chitosan oligosaccharide nanoparticles by A549 cells and evaluate the possibility of chitosan oligosaccharide nanoparticles used as a potential drug carrier.

METHODSChitosan oligosaccharide (CSO) was obtained by ultrafiltration separation after regulation of the condition of chitosanase degradation. The molecular weight of CSO was determined by gel permeation chromatography (GPC). Chitosan oligosaccharide nanoparticles (CSO-NPs) were prepared by a novel solvent diffusion method in an oil system after the carrier material grafted fluorescein isothiocyanate (FITC) and the particle size distribution and zeta potential were determined by light scattering and electrophoretic mobility. The cytotoxicity and uptake of FITC-labeled CSO-NPs in A549 cells following various incubation periods were studied by the MTT method and fluorescence microscopy, flow cytometric analysis, respectively.

RESULTSThe molecular weight (MW) of CSO was 18,678 u and the particles sizes of CSO-NPs were 133.3 nm (number average) and 368.2 nm (volume average), respectively. The IC50 of CSO and CSO-NPs were 944.36 and 643.16 mg x L(-1), respectively, and the result showed low cytotoxicity. Cellular uptake of CSO and CSO-NPs were relative to the concentration and the incubation time. Internalization of CSO-NPs increased 0.49 - 13.9 times more than that of the CSO with the same incubation time.

CONCLUSIONCSO and CSO-NPs have low cytotoxicity. CSO-NPs can significantly improved the uptake of CSO-NPs by A549 cells compared to the same molecular weight of CSO.

Adenocarcinoma ; pathology ; Chitin ; analogs & derivatives ; metabolism ; toxicity ; Chitosan ; Dose-Response Relationship, Drug ; Drug Carriers ; metabolism ; toxicity ; Epithelial Cells ; drug effects ; metabolism ; Humans ; Lung Neoplasms ; pathology ; Nanotechnology ; Oligosaccharides ; metabolism ; toxicity ; Particle Size ; Time Factors ; Tumor Cells, Cultured

OBJECTIVETo investigate the effects of chitosan on the biological activities of the fibroblasts derived from different tissues.

METHODSThe biological activities of the fibroblasts derived from different tissues were evaluated with a MTT method for fibroblast proliferation, photic and electronic microscope for morphologic and subcellular structure, 3H-proline uptake method for collagen secretion and ELISA box for the secretion of TGF-beta 1, FGF-AB, and IL-8.

RESULTSThis study showed that the chitosan inhabited the proliferation of the fibroblasts and the secretion of the TGF-beta 1, FGF-AB and collagen of the fibroblasts with a dose-depended manner in the normal skin, hypertrophic scar and keloid groups, but it stimulated the IL-8. However, there were no significant differences among the three groups (P > 0.05).

CONCLUSIONThe chitosan could inhibit the growth, proliferation, biosynthesis and secretion of the fibroblasts, and it may be used to treat different scars.

Adolescent ; Adult ; Cell Division ; drug effects ; Chitin ; analogs & derivatives ; pharmacology ; Chitosan ; Dose-Response Relationship, Drug ; Female ; Fibroblast Growth Factors ; secretion ; Fibroblasts ; drug effects ; metabolism ; ultrastructure ; Hemostatics ; pharmacology ; Humans ; Interleukin-8 ; secretion ; Male ; Microscopy, Electron ; Peptide Fragments ; secretion ; Transforming Growth Factor beta ; secretion

OBJECTIVETo observe the skin regeneration after hair follicle bulb cells were implanted into collagen/chitosan porous scaffolds in vitro.

METHODSThe cultured dorsal hair follicle bulb cells of 4d-old C57BL/6J mice were implanted into collagen/chitosan porous scaffolds in vitro. The skin regeneration was observed.

RESULTThe skin-like structure was formed on the collagen/chitosan porous scaffolds where were cultured the hair follicle bulb cells before 4th passages.

CONCLUSIONThe skin-like structure is generated in vitro when early passages of cultured hair bulb cells are implanted into collagen/chitosan porous scaffolds.

Animals ; Chitin ; analogs & derivatives ; Chitosan ; Collagen ; Hair Follicle ; cytology ; Mice ; Mice, Inbred C57BL ; Regeneration ; Skin ; cytology ; Tissue Engineering