María Susana Rodríguez

Modified chitosan carrying phosphonic and alkyl groups

Abstract The introduction of an alkyl chain onto a water soluble modified chitosan (N-methylene phosphonic chitosan) offer the presence of hydrophobic and hydrophilic branched for controlling solubility properties. A simple methodology for the preparation of a new chitosan derivative surfactant, N-lauryl-N-methylene phosphonic chitosan, has been developed. Its chemical identity was determined by FTIR and confirmed by 1H and 13C NMR. The degree of lauryl substitution was estimated to be 0.33. As a result of the amphiphilic properties, like surface activity typical for surfactants, this derivative opens new perspectives in pharmaceutical and cosmetic field.

Emulsification capacity of chitosan

Emulsification of sunflower oil by chitosan solutions with deacetylation degrees (DD) between 75 and 95% was studied. Chitosan solutions that allowed a wide range of viscosity were prepared in 0.2, 1.0, 2.0% concentration in 0.1 M HCl. The droplet size distribution, emulsion viscosity, emulsion stability and ageing behavior during 48 h were analyzed as function of the chitosan DD, solution concentration and viscosity. Chitosan produced stable water/oil/water (w/o/w) emulsions. The droplet size distribution was unimodal at low DD and at high DD, for all used concentrations, at intermediate DD, distribution was unimodal only when we used the most concentrated solutions. Meanwhile, droplet size distribution was independent of both chitosan solution viscosity and emulsion viscosity. Emulsion viscosity, emulsion stability and ageing were proportional to chitosan concentration.

N-methylene phosphonic chitosan. Effect of preparation methods on its properties

Abstract N-methylene phosphonic chitosan is prepared from chitosan with different acetylation degrees and sources using three reaction times. The degree of substitution is not dependent on chitosans source and degree of deacetylation but it depends on reaction time. Data are confirmed by 1H NMR and FT-IR. A significant decrease of viscosity and molecular weight is observed due to derivatization. It is demonstrated that N-methylene phosphonate chitosan is a powerful chelating agent of transition metal and calcium ions.

Interaction between chitosan and oil under stomach and duodenal digestive chemical conditions.

Chitosan, the N acetylated derivative of chitin, has an effect on the absorption of dietary lipids, but there is not enough scientific knowledge about the mechanism. To study the interaction between chitosan and oil, the action of this biopolymer has been evaluated through an experimental model of the stomach and duodenum tract, although the enzimatic activity had not been evaluated. We microscopically confirmed that chitosan in a hychloridic acid medium (pH 1.0–2.0) emulsified lipids and the emulsion was a water in oil in water type (w/o/w). When the pH value and speed of agitation were increased to mirror the duodenum medium conditions under which lipids are absorbed, the emulsion capacity was better with an increased number of droplets and the emulsion continued as the w/o/w type. At pH 6.2, chitosan precipitated and lipids were entrapped in the formed flocculus. The binding oil was quantitatively determined, and we also demonstrate that a larger oil quantity induced less retention, while the chitosan characteristics had no influence. These observations allow us to postulate that the interaction between chitosan and oil inhibited duodenal absorption and enhanced lipid excretion.

Nitric‐oxide‐mediated cell death is triggered by chitosan in Fusarium eumartii spores

BACKGROUND The genus Fusarium comprises a heterogeneous group of fungi important for agriculture. Fusarium solani f. sp. eumartii (F. eumartii), historically considered to be a fungal pathogen of potato, has also been associated with tomato disease. Currently, chitosan and its derivatives have been receiving more attention as environmentally friendly antimicrobial compounds in sustainable practices. The aim of the present work was to characterize downstream events associated with the mode of action of chitosan, including nitrosative reactive species, in order to identify new biomarkers of its cytotoxic action. RESULTS Data indicated that chitosan-mediated nitric oxide (NO) production might lead to conidial death, concomitant with the strong reduction in fungal pathogenicity in tomato plants. Following chitosan applications, a notably dose-dependent reduction in conidial viability was demonstrated in F. eumartii. Thereafter, the infectivity of chitosan-treated spores was tested by a bioassay using tomato seedlings. CONCLUSION All these data highlight NO valuable properties as a quantitative and qualitative biomarker of cytotoxic action of chitosan in conidial cells. In addition, these findings place the chitosan assayed here as a fungicide with a high potential of application in sustainable horticultural practices.

