Antioxidant, antifungal and antiviral activities of chitosan from the larvae of housefly, Musca domestica L

Antimicrobial, Optical and Mechanical Properties of Chitosan-Starch Films with Natural Extracts

Natural extracts possess several kinds of antioxidants (anthocyanins, betalains, thymol, carvacrol, and resveratrol) that have also demonstrated antimicrobial properties. In order to study these properties, extracts from cranberry, blueberry, beetroot, pomegranate, oregano, pitaya, and resveratrol (from grapes) were obtained. Growth inhibition tests of mesophilic aerobes, coliforms, and fungi were conducted in films prepared from the extracts in accordance with Mexican Official Norms (NOM). Optical properties such as transparency and opacity, mechanical properties, and pH were also analyzed in these materials. The films with beetroot, cranberry, and blueberry extracts demonstrated the best antimicrobial activity against various bacteria and fungi in comparison with unmodified chitosan–starch film. This study shows that the addition of antioxidants improved the antimicrobial performance of these films. It was also found that antimicrobial properties are inherent to the films. These polymers combined with the extracts effectively inhibit or reduce microorganism growth from human and environmental contact; therefore, previous sterilization could be unnecessary in comparison with traditional plastics. The presence of extracts decreased transmittance percentages at 280 and 400 nm, as well as the transparency values, while increasing their opacity values, providing better UV–VIS light barrier properties. Despite diminished glass transition temperatures (Tg), the values obtained are still adequate for food packaging applications.

Novel Amino-Pyridine Functionalized Chitosan Quaternary Ammonium Derivatives: Design, Synthesis, and Antioxidant Activity

Chemical modification of chitosan is increasingly studied for its potential of providing new applications of chitosan. Here, a group of novel chitosan quaternary ammonium derivatives containing pyridine or amino-pyridine were designed and successfully synthesized through chemical modification of chitosan. Pyridine and amino-pyridine were used as functional groups to improve the antifungal activity of chitosan derivatives. The chitosan derivatives' antioxidant activity against hydroxyl-radical and 1,1-Diphenyl-2-picrylhydrazyl (DPPH)-radical was tested in vitro. The results showed that chitosan derivatives had better water solubility and stronger antioxidant activity compared with chitosan in all assays. Especially, compounds 3C and 3E (with 3-amino pyridine and 2,3-diamino pyridine as substitute respectively) exhibited stronger hydroxyl-radical and DPPH-radical scavenging ability than other synthesized compounds. These data demonstrated that the synergistic effect of the amino group and pyridine would improve the antioxidant activity of chitosan derivatives, and the position of the amino group on pyridine could influence the antioxidant property of chitosan derivatives.

Chitosan nanoparticles plus quercetin suppress the oxidative stress, modulate DNA fragmentation and gene expression in the kidney of rats fed ochratoxin A-contaminated diet

This study aimed to evaluate the protective role of chitosan nanoparticles (COS-NPs) singly or plus quercetin (Q) against OTA-induced oxidative stress and renal genotoxicity. Twelve groups of male Sprague-Dawley rats were treated orally for 3 weeks included the control group, animals fed OTA-contaminated diet (3 mg/kg diet); COS-NPs-treated groups at low (140 mg/kg b.w.) or high (280 mg/kg b.w.) dose, Q-treated group (50 mg/kg b.w.), Q plus low or high dose of COS-NPs-treated groups and OTA plus Q and/or COS-NPs at the two tested doses-treated groups. The results indicated that COS-NPs were roughly rod in shape with average particle size of 200 nm and zeta potential 31.4 ± 2.8 mV. Animals fed OTA-contaminated diet showed significant changes in serum biochemical parameters, increase kidney MDA and DNA fragmentation and decreased GPx and SOD gene expression accompanied with severe histological changes. Q and/or COS-NPs at the two tested doses induced significant improvements in all tested parameters and succeeded to overcome these effects especially in the animals treated with Q plus the high dose of COS-NPs. It could be concluded that COS-NPs are promise candidate to enhance the antioxidant effect of Q and protect against the nephrotoxicity of OTA in high endemic areas.

