Novel Chitosan-Based Schiff Base Compounds: Chemical Characterization and Antimicrobial Activity.

Chitosan (CS) and its derivatives are receiving considerable attention for their great biocompatibility and broad-spectrum activities in many fields. In this work, we aimed to characterize the antimicrobial activity of novel chitosan Schiff bases (CSSB). CS was synthesized by double deacetylation of chitin (Cn) after its extraction from the armors of crustaceans Astacus leptodactylus, and CSSB-1 and CSSB-2 were synthesized by interaction of CS with 4-(2-chloroethyl) benzaldehyde (aldehyde-1) and 4-(bromoethyl) benzaldehyde (aldehyde-2), respectively, at room temperature. The synthesized compounds were characterized by elemental analysis, gel permeation chromatography (GPC), infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). The antimicrobial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria and against yeasts (Candida albicans) was significantly increased due to their higher solubility as compared to unmodified CS opening perspectives for the use of these compounds for antimicrobial prevention in different fields as, for example, food industry, cosmetics, or restoration.

Synthesis and characterization of new chitosan-based Schiff base compounds.

Chitin (Cn) was extracted from the armors of crustaceans Astacus leptodactylus (Lake Sevan, Armenia) and then converted to chitosan (Cs), its deacetylated derivative. Novel Schiff bases (CsSB) were synthesized by interaction of Cs with 4-(2-chloroethyl)benzaldehyde (aldehyde-1) and 4-(2-bromoethyl)benzaldehyde (aldehyde-2), and underwent dehydrohalogenation, under basic conditions (10°C), to yield respective vinyl derivatives. All newly synthesized compounds were structurally characterized by solubility tests, elemental analysis, infrared spectroscopy (FTIR), thermogravimetry (TGA), proton nuclear magnetic resonance ((1)H NMR), and X-ray diffraction (XRD).