Anti-ulcerogenic effect of chitin and chitosan on mucosal antioxidant defence system in HCl-ethanol-induced ulcer in rats

Amoxicillin-docosahexaenoic acid encapsulated chitosan-alginate nanoparticles as a delivery system with enhanced biocidal activities against Helicobacter pylori and improved ulcer healing

Encapsulation of amoxicillin (AMX) for drug delivery against Helicobacter pylori infection and aspirin-induced ulcers in rat's stomachs was performed using docosahexaenoic acid (DHA)-loaded chitosan/alginate (CA) nanoparticles (NPs) developed by ionotropic gelation method. The physicochemical analyses of the composite NPs were performed by scanning electron microscopy, Fourier transform infrared spectroscopy, zeta potential, X-ray diffraction, and atomic force microscopy. The encapsulation efficiency of AMX was increased to 76% by incorporating DHA, which resulted in a reduction in the particle size. The formed CA-DHA-AMX NPs effectively adhered to the bacteria and rat gastric mucosa. Their antibacterial properties were more potent than those of the single AMX and CA-DHA NPs as demonstrated by the in vivo assay. The composite NPs attained higher mucoadhesive potential during food intake than during fasting (p = 0.029). At 10 and 20 mg/kg AMX, the CA-AMX-DHA showed more potent activities against H. pylori than the CA-AMX, CA-DHA, and single AMX. The in vivo study showed that the effective dose of AMX was lower when DHA was included, indicating better drug delivery and stability of the encapsulated AMX. Both mucosal thickening and ulcer index were significantly higher in the groups receiving CA-DHA-AMX than in the groups receiving CA-AMX and single AMX. The presence of DHA declines the pro-inflammatory cytokines including IL-1β, IL-6, and IL-17A. The synergistic effects of AMX and the CA-DHA formulation increased the biocidal activities against H. pylori infection and improved ulcer healing properties.

Chitin and chitin-based biomaterials: A review of advances in processing and food applications

Chitin is the most abundant natural amino polysaccharide, showing various practical applications owing to its functional properties. However, there are barriers in the development due to the difficulty of chitin extraction and purification, regarding its high crystallinity and low solubility. In recent years, some novel technologies such as microbial fermentation, ionic liquid, electrochemical extraction have emerged for the green extraction of chitin from new sources. Furthermore, nanotechnology, dissolution systems and chemical modification were applied to develop a variety of chitin-based biomaterials. Remarkably, chitin was used in delivering active ingredients and developing functional foods for weight loss, lipid reduction, gastrointestinal health, and anti-aging. Moreover, the application of chitin-based materials was expanded into medicine, energy and the environment. This review outlined the emerging extraction methods and processing routes of different chitin sources and advances in applying chitin-based materials. We aimed to provide some direction for the multi-disciplinary production and application of chitin.

The Effect of Nano-chitosan and Nano-curcumin on Radiated Parotid Glands of Albino Rats: Comparative Study

Decreasing the salivary flow rate manifested by xerostomia occurs early during the irradiation treatment. The duration of depressed salivary function varies among patients. Various histopathological changes occur in the salivary glands. The current study was performed to investigate and compare between the possible anti-radiotherapeutic effect of the gamma rays-synthesized curcumin nanoparticles (Cur NPs), and chitosan nanoparticles (Cs NPs). They were utilized to overcome the histopathological changes associated with radiation therapy in albino rats’ parotid glands. Sixty adult male Albino rats were utilized, fifteen as control group, fifteen as radiated group and thirty as Cur NPs and Cs NPs treatment groups. The parotid glands were dissected and examined histologically, immunohistochemically for vascular endothelial growth factor (VEGF) as well as histo-morphometrically. The histological results proved the antiradio-therapeutic effect of Cur NPs, and Cs NPs, with the least degenerative changes in the Cur NPs treated group. A high significant increase in VEGF was recorded in the radiated group as compared to the other treated groups. Cs NPs have proved to be an anti-radiotherapeutic and anti-oxidant substrate in treating the histopathological changes in radiated parotid glands of albino rats. However, it was lagging behind Cur NPs in all analyses but non-significant differences between them have been recorded.