Preparation and in vitro antioxidant activities of 6-amino-6-deoxychitosan and its sulfonated derivatives

The 6-amino-6-deoxychitosan (NC) and their 2, 6-di-N-sulfonated derivatives were prepared via N-phthaloylation, tosylation, azidation, hydrazinolysis, reduction of azide groups and N-sulfonation, and their structures were systematically characterized by FT-IR, 2D HSQC NMR, XRD, gel permeation chromatography (GPC), and elemental analysis. The 6-amino-6-deoxychitosan showed effect in three selected antioxidant essays, including reducing power, superoxide anion radical scavenging ability, and hydroxyl radical scavenging effect. But the factors affecting each activity were different. The reducing power and the superoxide anion radical scavenging ability of NC were strong and closely related to the amino groups in the molecular chains. Both introducing N-sulfonated groups into NC and the concentration reduction of NC and its sulfonated derivatives decreased these activities. For the superoxide anion radical, the molecular charge property was also a significant influence factor. For the hydroxyl radical, NC only showed weak scavenging activity in a special inverse concentration-dependent manner. However, the incorporation of N-sulfonated groups significantly improved the scavenging activity, and the more N-sulfonated groups, the higher the concentrations, the stronger the activity was. The results could be due to the different conformations of NC and its sulfonated derivatives in aqueous solution.

Phytochemical profiles and antioxidant and antimicrobial activities of the leaves of Zanthoxylum bungeanum

The ethanol crude extracts (ECE) and their subfractions from Zanthoxylum bungeanum leaves were prepared and their phytochemical profiles and antioxidant and antimicrobial activities were investigated. Moreover, the effective HPLC procedure for simultaneous quantification of twelve compounds in Z. bungeanum leaves was established. The correlation between the phytochemicals and antioxidant activity was also discussed. The ethyl acetate fraction (EAF) had the highest total phenolic (97.29 mmol GAE/100 g) and flavonoid content (67.93 mmol QE/100 g), while the greatest total alkaloid content (4.39 mmol GAE/100 g) was observed in the chloroform fraction (CF). Twelve compounds were quantified by RP-HPLC assay. EAF exhibited the highest content of quercitrin, kaempferol-3-rhamnoside, quercetin, sesamin, and nitidine chloride (125.21, 54.95, 24.36, 26.24, and 0.20 mg/g); acetone fraction (AF) contained the highest content of chlorogenic acid, rutin, hyperoside, and trifolin (5.87, 29.94, 98.33, and 31.24 mg/g), while kaempferol-3-rhamnoside, xanthyletin, and sesamin were rich in CF. EAF and AF exhibited significant DPPH, ABTS radical scavenging abilities and reducing power (FRAP), whereas CF exhibited significant antifungal activity. Moreover, EAF also showed stronger antibacterial activity. In conclusion, Z. bungeanum leaves have health benefits when consumed and could be served as an accessible source for production of functional food ingredients and medicinal exploration.

Cloning, expression, and purification of a new antimicrobial peptide gene from Musca domestica larva

Musca domestica (Diptera: Muscidae), the housefly, exhibits unique immune defences and can produce antimicrobial peptides upon stimulation with bacteria. Based on the cDNA library constructed using the suppression subtractive hybridization (SSH) method, a 198-bp antimicrobial peptide gene, which we named MDAP-2, was amplified by rapid amplification of cDNA ends (RACE) from M. domestica larvae stimulated with Salmonella pullorum (Enterobacteriaceae: Salmonella). In the present study, the full-length MDAP-2 gene was cloned and inserted into a His-tagged Escherichia coli prokaryotic expression system to enable production of the recombinant peptide. The recombinant MDAP-2 peptide was purified using Ni-NTA HisTrap FF crude column chromatography. The bacteriostatic activity of the recombinant purified MDAP-2 protein was assessed. The results indicated that MDAP-2 had in vitro antibacterial activity against all of the tested Gram- bacteria from clinical isolates, including E. coli (Enterobacteriaceae: Escherichia), one strain of S. pullorum (Enterobacteriaceae: Salmonella), and one strain of Pasteurella multocida. DNA sequencing and BLAST analysis showed that the MDAP-2 antimicrobial peptide gene was not homologous to any other antimicrobial peptide genes in GenBank. The antibacterial mechanisms of the newly discovered MDAP-2 peptide warrant further study.

