CHEMICAL COMPONENTS AND ANTIOXIDANT ACTIVITY OF THE VOLATILE OIL FROM CASSIA TORA L. SEED PREPARED BY SUPERCRITICAL FLUID EXTRACTION

摘要

The seed of Cassia tora L. has been used as a traditional Chinese medicine for a long time and it is also an herbal tea in China. In this research, its volatile oil was recovered by employing supercritical fluid extraction using carbon dioxide and analyzed by gas chromatography (GC) and GC-mass spectrometry. The main components of the volatile oil were elucidated as (Z,Z)-9,12-octadecadienoic acid (26.74%), oleic acid (24.15%), n-hexadecanoic acid (13.99%), chrysophanol (7.26%), (E)-9-octadecenoic acid (4.52%) and octadecanoic acid (4.44%). This volatile oil was characterized by a high content of aliphatic acids (75.90%) and anthraquinones (7.26%). In the antioxidant assays, the volatile oil from C. tora L. seed demonstrated 2,2'-diphenyl-1-picryhydrazyl radical-scavenging activity in the concentration range from 20 to 500 og/mL, with the 50% inhibitory concentration (IC) value at 137 og/mL; it also showed a significant inhibitory effect against hydroxyl radicals with an IC value of 67 og/mL, lower than that of quercetin (IC = 8.15 og/mL), but superior to that of 4-terpineol (IC = 87.5 og/mL). The observed antioxidant activity of this volatile oil is probably caused by the presence of high levels of chrysophanol and, possibly, (Z,Z)-9,12-octadecadienoic acid. Juemingzi, the seeds of the legume Cassia tora L., is an important medicinal plant and has been used for over thousands years in China. The water extract from whole plants of C. tora L. shows strong antioxidative activity, but no report was found on the antioxidant activities of the volatile oil from C. tora L. seed. We estimate that some components with strong antioxidant activity are volatile ingredients in the seeds, and they will be valued highly on the treatment of hyperlipidemia, hypertension, oculopathy and inflammatory disease. So the components and antioxidative activities of the volatile oil from C. tora L. seeds were examined, in the hope that the volatile oil could be used as a potential fat-soluble antioxidant in functional foods or medicines.