Graphical Abstract

How Gut Bacterial Dysbiosis Can Promote Candida albicans Overgrowth during Colonic Inflammation

Candida albicans is a commensal opportunistic yeast, which is capable of colonising many segments of the human digestive tract. Excessive C. albicans overgrowth in the gut is associated with multiple risk factors such as immunosuppression, antibiotic treatment associated with changes to the gut microbiota and digestive mucosa that support C. albicans translocation across the digestive intestinal barrier and haematogenous dissemination, leading to invasive fungal infections. The C. albicans cell wall contains mannoproteins, β-glucans, and chitin, which are known to trigger a wide range of host cell activities and to circulate in the blood during fungal infection. This review describes the role of C. albicans in colonic inflammation and how various receptors are involved in the immune defence against C. albicans with a special focus on the role of mannose-binding lectin (MBL) and TLRs in intestinal homeostasis and C. albicans sensing. This review highlights gut microbiota dysbiosis during colonic inflammation in a dextran sulphate sodium (DSS)-induced colitis murine model and the effect of fungal glycan fractions, in particular β-glucans and chitin, on the modification of the gut microbiota, as well as how these glycans modulate the immuno-inflammatory response of the host.

Sepia officinalis ink mitigates gastric ulcer via modulation of antioxidant/anti-inflammatory pathways

Background

Sepia officinalis ink is a bioactive secondary metabolite rich in melanin granules, which has a wide range of nutritional and therapeutic values and also has been used to prevent various gastrointestinal disorders. Gastric ulcer, the most common gastrointestinal disease, is characterized by severe gastric mucosa damage, and its prevention is currently one of the main goals of clinical and experimental studies. Thus, the present study was focused on evaluating the potential gastroprotective efficacy of Sepia officinalis ink extract (SOIE) against ethanol-induced gastric ulcer in rats.

Results

The current results revealed that SOIE administration at the two selected doses improved significantly gastric mucosa integrity as indicated by the significant (P < 0.05) amelioration in gastric secretion indices (pH and volume) and the marked decrease in the ulcer index. Moreover, SOIE could counteract the gastric oxidative stress induced by ethanol via a marked decline in malondialdehyde content as well as a significant (P < 0.05) increment in glutathione content and antioxidant enzymes activities (catalase and glutathione-s-transferase). Additionally, SOIE treatment caused a significant (P < 0.05) reduction in gastric nitric oxide content. Respecting morphological and histopathological studies, SOIE treatment at 200 mg/kg body weight caused marked healing of gastric lesions as indicated by no hemorrhagic bands or injuries observed as well as significantly reduced severity score of ulcer.

Conclusions

SOIE could be used as a promising alternative antiulcerogenic compound to treat severe gastric lesions.

Protective Effects of Chitosan-Bilirubin Nanoparticles Against Ethanol-Induced Gastric Ulcers

Purpose

Gastric ulcers (GU) are a disease of the gastrointestinal tract that can be caused by excessive alcohol consumption and heavy use of nonsteroidal anti-inflammatory drugs. GU manifests predominantly as pathological damage, such as extensive inflammatory erosion and superficial bleeding of the gastric mucosa. Oxidative stress damage and the inflammatory response are now considered important predisposing factors for GU, suggesting that antioxidant and anti-inflammatory drugs could be treatments for GU. Nanoparticle drug carriers offer many advantages over conventional drugs, such as improved drug efficiency, increased drug stability, and increased half-life.

Methods

We designed chitosan-bilirubin conjugate (CS-BR) nanoparticles and assessed the anti-inflammatory and antioxidant abilities of CS-BR in gastric epithelial cells. Then, we evaluated the intragastric retention time and the anti-ulcer effects of CS-BR in vivo.

Results

The in vitro data showed that CS-BR nanoparticles protect gastric epithelial cells against oxidative/inflammatory injury. The in vivo study demonstrated that CS-BR nanoparticles accumulate permanently in the stomach and exert powerful antioxidant and anti-inflammatory effects against GU.

Conclusion

This study applied bilirubin to the treatment of GU and confirmed that CS-BR nanoparticles are effective at alleviating acute GU in an experimental model. The findings provide innovative ideas for prophylaxis against or treatment of GU.

