Comparison of inhibitory activity of bioactive molecules on the dextransucrase from Streptococcus mutans

Chitosan as a biomaterial for the prevention and treatment of dental caries: antibacterial effect, biomimetic mineralization, and drug delivery

Dental caries is a chronic, progressive disease caused by plaque, influenced by multiple factors and can damage the hard tissues of the teeth. In severe cases, it can also lead to the onset and development of other oral diseases, seriously affecting patients' quality of life. The creation of effective biomaterials for the prevention and treatment of dental caries has become one of the relentless goals of many researchers, with a focus on inhibiting the production of cariogenic plaque and retaining beneficial bacteria, guiding and promoting the reconstruction of dental hard tissues, and delaying the progression of existing caries. Chitosan is a natural cationic polymer extracted from the shells of crustaceans and shellfish. Since its discovery, chitosan has shown to have various biological functions such as antibacterial, biomimetic mineralization, drug delivery, etc., making it one of the most promising biopolymers for new caries prevention and materials of prostheses. Therefore, this article provides an overview of the anti-caries applications of chitosan, which mainly covers the basic research on the application of chitosan in caries prevention and treatment since 2010, with a focus on categorizing and summarizing the following characteristics of chitosan as a caries prevention material, including its antibacterial effect, biomimetic mineralization effect and delivery ability of caries prevention drugs and vaccines. It also explores the limitations of current research on chitosan as a caries prevention biomaterial and the difficulties that need to be focused on and overcome in the future to provide theoretical reference for the clinical implementation of chitosan as a caries prevention biomaterial.

Prioritization and characterization of validated biofilm blockers targeting glucosyltransferase C of Streptococcus mutans

To date, several Glucosyltransferase C (GtfC) inhibitors have been identified and experimentally validated. All these inhibitors have been validated at different experimental conditions like degree of purity, animal models, kinetic conditions, experimental environment etc.; and most of these inhibitors (ligands) proved to be quite effective in their respective validation environment. However, due to varied experimental validation conditions, and absence of molecular interaction data, there is no way to prioritize these validated ligands for their inhibition potential against GtfC. The present study is a novel attempt of comparative evaluation of the interaction of the validated ligands on a single platform and under similar conditions with a dual objective, i.e. ligand prioritization for their respective inhibitory potential and elucidation of the involved unknown molecular interactions. Carbohydrate derivatives (6-Deoxy sucrose and Trichloro-galactosucrose) were identified as the most promising GtfC inhibitors. In addition, Asp588, Trp517, and Asn481 amino acid residues of the domain A1 proved vital for the inhibitory effect. The study highlights the importance of the comparative analysis of the validated ligands in order to identify the most promising leads for drug discovery against dental caries.

Alkalic dextranase produced by marine bacterium Cellulosimicrobium sp. PX02 and its application

The enzyme dextranase is widely used in the sugar and food industries, as well as in the medical field. Most land-derived dextranases are produced by fungi and have the disadvantages of long production cycles, low tolerance to environmental conditions, and low safety. The use of marine bacteria to produce dextranases may overcome these problems. In this study, a dextranase-producing bacterium was isolated from the Rizhao seacoast of Shandong, China. The bacterium, denoted as PX02, was identified as Cellulosimicrobium sp. and its growing conditions and the production and properties of its dextranase were investigated. The dextranase had a molecular weight of approximately 40 kDa, maximum activity at 40°C and pH 7.5, with a stability range of up to 45°C and pH 7.0-9.0. High-performance liquid chromatography showed that the dextranase hydrolyzed dextranT20 to isomaltotriose, maltopentaose, and isomaltooligosaccharides. Hydrolysis by dextranase produced excellent antioxidant effects, suggesting its potential use in the health food industry. Investigation of the action of the dextranase on Streptococcus mutans biofilm and scanning electron microscopy showed that it to be effective both for removing and inhibiting the formation of biofilms, suggesting its potential application in the dental industry.

Oral Administration of Chitosan Attenuates Bleomycin-induced Pulmonary Fibrosis in Rats

BACKGROUND/AIM

Idiopathic pulmonary fibrosis (PF) is a fatal disorder of unknown aetiology with limited treatment options. Chitosan has antibacterial, antifungal, antioxidant, antitumour, and anti-inflammatory effects. This study aimed to investigate the effects of chitosan administration on bleomycin (BLM)-induced PF in rats.

MATERIALS AND METHODS

A PF rat model was established by endotracheal instillation of 5 mg/kg BLM; then, chitosan was administered in drinking water for 3 weeks. Histology, cell counts, and cytokine responses in the bronchoalveolar lavage fluid (BALF) and weight measurements (body and lung) were analyzed to assess its therapeutic effects.

RESULTS

Chitosan administration tended to reduce transforming growth factor (TGF)-β1 and interferon (IFN)-γ levels in BALF, and histopathological examination confirmed that chitosan attenuated the degree of inflammation and fibrosis in the lung.

CONCLUSION

This study revealed that oral chitosan exhibits potential antifibrotic effects, as measured by decreased proinflammatory cytokine levels and histological evaluation, in a BLM-induced PF rat model.

Anti-Oxidant Activity and Dust-Proof Effect of Chitosan with Different Molecular Weights

High molecular weight chitosan (HMWC) was degraded to prepare chitosan with different molecular weight based on the fenton reaction, which can produce aggressive OH-radicals produced from hydrogen peroxide in the presence of catalytic metal ions. The relative molecular weight, anti-oxidant activity, and fine dust removal effect of chitosan hydrolysates were elucidated to define their molecular weight and their potent biological activity. Our results demonstrate that chitosan hydrolysates derived from the hydrolysis of HMWC may possess significant free-radical scavenging activity as good anti-oxidants against the radical scavenging activity of DPPH and ABTS, respectively. Furthermore, chitosan hydrolysates can effectively eliminate fine dust, which may contain some particulate matter (PM) and unknown species of microorganisms from the air, suggesting that our data provide important information for producing air filters, dust-proof masks and skin cleaner for the purpose of human healthcare and well-being.

Aqueous Glycosylation of Unprotected Sucrose Employing Glycosyl Fluorides in the Presence of Calcium Ion and Trimethylamine

We report a synthetic glycosylation reaction between sucrosyl acceptors and glycosyl fluoride donors to yield the derived trisaccharides. This reaction proceeds at room temperature in an aqueous solvent mixture. Calcium salts and a tertiary amine base promote the reaction with high site-selectivity for either the 3'-position or 1'-position of the fructofuranoside unit. Because nonenzymatic aqueous oligosaccharide syntheses are underdeveloped, mechanistic studies were carried out in order to identify the origin of the selectivity, which we hypothesized was related to the structure of the hydroxyl group array in sucrose. The solution conformation of various monodeoxysucrose analogs revealed the co-operative nature of the hydroxyl groups in mediating both this aqueous glycosyl bond-forming reaction and the site-selectivity at the same time.