Synthesis and characterization of chitosan Schiff bases conjugated with chalcones for enhanced biological applications

This study synthesized novel chitosan Schiff bases conjugated with chalcones (1 and 2) to improve their biological applications. Chalcones were prepared via sonication by reacting acetyl triazole uracil with indole-3-carboxaldehyde and pyridine-4-carboxaldehyde. The chitosan derivatives (C1 and C2) were characterized using FTIR, ¹H NMR, TGA, DSC, elemental analysis, and XRD, confirming successful modification with altered thermal stability and crystallinity. The degree of substitution (DS) was 63.49 % for C1 and 96.37 % for C2. The compounds were evaluated for antimicrobial, antibiofilm, and cytotoxic activities. Polymer C1 showed broad-spectrum antibacterial activity, particularly against P. aeruginosa (84.56 % inhibition), B. cereus (68.22 %), S. sonnei (45.23 %), and E. coli (44.33 %). Polymer C2 selectively inhibited P. aeruginosa (87.38 %) and reduced its biofilm biomass by 75.30 %. In cytotoxicity tests, chalcone 1 was effective against Caco-2 colorectal cancer cells (IC₅₀ = 53.16 μg/mL), while polymer C1 exhibited moderate activity against MCF7 breast cancer (IC₅₀ = 86.28 μg/mL) and Caco-2 cells (IC₅₀ = 68.98 μg/mL). These findings highlight the potential of these chitosan-chalcone hybrids as antimicrobial and anticancer agents.