Antioxidant activity of each polar composition from methanol extracts of Sonchus brachyotus DC.

Objective: In order to research the active components and antioxidant activities of different solvent extracts of Sonchus brachyotus. Result: different solvents such as petroleum ethyl,ethyl acetate,n- butanol and distilled water were used to extract S.brachyotus extracts obtained by methanol.The contents of total phenolics and flavonoids in different solvent extracts were analyzed and nine kinds of phenolics were detected by HPLC.Meanwhile,DPPH·,ABTS+· scavenging capacity and total reducing power were determined to compare antioxidant activity of different solvent extracts. The correlation between phenolics content of different solvent extracts and its antioxidant activities was analyzed.Result: There were nine kinds of phenolic components at least in Sonchus brachyotus detected by HPLC and the contents of them were different in different solvent extracts. Ethyl acetate extracts had the highest content of total phenolics( 170.74 mg GA Eq. / g) and flavonoids( 6.01 mg RU Eq. / g) and the strongest antioxidant activity. There was significant correlation between antioxidant activities of different solvent extracts and flavonoids content. Conculsion: The datum suggested that Sonchus brachyotus was rich in phenolics and flavonoids which had potent antioxidant activity. Ethyl acetate could be used as solvent-extraction to obtain the antioxidant in Sonchus brachyotus such as caffeic acid,rutin,orientin,luteolin et al.