The use of chitosan, a natural polymer, has recently increased due to its antimicrobial and antifungal character, null toxicity, biocompatibility and ability to form biofilms and hydrogels. The areas of application and research include biomedical, pharmaceutical, biomaterials, water treatment and haircare and skincare products. However, the applications of chitosan are limited due to the difficulty associated with modification of its structure and its poor solubility in water. Among the main chemical modifications for functionalising the chitosan structure are the N-substitution, O-substitution (with or without protecting the reactive sites of the chitosan) and cross-linking with other compounds; these chemical modifications allow improvement of its chemical and physical properties. In relation to the current importance of the use of chitosan with chemical modification, the present review attempts to explain in a simple way the main chemical reactions carried out with chitosan and its wide range of applications, and provides a future perspective.

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Electrospun nanofibers from gelatin (G), chitosan (CS), and chitosan-polyvinyl alcohol (CS-PVA) were developed by electrospinning process. Mechanical properties were determined by the tensile test, the elastic modulus values of the nanofibers were G (15.418-34.34 MPa) and . The morphological characterization by SEM revealed that the systems with 15% G and 6% CS-PVA showed morphological homogeneity. Structural characterization by FTIR indicated an interaction among some functional groups of the component. Thermal analysis by DSC and TGA showed degradation temperatures for G (330 °C), CS (210 °C to 370 °C), and PVA (310 °C to 420 °C). The contact angles values denoted the hydrophilic nature of the material. Finally, the antimicrobial assay proved that both 15% G and 7% PVA on the CS-PVA system presented the best antimicrobial effect. The results indicate that the electrospun nanofibers fabricated with G or CS-PVA can be used as wound healing dressings.

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Moringa oleifera (MO) is a native tree species found in the south of the Himalayas, India, Bangladesh, Afghanistan and Pakistan that is used commercially to produce tea, animal fodder and herbal medicines. The aim of the present study was to determine the nutritional characteristics of different parts of the MO plant from two regions of Mexico (States of Guerrero and Sonora). The proximal composition analyses (protein, lipids, ashes and fiber) were carried out according to the methods of the Association of Official Analytical Chemists (AOAC), and the antioxidant capacity and phenolic compounds were determined by spectrophotometric methods. Protein (38.5%) and lipid contents (42.2%) were higher in MO seeds compared to other plant parts. These results were similar between the two regions of Mexico that were evaluated. MO flowers from Guerrero showed the highest content of phenols and tannins (1908.71 mg Gallic Acid Equivalents (GAE) 100 g-1, 220.27 mg Catechin Equivalents (CE) 100 g-1, respectively) while MO leaves from Sonora showed the highest flavonoid content (2859 mg GAE 100 g-1). The Trolox Equivalent Antioxidant Capacity (TEAC) analysis showed that MO husks obtained from Guerrero had the highest antioxidant capacity (224.45 μmol Trolox Equivalents (TE) g-1). The Oxygen Radical Absorbance Capacity (ORAC) test showed that MO flowers from Guerrero had the high- est antioxidant capacity (382 μmol (TE) g-1). The differences between MO from the two different regions reported in this attributed to factors such as soil type, climatic conditions and the growing region.

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