Antioxidant defense of fish collagen peptides attenuates oxidative stress in gastric mucosa of experimentally ulcer-induced rats

The aim of the present study was to investigate the ability of fish collagen peptides (FCP) from the skin of great hammerhead shark (Sphyrna mokarran) to avert the occurrence of gastric ulcer in experimental rats. FCP treatment prevented the formation of ulcerative lesions on gastric tissues with 86% of inhibition. The histopathology analysis of gastric tissue revealed that the FCP intake prevented the occurrence of hemorrhage and erosion in gastric tissue with formation of mild edema and necrosis, as well as normalized the pH and volume of gastric juice. It also downregulated the expression of pro-inflammatory marker interferon-ɤ (IFN-ɤ) and upregulated the anti-inflammatory marker interleukin-4 (IL-4) in gastric tissue. FCP is capable to modulate the oxidative stress by enhancing the activity of antioxidant defense enzymes superoxide dismutase (SOD) and catalase and by lowering the levels of membrane lipid peroxidation.

Formulation, optimization and characterization of allantoin-loaded chitosan nanoparticles to alleviate ethanol-induced gastric ulcer: in-vitro and in-vivo studies

Allantoin (ALL) is a phytochemical possessing an impressive array of biological activities. Nonetheless, developing a nanostructured delivery system targeted to augment the gastric antiulcerogenic activity of ALL has not been so far investigated. Consequently, in this survey, ALL-loaded chitosan/sodium tripolyphosphate nanoparticles (ALL-loaded CS/STPP NPs) were prepared by ionotropic gelation technique and thoroughly characterized. A full 24 factorial design was adopted using four independently controlled parameters (ICPs). Comprehensive characterization, in vitro evaluations as well as antiulcerogenic activity study against ethanol-induced gastric ulcer in rats of the optimized NPs formula were conducted. The optimized NPs formula, (CS (1.5% w/v), STPP (0.3% w/v), CS:STPP volume ratio (5:1), ALL amount (13 mg)), was the most convenient one with drug content of 6.26 mg, drug entrapment efficiency % of 48.12%, particle size of 508.3 nm, polydispersity index 0.29 and ζ-potential of + 35.70 mV. It displayed a sustained in vitro release profile and mucoadhesive strength of 45.55%. ALL-loaded CS/STPP NPs (F-9) provoked remarkable antiulcerogenic activity against ethanol-induced gastric ulceration in rats, which was accentuated by histopathological, immunohistochemical (IHC) and biochemical studies. In conclusion, the prepared ALL-loaded CS/STPP NPs could be presented to the phytomedicine field as an auspicious oral delivery system for gastric ulceration management.

Therapeutic and Preventive Effects of Olea europaea Extract on Indomethacin-Induced Small Intestinal Injury Model in Rats

Background

Olea europaea (known as olive fruit) has anti-inflammatory and antioxidant activities and many potential health benefits including gastric inflammation reduction has been shown previously. This study aimed to investigate the preventive and therapeutic effects of O. europaea extract on the early histological changes in indomethacin-induced small intestinal injury model with the plasma D-lactate concentration being measured as a tool for determination of intestinal permeability.

Methods

In this experimental study, two separate protective and therapeutic protocols were designed. In both experiments, male Wistar rats were randomly divided into 4 groups and either pretreated with 0, 100, 200, or 400 mg/kg/day of O. europaea extract or received the treatment after administration of indomethacin. Their small intestines were examined to compare the histological changes. The intestinal injury severity was evaluated according to the presence of eosinophils, plasma cell infiltration, edema, congestion, and hyperplasia of the crypt using a histological scoring system. Also, measured were the presence of neutrophils, decreased villus length-to-crypt depth ratio, and destructed villus architecture. The plasma concentration of D-lactate was measured as well.

Results

The therapeutic use of O. europaea decreased the eosinophil, edema, congestion, and crypt hyperplasia scores compared to the control group. Although no significant difference was seen between groups of the preventive experiment in plasma cell infiltration score, villus length-to-crypt depth ratio, neutrophil infiltration, and percentage of destructed villus architecture, treatment with O. europaea caused a reduction in edema, eosinophil, congestion, and crypt hyperplasia score. In both experiments, no significant difference was seen between groups for villus length-to-crypt depth ratio, neutrophil infiltration, and percentage of destructed villus architecture. Plasma D-lactate concentration was decreased in all O. europaea-treated groups compared to the control group in the therapeutic and preventive experiments (p < 0.01, one-way ANOVA followed by the Dunnett test).

