Production of antimicrobial powders of guaiacol oligomers by a laccase-catalyzed synthesis reaction

Abstract

Guaiacol oligomers were synthesized by enzyme-catalyzed polymerization with laccase as the catalyst. The polymerization procedure in aqueous media was followed by UV-Vis spectra. The oligomers were characterized by NMR and MALDI-TOF spectra. The UV-Vis spectra observation showed a new peak formed in the range of 380-530nm indicating that new substances formed. The NMR results indicated that phenolic hydroxyl participated in the polymerization. The MALDI-TOF spectra revealed the weight average polymerization degree of guaiacol oligomers is 10 and the mass of the repeating unit is 122. The thermal stability was studied by TGA/DSC analysis. Guaiacol oligomers were more thermally stable than guaiacol, which can be ascribed to the long -conjugated chains. Antioxidant behavior based on ABTS.+ radical showed a concentration-dependent activity and reached a plateau at 800g/mL. The prepared guaiacol oligomers displayed antimicrobial activity against Staphylococcus aureus and Escherichia coli, in which the inhibition percentage is up to 99%.