Study on the Extraction Process and Antioxidant Activity of Volatile Oil from Tibetan Medicine Artemisia Sphaerocephala Krasch.

OBJECTIVE To optimize the supercritical CO₂ extraction process of volatile oil of Artemisia sphaerocephala Krasch. by Box-Behnken response surface methodology and the antioxidant activity of the extract was investigated. METHODS With the extraction yield of Artemisia sphaerocephala Krasch. volatile oil as the response value, three main factors of extraction time, extraction temperature and extraction pressure were screened out through a single factor experiment. The Box-Behnken central combination test design was conducted to establish a secondary regression of the extraction yield of volatile oil. Optimal combination conditions was obtained. The antioxidant activity was evaluated by measuring the scavenging ability of volatile oil to 1,1-diphenyl-2-picrylhydrazyl(DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) free radicals. RESULTS The best extraction process of Artemisia sphaerocephala Krasch. volatile oil was extraction time 55 min, extraction temperature 59 ℃, extraction pressure 32 MPa. Under this condition, the extraction yield of volatile oil was(1.99±0.087)%, which was about 1.9 times that of the traditional steam distillation method(extraction yield rate was 1.05%) 1.9 times. The IC₅₀ values of DPPH and ABTS radicals of Artemisia sphaerocephala Krasch. volatile oil extracted by supercritical CO₂ were 0.264 and 0.045 mg·mL^-1, respectively. CONCLUSION The optimized extraction process of Artemisia sphaerocephala Krasch. volatile oil is stable and reliable, and the extracted volatile oil has good free radical scavenging effect, which is expected to be a new kind of natural antioxidant.