Chitosan with phosphonic and carboxylic group: New multidentate ligands

Chemical modifications of polysaccharides are increasingly studied and they have potential providing new applications. N-methylene phosphonic N-methylene carboxylic chitosan was obtained in water soluble form using N-methylene phosphonic chitosan and glyoxylic acid (via aldimine formation) under reduction conditions with sodium borohydride. The modified chitosan was characterized by 1 H NMR, 13 C NMR and FTIR spectroscopy. A practical simple and safe preparative procedure has been established to obtain this novel water-soluble and filmogenic chitosan. Taking advantage of the introduction of multidentate ligands into chitosan macromolecule this derivative opens interesting perspectives including the posibility to chelate Ca(II) and others bivalent metals with technological and biomedical potential applications.

Dietary Fiber and Availability of Nutrients: A Case Study on Yoghurt as a Food Model

© 2012 Dello Staffolo et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Dietary Fiber and Availability of Nutrients: A Case Study on Yoghurt as a Food Model

Chitosan Interaction with Iron from Yoghurt Using an In Vitro Digestive Model: Comparative Study with Plant Dietary Fibers

The objective of this work was to investigate the interaction of chitosan with iron from yoghurt by an in vitro gastrointestinal tract model. Taking into account that chitosan is a polysaccharide included in fiber definition by Codex Alimentarius; chitosan behavior was studied and compared with different plant fiber (wheat, bamboo, apple, psyllium and inulin) behaviors, in the same in vitro conditions. Ferrous sulfate was added to yoghurts with each type of fiber. The gastric environment was simulated with HCl (pH 1.0–2.0). The duodenal environment was simulated with NaHCO3 (pH 6.8–7.2) and a dialysis tubing cellulose membrane. Results showed that chitosan had the highest iron retention percentages (53.2% at 30 min; 56.8% at 60 min) interacting in a more pronounced manner with iron than the plant fibers used in this work.

Chemical composition and nutritional value of Argentine commercial edible mushrooms

AbstractThe chemical composition and nutritional value of four edible mushroom varieties (Champignons, Portobellos, Girgolas and Shiitakes) commonly cultivated and consumed in Argentina was determined. The analysis of the chemical composition included the analysis of water content, crude protein, lipids, ash, carbohydrates, mineral composition and bioactive components (dietary fiber, chitin content and phenolic compounds). Results show that edible mushrooms are rich sources of water and carbohydrates and have low amounts of lipids. Also, they are rich in potassium and phosphorus whereas they have a low content of sodium. The composition of bioactive components reveals that mushrooms are rich in fiber and have an interesting amount of total phenolic compounds that imply an antioxidant capacity. Chitin content is an important part of total fiber and in this work a new method for chitin isolation is proposed. Multivariate analysis (principal component analysis) was applied to discriminate among the different mushrooms varieties and to establish relationships among samples and nutritional parameters.

Synthesis, characterization and evaluation of reactional parameters on substitution degree of N-hexyl-N-methylene phosphonic chitosan

N-methylene phosphonic chitosan (NMPC) is treated with hexyl aldehyde to give an imine, which is easily converted into N-hexyl-N-methylene phosphonic chitosan (HNMPC) under mild conditions. The structure of this new chitosan derivative is characterized by FT- IR, 1H, 13C, 31P, 1H13C-HSQC NMR, SEM and XRD. The influence of reactional parameters on the substitution degree (DS), evidenced that a mol ratio 1.50:1.00 (hexyl aldehyde: free amino groups); a reaction time of 1 h. and 45 °C of temperature afford the best DS. HNMPC molecular weight is 12,768.62 Da. It shows good emulsifying properties giving o/w emulsions with high stability in time. Microscopic observation as well as particle size distribution show an unimodal droplet size distribution with low droplet diameters. Preliminary tests lead us to believe that this new polymer has good film forming properties.