Conclusion

O. europaea extract can be used to decrease some side effects of indomethacin on intestinal tissue and enhances the gastrointestinal function. O. europaea extract could be considered as a potential herbal supplement in the treatment of intestinal morphological injuries.

The Effect of Chitosan on the Erythrocyte Antioxidant Potential of Lead Toxicity-Induced Rats

In the present study, the effects of chitosan on erythrocyte malondialdehyde (MDA) and glutathione (GSH) levels and glutathione peroxidase (GSH-Px), glutathione reductase (GR), and glucose-6-phosphate dehydrogenase (G6PDH) enzyme activities in lead toxicity-induced rats were investigated. Twenty-eight male Wistar albino rats were divided into four groups of control (C), lead group (Pb group), lead + chitosan group (Pb + CS group), and chitosan group (CS group). Lead groups were administered 50 mg/kg lead acetate intraperitoneally (ip) for 5 days and chitosan groups were administered 200 mg/kg chitosan for 28 days via gavage. At the end of the study, lead levels were measured in the blood; MDA and GSH levels and GPx, GR, and G6PDH activities were measured in the erythrocyte. It was determined that, in parallel with the increase of full blood lead levels in the Pb group, erythrocyte MDA levels increased significantly, while GSH levels and GSH-Px, GR, and G6PDH activities decreased when compared to those in the C and CS groups (p ˂ 0.05). There was a statistically significant decrease in lead and MDA levels and GSH level and GSH-Px activity increased (p ˂ 0.05) in the Pb + CS group, where chitosan was administered as a protective agent in addition to lead, when compared to the Pb group. There were no differences between the Pb + CS group and the other three groups based on GR and G6PDH activities (p ˃ 0.05). No statistically significant difference was found between the C and CS groups based on the parameters of analysis (p ˃ 0.05). The findings of the present study demonstrated that lead increased oxidative stress by increasing free radical production in erythrocytes, and chitosan was effective in removing the lead from the circulation and enforced the antioxidant defense system.

Remodeling of the Candida glabrata cell wall in the gastrointestinal tract affects the gut microbiota and the immune response

The gastrointestinal (GI) microbiota acts a natural barrier to the proliferation of opportunistic pathogens. Candida glabrata is an opportunistic yeast pathogen that has adapted to colonize all segments of the human GI tract. We observed an increase in Escherichia coli, Enterococcus faecalis, and Bacteroides vulgatus populations, and a decrease in Lactobacillus johnsonii, Bacteroides thetaiotaomicron, and Bifidobacterium animalis in mice with DSS-induced colitis. This reduction was more pronounced for L. johnsonii during C. glabrata overgrowth. In addition, C. glabrata overgrowth increased mouse mortality and inflammatory parameters, and modulated the expression of intestinal receptors and signaling pathways. The C. glabrata cell wall underwent various changes during the course of C. glabrata colonization, and showed a significant increase in chitin. C. glabrata deficient in chitin synthase-3 induced fewer inflammatory parameters than the parental strain during intestinal inflammation. Oral administration of chitin attenuated the impact of colitis, and reduced the number of aerobic bacteria and C. glabrata overgrowth, while chitinase-3-like protein-1 increased. This study provides evidence that inflammation of the gut alters the microbial balance and leads to C. glabrata cell wall remodeling through an increase in chitin, which is involved in promoting persistence of C. glabrata in the gut.

