A novel α-L-Rhamnosidase renders efficient and clean production of icaritin

Icaritin is a clinically effective and safe drug candidate for treating various cancers; however, the efficient and clean production remains challenging. Herein, a novel α-L-rhamnosidase (Rhase-I) was discovered from Talaromyces stollii CLY-6. Comprehensive studies showed that the Rhase-I can efficiently cleave both the outer and inner rhamnosidic bonds of epimedin C with the highest hydrolytic activity ever reported towards the rhamnosidic linkage between rhamnose and aglycone (13.52 U/mg and 179.67 mM−1 s−1 against icariin). Remarkably, the highest icaritin productivity 93.16 g/L/h/g of Rhase-I was achieved by applying Rhase-I together with a glucosidase (Bglsk) into an optimized two-step catalysis process. This enzymatic technology allows icaritin production to proceed under milder conditions (30–45 °C) with less environmental issues (no acid/base consumption), shorter duration (1 h), and higher production efficiency (93.16 g/L/h/g of Rhase-I), which offers a great opportunity for industrial clean icaritin production.