Biotransformation of Sophorabioside in the Fruits and Small Branches of Sophora japonica into Sophoricoside Using α-L-Rhamnosidase from Chloroflexus aurantiacus

Abstract

Sophora japonica L., a medicinal herb used in East Asia, contains bioactive flavonoids such as sophoricoside and sophorabioside. Sophoricoside, a more bioavailable and therapeutically potent form, is known for its pharmacological properties, including anti-inflammatory, -cancer, and -osteoporotic effects. However, conversion of sophorabioside into sophoricoside has not been extensively studied. In this study, we aimed for the enzymatic conversion of sophorabioside, abundant in the S. japonica fruits and small branches, into sophoricoside using α-L-rhamnosidase from Chloroflexus aurantiacus. Optimal reaction conditions for this biotransformation were established, with maximal enzymatic activity observed at pH 6.0 and 55o C. Substrate specificity analysis revealed high selectivity of the enzyme for neohesperidose-containing flavonoids, including sophorabioside. Sophoricoside was efficiently produced from S. japonica fruit and branch extracts, enhanced by 2.5% methanol. The biotransformed extracts demonstrated significant lipoxygenase inhibitory activity, suggesting enhanced anti-inflammatory potential, highlighting the potential of S. japonica-derived sophoricoside-enriched products as functional food supplements with improved therapeutic properties.