Dietary Chitosan Supplementation Ameliorates Isoproterenol-Induced Aberrations in Membrane-Bound ATPases and Mineral Status of Rat Myocardium

Myocardial infarction is one of the major public concerns in both developed and developing countries. Recently, there is growing interest in potential healthcare applications of marine natural products in the field of cardiovascular research. In the present study, we have examined the membrane-stabilizing potential of marine mucopolysaccharide-chitosan in modulating the aberrations of thiol-dependent membrane-bound ATPases activities, mineral status, and cardiac diagnostic markers in isoproterenol-induced myocardial infarction condition in rats. Dietary intake of chitosan significantly (p < 0.05) counteracted the isoproterenol-induced lipid peroxidation and maintained the levels of thiol contents and cardiac biomarkers at concentrations analogous to that of normal controls in the rat myocardium. Chitosan administration also significantly mitigated isoproterenol-induced aberrations in the membrane-bound ATPase activities in the heart tissue and preserved the myocardial mineral status in serum and heart tissue of experimental rats at near normal value. The results of the present study have indicated that the salubrious effect of dietary chitosan supplementation in attenuating the experimentally induced myocardial infarction condition is probably ascribable to its antioxidant defense and membrane-stabilizing properties.

Gastroprotective effect of kefir on ulcer induced in irradiated rats

The current study was designed to investigate the protective effect of kefir milk on ethanol-induced gastric ulcers in γ-irradiated rats. The results of the present study revealed that treatment with γ-irradiation and/or ethanol showed a significant increase in ulcers number, total acidity, peptic, H(+)K(+)ATPase, MMP-2 and MMP-9 activities and MDA level, which were accompanied by a significant decrease in the mucus content, the stomach GSH level, the GSH-Px activity and DNA damage. Pre-treatment with kefir milk exert significant improvement in all the tested parameters. Kefir milk exerts comparable effect to that of the antiulcer drug ranitidine. In conclusion, the present study revealed that oral administration of kefir milk prevents ethanol-induced gastric ulcer in γ-irradiated rats that could attribute to its antioxidant, anti-apoptotic and radio-protective activities.

Alcohol stress, membranes, and chaperones

Ethanol, which affects all body organs, exerts a number of cytotoxic effects, most of them independent of cell type. Ethanol treatment leads to increased membrane fluidity and to changes in membrane protein composition. It can also interact directly with membrane proteins, causing conformational changes and thereby influencing their function. The cytotoxic action may include an increased level of oxidative stress. Heat shock protein molecular chaperones are ubiquitously expressed evolutionarily conserved proteins which serve as critical regulators of cellular homeostasis. Heat shock proteins can be induced by various forms of stresses such as elevated temperature, alcohol treatment, or ischemia, and they are also upregulated in certain pathological conditions. As heat shock and ethanol stress provoke similar responses, it is likely that heat shock protein activation also has a role in the protection of membranes and other cellular components during alcohol stress.

In vitro characterization of a chitosan skin regenerating template as a scaffold for cells cultivation

Chitosan is a marine-derived product that has been widely used in clinical applications, especially in skin reconstruction. The mammalian scaffolds derived from bovine and porcine material have many limitations, for example, prion transmission and religious concerns. Therefore, we created a chitosan skin regenerating template (SRT) and investigated the behavior of fibroblast cell-scaffold constructs. Primary human dermal fibroblasts (HDF) were isolated and then characterized using vimentin and versican. HDF were seeded into chitosan SRT at a density of 3×10⁶ cells/cm² for fourteen days. Histological analysis and live cells imaging revealed that the cell-chitosan constructs within interconnected porous chitosan showed significant interaction between the cells as well as between the cells and the chitosan. Scanning electron microscopy (SEM) analysis revealed cells spreading and covering the pores. As the pore sizes of the chitosan SRT range between 40–140 μm, an average porosity is about 93 ± 12.57% and water uptake ratio of chitosan SRT is 536.02 ± 14.29%, it is a supportive template for fibroblast attachment and has potential in applications as a dermal substitute.

