An efficient approach for the enzyme-enhanced extraction of camptothecin and 10-hydroxycamptothecin from the samara of Camptotheca acuminata using an ionic liquid solution

An efficient approach for enzyme-enhanced extraction using an ionic liquid solution (ILEEE) of the major alkaloidal components camptothecin (CPT) and 10-hydroxycamptothecin (HCPT) from the samara of Camptotheca acuminata is presented. The enzyme pretreatment in an aqueous ionic liquid (IL) media was used for the enhancement of extraction yield. The activity of hemicellulase was investigated in various ILs with imidazolium-based cations ([C2MIM]+, [C4MIM]+, [C6MIM]+, [C8MIM]+, [C10MIM]+) and anions (Br−, Cl−, Ac−, HSO4−, NO3−). The optimal ionic liquid for the hemicellulase extraction process was found to be a 0.75 M [C8MIM]Br aqueous solution. Single factor experiments and Box–Behnken design found the optimal operational parameters for ILEEE to be an incubation temperature of 40 °C, incubation time of 12 h, extraction phase of pH 4, liquid-solid ratio of 30 mL/g, 0.75 M [C8MIM]Br and a hemicellulase concentration of 0.441 mg/mL. Under these optimized extraction conditions, the total yield of CPT and HCPT was 1043 ± 51.2 μg/g. SEM images of the samples revealed that hemicellulases hydrolyze the cell wall, leading to structure breakdown, which enabled [C8MIM]Br to have a high dissolving power for the targeted components. These factors are the main causes for the increasing in the total yield of the CPT and HCPT when using the ILEEE extraction method.