Cloning, expression, and purification of a new antibacterial substance gene from larvae of Musca domestica (Diptera: Muscidae)

Musca domestica L. (Diptera: Muscidae), the housefly, exhibits unique immune defenses and can produce antibacterial substances upon stimulation with bacteria. On the basis of the cDNA library constructed using the suppression subtractive hybridization method, a 1188-bp antibacterial substance gene, which we named AS566, was amplified by rapid amplification of cDNA ends from M. domestica larva stimulated with Salmonella pullorum (Enterobacteriaceae: Salmonella). In this study, the full-length AS566 gene was cloned and inserted into a His-tagged Escherichia coli (Enterobacteriaceae: Escherichia) prokaryotic expression system to enable production of the recombinant protein. The recombinant AS566 protein was purified in denatured form from inclusion bodies and renatured to obtain functionally active AS566 protein. The bacteriostatic activity of the recombinant purified AS566 protein was assessed using the Oxford plate assay system and the results indicated that AS566 had antibacterial activity against six bacteria, including an E. coli clinical isolate, S. pullorum, Streptococcus bovis (Streptococcaceae: Streptococcus), Streptococcus suis, and Staphylococcus aureus (Staphylococcaceae: Staphylococcus) in vitro. The antibacterial activity of AS566 toward Gram- bacteria was two times greater than that against Gram+ bacteria. The sequencing results and BLAST analysis showed that the antibacterial substance gene AS566 was not homologous to any other antibacterial substance genes in GenBank. The antibacterial mechanisms of the newly discovered AS566 protein warrant further study.

Overview of bacterial cellulose composites: a multipurpose advanced material

Bacterial cellulose (BC) has received substantial interest owing to its unique structural features and impressive physico-mechanical properties. BC has a variety of applications in biomedical fields, including use as biomaterial for artificial skin, artificial blood vessels, vascular grafts, scaffolds for tissue engineering, and wound dressing. However, pristine BC lacks certain properties, which limits its applications in various fields; therefore, synthesis of BC composites has been conducted to address these limitations. A variety of BC composite synthetic strategies have been developed based on the nature and relevant applications of the combined materials. BC composites are primarily synthesized through in situ addition of reinforcement materials to BC synthetic media or the ex situ penetration of such materials into BC microfibrils. Polymer blending and solution mixing are less frequently used synthetic approaches. BC composites have been synthesized using numerous materials ranging from organic polymers to inorganic nanoparticles. In medical fields, these composites are used for tissue regeneration, healing of deep wounds, enzyme immobilization, and synthesis of medical devices that could replace cardiovascular and other connective tissues. Various electrical products, including biosensors, biocatalysts, E-papers, display devices, electrical instruments, and optoelectronic devices, are prepared from BC composites with conductive materials. In this review, we compiled various synthetic approaches for BC composite synthesis, classes of BC composites, and applications of BC composites. This study will increase interest in BC composites and the development of new ideas in this field.

Influence of the physico-chemical characteristics of chito-oligosaccharides (COS) on antioxidant activity

Chito-oligosaccharides (COS) are being used as important functional materials for many applications due to their bioactivities. The aim of this research has been to assess the relationship between the physico-chemical characteristics, average molecular weight (Mw), acetylation degree (DA), polymerization degree (DP) and specially sequence composition determined by MALDI-TOF MS and the antioxidant properties of COS. These oligosaccharides were obtained by enzymatic depolymerization with chitosanase and lysozyme using a specific chitosan and its reacetylated product. The COS fraction below 5 kDa obtained from chitosanase depolymerization showed the highest capacity to scavenge DPPH radicals and to reduce Fe(3+). A correlation was found between the relative amount of molecules with a given A/D (acetylated vs deacetylated units) ratio within the COS and their antioxidant activity, which could be used to predict the antioxidant behavior of a fraction of chito-oligosaccharides.