Antiaging effect of dietary chitosan supplementation on glutathione-dependent antioxidant system in young and aged rats

Aging has been defined as the changes that occur in living organisms with the passage of time that lead to functional impairment and ultimately to death. Free radical-induced oxidative damage has long been thought to be the most important consequence of the aging process. In the present study, an attempt has been made to study the salubrious effects of dietary supplementation of chitosan on glutathione-dependent antioxidant defense system in young and aged rats. The dietary supplementation of chitosan significantly reduced the age-associated dyslipidemic abnormalities noted in the levels of total cholesterol, HDL-cholesterol, and LDL-cholesterol in plasma and heart tissue. Its administration significantly (P < 0.05) attenuated the oxidative stress in the heart tissue of aged rats through the counteraction of free radical formation by maintaining the enzymatic [glutathione peroxidase (GPx) and glutathione reductase (GR)] and non-enzymatic [reduced glutathione (GSH)] status at levels comparable to that of normal young rats. Our results conclude that dietary intake of chitosan restores the depleted myocardial antioxidant status and suggest that it could be an effective therapeutic agent in treatment of age-associated disorders where hypercholesterolemia and oxidative stress are the major causative factors.

Gastroprotective activity of atractylenolide III from Atractylodes ovata on ethanol-induced gastric ulcer in vitro and in vivo

Objectives

The rhizome of Atractylodes ovata De Candolle is popularly used in traditional Chinese medicine to treat gastrointestinal diseases. However, the major gastroprotective compounds of A. ovata have not been identified. This study reports on the principal gastro- protective component of A. ovata.

Methods

Five sesquiterpenoids (atractylon, atractylenolides I, II, III and biatractylolide) were isolated from the extracts of A. ovata rhizome via silica gel column chromatography. The gastroprotective effects of these five sesquiterpenoids were measured in in-vitro ethanol-induced primary culture rat gastric mucosal (PRGM) cell damage and in-vivo ethanol-induced acute rat gastric ulcer models.

Key findings

Atractylon, atractylenolide I and biatractylolide were strongly toxic in PRGM cells, whilst atractylenolides II and III were not. Atractylenolide II did not show cytoprotective effects, but oral administration of atractylenolide III dose-dependently prevented ethanol-induced PRGM cell death and cell membrane damage. The EC50 values were 0.27 and 0.34 mm, respectively. In the in-vivo assay, atractylenolide III 10 mg/kg significantly reduced 70% ethanol-induced Wistar rat gastric ulcer. Atractylenolide III could inhibit matrix metalloproteinase (MMP)-2 and MMP-9 expression through upregulation of tissue inhibitors of metalloproteinase from the gastric ulcerated tissues.

Conclusions

Atractylenolide III was the major gastroprotective component of A. ovata in ethanol-induced acute gastric ulcer. It is suggested that the gastroprotective mechanism of atractylenolide III was via inhibition of the MMP-2 and MMP-9 pathway.

Modified chitosans for oral drug delivery

The cationic polysaccharide chitosan has been extensively studied for oral drug delivery. In recent years, chemically modified chitosans developed in order to improve the properties of chitosan for oral drug delivery have gained increasing attention. Representatives of these novel polymers are trimethyl-chitosans, thiolated chitosans, carboxymethyl chitosan and derivatives, hydrophobic chitosans, chitosan succinate and phthalate, PEGylated chitosans and chitosan-enzyme inhibitor conjugates. Besides their use for oral delivery of therapeutic peptides and proteins, they have recently been evaluated regarding their potential for the delivery of other substance classes, including genes and efflux pump substrates. Within the current review, various modified chitosan derivatives, their properties and synthesis are discussed.

Beneficial preventive effects of gastric mucosal lesion for soy-skim milk fermented by lactic acid bacteria

In this study, Lactobacillus paracasei subsp. paracasei NTU101 and Lactobacillus plantarum NTU 102 were used as starter to ferment soy-skim milk, and the optimal mixing ratio was evaluated. The influence of lactic acid bacteria (LAB)-fermented soy-skim milk on mucosal integrity in a gastric mucosal lesion rat model was also investigated. After 24 h, cell densities of L. paracasei subsp. paracasei NTU 101 and L. plantarum NTU 102 fermented in 75% soy milk and 25% milk (optimal condition) were 1.2 × 10(9) and 2.5 × 10(9) CFU/mL. After 180 days at 4 °C, the cell densities of the freeze-dried powders of the fermented soy-skim milks were 1 × 10(9) CFU/g; slight variations in pH and acidity were observed. Pylorus ligation with acidified ethanol treatment was used as the gastric lesion animal model. LAB-fermented soy-skim milk reduced the gastric lesion index and the lipid peroxides (LPO) of gastric mucosa and serum. Administration of the fermented soy-skim milk enhanced superoxide dismutase (SOD) activity and prostaglandin E(2) (PGE(2)) synthesis. Therefore, LAB-fermented soy-skim milk at 10(9) CFU/day protects against gastric injury.

