Phthalic anhydride esterified chicha gum: characterization and antibacterial activity

• The chemical characterization confirmed the chicha gum esterification. • Chicha gum becomes more hydrophobic after being treated with phtalic anhydride. • The derivatives showed inhibitory effect against Gram-negative bacteria. • The derivatives were promising in infection treatment. The objective of this research was to modify chicha gum with phthalic anhydride to obtain a new biologically active material. The chemical modification of the gum structure was proven through FTIR, elemental analysis, XRD, TG, and DSC. The derived materials demonstrated excellent inhibitory effect against P. aeruginosa and K. pneumoniae species (rating 100% inhibition) and could also inhibit Escherichia coli growth. The best antimicrobial activity observed for the derivatives suggests that chicha gum hydrophobization due to the addition of phthalic groups improved the interaction of these derivatives with bacterial cell wall components. On the other hand, the derivatives increased CC 50 in macrophages but did not present acute toxicity or hemolytic activity, indicating that they are promising for use in prophylaxis or treatment of infections caused by Gram-negative bacteria.