Extraction and identification of an antioxidative component from Jue Ming Zi (Cassia tora L.)

The antioxidant activity of two cultivars of "jue ming zi" (Cassia tora L. and Cassia occidentalis L.) was investigated. The results indicated that methanolic extracts from C. tora L. (MECT) and C. occidentalis L. (MECO) produced stronger antioxidant activity and gave higher yields of extract than other organic solvents, The MECT showed stronger antioxidant activity than did the MECO on peroxidation of linoleic acid. MECT at 200 ppm was stronger than 200 ppm of alpha-tocopherol, but weaker than 200 ppm of butylated hydroxyanisole. Amberlite XAD-2 column chromatography separated MECT into eight fractions. Of the eight fractions, fraction V possessed significant antioxidant activity and showed 85.8% inhibition on peroxidation of linoleic acid. Subsequently, fraction V was separated into two subfractions, Va and Vb, by Toyoperal HW-40 F gel filtration chromatography. The subfraction Vb exhibited stronger antioxidant activity than did subfraction Va and was identified as 1,3,8-trihydroxy-6-methyl-9,10-anthracenedione (emodin) on the basis of W-vis spectral, HPLC, IR, MS, and NMR analysis.