Chitosan and its antimicrobial potential--a critical literature survey

Chitosan, an aminopolysaccharide biopolymer, has a unique chemical structure as a linear polycation with a high charge density, reactive hydroxyl and amino groups as well as extensive hydrogen bonding. It displays excellent biocompatibility, physical stability and processability. The term 'chitosan' describes a heterogeneous group of polymers combining a group of physicochemical and biological characteristics, which allow for a wide scope of applications that are both fascinating and as yet uncharted. The increased awareness of the potentials and industrial value of this biopolymer lead to its utilization in many applications of technical interest, and increasingly in the biomedical arena. Although not primarily used as an antimicrobial agent, its utility as an ingredient in both food and pharmaceutical formulations lately gained more interest, when a scientific understanding of at least some of the pharmacological activities of this versatile carbohydrate began to evolve. However, understanding the various factors that affect its antimicrobial activity has become a key issue for a better usage and a more efficient optimization of chitosan formulations. Moreover, the use of chitosan in antimicrobial systems should be based on sufficient knowledge of the complex mechanisms of its antimicrobial mode of action, which in turn would help to arrive at an appreciation of its entire antimicrobial potential.

A ninety-day feeding, subchronic toxicity study of oligo-N-acetylglucosamine in Fischer 344 rats

Oligo-N-acetylglucosamine (OAG) is a hydrolyzed derivative of chitin that has been used as a sweetener in foods. Since, no information has been published about the safety of OAG, a 90-day feeding study was conducted, using F344 Fischer rats of both sexes, to characterize and evaluate the toxicity of OAG, and the results of the study are presented here. Dietary levels of 0% (control), 0.2%, 1%, and 5% OAG did not change any measurements in ophthalmological examinations, clinical signs, body weights, food consumption, hematology, blood biochemistry, urinalysis, necropsies, organ weights or histological examinations. The sole finding, which could not be clarified to be attributed to OAG or not, was a decrease in the relative weight of the submaxillary gland to body weight in the male animals given the 5% OAG diet. Although no lesions were found in either gross or histological examination in the present study, further studies using OAG levels higher than 5% might provide a clue to the mechanisms underlying the decreased organ weight observed here. Taken together, under the conditions in the present study, the No Observed Adverse Effect Level (NOAEL) for males was found to be 1% (0.641 g/kg/day); and that for females, 5% (3.64 /kg/day) or more, based on the lack of toxicological effects.

Hepatoprotective activity of chitosan against isoniazid and rifampicin-induced toxicity in experimental rats

Tuberculosis is a dangerous disease and its death toll is increasing year by year. Intake of isoniazid and rifampicin, the most common antitubercular drugs, lead to fatal hepatotoxic condition. We have studied the protective effect of chitosan supplementation against the hepatotoxicity induced by antitubercular drugs with respect to the changes in the levels of protein, albumin-globulin ratio, urea and bilirubin in the serum and diagnostic marker enzymes (alanine amino transferase, aspartate amino transferase, acid phosphatase and alkaline phosphatase), protein, glycoprotein conjugates (hexose, hexosamine and sialic acid), lipid peroxidation and reduced glutathione in the liver tissue of normal and experimental groups of rats. Co-administration of chitosan was found to significantly prevent the antitubercular drugs-induced alterations in the levels of diagnostic marker enzymes, bilirubin and albumin/globulin ratio in experimental groups of rats. Isoniazid and rifampicin-induced lipid peroxidation was also found to be prevented by the administration of chitosan. Further, chitosan administration increased the levels of urea and protein (in serum and liver) in experimental groups compared to hepatotoxicity-induced group of rats. Levels of glycoconjugates were also maintained to near normal level by chitosan co-administration. From the results obtained, it can be concluded that chitosan is beneficial against antitubercualr drugs-induced hepatoxicity.

