Abstract:

Extracts of Stellera chamaejasme by supercritical fluid extraction (SFE) were shown to have acaricidal activities against Tetranychus cinnabarinus. In this experiment, the supercritical parameters of CO₂ in SFE were optimized for extracting the components of Stellera chamaejasme by uniform experimental design, and the extracts were further analyzed by GC/MS method. The results showed that the optimal condition of supercritical CO₂ extraction was extracting pressure 49 MPa, extracting temperature 15 ℃, resolution pressure 43 MPa, and resolution temperature 6.25 ℃. Under the optimal condition, the theoretical extract rate was 3.77%, and the measured extract rate was 3.75%. Extracts of Stellera chamaejasme with the optimal SFE condition had higher contact and systemic toxicity against Tetranychus cinnabarinus in comparison with that by cold-soaked extraction method, with LC₅₀ value of 2.407 mg·mL^-1 and 2.990 mg·mL^-1, respectively. There were 13 compounds detected in the extracts, which accounted for 99.99% of all components. The major compounds were squalene, 9,12-octadecadienoic acid (Z,Z)-,n-hexadecanoic acid,quinoline, and campesterol. Squalene was for the first time found from S. chamaejasme. Squalene was found to have contact and systemic toxicity against T. cinnabarinus, with LC₅₀ value of 9.918 mg·mL^-1 and 12.918 mg·mL^-1, respectively.

Key words: Stellera chamaejasme, supercritical fluid extraction (SFE), GC/MS, Tetranychus cinnabarinus, acaricidal activities, squalene