Abstract: The total flavonoids from Elsholtzia densa Benth.were extracted by ultrasonic extraction method and purified with D101 macroporous adsorption resin. In vitro antioxidant test and MTT assay were used to evaluate its antioxidant and anti-tumor activity.The results showed the total flavonoids had good scavenging ability on hydroxyl radical (·OH),DPPH free radical (DPPH·) and super oxide anion radical (O·2).Its scavenging capacity for O·2 was better than that of VC.MTT assay results showed that the total flavonoids from E.densa significantly inhibited the growth of four cell lines in a dose and time-dependent manner (P<0.05).At 48 h treatment,the inhibitory effect of flavonoid was better on human cervical carcinoma Hela cells (IC₅₀ 0.5 mg/mL) than other cells.Morphological observation revealed that SMMC-7721 and Hela cell lines showed cytotoxicity including cell wrinkle,reduction of cellular cohesiveness and breakage of cell membranes after treatment with the E.densa total flavonoids.AO/EB staining showed that the number of apoptotic cells was gradually increased with the increasing of the concentration of total flavonoids.The results suggested that E.densa total flavonoids had excellent antioxidant activity and can be used as a natural antioxidant.It also had inhibitory effect on growth of tumor cells,and can be used as a potential anticancer drug for further study.

Key words: Elsholtzia densa Benth., total flavonoids, antioxidant activity, anti-tumor activity