Protective effect of glucosamine against ibuprofen-induced peptic ulcer in rats

BACKGROUND

Helicobacter pylori is the major causative factor of ulcer but the use of ibuprofen and other non-steroidal anti-inflammatory drugs have also been implicated in development of ulcer. The purpose of the present study was to determine the anti-ulcer effect of glucosamine.

METHODS

The protective effect of glucosamine on ibuprofen-induced peptic ulcer in male albino rats was studied with respect to changes in the volume of gastric juice, acid output, pepsin activity, activities of membrane bound ATPases, protein content, glycoprotein components and histopathology.

RESULTS

Oral administration of ibuprofen caused significant increase in the number of lesions in the gastric mucosa, increases in the volume of gastric juice and acidity, and decreased activity of pepsin. The levels of protein content and glycoprotein components (hexose, hexosamine and sialic acid) and ATPase activities were also observed. Oral pretreatment with glucosamine resulted in significant reduction in the number of lesions in the gastric mucosa and decreases in the volume of gastric juice and acidity. The pepsin activity was also maintained at near normalcy. Prior oral administration of glucosamine significantly prevented the ibuprofen-induced depletion of protein and glycoprotein components and maintained the activities of membrane bound ATPases as compared to untreated ulcer induced group of rats.

CONCLUSION

The anti-ulcerogenic activity of glucosamine might be ascribable to its ability to neutralize the hydrochloric acid secreted into the stomach and to its capability to strengthen the mucosal barrier by increasing mucosal glycoprotein synthesis and to its free radical scavenging property. Histopathological investigations of the mucosal tissue also support the anti-ulcerogenic effect of glucosamine.

Preparation, Characterization and in Vitro Dissolution Studies of Solid Systems of Valdecoxib with Chitosan

In the present study, the solubilizing and amorphizing properties of Valdecoxib (a poorly water soluble anti inflammatory drug) with low molecular weight chitosan (a polymer), have been investigated. Binary systems of varying drug/polymer ratios were prepared using different techniques (physical mixing, co-grinding, kneading) and were tested for dissolution. Drug carrier interactions were investigated in both the liquid and solid state, by phase solubility analysis, differential scanning calorimetry, powder X-ray diffractrometry, FT-IR spectroscopy and scanning electron microscopy. The solubility of the drug increased with increasing polymer concentration showing A(N) type phase solubility diagram. Differential scanning calorimetry, powder X-ray diffractrometry and scanning electron microscopic studies of binary systems suggested generation of amorphous form of drug (in kneading and co ground mixtures). IR spectroscopy revealed the presence of hydrogen bonding in kneading and co ground mixtures. Drug dissolution was improved with increasing the polymer concentration in the mixture (Kneaded>co ground>physical mixture), which was attributed to the amorphonization and/or decreased drug crystallinity, size and polymer wetting effect. Enhanced dissolution combined with its direct compression feasibility and anti ulcerogenic action results in low molecular weight chitosan for developing fast release oral solid dosage forms of valdecoxib.

Effect of chitosan supplementation on antitubercular drugs-induced hepatotoxicity in rats

We have studied the protective effect of chitosan on isoniazid- and rifampicin-induced hepatotoxicity with respect to the changes in the levels of diagnostic marker enzymes (in serum), lipid components and lipid peroxidation (in serum and liver). The oral administration of antitubercular drugs caused a significant elevation in the levels of diagnostic marker enzymes and cholesterol, triglycerides, free fatty acids and lipid peroxidation in serum and liver of experimental rats. There was a slight decline in the level of phospholipids in liver tissue also observed. Co-administration of chitosan significantly prevented the antitubercular drugs-induced elevation in the levels of serum diagnostic marker enzymes (alanine amino transferase, aspartate amino transferase, lactate dehydrogenase, acid phosphatase and alkaline phosphatase) in experimental groups of rats. It exerted a significant antilipidemic effect against isoniazid- and rifampicin-induced hepatitis by maintaining the levels cholesterol, triglycerides, free fatty acids and phospholipids in serum and liver at near normalcy. A tendency to prevent the isoniazid- and rifampicin-induced lipid peroxidation was also observed. The results of the present study indicated that the hepatoprotective effect of chitosan might be ascribable to its antilipidemic effect and/or antioxidant property.