Acetone:Water fractionation of pyrolytic lignin improves its antioxidant and antibacterial activity

Pyrolytic lignin is the water-insoluble fraction of the bio-oil from rapid pyrolysis. The separation of pyrolytic lignin can improve the extraction of monophenols. Studies reveal the efficacy of phenolic aromatic compounds derived from lignin as antioxidants and as antimicrobials. In this study, we used aqueous acetone solutions to improve the fractionation of eucalypt pyrolytic lignin. Experiments to obtain the pyrolytic lignin were carried out based on a central composite factorial design, and the characterizations were performed by GPC, NMR, FTIR, TGA, GC-MS, antioxidant assays, and antibacterial activity analysis. The most soluble fraction resulted in a more homogeneous fraction, concentrating phenolic, carboxylic, and lower molecular weight compounds. The antioxidant activity was mainly attributed to phenolic compounds with methoxy substituents. Pyrolytic lignin fractions also showed antimicrobial action against Staphylococcus aureus and Escherichia coli.

Automated summary

Pyrolytic lignin, the water-insoluble fraction of bio-oil from rapid pyrolysis, was separated to improve extraction of monophenols. Phenolic compounds derived from lignin were found to be effective antioxidants and antimicrobials. Aqueous acetone solutions were used to fractionate eucalypt pyrolytic lignin, resulting in fractions with higher concentrations of phenolic, carboxylic, and lower molecular weight compounds. The antioxidant and antimicrobial activities were mainly attributed to phenolic compounds with methoxy substituents.