An Enzymatic Flow-Based Preparative Route to Vidarabine.

Area of Science:

• Biocatalysis and Enzyme Engineering
• Flow Chemistry
• Antiviral Drug Synthesis

Background:

• Vidarabine (ara-A) is an important antiviral nucleoside analog.
• Enzymatic synthesis offers a greener alternative to traditional chemical methods.
• Continuous-flow processes can enhance reaction efficiency and scalability.

Purpose of the Study:

• To redesign the bi-enzymatic synthesis of vidarabine (ara-A) under continuous-flow conditions.
• To optimize immobilization carriers and reaction parameters for preparative biotransformation.
• To explore the potential of the developed bioreactor for synthesizing other purine nucleosides.

Main Methods:

• Immobilization of uridine phosphorylase (CpUP) and purine nucleoside phosphorylase (AhPNP) on glyoxyl-agarose and EziG™1 carriers.
• Development of a continuous-flow reactor system.
• Optimization of substrate concentration, molar ratio, temperature, pressure, and residence time.

Main Results:

• Achieved 1 g of vidarabine with 55% isolated yield and >99% purity.
• Demonstrated successful preparative biotransformation over a 1-week continuous run.
• Nucleoside product was easily collected by filtration after precipitation.

Conclusions:

• The continuous-flow biotransformation using immobilized CpUP and AhPNP is an efficient method for vidarabine synthesis.
• The optimized process yields high-purity antiviral drug.
• The developed bioreactor system holds promise for the preparation of diverse purine nucleosides based on enzyme substrate specificity.