Novel sulfoxide chitosan derivative: synthesis, characterization, antimicrobial, antioxidant and anti-cancer study and comparison with sulfone counterpart

Novel sulfoxide based chitosan conjugate with potential applications has been synthesized and characterized by FT-IR and ¹H NMR spectroscopy and X-ray diffraction (XRD) analyses. Surface morphology and elements present in the derivative were determined by FE-SEM and EDX analyses respectively. Agar well diffusion method was employed to study the antimicrobial property of the synthesized conjugate which exhibited enhanced antimicrobial activity against gram-negative bacteria <i>Escherichia coli</i> (<i>E. coli</i>), gram positive bacteria <i>Bacillus subtilis</i> (<i>B. subtilis</i>) and fungi <i>Aspergillus niger</i> (<i>A. niger</i>) in comparison to chitosan. The synthesized derivative was also tested for the antioxidant property using DPPH radical scavenging method and was found to possess better antioxidant activity (37.0 ± 1.2%) as compared to that of native chitosan (9.5 ± 0.9%). It also showed anticancer property (tested for HepG2 cells) with 53.6 ± 1.3% cell viability. Moreover, it also showed low cytotoxicity when tested against PBMCs (peripheral blood mononuclear cells) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Further, synthesis of a sulfone based chitosan derivative was also carried out via a novel route. This derivative was also studied for the aforementioned properties and applications and a comparative study of the results obtained is reported herein.