Anticancer and antimicrobial potential of novel xanthan gum derivatives synthesized via quaternary ammonium grafting

Abstract

Two new xanthan gum derivatives were synthesized by a Schiff base reaction with quaternary ammonium salts (PYB: 1-(2-aminoethyl) pyridinium bromide and TAB: 1-(2-aminoethyl) trimethylammonium bromide) to grant biological properties. The quaternary ammonium salts were synthesized through a quaternization reaction between trimethylamine or pyridine, and 2-bromoethylamine hydrobromide, obtaining two quaternary ammonium salts with a NH₂ group, which were chemically grafted onto the aldehyde groups of xanthan gum (XG) previously oxidized with sodium periodate. FTIR-ATR and ¹H NMR confirmed the chemical structures of the XG derivatives (XG-PYB and XG-TAB). Additionally, TGA analyzed thermal stability. Antiproliferative activity in breast cancer cells (MCF-7) through a cell proliferation assay (MTT) was tested, and the antibacterial activity through microbial challenge tests on Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa) were assessed. The minimum inhibitory concentration (MIC) and SYTOX Green assay on E. coli and S. aureus were also conducted, demonstrating that XG-TAB is the most promising molecule, as it showed greater thermal stability, decreased cancer cell viability, and almost completely inhibited bacterial growth of E. coli ATCC 11229 and S. aureus ATCC 6538, respectively by damage in plasmatic membrane. Furthermore, the biocompatibility of both derivatives was evaluated, showing no toxic effect on human-blood erythrocytes.