Conversion of steroid saponins into diosgenin by catalytic hydrolysis using acid-functionalized ionic liquid under microwave irradiation

The catalytic hydrolysis with an acid-functionalized ionic liquid under microwave irradiation was successfully developed to convert steroid saponins into diosgenin. The typical acid-functionalized ionic liquid, 1-sulfobutyl-3-methylimidazolium hydrosulfate ([BHSO3MIm]HSO4), was used to evaluate the catalytic efficiency. The results strongly suggested that acid-functionalized ionic liquid under microwave irradiation significantly improved the hydrolysis efficiency of steroid saponins. In addition, we optimized hydrolysis parameters, including the ionic liquid concentration, the ratio of solvent to solid, the reaction temperature, and reaction time. Under the optimal conditions, this approach achieved the highest yield of diosgenin (29.97 ± 0.51 mg) with 0.3 g steroid saponins. Compared with regular hydrochloric acid hydrolysis, the developed approach obtained 96% diosgenin and reduced 93% reaction time, indicating that the catalytic hydrolysis with an acid-functionalized ionic liquid under microwave irradiation had a broad application prospect in diosgenin production.