Antioxidant functionalization of pullulan with ferulic acid using enzymatic catalysis

Area of Science:

• Biochemistry and Polymer Science
• Green Chemistry and Enzymatic Synthesis
• Food Science and Nutraceuticals

Background:

• Ferulic acid (FA) is a potent antioxidant with limited bioavailability.
• Pullulan (Pull) is a biocompatible polysaccharide with potential for functionalization.
• Developing novel antioxidant compounds with improved properties is of significant interest.

Purpose of the Study:

• To synthesize antioxidant pullulan-ferulic acid (Pull-FA) conjugates using a green enzymatic method.
• To characterize the structure, purity, and grafting rate of the synthesized Pull-FA.
• To investigate the self-association behavior and antioxidant activity of Pull-FA.

Main Methods:

• Enzymatic grafting of ferulic acid onto pullulan.
• Characterization using ¹³C NMR, MALDI-TOF MS, SEC/MALS/DRI/UV/visco.
• Evaluation of antioxidant activity via DPPH assay and aggregative behavior using Nile red and light scattering.

Main Results:

• Successful synthesis of high-purity Pull-FA with grafting rates up to 8.8%.
• Proposed chemical structure involving ferulic acid dimer (β-5) grafting.
• Demonstrated pH-dependent intra- and intermolecular self-association, leading to physical gel formation, and enhanced antioxidant activity correlated with grafting rate.

Conclusions:

• Innovative green enzymatic synthesis provides a viable route to antioxidant Pull-FA conjugates.
• Pull-FA exhibits tunable self-assembly properties and potent antioxidant activity.
• These novel conjugates hold promise for applications requiring enhanced antioxidant delivery and functional ingredients.