Abstract: The cytotoxicity of total flavonoids from Cichorium endivia L. seeds towards RAW264.7 cells was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and the antioxidant activities were investigated based on total antioxidant activity, 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt cation radical (ABTS+·) scavenging capacity, superoxide anion radical scavenging capacity and inhibition on Fe2+-induced lipid peroxidation in egg yolk. These activities were compared with those of the common antioxidants vitamin C (VC) and tert-butylhydroquinone (TBHQ). Furthermore, the total flavonoids extracted from C. endivia seeds were screened for those scavenging hydroxyl radical by a high-performance liquid chromatography (HPLC) method. MTT assay showed that the total flavonoids were toxic towards RAW264.7 cells at a concentration of 1 mg/mL, but they were hardly toxic at a certain lower temperature. Antioxidant assays revealed that the total antioxidant activity and ABTS+· scavenging activity of these compounds were lower than those of VC and TBHQ. However, at low concentration, the total antioxidant activity was similar to that of TBHQ. The superoxide anion scavenging capacity of these samples was in the decreasing order of VC > total flavonoids from C. endivia seeds > TBHQ. The lipid peroxidation inhibitory activity of the total flavonoids was higher than that of VC, but lower than that of TBHQ. The HPLC analysis indicated that hydroxyl radical scavenging capacity of chlorogenic acid was higher than that of cynarin, which showed a scavenging percentage of 66.42% and 46.00%, respectively.

Key words: total flavonoids from Cichorium endivia L. seeds, MTT assay, hydroxyl radical scavenging capacity, recognition