Synergistic effects of binary ionic liquid-solvent systems on enzymatic esterification of esculin

Area of Science:

• Biocatalysis
• Green Chemistry
• Enzyme Engineering

Background:

• Enzymatic esterification of phenolic glycosides is crucial for producing valuable compounds.
• Optimizing solvent systems is key to enhancing enzyme activity and conversion rates.
• Naturally occurring flavonoids, like esculin, are important targets for derivatization.

Purpose of the Study:

• To develop an effective binary ionic liquid-solvent system for enzymatic esterification of flavonoids.
• To investigate the synergistic effects of ionic liquids and solvents on enzyme catalysis.
• To improve the catalytic efficiency and stability of Novozym 435 in esterification reactions.

Main Methods:

• Utilized binary systems of ionic liquids ([OMIM][BF4], [TOMA][Tf2N]) with organic solvents (toluene, hexane).
• Employed Novozym 435 as the catalyst for the esterification of esculin.
• Analyzed reaction kinetics and enzyme efficiency (kcat/Km) under various conditions.

Main Results:

• Achieved >90 mol% conversion of esculin in [OMIM][BF4]-toluene and [TOMA][Tf2N]-hexane systems within 96 hours at 60°C.
• The [TOMA][Tf2N]-hexane system demonstrated a 55-fold increase in Novozym 435's catalytic efficiency compared to t-butanol.
• Identified superior matching of properties and structures between IL and solvent as critical for enhanced performance.

Conclusions:

• Binary ionic liquid-solvent systems offer a powerful approach for efficient enzymatic esterification of flavonoids.
• The [TOMA][Tf2N]-hexane system provides a highly effective and protective environment for Novozym 435.
• Optimized solvent-enzyme interactions are crucial for maximizing catalytic performance and stability.