Schiff's base transformation: Enhancing biological activity of xanthan gum by grafting with acrylonitrile

The graft copolymerization of acrylonitrile (ACN) onto xanthan gum (XG) was performed via free radical polymerization using ammonium persulfate (APS) as the initiator. Key parameters influencing the grafting process were optimized, and Schiff base derivatives were synthesized through reactions with aromatic aldehydes to modify the grafted copolymer further. The modified copolymers were characterized using FT-IR, X-ray diffraction, thermal analysis, and scanning electron microscopy. This study evaluated the antimicrobial and antifungal efficacy of Ethylene diamine-modified XG-g-PAN compounds. EDA XG-g-PAN V exhibited the strongest antibacterial activity against Gram-positive and Gram-negative bacteria, exhibiting the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. For antifungal activity against C. albicans, XG-g-PAN III and EDA XG-g-PAN V were most effective, with MIC values of 62.5 μg/mL and 83 μg/mL, respectively. EDA XG-g-PAN V significantly inhibited S. aureus growth over 24 h and demonstrated dose-dependent bacterial membrane disruption, as evidenced by protein leakage assays. The cytotoxic effects of EDA XG-g-PAN V were tested on HL-7702 liver cells, NIH3T3 fibroblast cells, and HaCaT keratinocytes, showing a concentration-dependent response. At lower doses (<125 μg/mL), cell viability exceeded 80 %, indicating good compatibility for biomedical use, whereas higher doses (>500 μg/mL) significantly reduced viability to around 60 %.