One-pot synthesis of sulfone-based chitosan derivatives from alkene: characterization, antimicrobial, antioxidant and anti-cancer activity

Abstract Chitosan β-ketosulfone derivative was synthesized by chemical modification of chitosan with in situ generated β-ketosulfone using styrene, benzenesulfinic acid sodium salt in the presence of potassium persulphate and air in an aqueous medium. The chemical structure of the derivative was confirmed by various characterization techniques. The IR spectrum of chitosan β-ketosulfone showed new bands at 2366 cm−1 and 1367 cm−1 corresponding to the imine and sulfone functional group respectively. In the 1H NMR spectrum of the derivative, chitosan proton signals and new proton signals between δ 7.3 ppm and 7.7 ppm (aromatic region) were observed. Chitosan β-ketosulfone derivative showed better antimicrobial activity against A. niger fungi, gram-negative (E. coli) and gram-positive (B. subtilis) bacteria than native chitosan. The derivative also exhibited improved antioxidant activity over chitosan. The DPPH and ABTS radical scavenging activity of chitosan β-ketosulfone derivative at 1.6 mg/mL concentration were observed as 68.6 ± 1.5% and 90.2 ± 1.4% respectively at the same concentration. Moreover, the MTT cytotoxicity assay of the synthesized product on PBMCs (peripheral blood mononuclear cells) and HepG2 cells displayed encouraging results, which pave the pathway for the utilization of the derivative for further biomedical applications. Graphical Abstract Highlights Chitosan β-ketosulfone derivative synthesized via a novel route starting from simple starting materials better antimicrobial activity than native chitosan improved antioxidant activity over chitosan established on the basis of DPPH and ABTS radical scavenging assay potent anti-cancer activity