Redesigning the synthesis of Vidarabine via a multienzymatic reaction catalyzed by immobilized nucleoside phosphorylases

We here report on the enzymatic synthesis of the antiviral drug Vidarabine (arabinosyladenine, araA) starting from arabinosyluracil and adenine. To this aim, uridine phosphorylase from Clostridium perfringens (CpUP) and a purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNP) were used as covalently immobilized biocatalysts. Upon investigation of the optimal conditions for the enzyme activity (phosphate buffer 25 mM, pH 7.5, 25 ° C, DMF 12.5-30%), the synthesis of araA was scaled up (2 L) and the product was isolated in 53% yield (3.5 g/L) and 98.7% purity. A E-factor comparison between the enzymatic synthesis of araA and the classical chemical procedure clearly highlighted the “greenness” of the enzymatic route over the chemical one (E-factor: 423 vs 1356, respectively).